Travel friendly 13s1p battery pack using 18500 cells, need cell and BMS recommendation.

[scm007]

I am building travel friendly < 100wh battery packs for a 48V ebike motor. Originally I was going to target the Panasonic NCR18500A cell : NCR18500A - Lithium-ion Batteries - Secondary Batteries (Rechargeable Batteries) - Panasonic

This cell has a capacity of 2.040 ah @ 3.6V. 13 of these in series yields 46.8V x 2.040 AH = 95.5 WH.

However the voltage is 3.6V. My understanding is that I need 3.7V cells (13*3.7 = 48.1) (13*3.6 = 46.8)?

I will have 5 of these that I will wire together with a parallel switching circuit that drains the subpacks properly (off the shelf item). Charging I haven't figured out yet but will likely just charge them in parallel once I know they are all approx the same voltage.

I am an experienced engineer but I have never built ebike batteries before. I would prefer to order from a supplier who can build the packs for me. I don't mind ordering from China.

Can someone recommend:
1.) High quality 18500 cell that 13s1p will be 48V and < 100WH
2.) BMS to manage the cells
3.) Manufacturer who can create ~10 of these prototypes.

Thanks!

 

[DaLanMan]

Oh my, you don't have small asks.

The unit you just described does not exist. I probably build more 12v systems than any one here, and I am not the most knowledgeable nor the most experieenced, but you have kind of landed directly in the wheel house of what I do build a lot of.

3.6 x 4 =14.4
3.7x4 = 14.8

It is a nominal 12v system, so the average is around 12v, keep in mind cars are iirc mostly at 14.2 in any case, there are a number of ways to skin the cat you are talking about. None of them however involve a manufacturer pausing in working on production lines to put out thousands of units to say "oh hey, there is this chap thatr wants a discount 12v unit. We should do that this week instead" I know, I was trying to order in the hundreds of units and the price per was well, it would have been cheaper to just buy the giant units that go in solar arrays and hire someone to carry them about...

So, you want a single battery, which is gonna rate between 2000 and 3500 mAh without you know, parrallel circuits to bring that capacity up.

I have made some units that were 2p producing 20Ah, they are expensive and in the grander scheme of things only easier on the builder, no one else because the weight factor at the low end is just not applicable.

you might do well with your goal with a headway cel (9 Ah iirc) and run those up in a 3p config, so you had end up with something a wee bit bigger than a motorcycle battery and it has the capacity you are looking for. Well, You are realistically looking for because I am rather forced to assume ya did not come here looking for your own breed of unobtainium.

You may also want to consider the new Sodium Ion batteries, My first batch from ltierally the first batch out of production had a 30% failure rate around the 50th cycle, but the rest of them are happily loading and unloading electrons now for over 20 days and showing no signs of strain. those are showing up in the 14-18Ah per cel, which puts you a *LOT* closer to your stated goal. If you are looking to hire someone to build those, you have found the 1 item I would take money to build. I ain't a manufacturer, I am fairly certain they don't let ya bring your dogs to work...

I will even let ya buy some of the nifty new boxes I have being delivered from China, I was getting irritable about not being able to put any cushion in the old ones that were designed to hold 18650's...