52V, 20Ah Downtube Battery pack Design Feedback

[m@Robertson]

So, I have an orange bike, and a green bike. And a black one. You can see where this is going. Maybe look into a snap-on cosmetic cover at that spot rather than a permanent molded-in (or whatever) choice. That would let you do covers for a variety bigger than just these three.

Failing that you can't go wrong with basic black.

Super interested in this.

If this pack is a little longer than the Hailongs etc. consider making the locking mechanism sideways-sliding. I've seen that done on some mounts for Bullitts. The top/forward lock releases to the side. The bottom lock allows the pack to rotate and when it reaches a certain point the pack can be pulled up and off. This of course requires two locking latches not 3 or 4, unless you make the whole thing slide sideways instead which lets you have multiple attachment points.

 

[Ravi Kempaiah]

How about waterproofing?

IP 68.
2 hours - submerged in water at 1m depth. No problem!

 

[m@Robertson]

You know what would be really neat on this? Something that might be a lot easier than the norm thanks to the high level of electronics sophistication you are working with: Build in what is now commonly called a battery blender to parallel two packs.

I feel unclean just writing 'battery blender' without following it with 'don't use one'. But with a quality manufacturer behind the effort, the uncertainty that goes with using one of those black boxes could go away.

I ride cargo bikes with large power backing them up. Also I have 2wd bikes same deal (and 2wd cargo bikes ). 20 ah is on the 'barely acceptable' range of size. Being able to parallel two of them would give me 40ah, which is a bit more than the 35ah I have now, which I take for granted and which gives me a completely range-anxiety-free experience.

 

[Ravi Kempaiah]

So, I have an orange bike, and a green bike. And a black one. You can see where this is going. Maybe look into a snap-on cosmetic cover at that spot rather than a permanent molded-in (or whatever) choice. That would let you do covers for a variety bigger than just these three.

Failing that you can't go wrong with basic black.

Super interested in this.

If this pack is a little longer than the Hailongs etc. consider making the locking mechanism sideways-sliding. I've seen that done on some mounts for Bullitts. The top/forward lock releases to the side. The bottom lock allows the pack to rotate and when it reaches a certain point the pack can be pulled up and off. This of course requires two locking latches not 3 or 4, unless you make the whole thing slide sideways instead which lets you have multiple attachment points.

That colorful piece that you see is a door for the charge port. It houses an ultra-fast 20A charge port like the one shown below.
The door also acts as a shield to protect the discharge port at the bottom.
We have looked at sideways option as well and currenlty we have integrated ABUS lock into this.

I have read your blog and have always respected your generosity in sharing knowledge and a high level of detail.
Apart from safety, longevity, fast charging, and interoperability, what other features do you think a battery like this should have ?
Oh! By the way, you can daisy-chain two batteries, and the BMS will detect that and act as a master/slave to work in unison.

 

[m@Robertson]

We have looked at sideways option as well and currenlty we have integrated ABUS lock into this.

Thats a big deal for me. I leave my bikes parked outside of stores, and it was a huge deal for me when I started building the batteries under my cargo floors so they could be just left on the bike, and even if someone knows the pack is there - which is never - there's nothing they can do about it. So if you have a high security option holding the pack to the frame, that would be a big plus as these packs are not going to be hidden I expect.

I have read your blog and always respected your genesority in sharing knowledge and a level of detail.

Thank you !

Apart from safety, longevity, fast charging and interoperability, what others features do you think a battery like this should have ?

Well, since you asked

1. Maintain the ability to slow-charge. You already know the benefits of slow-charging over fast. I am firmly in the slow camp. My main white bike with its built-in charger is fixed at 3.0a by virtue of the fact it is sealed under the floor and thus not adjustable, That is as fast as I ever want to go ... and thats on a 35ah pack I know can take a lot more. My normal charging speed is about 0.80a. This is solved if your charger has adjustable voltage and current.
2. High amp output. On my 2wd cargo bikes, I have a 30a BBSHD in the back, and either a 25a or a 30a (peak) front KT controller. On my non-cargo bike awd's, its 30a BBSHD plus 35a front KT. Or a 35a KT front and another 35a KT rear. Now, all of my controllers are set to roll power on slowly, so I don't have sharp spikes, but I still need a BMS whose continuous rating is peak + 10a fudge (have learned the hard way I need the fudge). So in a perfect world - and I know this is a big ask - up to an 80a continuous power output BMS on a single pack, so if I want to do just a single 20ah pack on my Great Pumpkin non-cargo bike, I can do it. OR something dialable that I can in turn work with and maybe dial back a controller to fit under the cap. The 30a BBSHD+30a KT with the KT dialed down to the slowest of the slow start modes is what I am building with nowadays. Everything else is legacy.
3. As long as I am just creating a wish list, give the interface the ability to adjust when it turns away the charge current. So let me set it to 55.4v for instance. I would still want a current-adjustable charger, and still use my mechanical cutoff timer. But having the BMS be adjustable too would add a new layer to the charge-safety onion. If your chosen charger is not adjustable for current and voltage, this becomes a much bigger deal.
4. Give me the ability to use my own charger. i.e. sell me a dumb plug with two pigtails, red and black (or an adapter that goes from your pack plug to a female XT60... like what Grin does). That would let me continue to take advantage of the Mean Wells I have mounted on bikes, have sitting in office garages etc. Plus my Satiator.

