Luna X2 Impressions (Hydra Comparison)

[kwseattle]

Friend of mine just bought a Luna X2 with the Bafang M600 motor and Rockshox suspension. It was on sale for $4,200, shipped quickly, and arrived within a week.

Same angle direct comparison to my Hydra:

As you can see, the Dengfu E10 frame geometry for the M600 build is slightly different than the M620 geometry. The downtube is at a shallower angle and the shock mounts to the downtube instead of the top tube. It looks like the seatpost position is moved slightly forward with a shorter top tube.

Some thoughts after a few short hours of comparison:

• The Sram SX Eagle 12 speed shifter they fitted to the X2 is really bad. It jammed twice when just trying to test out running through the gears. The upshift lever is also reversed from how Shimano does it which is an ergonomic nightmare... it's really hard to find a position on the handlebars where hitting that thing is easy. The actuation force was too high for shifting down to larger gears, and it just didn't feel very good. It came with a 38T chainring and 11-51T cassette.
• The Rockshox Yari fork and Deluxe Select+ shock seem okay, haven't ridden it on trails to see how they feel. The shock is much shorter on the X2 than on my Hydra.
• The KS branded dropper post isn't great, the lever is a weird shape, requires too much effort, and the travel is like half that of the Crankbrothers one on my Hydra. For some reason when adjusting the fixed position height, it started acting weird and slowly letting the seat down.
• I don't like the Sram hydraulic disc brakes. They don't bite very hard and one of the rotors arrived warped so that'll need to be fixed at a shop. The lever action feels good at least.
• The Bafang M600 is QUIET! Luna fits a custom PEEK gear into the M600 and you can literally barely hear it. Very jealous of that. This motor is the main reason I'd consider a bike like this.
• My friend ordered the stock motor controller instead of Luna's ludicrous controller, but the stock controller is okay. The torque sensor isn't as good/sensitive as the Hydra's and obviously it's not super powerful in comparison to the M620 with Archon X1. In my 500 watt assist level my bike felt faster than in max assist on the X2. I think it's tuned to class 3 from the factory.
• The wiring harness for the M600 has higher quality connectors than the M620 ones, and you can unplug the harness directly from the display. I wish Bafang would update this for the M620. The speed sensor has a connector in-line which makes replacement easy.
• General build quality is pretty good, there could be some cable management improvements up front. Paint quality is pretty good too.
• Luna's custom pedals are not very grippy (dangerously so) and I would immediately replace them if it were my bike.
• It came with a much cheaper WTB saddle than the Fizik one fitted to my Hydra.
• We weighed our bikes without the batteries and the Luna X2 was 6 pounds lighter. (The M620 is HEAVY)
• The battery case is identical, though its a 48V 17.5 AH battery as opposed to the 52V ~14 AH Hydra battery.

In general with a couple of changes (dropper, pedals, brakes, shifter, upgraded controller) I would really like the X2, I think Watt Wagons should definitely put together a Dengfu E10/Bafang M600 package as a cheaper option for people who would like less power, a quieter motor, and better customization options than Luna offers.

 

[TomD]

Nice write up. As far as the SRAM brakes I think it's just a matter of dialing them in. I wasn't impressed with them initially on my Luna X1 and had a slightly warped rotor but over time things worked themselves out I'm quite happy with them. I've actually had more headaches with my Magura brakes with noise / shudder that never resolved even after replacing rotors and pads. Only reason I prefer Magura is they are less headache to bleed due to non-toxic fluid.

 

[Deacon Blues]

I wonder why Luna seems to have an ample supply of frames, while WW doesn't. Don't both frames come from China?

 

[TomD]

My understanding is Luna (and Biktrix) bought out most of the frame capacity last year leaving WW in a pickle (in addition to the alleged IP theft by Dengfu). Last I heard bikes are not selling and Biktix cancelled a large portion of their order. I'd guess Luna's inventory is piling up as well.

 

[loamoaf]

Both 220mm Magura MDR-P rotors I bought for my wheelsets came warped right out of the package. I have spent so much time trying to true them but being just the floating steel ring around the aluminum carrier/spider it just feels like I am moving the bend around the ring instead of straightening it out. I don't even know if a bike shop will try to true one of these 2 piece rotors...

6lbs is a lot of weight on a bike - I clock my spare M620 in at 14.8lbs lol... is your friend's X2 tubeless or does it have Tannus like your Hydra? I know my Tannus inserts are around 300g each, but if both bikes have em that's pretty impressive especially considering the larger battery. I wonder how the X2 would be with the Ludacris controller, in terms of response/power/efficiency compared to the Archon. My 52V18Ah pack is coming in at 10.2lbs without the cover so that's 25lbs electrifying the bike!

