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EVE C40 20ah cylindrical cells

I've got a double motor cargo ebike that I intend to use the battery in, I'm not completely sure what current I will draw yet but I'd guess a brief surge of 50 amps every now and then and constant of around 12 amps.
Range is more important to me than performance, I haven't ordered a bms yet because I don't really know what to get other than I'd like Bluetooth and I already know my way around the jk app so just as well get another.
I wouldn't mind a little help choosing the bms though if anybody has any thoughts.
 
Cool. I would do 2 parallel.

I would expect a 2.4C draw to severely shorten their lifespan.

2p would give you gobs of range.

I have enough (6) batteries to go 200 miles on my ebike. With the batteries in my trailer :)
 
You need to know your draw.

I got a 2000 watt hub that pulls 40 amps a lot of the time.

2 motors could be 60-80 amps startup draw, getting up to speed. Every single stop sign lol
 
I've got a bafang m600 mid drive and a rear geared hub motor both are all about torque, the mid drive uses the chain and I've got a large sprocket on the cassette, I live in a very hilly area and rarely go faster than 18mph.
 
Hey Frugal!
I have some numbers that might help you along the way.

So I've built my E-bike this summer, as you know. At one run I watched the current draw of the JKbms live through the app. Uphill full load the continuous draw was up to 14A (maybe 15A, not 100% sure). Anyway, the motor is standard rated 250W. 36V battery (NMC) was fully charged to 4.13V /cell, 10s makes it 41.3V. Calculated 250/36=6.9A

My suspicion is the 14A draw on a system rated 7A is probably due to very poor efficiency of the E-bike motor-controller. Though I am still very novice, others are welcome to correct me here.

Given each your twin motors are larger than mine, if I remember correct.
 
I'm hoping these cells will be a pleasure to assemble due to threaded terminals, if they are as advertised the plan is to buy another 16 and either make a 40ah or two 20ah.
 
Frugal Devonian said:
I'm hoping these cells will be a pleasure to assemble due to threaded terminals, if they are as advertised the plan is to buy another 16 and either make a 40ah or two 20ah.
Click to expand...
I would have them secure "as a unit" the shifting, bousing, and vibration will not play nice with screws.
 
ScrotpusGobbleBottom said:
I would have them secure "as a unit" the shifting, bousing, and vibration will not play nice with screws.
Click to expand...
I've started thinking about this I thought I might drill matching holes in two pieces of perspex and make a sandwich with the busbars on the outside maybe, I'd probably swap the nuts with nylocks, until I get them in front of me I won't know what's possible.
 
I envy you and your LFP cells already. When I planned my bike, I was aiming at LFP but due to several circumstances at that time, ended with NMC from EV-module.

48V with NMC is 13s, ~40-54.5V (?)
48V with LFP is 16s ~48-55V (?)

Differences in voltage-range and position are absolutely noticeable. Although I am curious. When your bike with LFP pulls fully, the battery meter in the display drastically drops from say full to half or maybe even less?
 
I haven't noticed much of a voltage drop under load but I haven't been methodical with recording data as yet, I'd say I'm attracted to lifepo4 for cycle life and charge speed but it is heavy so doesn't seem popular for eBikes also a bit safer maybe.
 
MrSparkle said:
Hey Frugal!
I have some numbers that might help you along the way.

So I've built my E-bike this summer, as you know. At one run I watched the current draw of the JKbms live through the app. Uphill full load the continuous draw was up to 14A (maybe 15A, not 100% sure). Anyway, the motor is standard rated 250W. 36V battery (NMC) was fully charged to 4.13V /cell, 10s makes it 41.3V. Calculated 250/36=6.9A

My suspicion is the 14A draw on a system rated 7A is probably due to very poor efficiency of the E-bike motor-controller. Though I am still very novice, others are welcome to correct me here.

Given each your twin motors are larger than mine, if I remember correct.
Click to expand...
Rated current draw is typically about efficiency, and higher rpms are typically more efficient (more power on the drive shaft vs electricity used). It happens at a certain rpm and load. Higher load and rpm is lower and the draw is higher and efficiency is less and the electrical wattage is higher. Often the 250w rating is the rating where the motor can sustain (though with some cheaper motors it is sometimes the absolute max power it can produce and at that power level the motor will overheat is sustained--black and decker tool motors are rated at like 300w for the tiny 775 motors that they use), the rating is not the max wattage rating that the motor can draw, and it is very unlikely that this is a motor controller in-efficiency rather than simply a motor being run at a lower less efficient rpm.
 
I should of mentioned how I ride I think, I don't use the throttle I use pas and change gear a lot to achieve the right cadence to reduce the draw on the battery and get better range,that being said I wouldn't want to build a battery that wasn't capable of delivering some good power for a short period say 5 mins.
 
ScrotpusGobbleBottom said:
These are the ones I got
Gray. 40 amp .4 amp balance

Click to expand...

I would get higher current than 40A for a motor. Motors can often pull massive amounts of current on startup. The "tiny" 775 motors that black and decker uses in their tools can pull >100A on start and will fault a lot of BMS's on over-current. I would not get one with less than 100A just because of the starting surge (if you aren't using a PWM/slow start setup), and if the higher current ones are only a bit more then might go larger.
 
I agree, my ebike does 40 amps continuously if accelerating.

I agree that the OP should be looking at 60 to 100 for max so then 40 isn't stressing it.
The size is similar so no problem there.
 
ScrotpusGobbleBottom said:
I agree, my ebike does 40 amps continuously if accelerating.

I agree that the OP should be looking at 60 to 100 for max so then 40 isn't stressing it.
The size is similar so no problem there.
Click to expand...
I agree and maybe then some.
I have dismantled a number of different E-bike batteries for 250W systems of several brands. What I found that all batteries for 250W systems had 30A fuses. (I believe that is due to mentioned surge, startup current that can be ~x4? nominal.)
Considered OP have dual motor and those are larger(?) than 250W, even 100A BMS might be on the verge?
 
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