Oh! BTW, you can daisy chain two batteries and the BMS will detect that and act as master/slave to work in unison.

• To add to the list above on this topic: It sounds like you already have this covered, but for two packs working together I would want it to work just like a manual permanent parallel pack connection. Doubling the (on paper at least) BMS limits and in particular, to charge both packs while connected via a single charge connection. IIRC that normally means a BMS with overcharge protection covering the output side where the two packs are connected. No idea what it would mean with your firmware but the thing I would not live without if choosing this route is the ability to just plug in and (more slowly) charge up both packs in one go.

There was one other thing but its slipped my mind. This is plenty as it is, right?

 

[Ravi Kempaiah]

1. Maintain the ability to slow-charge. You already know the benefits of slow-charging over fast. I am firmly in the slow camp. My main white bike with its built-in charger is fixed at 3.0a by virtue of the fact it is sealed under the floor and thus not adjustable, That is as fast as I ever want to go ... and thats on a 35ah pack I know can take a lot more. My normal charging speed is about 0.80a. This is solved if your charger has adjustable voltage and current.
2. High amp output. On my 2wd cargo bikes, I have a 30a BBSHD in the back, and either a 25a or a 30a (peak) front KT controller. On my non-cargo bike awd's, its 30a BBSHD plus 35a front KT. Or a 35a KT front and another 35a KT rear. Now, all of my controllers are set to roll power on slowly, so I don't have sharp spikes, but I still need a BMS whose continuous rating is peak + 10a fudge (have learned the hard way I need the fudge). So in a perfect world - and I know this is a big ask - up to an 80a continuous power output BMS on a single pack, so if I want to do just a single 20ah pack on my Great Pumpkin non-cargo bike, I can do it. OR something dialable that I can in turn work with and maybe dial back a controller to fit under the cap. The 30a BBSHD+30a KT with the KT dialed down to the slowest of the slow start modes is what I am building with nowadays. Everything else is legacy.
3. As long as I am just creating a wish list, give the interface the ability to adjust when it turns away the charge current. So let me set it to 55.4v for instance. I would still want a current-adjustable charger, and still use my mechanical cutoff timer. But having the BMS be adjustable too would add a new layer to the charge-safety onion. If your chosen charger is not adjustable for current and voltage, this becomes a much bigger deal.
4. Give me the ability to use my own charger. i.e. sell me a dumb plug with two pigtails, red and black (or an adapter that goes from your pack plug to a female XT60... like what Grin does). That would let me continue to take advantage of the Mean Wells I have mounted on bikes, have sitting in office garages etc. Plus my Satiator.

1. We can actually set the charge current just from the cloud portal, and the BMS will signal the charger to change the current. We have just begun working with a charger manufacturer to implement this. You can change anywhere from 1A to 20A.
2. The BMS is designed for 50A peak and can handle 30A all day long.
3. We have implemented the charging algorithm to extend life. This is how we will be able to offer a 5-year warranty.
4. Unfortunately, the charger needs to have CAN communication. The handshake between the charger and BMS is a must for a variety of safety reasons. Every EV has this, and it boggles my mind that E-bikes use chargers with little to no safety. This must change.

 

[Ravi Kempaiah]

I had a technical discussion with @scrambler and showed him some of the core technology we are developing for batteries and how it will improve safety, performance, and longevity.
Without getting into some confidential design details, if you could share some thoughts here, @scrambler , that might help the community.

 

[keithj69]

I've been using home automation since it's inception and I can't think how I would want to incorporate my ebike battery.
What are some scenarios that you think may be useful.

One would be if you can read the state of battery charge on last connect good know if you need to charge the battery before the next big ride. Or if the battery reaches 80% during the charge, turn off the power that the charger is connected. Maybe if a Bluetooth beacon (air tag type) was added to the battery, you could track it in the H.A.