Probably be an interesting test to rent a Turbo SL model or something like Orbea Rise after/if I get my Archon to see how a sub-40lb bike rides compared to a ~60lb monster. What's really wild is how many 80lb+ monsters out there - never seen one off pavement!
I'd be wary of claims of alleged IP theft... Dengfu has refused to sell frames where companies own the rights in the past and said as much when I inquired about other frames (E10 in particular) when ordering my E06 - and the Hydra frame is identical to the Black Forest Bikes X3 which was available before the Hydra (and BFB is an Innotrace partner, to boot). I have seen the same mold sold by Tantan. When it comes to WW's situation with the carbon frames I'm wondering if it may just be a case of them waiting for a certain number of orders to place an order for frames and choosing the most ecnomical shipping option and as a result getting their order caught up in the super fun container pile up. I only have my frame of reference but if I had to pass judgment based on my experience I would say it's largely on WW's hands and they are simply deflecting to someone unaware and unable to speak in their own defense. I'm also just pre-salting myself up in anticipation of a response I'm not going to be happy with to this check-in email I'm about to send, so consider that when reading this opinion...

Great write up though! The longer travel rear on the Hydra is the one thing I wish I got with the E06. With the shock setup I'm using I get about 136mm of travel vs the 120mm it gets with the 44/45mm rear shock the full bike ships with. Honestly though I'm still kind of a weenie so idk if I'm going be riding trails where I need any more than that hehe
Interesting that Biktrix/Luna inventory is piling up - Luna's bikes usually are always luck of the draw whether they're in stock or not.

 

[kwseattle]

Nice write up. As far as the SRAM brakes I think it's just a matter of dialing them in. I wasn't impressed with them initially on my Luna X1 and had a slightly warped rotor but over time things worked themselves out I'm quite happy with them. I've actually had more headaches with my Magura brakes with noise / shudder that never resolved even after replacing rotors and pads. Only reason I prefer Magura is they are less headache to bleed due to non-toxic fluid.

Hopefully I can help him get them sorted. My Magura brakes are a bit noisy too but I don't mind considering how damn well they work, and the mineral oil is a bonus too!

Both 220mm Magura MDR-P rotors I bought for my wheelsets came warped right out of the package. I have spent so much time trying to true them but being just the floating steel ring around the aluminum carrier/spider it just feels like I am moving the bend around the ring instead of straightening it out. I don't even know if a bike shop will try to true one of these 2 piece rotors...

6lbs is a lot of weight on a bike - I clock my spare M620 in at 14.8lbs lol... is your friend's X2 tubeless or does it have Tannus like your Hydra? I know my Tannus inserts are around 300g each, but if both bikes have em that's pretty impressive especially considering the larger battery. I wonder how the X2 would be with the Ludacris controller, in terms of response/power/efficiency compared to the Archon. My 52V18Ah pack is coming in at 10.2lbs without the cover so that's 25lbs electrifying the bike!

Probably be an interesting test to rent a Turbo SL model or something like Orbea Rise after/if I get my Archon to see how a sub-40lb bike rides compared to a ~60lb monster. What's really wild is how many 80lb+ monsters out there - never seen one off pavement!
I'd be wary of claims of alleged IP theft... Dengfu has refused to sell frames where companies own the rights in the past and said as much when I inquired about other frames (E10 in particular) when ordering my E06 - and the Hydra frame is identical to the Black Forest Bikes X3 which was available before the Hydra (and BFB is an Innotrace partner, to boot). I have seen the same mold sold by Tantan. When it comes to WW's situation with the carbon frames I'm wondering if it may just be a case of them waiting for a certain number of orders to place an order for frames and choosing the most ecnomical shipping option and as a result getting their order caught up in the super fun container pile up. I only have my frame of reference but if I had to pass judgment based on my experience I would say it's largely on WW's hands and they are simply deflecting to someone unaware and unable to speak in their own defense. I'm also just pre-salting myself up in anticipation of a response I'm not going to be happy with to this check-in email I'm about to send, so consider that when reading this opinion...

Great write up though! The longer travel rear on the Hydra is the one thing I wish I got with the E06. With the shock setup I'm using I get about 136mm of travel vs the 120mm it gets with the 44/45mm rear shock the full bike ships with. Honestly though I'm still kind of a weenie so idk if I'm going be riding trails where I need any more than that hehe
Interesting that Biktrix/Luna inventory is piling up - Luna's bikes usually are always luck of the draw whether they're in stock or not.

I'm scared about two piece rotors on a bike for this reason lol. His bike came with regular tubes, no Tannus armor (with Schrader valves for some reason). That would certainly explain part of the discrepancy. The M600 is quite a bit smaller though so I'm assuming most of the weight comes from the M620 on the Hydra. I weighed my Hydra battery at about 8 pounds, putting the whole bike right at about 60.

