Battery compromise for an EMotorcycle

[Wheelsandall]

I’m converting my 81 Yamaha xs400 to electric using a qs180 motor and FarDriver 961200 controller and a 400amp BMS. I’m looking for a decent cell to start building the battery pack.

I’m not looking for anything crazy here just to have fun at no more than 80-85mph. It will be a 24s battery and parallel will be determined by the cell I end up with. Usually I just harvest whatever cells I can find but most of them are around 10 amp discharge rate so it would take a whole latta batteries to get in the range. I was looking at the eve 50pl with a 50 amp discharge and maybe 6p for 300 amps. Do you think I need that much? Is there a better option? Preferably in the 21700 package. I’m looking for best bang for the buck since the motor kit pretty much blew my budget. Also range is not super important since I’ll probably only ride it to work which is about 12 miles round trip.

 

[bananu7]

Do you think I need that much?

Well, that's already almost at the limit of the cells, so... probably?

Keep in mind that using such high power cells in a 6p configuration puts a lot of pressure on the battery construction. You're going to need copper-nickel sandwich, likely precut plates, to make sure you can actually pull that much from the cells. It's way easier to build big high power batteries than small high power ones, especially considering you start getting capacity "for free" once you're past your required power threshold.

I’m looking for best bang for the buck

Disclaimer: I haven't yet built my battery, though i hope i will soon, so I don't know how well they will work in practice.

If you have space, I'd go with 24s1p on high-power pouch cells. The 50PL would cost about 650 euro here for the required 24x6=144. LG P41 would be less than half that for 24x.

 

[Wheelsandall]

You have just opened my eyes to the pouch battery. It doesn’t look like we can get the lg p41 in the states but I’m going to keep looking. They don’t have an amperage rating per se but they have a C rating.

 

[adsc]

If you have space, I'd go with 24s1p on high-power pouch cells. The 50PL would cost about 650 euro here for the required 24x6=144. LG P41 would be less than half that for 24x.

What are your sources? Only source I've found is 1200 € for 24x LG P41.

 

[j bjork]

Why 24s? And why just 6p? It will stress the cells a lot, and the range will be terrible when you also want high speed.
I would probably go 28s, or at least 26. Maybe 24 if I were using 12s ev modules or similar. If you want best bang for the buck, that is probably the way.

 

[Wheelsandall]

My BMS is 24s that’s really the only reason. I could go go more parallel in just being cheap. This would be the first battery I build from new cells and they ad up quick. I’ve been looking for pouch cells but there’s not much available in the states and shipping/import fees are astronomical from Asia.

 

[mrmojorising]

My BMS is 24s that’s really the only reason. I could go go more parallel in just being cheap. This would be the first battery I build from new cells and they ad up quick. I’ve been looking for pouch cells but there’s not much available in the states and shipping/import fees are astronomical from Asia.

You could check out Lithium battery for ebike. I've seen the business mentioned a few times in Emoto forums. They use pouch cells and are Canada-based, so maybe shipping is easier? (I don't know what battery shipping within North America is like). Looks like they have a few 22S - 26S, 32Ah packs for 1k USD.

Otherwise, you'd be hard-pressed to beat Amorge on price & build quality, unless you already have significant high-power build experience and all of the building supplies.

6P for 300 amps needs some really thick copper, so you either need a very powerful welder, or a mid-tier welder and wellgo style pre-cut busbars. Both options can be pretty expensive

Not sure how experienced you are in building batteries, so that's more of a deciding factor. Building overall isn't economical unless you have the tools, experience, and need something custom. Unless you're like me and do it for fun & learning

 

[Wheelsandall]

Ya I’m starting to think I should build a medium duty battery for the time being since I don’t have a heavy duty welder and am only going 24s. Basically I just want this bike to be able to run on the highway. Maybe just save my pennies for something prebuilt

 

[Wheelsandall]

Well I came across these two batteries full of lifepo4 cells at work. They’re 105ah each but I don’t know about a c rating or discharge amperage yet. They seem to be talking a charge. Aside from the size I’m wondering if I can use these

 

[adsc]

My battery is 24s1p LFP 105Ah. But it only gives 72V nominal. Also LFP usually has a 1C rating (both for charging and discharging), so not really a performant pack.

