Which high capacity 18650 cell for 250w ebike battery pack with heavy usage?

I'm building a new battery pack for my food delivery ebike. I's 36V, 250W - and will draw 15A peak. Will do 10s6p, so typical draw per cell will be less than 1A and 2.5A peak.
The battery will get a *LOT* of use, so maximum cycle life is very important!
Will get charged to 4.1V per cell and almost fully discharged every day.

Options so far:
LG MJ1
Sanyo NCR18650GA
Panasonic NCR18650GA
Panasonic NCR18650B
Samsung INR18650-35E

To all the battery experts: Which one would you pick? Any other cells i should consider?

Something is wrong with your math. 36v 250w motor should draw 7 amps. I guess maybe 10 max under load.

The controller is 7A continuous, 15A peak. (Which is the legal limit in the EU)

If you have the ability to custom configure the setpoint for LFP, maybe add another string to get the same range

A123 APR18650M1A

will last many times longer than the hotter-running LI chemistries like LiCo.

Also much safer, less likely to burn.

LTO even more so, but that's 2.4V, way less dense, I doubt even comes in that little cylinder form factor

vulcanears said:

Will get charged to 4.1V per cell and almost fully discharged every day

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Besides lowering the C-rate, you will get **much** greater longevity - and really not reduce range by much - by reducing that latter DoD.

Stopping at 3.3V for example, higher the better, so your call. But 3.1V would be my absolute LVC floor, even under load.

If you really need to prioritize range then just plan on replacing earlier.

Consider swappable packs?

john61ct said:

[...]
Stopping at 3.3V for example, higher the better, so your call. But 3.1V would be my absolute LVC floor, even under load.
[...]
Consider swappable packs?

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Good point. 4.1V to 3.3V then.

Will have 2 battery packs anyway (1 getting charged, 1 being used - I can swap every few hours)

Energy density is pretty crucial in my case, so the APR18650M1A is not really an option.

Your call, but consider, swapping packs makes density less critical.

If the difference is 10 years vs just three. . .

1000 cycles in 3 years would be more than enough. I assume there will be better battery technology out there by that point anyway.

Still don't know which one of the mentioned cells would be best for my purpose.

Cycle through your choices plugging the string into https://www.google.com/search?q=site%3Aendless-sphere.com%2Fforums%2F+LG+MJ1

and make your own mind up based on detailed and objective data. Price per mAh obviously a big factor

The advantage A123 is fast charging and long life. Charge a 20ah pack in a hour. LTO l will last forever. What kind of bike and how much room do you have do you have room in the Triangle ? 18650 is a small format.
At your discharge rate it help for longevity.

999zip999 said:

The advantage A123 is fast charging and long life. Charge a 20ah pack in a hour. LTO l will last forever. What kind of bike and how much room do you have do you have room in the Triangle ?

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That's great, but they have 1100mAh, right? The whole pack capacity just would be too small. 60 cells are already heavy enough - so just getting more cells is not an option in my case.

26650 is 2.5 ah . Yes they are big and heavy and a 10 year battery. And in 4years (18650) a battery should be of ? How much room do you have ?

The 3.5Ah cells will have somewhat worse cycle life because of added SiO2 in the anode.
So I'd probably go with the NCR18650B considering your low amp draw.

For your amp draw 18650 is fine just don't leave it on the shelf at 4.2v or 42volts. And dont run to cutoff.

i would pick none of them. the cycle life of all those cells is shit.

get a samsung 29E or a panny PF if you want cycles, those cells are almost industructable if you stop charging at 4.1V maximum and stop at 3V under load.
might want to add 1 more cell in P if you need the capacity.

If you have to go 18650 and Li-Ion chem and if range is no issue with a 6P setup (I'd say 25 miles), Id go with Sony VTC4... Thes cell will run coll because they have low internar resistance (21 mOhm DC IR), thus very good cycle life.

If really you don't care for range for a 6P setup (think 12-15 miles) and you want inclredible cycle life and 10 year + lifespan, go with A123 18650 LiFePO4 nanophosphate 18650 cells (1100 mAh, yellow wrapped cells). Very very low internal resistance. Very good discharge rate. Will run super cool in your setup. But range sucks... On the plus side, charge rate can be quicker on LiFePo4.

But consider this 250W is such a soft setup, even running cells rated for max 10A discharge rate in a 4P configuration should last a good 3 years (just don't store at 4.20V)… So if it's range you are after Samsung 30Q (3000 mAh, 15A) or MJ1 would be a well balanced solution. You could also go Panasonic GA 3400 mAh 8A cell and they should still last 4-5 years.

If you can exit the 18650 format for something bigger format,

Then consider A123 MA1 LiFePO4 nanophosphate 2500 mAh 26650 cells. Best cycle life, but bulky and heavy for a not so great range (think 30 miles for a 6P setup).

I would personally go with the Samsung 40T 21700 cells. 30A rating means the have pretty low internal reistance (meaning they run cool and thus good cycle life) and at the same time have 4000 mAh capacity and don't tale so much space or weigth too much. Just, they are a bit pricy cells.

Think about it a 6P setup of samsung 40T cells at 36V, thats 864Wh of capacity and a max discharge rate of 180A, that your bike will baby up at 7A continuous and 15A burst.

With a 250W eBike, you really have a lot of options as most ebike battery will survive very long du to very low current stress. For range you can expec 10Wh per kilometer so around 80-85 km (50 miles) good enough ?