I really would love to try riding even a non-powered mountain bike to see how different it is on trails. I have no experience with regular MTBs but I am loving riding singletrack so much that I'm starting to consider buying a second bike I can actually lift onto the roof of my car and take to bike parks that don't allow ebikes. Trying to cram the Hydra into the trunk of my 3-series is really tricky

I was originally going to buy a Luna Apollo last year, but couldn't get word on availability, so I decided on the Hydra. I do find it interesting they have so much more frame availability than WW seems to have.

 

[kwseattle]

One other thing to note, the battery disconnect button right by the battery lock actually functions on the X2, whereas the button on my Hydra does nothing. I think I asked Pushkar about this a while back, but can't recall the reasoning. I looked inside my frame and the button appears to be wired up, it just doesn't do anything.

When taking out the battery and putting it back in on the X2, there's no spark like there is on the Hydra. I was thinking maybe it has to do with this button being non-functional on the Hydra, but I don't know if that would help.

 

[TDA78]

You can disable the Hydra 52V battery output in the BMS app to avoid the spark.

I've wired up and enabled the switch function in my 52V battery but the spring contacts in the battery cradle are unreliable on rough terrain. I tried to filter the brief disconnections with a capacitor but still need to try a larger value.

I think I've read the switch works with the 48V batteries. Probably a different BMS that can deal with the poor connection to the switch.

 

[bexamous]

Cool writeup, wish he’d had gone for the VESC controller. X2 w/VESC vs Hydra w/Innotrace is IMO the hard to choice. X2 is also good bit cheaper than a Hydra, you could always replace a couple parts you were not happy with and stil come out ahead. I dunno ignoring cost I’d still consider it tossup. I limit my Hydra to 1000watts and its ‘enough’. Not sure how M600 power tranlates but I think I could deal with less power for a lighter bike with quieter motor.

 

[loamoaf]

Interesting about the battery disconnect... If there's no switch on the battery and no anti-spark connector then it's going to spark - reading the meanual on my BMS it says it goes to sleep after a timer that can be set by the user or can be turned off via the app as TDA mentioned so I would think that's the best course of action. I imagine you could put an inline switch on one of the pack leads but I'm unsure what kind of switch can do 50A without getting very hot - on my UPP battery it seems like the switch is to a dedicated input on the BMS and acts like a relay, since it has separate charge & discharge ports and neither function with the switch off. For my packs I erred on the side of caution and got some XT90S connectors.

Here's what my pack looks like before any welding or fish paper/tape/thermofrom cover. If I did it again I'd reprint the holders to shift all the cells away from when the connector about 1cm (max they can go and still give clearance for B- lead) so that I could fix the XT90S connector into the end plate - kind of like how Luna Wolfpacks are. That would make fitting the pack in a little easier as I had to enlarge the pass through on the retainer plate that bolts into the frame to make it easier to get the connector through. I had to print the cell holders because the cells are a fraction of a mm too girthy to squeeze into regular honeycomb holders, so after these two packs I need to order some P42A's to use the honeycomb holders I got - maybe not a bad idea for a 13Ah lighter weight pack either. Benefit of printing them though is much stronger materials and having interlocking end plates so the pack is safe and sturdy, probably went thicker than I needed with the cell holder pieces... The frame came with some blade connectors that would work very well for ease of insertion/removal but no antispark and I didn't know how well that would play with the BMS's I got - to be honest if the BMS wasn't common port I'd say the blades are the way to go as long as you're mindful about that switch.

I'm super interested in trying to get a Taramps VESC working with an M600 or M620. There's a ton of material out there regarding working with VESC since it's all open source but almost entirely geared toward electric skateboards. I think most of it is fairly straight forward but things get hairy translating torque sensor input/output into a throttle signal that plays nice with the VESC.

@kwseattle definitely look into a hitch rack. I got a 1UP and it's pretty nice, with the fatbike spacers I can squeeze either wheelset on there, just got a single slot one but you can get additional slots to add onto it. I think Quikrstuff is another good one but iirc their lead time is much higher. Only caveat is the hitch receiver I put on my car to use the rack is the new lowest point on my car, way behind the rear axle, and I have to be careful on some dips and hills on account of have soft, old people luxury suspension instead of the sports edition... shouldn't be an issue on a 3-series that's for sure. Trying to resist trading in a car I own for something I'm making a parment on, but I also don't want to spend money on firming up the rear before suspension service is due. I look like a fool upgrading half the stuff in my life for a bike I still don't have the [intended] motor for lol.

Think I'll stop dicking around and get the pack welded up this week. Decided to go with copper sheet + nickel tab for lowest resistance, but I need to use a conformal coating I got that's real thin like water to seal up the copper from the humidity & coastal air. I printed the cell holders with isolated pockets with the intention that if I wanted I could just pot the ends, but I don't want to use a material that would block the cell vents on both ends and haven't really looked into alternative potting compounds. WW's delays have kind of enabled my worst habit of procrastinating on projects with this one...

