High capacity li-ion battery

[autx790]

This is not a flashlight application, but I'd think someone in here might be able to help...
I need to make a large capacity li-ion battery (60Ahr.) However, I do not need a large discharge rate. I will probably make three 20Ahr cells and switch them in and out as need.

2.6Ahr 18650s i've found to be the easiest to purchase, but I'd rather not have to solder 8 or 9 of these together so a cell with a higher capacity (at least 4Ahr) and light weight would be nice. Can anyone recommend a good, reliable, high capacity cell to construct these batteries with, as well as a good retailer?

I will be doing all the BMS myself, I just can't seem to find a retailer for anything other than lipo(which i'm not apposed to) or 18650 cells.

Currently I'm looking into what SAFT has to offer.

Thanks!
Peyton

 

[rmteo]

Have you considered polymer Li-Ion (Li-Poly) cells for high capacity packs? Being no-cylindrical, they are much easier to put together and more space efficient. For example, 4 of these 5000mAH cells will do what you want.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4061
Your 20A battery will be about 74x64x36mm and 380gm. (13.4oz.)

 

[SilverFox]

Hello Autx,

Welcome to CPF.

These may be worth looking into...

Tom

 

[autx790]

Thanks for the responses!

I have considered polymer, and still am, but don't know much about these websites that sell them (allbattery, batteryspace, etc.) I've a good bit of bad reviews about them. I used some tenergy packs from allbattery in the past and wasn't too pleased with the performance, but the protection circuitry worked well

Thanks Tom, I have looked into those and I am waiting to hear back from Saft about their 7Ahr cells, or others that might work for me.

I guess i know who the manufacturers are but not too educated on quality and reliable places to purchase the cells. The bigger li-ion cells seem to make you deal directly with the manufacturer's sales group. Along with being 60Ahr (total) it will be a 12S configuration, so with that number of cells, i want to make sure i get good/reliable quality. Any thought?

Thanks!
Peyton

 

[jeffosborne]

I have a thought about your project. How about the plan for a charger? A 12S configuration will require a custom parallel charger, me thinks. Also a question - what will you do with this high-amp 44 volt battery? Just curious... Cheers, Jeff

 

[monkeyboy]

How about these.

They even make a single 60Ah cell.

 

[Burgess]

Wow -- Cool !


_

 

[BillyNoMates]

I usually source my battery packs from Remote Control apps. These guys usually go for very high discharge rates (25C) and you can often find the lower discharge rate cells (15C and below) at relatively cheap prices.

Suprised you didn't like the Tenergy cells. I've been happy with my LiPo cells (not the same make) - good charge retention capability (much better than NiMH) and good current delivery. Rated capacity was about correct as well.

 

[VidPro]

Have you considered polymer Li-Ion (Li-Poly) cells for high capacity packs? Being no-cylindrical, they are much easier to put together and more space efficient. For example, 4 of these 5000mAH cells will do what you want.
http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4061
Your 20A battery will be about 74x64x36mm and 380gm. (13.4oz.)

i have been using this one, its working darn good so far, i put the 8amp protection on it. for the price its very nice.

 

[autx790]

Wow, thanks for all the feedback.

Jeff, I will be building my own charger as well. The application is for backup power to a solar power unit which will be powering a WiFi radio. The radio will only draw 42W peak, which should be roughly 1A give or take a little. I'm going for a large capacity cell to allow for at least 3 days of run time on the battery alone in case there are a few cloudy days back to back. Of course the radio could also be configured to cut back power in that situation.

monkeyboy, those are some crazy powerful cells! Kind of scary. They are a bit too heavy for my application though But I'm sure I can find a way to have fun with them down the road

Billy, I guess the tenergy weren't too terible, but I was using them for an autonomous robot to try and climb a cable. They just couln't put out the power expected them to. I got better performance out of some LiPo cells of the same capacity and physical size. But since I don't need much power they may work.

Vidpro, I may end up going with LiPo cells like those. I may go with a bigger cell like these http://www.all-battery.com/polymerli-ionbattery37v11000mah7872185.aspx

I don't have much experience with LiPo BMS. Do they basically need the same balancing, OV/UV protection, Temp monitor, etc. or is there any difference between a LiPo BMS and a Li-ion one?

 

[AilSnail]

yo - what is LiPo BMS?

I think the balancing and Uv/OV and temp requirement is the same.

life is same or less for lipo I think.

These LiFePo4 cells last longer but less capacity and not good in cold, according to the chart.

 

[gSPIN]

3.2V 60Ah single cell Lithium FerroPhosphate & cheap to boot.
unfortunately it's a high rate discharge cell which isn't what ur looking for.
http://shop.junglemotors.com/product.sc?categoryId=2&productId=16