 

[Wheelsandall]

Ya I think I might try it but I’ll get a 28s BMS to get the voltage higher. Since these won’t cost me anything I can spend a little on another BMS

 

[Wheelsandall]

100 amps is still a decent amount but I’ll have to see how the qs180 likes it

 

[Elec’73]

A reasonably priced reuse option that will work well with a qs180 motor is 4x (6s2p) hyundai Ioniq5 / Kia EV6 battery modules. Tear down videos are also available.

 

[Wheelsandall]

Are they lifepo4?

 

[Wheelsandall]

checking around for them it looks like some of them are 6s 2p

 

[Elec’73]

There are also some more powerful Kia EV9 (4s3p) same dimension modules, used & for sale

 

[Apartunis]

These seem like a pretty nice match to the project:

Jeep Cherokee PHEV 44v Battery 2.1kWh modules Samsung Cells 12s

PLEASE READ THE DESCRIPTION CAREFULLY. Shipping to Lower 48 USA states only via Ground Shipping. No shipping to PO Boxes. No international shipping including Hawaii, Guam, Puerto Rico. EV modules with high quality Samsung cells! These 44v 47Ah 2.1kWh li-ion modules are removed from wrecked...

jag35.com

Despite the URL, these packs are 12S.

 

[Wheelsandall]

I ended up ordering 4 of these similar to the Jeep pack but half the ah rating but we’ll see how it goes. Couldn’t argue the price.

Honda Clarity! - 12s NMC Module 44.4vDC 200A Continuous, 400A Burst - JAG35.com Jehu Garcia DIY Powerwalls Lithium Ion Batteries EV eBike eScooter Emergency Solar Off-grid

PLEASE READ THE DESCRIPTION CAREFULLY. Shipping to Lower 48 USA states via Fedex Ground only. Plz note that we can't ship to PO boxes. No international shipping including Hawaii, Guam, Puerto Rico. Non-USA customers click here. This 44.4v battery module has powerful B-MAX cells and can be used...

jag35.com

 

[mrmojorising]

I ended up ordering 4 of these similar to the Jeep pack but half the ah rating but we’ll see how it goes. Couldn’t argue the price.

Honda Clarity! - 12s NMC Module 44.4vDC 200A Continuous, 400A Burst - JAG35.com Jehu Garcia DIY Powerwalls Lithium Ion Batteries EV eBike eScooter Emergency Solar Off-grid

PLEASE READ THE DESCRIPTION CAREFULLY. Shipping to Lower 48 USA states via Fedex Ground only. Plz note that we can't ship to PO boxes. No international shipping including Hawaii, Guam, Puerto Rico. Non-USA customers click here. This 44.4v battery module has powerful B-MAX cells and can be used...

jag35.com

No wonder they're on clearance, that energy density is abysmal. Probably would've been better off with some new lifepo4 cells at that weight for only a little more cost

Oh well, hopefully they're easy to hook up

 

[Wheelsandall]

So 2 of the batteries came in. I believe the reason they have such a low density is because of the mounts on either side adding weight. They’re basically 2 extra battery sizes but they make a super sturdy mount with (4)1/2” holes on each corner to get some heavy duty bolts through. I’ll take that trade off since it give multiple options for mounting. I could always take them off and figure something else out if need be.

 

[jkrienert]

...mounts on either side adding weight.

Keeping might be a useful tradeoff for its integrated convective cooling effects on the pack, if there are any(?).

 

[j bjork]

There is no use taking the end plates off. Then you have to replace them with something else to keep the cells compressed, and that will be just as heavy.