 

[tomjasz]

Think I'll stop dicking around and get the pack welded up this week. Decided to go with copper sheet + nickel tab for lowest resistance

Nice!, your CNC rack?

 

[rtp]

Friend of mine just bought a Luna X2 with the Bafang M600 motor and Rockshox suspension. It was on sale for $4,200, shipped quickly, and arrived within a week.

Very cool you've got both on hand. No major disagreements there honestly. I'm assuming you didn't get the LudiV2 controller, or did you?
A few comments below.

Some thoughts after a few short hours of comparison:

• The Sram GX Eagle 12 speed shifter they fitted to the X2 is really bad. It jammed twice when just trying to test out running through the gears. The upshift lever is also reversed from how Shimano does it which is an ergonomic nightmare... it's really hard to find a position on the handlebars where hitting that thing is easy. The actuation force was too high for shifting down to larger gears, and it just didn't feel very good. It came with a 38T chainring and 11-51T cassette.

Yeah, I think it's actually an NX, but I replaced it with a GX MMX shifter - is ok, $42 or so. Might be whatever you're used to, but I'm pretty ok with the new GX shifter.

• The Rockshox Yari fork and Deluxe Select+ shock seem okay, haven't ridden it on trails to see how they feel. The shock is much shorter on the X2 than on my Hydra.

Yes, E10 (X2) vs E22(23?) use different shocks, 210x55 for E10, and something like 265x<something> for E22/23/Hydra. Similar travel though - I think the X2 has 160mm rear travel.

• The KS branded dropper post isn't great, the lever is a weird shape, requires too much effort, and the travel is like half that of the Crankbrothers one on my Hydra. For some reason when adjusting the fixed position height, it started acting weird and slowly letting the seat down.

Yes, it's annoying. Also too short, and positioned completely weirdly as comes from Luna. Replaced with an SDG Tells 170mm on mine and didn't think about it again. Some of them are 'fidgety' coming from Luna, and may need to loosen the seat post clamp and possibly adjust the cable on receiving, then it's as good as it gets. Might be ok for shorter riders.

• I don't like the Sram hydraulic disc brakes. They don't bite very hard and one of the rotors arrived warped so that'll need to be fixed at a shop. The lever action feels good at least.

Were the brakes bedded in or 'just ride'? Do 15 or so moderate to walking speed hard stops, then let it sit. Or swap pads (and still bed them in).
The G2s are pretty solid on mine, but I've swapped to 200mm F/R, moving to 220mm front, and have changed pads.

• The Bafang M600 is QUIET! Luna fits a custom PEEK gear into the M600 and you can literally barely hear it. Very jealous of that. This motor is the main reason I'd consider a bike like this.
• My friend ordered the stock motor controller instead of Luna's ludicrous controller, but the stock controller is okay. The torque sensor isn't as good/sensitive as the Hydra's and obviously it's not super powerful in comparison to the M620 with Archon X1. In my 500 watt assist level my bike felt faster than in max assist on the X2. I think it's tuned to class 3 from the factory.

No surprise. Looks like Luna is starting to make standalone LudiV2 controllers available, at least for Luna X1/X2 customers. Either of the Innotrace or LudiV2 controllers will have the capability for better/faster responsiveness, as they run at higher sampling rates and overall are just better controllers vs the Bafang OE ones. I suspect 'the torque sensor isn't as good' is really down to the controller, but not 100% there. (They use the same torque sensor on numerous motors, imagine the M620 one is just 'scaled up' but the same general technology etc.).

The M600 being lighter is going to hit thermal cutoff/throttling at some point, well before the M620, when e.g. riding by throttle or under sustained max power. I haven't hit this myself yet, but I nearly never am running in max PAS and never in 'Ludi' max power profile.

• The wiring harness for the M600 has higher quality connectors than the M620 ones, and you can unplug the harness directly from the display. I wish Bafang would update this for the M620. The speed sensor has a connector in-line which makes replacement easy.
• General build quality is pretty good, there could be some cable management improvements up front. Paint quality is pretty good too.
• Luna's custom pedals are not very grippy (dangerously so) and I would immediately replace them if it were my bike.

Yes on the pedals. Guess it's better than no pedals but replaced on day 1.

• It came with a much cheaper WTB saddle than the Fizik one fitted to my Hydra.

It's also 135mm, narrow - at least mine was. Replaced immediately with Ergon SMC-Core. Hard to say if it's literally 'what they can get in quantity' or ?? Would at the least do a wider seat width for a majority of riders.