But to be frank, alhough the worst posaible option for cycle life, you could even get away with 6P of laptop cells for such a low power 250W setup (1.2A/cell continuous ; 2.5A/cell burst). Not that i would recommend that last option.

So choice is hard to make because there a just som many options. What would help is to define exactly what kind of range you need. Would you want smaller than 6P ?

In the end, i would probably choose something cheap but good. samsung 30Q or Pananasonic GA. But if you want smaller than 4P, dont tkae the GA cells.

Pretty simple choice IMO. Pick the lowest internal resistance 18650 cell you can afford.

Even though your setup will not challenge a good cell like the Samsung 30Q, any cell will last longer if you don't get it hot. Cooler the better, not meaning cold weather, but meaning not having a pack that gets almost too hot to hold in your hand each cycle. Cheap no name18650 cells will do that, under fairly low amps too. But that cheap pack, it will still go 2 years, and 500 cycles.


Any of the better cells you mention should go double that, on your typical amps draw. Especially if you balance them at 4.1v. Most bms goes to 4.2v, so you might end up doing a weekly charge to 4.2 just to get them balanced. Just ride it down to lower voltage immediately, and the higher charge will do little harm.


If you don't go 18650, don't fail to consider RC lipo. Touchy cells to be sure, but cheap, and you run 20 ah of the 30-60 c stuff at less than 1c, and the pack will be stone cold the whole ride. And you will get three years from it for sure. I like to buy 10 ah of it each year, and then run it in parallel with other packs that are one or two years old. Small and affordable buy every year, but always have up to 30 ah of it around.

Thank you so much for your insight, everyone

Matador said:

[...]
For range you can expec 10Wh per kilometer so around 80-85 km (50 miles) good enough ?
[...]
So choice is hard to make because there a just som many options. What would help is to define exactly what kind of range you need. Would you want smaller than 6P ?
[...]

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I ride 100km on long days, but I live right in the city center, so I can swap battery packs at home once or twice a day. So I thought the best option was to get 2 packs around 600Wh-700Wh each and cycle them between 4.1V and 3.3V.

I would like to go with Reention or Hailong battery packs, because I find the form factor very convenient. (If there are better options out there, I'm always grateful for brainstorm inspiration!) They come with 18650 cell holders, so using different battery sizes would mean a lot more work when building packs.

the best thing is to find a space on your bike that can store as many cells and humanly possible.
1 battery made of 100 cells lives 4 times as long as 2 batteries of 50 cells each.
and it saves you recharging swapping batteries because that shit needs to happen at the worst time.
because you already have a delivery bike you are already hauling weight. having 1 big battery instead of 2 smaller ones that you need to swap gets old really fast and after a while you dont notice the extra weight and you can crank up the power more without damaging/wearing the pack much.
having a bigger pack also helps a lot during cold or really hot weather as the temperature is more even and you will get more consistent performance from it and dont have to worry as much about heat.

vulcanears said:

The controller is 7A continuous, 15A peak. (Which is the legal limit in the EU)

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As others have said, managing charge/discharge maximums/minimums, and over-building pack is the best way to achieving long life from your battery pack. Also, choose a tried-and-true cell (Sanyo 29E is a good one)...it may not be the best power density or maximum amp ratings...but in the long run it has a proven track-record.

FYI if you motor is rated at 250W, the only way it would ever draw 15 amps is maybe if it was stalled (not turning at all).
The controller's maximum amp rating is only a rating which the controller can handle....it has little (maybe lower resistance, so less wasted power generated as heat) bearing on how much current is actually delivered to the drive motor. That is a function of maximum voltage of battery and resistance and KV of motor. If motor is rated for 250W at a specific RPM, then the motor will only draw about 6amps under load at the maximum wattage rating of motor.

PS: My controller is rated for 38amps....500W motor never draws more than 20, and that is on the hills.

pullin-gs said:

[...] FYI if you motor is rated at 250W, the only way it would ever draw 15 amps is maybe if it was stalled (not turning at all).
The controller's maximum amp rating is only a rating which the controller can handle....it has little (maybe lower resistance, so less wasted power generated as heat) bearing on how much current is actually delivered to the drive motor. That is a function of maximum voltage of battery and resistance and KV of motor. If motor is rated for 250W at a specific RPM, then the motor will only draw about 6amps under load at the maximum wattage rating of motor. [...]

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God, I'm researching eBike building for the last months and it surprises me every day, how many misconceptions I have in my head.

My rear hub motor is the Bafang G310:
https://www.bafang-e.com/oem-area/components/component/motor/rm-g310250dc/
https://www.ebikes.ca/mg310-std.html

Controller is the S06S.
https://bmsbattery.com/controller/546-s06s-250w-torque-simulation-sine-wave-controller-ebike-kit.html

Would have bought something beefier, but I'm desperately trying to stay within the constraints of EU law, which says "250w continuous power output, 25 km/h max" (whatever that means).

The speed limit is easily capped no matter how much potential power output.

Note that mechanical power **output** (HP equivalent) is much smaller than **electrical** input.

Let's just say a motor that consumes 1000W in brief high-torque peaks, can in theory run at 400W max continuous, and qualifies within the legal limit.

Having a very limited **battery** bank, so that that actual draw at **twice** that level only can only last say twenty minutes, IMO a case can be made that still qualifies **as an overall system**.

Ok now what bike are you going to use? And what kind of battery space do you have for a battery

999zip999 said:

Ok now what bike are you going to use? And what kind of battery space do you have for a battery

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This frame with different components. Rear rack is a possibility.