14.5ah vs 17.5ah?

[greeno]

Mr “T” I think burlguy is refering to the stock Biktrix 48v 21ahr battery that came with my buddys bike. Not the “amateur” builds I make. He has allready sold that battery for 3 bills down here in SD. Sorry

 

[ExPatBrit]

Read carefully, “we build our own battery's”.

Rethink spending your dollars on amateur builds. It may not be as good a deal as it appears. I’d be asking if the seller has a hazmat shipping account and for far more details on the battery. Beware.

40 year EE , I still have all my fingers and even I am scared of messing with big Lithium batteries , so I would not consider that,
but an official Biktrix 48v battery was tempting. 52v meh! Like putting a bigger water tank to get more shower pressure.

 

[greeno]

I think of the 48-52 debate as putting regular or premium gas in your car. As far as being scared of electricity or lithium Ion batteries I respect their potential and hazards but not scared in the least. Joined the IBEW 569 back in 78’ and was a contractor for over 20 years. Retired back in 2012. Did alot of Industrial work. Co- gens, 12kv distribution and all the splicing, substations and utility control work for SDGE. Got all me fingers too! The only problem I see is like Tom J pointed out trying to put the 52v extra batteries in a pack made for 48. Why would someone do that? Thats just dumb and asking for trouble. On another note: motors use wattage V x A ohms law. Lower voltage uses higher amperage for the same wattage. Why would you not go with a higher voltage to use less amperage to get the same wattage? Utility companies use extremely high voltage for distribution and then drop down after getting closer to the end user otherwise they would have to use huge current carrying condictors. jMO

 

[ExPatBrit]

I think of the 48-52 debate as putting regular or premium gas in your car. As far as being scared of electricity or lithium Ion batteries I respect their potential and hazards but not scared in the least. Joined the IBEW 569 back in 78’ and was a contractor for over 20 years. Retired back in 2012. Did alot of Industrial work. Co- gens, 12kv distribution and all the splicing, substations and utility control work for SDGE. Got all me fingers too! The only problem I see is like Tom J pointed out trying to put the 52v extra batteries in a pack made for 48. Why would someone do that? Thats just dumb and asking for trouble. On another note: motors use wattage V x A ohms law. Lower voltage uses higher amperage for the same wattage. Why would you not go with a higher voltage to use less amperage to get the same wattage? Utility companies use extremely high voltage for distribution and then drop down after getting closer to the end user otherwise they would have to use huge current carrying condictors. jMO

Sounds like you have gained some expertise and have a facility to build batteries.
I am a bit more cautious . Working with reading glasses doesn’t inspire confidence.
OSHA says anything above 50 volts is potentially lethal, there is some major wiggle room in that.
If u look at Biktrix replacement battery pricing both the 48v 21Ah (1008 Watt Hours) and the 52v 17.5 Ah (910 Watt hours) are the same price. Price/ Watt hour is 11% more.the 52 v will have a slightly higher max to cutoff differential so somewhat of a wash.
Another concern I have is the reliability of the battery output connector on this type of battery. They.
were reliable at 36 volt, but 52 volt (58 fully charged ) could be strech
My current 48v Bike has a bafang geared rear hub with a 35A controller , hub motors benefit from the extra volts and provide a speed increase. My Bixtrix ( inbound) with mid-drive is probably fine at 48 volt.
At some point designs will improve, and price will drop , worth thinking about.

 

[greeno]

I also have reading glasses, and distance glasses hmmph...
It's all about the watts as far as range is concerned and voltage as far as "snap" is concerned. Connectors shouldn't be an issue. The battery's I have been making have XT60 plugs for charging ( overkill I know ) and I cut off the Anderson plugs on the motors and solder on a XT90 for connection to the power supply. A friend of mine just recently purchased an Apex from L--- and had the black wire in the XT90 connector coming from the motor come loose from the plug. He sent me some pics. So he wanted to know if I could take a look at it for him but I was busy so he instead got ahold of L--- and took the bike up to their facility last Wednesday so they could access the problem. Hopefully they took the 15 minutes it would take to fix it and send him on his way and not have him leave it for repair. Bummer on a new bike.
I will be calling him tomorrow to see how it turned out.

 

[tomjasz]

Why would someone do that? Thats just dumb and asking for trouble.

That's exactly what most cheap China direct sources do. Hailong cases are not suitable for higher Ah 52V batteries.

 

[greeno]

I wonder why, it's just an injected mold why not make it larger. I know L--- just heat shrinks some of their packs and sell them that way. Like I don't have enough going on I even thought about buying a 3d printer and making my own hard shell cases but I'm not quite there yet.

 

[tomjasz]

I wonder why, it's just an injected mold why not make it larger. I know L--- just heat shrinks some of their packs and sell them that way. Like I don't have enough going on I even thought about buying a 3d printer and making my own hard shell cases but I'm not quite there yet.

Just buy Reention cases. Far superior quality and cases big enough for 52v 17Ah.

 

[greeno]

I just checked out the "Marketplace" that has the cases for the bigger battery's and nice to see options.
On their bigger triangle packs Im sure they are spot welded yeah? Also looks like they use the plastic spacers to hold the batteries and I hope they install BMS, seal, insulate and pad the battery as a whole correct?

Kinda pricey IMO but on par with what I have seen before. Looks like a good option if the size is correct. Actual price on parts for the 31ahr 52v would be around about $600 or so with no labor. Bags look similar to the ones we use. Been having good luck with Bes Tech Pwr BMS's. I think the Sanyo GA's work the best too 3.45mahr, 10a battery.

 

[greeno]

You can Sanyo GA batteries all day ( when there in stock ) for 4 bucks each.
31ahr battery 14s x 9p = 126 batteries x $4.00

Batteries (126) $504
Shipping $ 15
Insulator pads $ 6
Hot Glue $ 2
Nickel belt $ 15
Solder $ 1
BMS $ 50
XT cons $ 5
Wire/cons $ 2
Kapton tape $ 1
Insul paper $ 1
3/16" foam board $ 2
Shrink tubing $ 1
Gorilla Tape $ 1
Tri Bag $ 50
_______
My mistake: $656

Then there's labor to design, build, test, charge up and order items
Hot glue gun
Spot welder and lipo battery
Battery charger

I purchased all the equipment myself, I charge $1000 to build the battery........ hahahahaha. I charge ZERO for my time to build. They pay me what it costs which is fair.
I did buy One of Micah's books and have spoke to him a few times. Actually use their 52v 14s BMS's they sell

There is a cost savings but the main reason is to build something that fits a particular bike geometry shape and have enough range for a full days ride. A 40 mile ride is pretty typical.

If I have a need for something and it's not available I'm not afraid to build it.

 

[greeno]

In your case the battery that I guess you would need the savings wouldn't be that much. Redid the math on mine for your 48v 14ahr battery and my cost would of been around $360 just for parts. Smaller battery, less material, less savings.

 

[tomjasz]

Those case costs are high when ordered singly. Battery building on this scale is expensive. Hot gluing cells is a bad practice. I discovered, for me, shrink wrap packs save me money and can have several size and shape layouts not possible in cases cell packs. My move has been back to 15a-18a 36v. 3p builds minimum.

All of my updated battery supplies, and some unused, parts and tools will soon be available. All personal purchases not purchased for resale. I’m done.