• We weighed our bikes without the batteries and the Luna X2 was 6 pounds lighter. (The M620 is HEAVY)

Interesting. I still need to weigh my X2 with new wheelset, shock, bigger rotors etc. The Alec MD35 wheelset isn't particularly light on the X2 (or Z1) - the motor should maybe be 2-3# difference, so not sure where the others are although some of it may also be in the frame differences. They also use the same rear triangles and rear shock linkage.

In general with a couple of changes (dropper, pedals, brakes, shifter, upgraded controller) I would really like the X2, I think Watt Wagons should definitely put together a Dengfu E10/Bafang M600 package as a cheaper option for people who would like less power, a quieter motor, and better customization options than Luna offers.

Yeah, the question is at what price?

From convo with a Dengfu rep, it seems like the new Biktrix 'Montes' are really the E10 and E22/23 with the 'diamond' modification for the front shock mount, making it a 'different frame.' Their pricing on at least the Monte Ultra (CANBUS motor even) are quite non-competitive for the parts. I think they came back to reality and dropped the pricing on the Monte Lite (M600/E10+'diamond' shock mount) as being quite non-competitive with the X2 (especially the Rockshox version).

A competitive M600 offering would really need to be in the $4K (no third pty controller) - $5K range on the M600, or most will just buy the X2, which isn't a bad bike (and the controller is pretty nice, has seen numerous updates, and doesn't wait to eventually get a programming cable and account).

I do wish I knew someone locally with a Hydra just for grins and to swap rides for a bit. I suspect most of us don't 'need' the M620 power unless using it on-road (although there it'd be a bunch of fun).
Field weakening was just added as an option in the latest V2 firmware and app, which can gain a few mph at the top end, but generates more heat. Realistically I haven't had the X2 beyond 30MPH and that was only for a quick 'what can it do?' test...normal speeds are more like 25mph and below, versus the BBHSD and Ultras seem to be able to more easily reach and sustain 35MPH-ish+. Will eventually go do another on-road max speed test - just not near the top of my list for my use.

 

[rtp]

Both 220mm Magura MDR-P rotors I bought for my wheelsets came warped right out of the package. I have spent so much time trying to true them but being just the floating steel ring around the aluminum carrier/spider it just feels like I am moving the bend around the ring instead of straightening it out. I don't even know if a bike shop will try to true one of these 2 piece rotors...

6lbs is a lot of weight on a bike - I clock my spare M620 in at 14.8lbs lol... is your friend's X2 tubeless or does it have Tannus like your Hydra? I know my Tannus inserts are around 300g each, but if both bikes have em that's pretty impressive especially considering the larger battery. I wonder how the X2 would be with the Ludacris controller, in terms of response/power/efficiency compared to the Archon. My 52V18Ah pack is coming in at 10.2lbs without the cover so that's 25lbs electrifying the bike!

Probably be an interesting test to rent a Turbo SL model or something like Orbea Rise after/if I get my Archon to see how a sub-40lb bike rides compared to a ~60lb monster. What's really wild is how many 80lb+ monsters out there - never seen one off pavement!
I'd be wary of claims of alleged IP theft... Dengfu has refused to sell frames where companies own the rights in the past and said as much when I inquired about other frames (E10 in particular) when ordering my E06 - and the Hydra frame is identical to the Black Forest Bikes X3 which was available before the Hydra (and BFB is an Innotrace partner, to boot). I have seen the same mold sold by Tantan. When it comes to WW's situation with the carbon frames I'm wondering if it may just be a case of them waiting for a certain number of orders to place an order for frames and choosing the most ecnomical shipping option and as a result getting their order caught up in the super fun container pile up. I only have my frame of reference but if I had to pass judgment based on my experience I would say it's largely on WW's hands and they are simply deflecting to someone unaware and unable to speak in their own defense. I'm also just pre-salting myself up in anticipation of a response I'm not going to be happy with to this check-in email I'm about to send, so consider that when reading this opinion...

Same - I tried unsuccessfully to get an E10 or E22/23 frame. 'Can't sell to US' etc.

I'm also super interested in taking an Orbea Rise for a spin, mainly as most of my riding is in low PAS. My X2 is lighter, but OMG on my prior BBHSD fat bike - I suspect the 70# weight is without battery. I have taken it off-road and even a few *small* jumps, but really nowhere near 'shredding' anything, etc.

Interesting that Biktrix/Luna inventory is piling up - Luna's bikes usually are always luck of the draw whether they're in stock or not.

May well have been over-ordering/over-estimating size of current buyer pool, easy to do after e.g. a loooong time of delays in shipping to 'over-order.' Luna sold out of original X2 batch within hours (medium) to a couple of days. No visibility on Biktrix but was curious to hear on satisfaction of Monte Lite (M600) owners in particular, as the Monte Ultra is CANBUS so basically - zero interest there...Rohsna said they have a FB group, but haven't seen anyone on EBR posting with one, etc. as of yet. Part of it may be the pricing. The Monte line is painted better, but low end components, so X2 Rockshox + V2 is > Monte Lite, while the $6k (or more?) Monte Ultra with CANBUS is in Hydra territory...

 

[rtp]

One other thing to note, the battery disconnect button right by the battery lock actually functions on the X2, whereas the button on my Hydra does nothing. I think I asked Pushkar about this a while back, but can't recall the reasoning. I looked inside my frame and the button appears to be wired up, it just doesn't do anything.

When taking out the battery and putting it back in on the X2, there's no spark like there is on the Hydra. I was thinking maybe it has to do with this button being non-functional on the Hydra, but I don't know if that would help.

Ironically, this is something many E10 DIY builders wind up disabling as it's another 'water sensitive' area - when it becomes wet, it can lead to 'clicking' as the switch and BMS cycle. Not an issue for dry locations or less technical riding, of course.

 

[loamoaf]

@tomjasz not CNC'd but SLA printed - white is Tough Resin & dark is Somos Taurus. the end plate with the plug is actually FDM printed ABS but I don't think I'll ever use FDM printing for anything like this again. I've used MJF in the past but the surface finish & cost on SLA printing as well as available materials to choose from makes it the preferred choice. The Tough Resin is very resilient in that I can bend and twist the cell holder but not a great deal, and it retains its original shape very well. The pieces I had done in Somos Taurus are too short and solid to really get any flexing or anything out of. I'd like to try getting the cell holders printed thinner (these are 1cm) and in a single piece with just little standoff pegs between the two sides I could cut myself, and see how that brings the price per pack down on the two materials. It'd be cool to compare the Somos Taurus vs Tough Resin as well, which means printing some pieces I'm willing to break...

Getting my little hobby station set up to build batteries I wound up with 5x 14s 60A BMS's and enough 21700's to make 2x 14s4p packs. The cells I picked should deliver ~750Wh at 1000W continuous or ~705Wh at 2000W continuous - slightly lower capacity below 1000W than if the pack were made with 50E2's but considerably better above, though above 2500W not quite as good a P42A. the 4p pack sticks out not quite 1cm from the frame, a 3p would fit flush with ample room to spare, but then it becomes a question of whether capacity within desired output range is going to be better doing a 3p with 21700's or a 4p with 18650's. Honestly break-even on pricing won't even happen until I build and use a 3rd battery pack - I may have to get into drones or RC planes as a side hobby to justify it all.

All in all though once the cells are in the holders there is no flexing or wiggling the pieces around. Held together just by friction pretty well but there are holes for little screws to lock everything in, in addition to pegs/dimples in the design of the pieces (looks like you could pull the end plates off but the pegs & dimples prevent that). Big benefit of the SLA printing is I can include tight little channels with relatively sharp bends for small zip ties to secure the BMS to the cell holders that way. You can't see in the pic but there's also about 1.5mm of dishing in the top edges of the cell holders to keep the BMS centered in there as well. Just took a day with a cell, BMS, OEM pack/frame end plates, and the calipers to get something modeled up, but I iterated a few times in the design which ultimately includes a more solid plate that secures to the bike frame up where the lock is. On some Specialized ebikes you see a little bumper on the downtube to prevent the fork from smashing into the frame - I printed a little carrier to fit some rubber bumpers into that bolts into that plate with the battery lock in it to do just this. I also printed a hanger for the speed sensor that replaces a washer/spacer on the rear axle, and a soft silicone plug to fit a magnet into the rear brake rotor so I'm not using spoke magnets. Magura wants $22 for a rotor magnet but I can print a few plugs for $5 and get a few magnets for less than a buck each sooooo... why not?

 

[kwseattle]

You can disable the Hydra 52V battery output in the BMS app to avoid the spark.

I've wired up and enabled the switch function in my 52V battery but the spring contacts in the battery cradle are unreliable on rough terrain. I tried to filter the brief disconnections with a capacitor but still need to try a larger value.

I think I've read the switch works with the 48V batteries. Probably a different BMS that can deal with the poor connection to the switch.

I really don't want to disable the battery in the BMS every time remove/install the battery, I do it almost every time I ride it because it's significantly easier to get the bike into the trunk of my car without the battery installed lol.

How did you wire up the switch? Is that in the battery itself?

Interesting about the battery disconnect... If there's no switch on the battery and no anti-spark connector then it's going to spark - reading the meanual on my BMS it says it goes to sleep after a timer that can be set by the user or can be turned off via the app as TDA mentioned so I would think that's the best course of action. I imagine you could put an inline switch on one of the pack leads but I'm unsure what kind of switch can do 50A without getting very hot - on my UPP battery it seems like the switch is to a dedicated input on the BMS and acts like a relay, since it has separate charge & discharge ports and neither function with the switch off. For my packs I erred on the side of caution and got some XT90S connectors.

Here's what my pack looks like before any welding or fish paper/tape/thermofrom cover. If I did it again I'd reprint the holders to shift all the cells away from when the connector about 1cm (max they can go and still give clearance for B- lead) so that I could fix the XT90S connector into the end plate - kind of like how Luna Wolfpacks are. That would make fitting the pack in a little easier as I had to enlarge the pass through on the retainer plate that bolts into the frame to make it easier to get the connector through. I had to print the cell holders because the cells are a fraction of a mm too girthy to squeeze into regular honeycomb holders, so after these two packs I need to order some P42A's to use the honeycomb holders I got - maybe not a bad idea for a 13Ah lighter weight pack either. Benefit of printing them though is much stronger materials and having interlocking end plates so the pack is safe and sturdy, probably went thicker than I needed with the cell holder pieces... The frame came with some blade connectors that would work very well for ease of insertion/removal but no antispark and I didn't know how well that would play with the BMS's I got - to be honest if the BMS wasn't common port I'd say the blades are the way to go as long as you're mindful about that switch.

I'm super interested in trying to get a Taramps VESC working with an M600 or M620. There's a ton of material out there regarding working with VESC since it's all open source but almost entirely geared toward electric skateboards. I think most of it is fairly straight forward but things get hairy translating torque sensor input/output into a throttle signal that plays nice with the VESC.

@kwseattle definitely look into a hitch rack. I got a 1UP and it's pretty nice, with the fatbike spacers I can squeeze either wheelset on there, just got a single slot one but you can get additional slots to add onto it. I think Quikrstuff is another good one but iirc their lead time is much higher. Only caveat is the hitch receiver I put on my car to use the rack is the new lowest point on my car, way behind the rear axle, and I have to be careful on some dips and hills on account of have soft, old people luxury suspension instead of the sports edition... shouldn't be an issue on a 3-series that's for sure. Trying to resist trading in a car I own for something I'm making a parment on, but I also don't want to spend money on firming up the rear before suspension service is due. I look like a fool upgrading half the stuff in my life for a bike I still don't have the [intended] motor for lol.

Think I'll stop dicking around and get the pack welded up this week. Decided to go with copper sheet + nickel tab for lowest resistance, but I need to use a conformal coating I got that's real thin like water to seal up the copper from the humidity & coastal air. I printed the cell holders with isolated pockets with the intention that if I wanted I could just pot the ends, but I don't want to use a material that would block the cell vents on both ends and haven't really looked into alternative potting compounds. WW's delays have kind of enabled my worst habit of procrastinating on projects with this one...View attachment 123658

That's a pretty serious project there, I have way too many other expensive hobbies to dive into li-ion battery pack construction but I'm waiting for the capital (a new job) and a place to put a new FDM printer or two. I haven't found any use cases that require the precision of SLA printing yet, and SLS is pretty much out of reach for a hobbyist price wise.

I'm looking at the Stealth Hitch for my 335d which would make it invisible when folded up into the bumper, but the hitch itself and a platform rack are going to run ~$1000, then I need to either pull off the rear bumper and crash bar myself and install it, then cut the relief in the bumper for hitch clearance, or pay someone else to install it for me.

Ironically, this is something many E10 DIY builders wind up disabling as it's another 'water sensitive' area - when it becomes wet, it can lead to 'clicking' as the switch and BMS cycle. Not an issue for dry locations or less technical riding, of course.

Definitely interesting hearing your thoughts on the X2 as well, it's a great package for a great deal and with a few small mods it would be even better. The brake pads probably hadn't been properly bedded and I think that's why the brakes didn't feel right to me. I wish I could try out the Ludicrous controller but my friend doesn't want/need the extra power lol. Before I end up with another e-bike I've actually been looking at manual bikes because I'd love to be able to throw one on the roof rack of my car and take it to the local bike parks that don't allow e-bikes.

I guess it's okay that the battery switch doesn't work on my Hydra, just wish I could prevent the battery spark without opening up the mediocre xiaoxiang BMS app on my phone to disable it first. IIRC someone mentioned a while back to power it back on it must be connected to the charger?

 

[TDA78]

How did you wire up the switch? Is that in the battery itself?

It involves soldering wires directly to the BMS circuit board where a connector is missing and also to the gold terminals on the case. I'll post details when I have it working reliably. Currently, assist is lost over every bump.

I guess it's okay that the battery switch doesn't work on my Hydra, just wish I could prevent the battery spark without opening up the mediocre xiaoxiang BMS app on my phone to disable it first. IIRC someone mentioned a while back to power it back on it must be connected to the charger?

If you leave the output disabled for a long time, the Bluetooth stops working and must be woken up with a brief charge. This doesn't happen with the switch function.

 

[kwseattle]

It involves soldering wires directly to the BMS circuit board where a connector is missing and also to the gold terminals on the case. I'll post details when I have it working reliably. Currently, assist is lost over every bump.

If you leave the output disabled for a long time, the Bluetooth stops working and must be woken up with a brief charge. This doesn't happen with the switch function.

Gotcha, I'm not sure I would feel comfortable taking apart my battery but I would be interested in the details.

I'll try toggling it in the app to see how it works!

 

[loamoaf]

IME for mechanical stuff that needs to fit together, aside from available materials, FDM just has too many limitations and deviations. With SLA I know that if what I'm modeling fits together and works, then the SLA print will work - and I don't have to do any extra tom-foolery with the model to make it friendly to the FDM printing process. Round holes are always round, no need for supporting geometry or to orient the model a certain way - for me it's just easier from a design aspect. This is partly because I'm lazy and partly the nature of the things I use printing for - and benefit over MJF is it doesn't really require any surface finishing. MJF seems to be cornered by HP products which would explain their high price:quality ratio. For this though I just used a 3D printing service since the cost of a good SLA printer probably still outweighs my little emtb endeavor even with the welding stuff, second fat wheelset, and backup M620... not a responsible purchase right now ha! The bench supply I got to operate my welding stuff does triple duty as a power source for other equipment and a smart 'universal' charger for anything up to 60V

For getting your hitch installed yourself there's always Stew's Garage in Kirkland. Just rent a lift and all the tools are all right there - I think they recently raised their rate to $46/hr from $40. That place comes in handy when you don't want to pay $120/hr labor and a 30% mark up on parts for some goon to twist all your nuts overspec with the full ugga duggas of the air tools. The only way I justified the pricey hitch rack was that I could take it with me - lucky for me the hitch itself only ran $130 or so and no cutting my bumper. I'm not familiar with them but I think certain generations/models of BMWs have a trim piece on the bottom of the bumper you can swap out instead of cutting a hole or replacing the entire bumper? I may be thinking of the X series

I do agree though, I would prefer a mechanical on/off switch for my pack/BMS. I can have complete confidence in a switch like that being disconnected but a sleep state on any machine is never truly off. One of the downfalls of connected technology - easier to operate something with the push of a finger vs connecting with a phone.

 

[kwseattle]

IME for mechanical stuff that needs to fit together, aside from available materials, FDM just has too many limitations and deviations. With SLA I know that if what I'm modeling fits together and works, then the SLA print will work - and I don't have to do any extra tom-foolery with the model to make it friendly to the FDM printing process. Round holes are always round, no need for supporting geometry or to orient the model a certain way - for me it's just easier from a design aspect. This is partly because I'm lazy and partly the nature of the things I use printing for - and benefit over MJF is it doesn't really require any surface finishing. MJF seems to be cornered by HP products which would explain their high price:quality ratio. For this though I just used a 3D printing service since the cost of a good SLA printer probably still outweighs my little emtb endeavor even with the welding stuff, second fat wheelset, and backup M620... not a responsible purchase right now ha! The bench supply I got to operate my welding stuff does triple duty as a power source for other equipment and a smart 'universal' charger for anything up to 60V

For getting your hitch installed yourself there's always Stew's Garage in Kirkland. Just rent a lift and all the tools are all right there - I think they recently raised their rate to $46/hr from $40. That place comes in handy when you don't want to pay $120/hr labor and a 30% mark up on parts for some goon to twist all your nuts overspec with the full ugga duggas of the air tools. The only way I justified the pricey hitch rack was that I could take it with me - lucky for me the hitch itself only ran $130 or so and no cutting my bumper. I'm not familiar with them but I think certain generations/models of BMWs have a trim piece on the bottom of the bumper you can swap out instead of cutting a hole or replacing the entire bumper? I may be thinking of the X series

I do agree though, I would prefer a mechanical on/off switch for my pack/BMS. I can have complete confidence in a switch like that being disconnected but a sleep state on any machine is never truly off. One of the downfalls of connected technology - easier to operate something with the push of a finger vs connecting with a phone.

Yeah, SLA is super nice for that! Support material and DFM for FDM printing certainly is a pain.

I have thought about using Stew's garage but damn, just a little more $ and a mechanic will do all of the work for me... since they can do the job faster it would probably be similar cost. Also any time I dive into a project like that, something breaks or I need to order a part online and I end up having to wait a few days, so Stew's scares me because of that. They offer overnight parking for a fee I think. I almost went there to replace the gas tank on my old e30 325is but it only cost like marginally more to have it done by a mechanic. Unfortunately the 3-series doesn't have a panel in the bumper to remove, it will require cutting for the Stealth hitch.