Lifepo4

[semmel]

Hello,

LiFePO4 it not a brand it is a battery technology. There are different manufacturer so every cell has other specs. Do not reflect the behavior from one cell to all other cell types.
A sample: We in the model airplane section use the A123 cells (called KonionX in europe - assembled from BMZ) with huge success because this cell can be used with high discharge rate at >20C (10Ah pack brings constant 200A).
see C20 discharge diagram: Elektromodellflug - BMZ 26650-X - LiPo-FePo4 im Test
At this hight discharge rate this cell lives more then 300 cycle and is not at the end of there live (this was the first year - next year we will see more cycles).

In compare to the LiPo (Lithium Polymere Cells) which we also use for model airplanes. LiPo at this high discharge rate are at end of live after 100 cycles. With lower (C10) discharge rates LiPo live up to 300 cycles and are at end of live after 2 years.

But when i check the website of other LiFePO4 cell manufacturer then is see that there maximum constant discharge rate is lower then that of the A123 cells. What the Killacycle can do with A123 cells is not possible with every other LiFePO4 cell.

So i think we have to be careful if we speak about at technology we should speak about the type of the cell and not the technology itself.

Thanks,
Luke

[Syman]

What do people think of this battery ThunderPower TP6000-5S3PL


6000 mAh, 18.5V (charge as 5 cells), 13G wire,6-pin balancer connector
Rating: 10 -12C continuous, 18C(108A) burst
Dimension: 50mm x 325mm x 23mm
Weight: 627gm

I want to put two together to create a 37V pack.

[Jeremy]

That's a very expensive way to buy a 37V 6Ah battery. I'm sure it would work OK though.

I paid about £150, including postage, for a 36V 10Ah LiFePO4 pack, complete with battery management system and charger, to give you an idea of prices.

Jeremy

[Syman]

Could you post a link to the web site where you can buy a battery for this price. I find that very hard to belive

[Jeremy]

I paid $239, plus $60 shipping, for my 36V 10Ah LiFePO4, including a BMS and charger, which equates to pretty close to £150. Others on here are using the same packs, as are a lot of people on the Endless Sphere, and they do seem to be pretty good. I was lucky in that the package didn't get charged by customs, but if it had I guess I'd have had to pay perhaps another £35 or so in VAT and handling fees, still much less than half the price of those one's you linked to and with much greater capacity.

This thread: TongXin (a.k.a. Nano) motor project ) has some pictures of my bike project and the battery, as well as the specs.

The seller of these LiFePO4 packs is Li Ping, in China. You can buy them relatively safely via Ebay (his shop is here: eBay Store - PingBattery: 36V LiFePO4 Batteries, 48V 24V Battery, Electric Bike Scooter ). If you don't want to bid via Ebay, then if you email Li Ping he will make you a pack up and send you a PayPal invoice. He warned me a few days ago that the lead time for a new pack to order was around 10 to 15 days, as he has been selling a lot of packs lately.

Jeremy

[Syman]

Thanks for the info. I have seen these batteries and i dont think they will do for me. I am wanting to pull 33Amps. I seem to remember they can only do 10Amps. I have also seen people talking about them cutting out when to much power is demanded.

So do you think they would do 33amp?

[Jeremy]

The 10 Ah pack will deliver about 35 amps before the BMS current limiter kick in. This can be increased slightly, to about 40 amps, by slightly reducing the resistance of the shunt on the BMS (just a matter of applying some more solder to make the shunts a little shorter).

If you really only need 33 amps maximum, then the standard pack will be fine. The specs are on Ping's adverts, if you need confirmation of the ratings. Many have found these packs to be quite conservatively rated in practice.

Jeremy

[Syman]

Cool
I am thinking of buying one now. They say they can make a diffrent shape. I am gonig to ask them if they can do one that is 300 x 55 x 150mm fat, to fit in my bike frame.

Thanks

[Jeremy]

The base unit in these packs is a cell that is 135mm tall, 100mm wide and about 4mm thick. This is a 5Ah cell. The 10Ah packs have 24 of these cells wired as a 12S, 2P pack, making each 10Ah sub pack about 135mm x 100mm x 8mm. you also need to allow space for the BMS circuit board, which for a 12 unit pack is smaller than the footprint of one cell, but around 12 to 15mm deep.

Looking at the space you have available, I think you should be OK. You would need a pack that's made up of three stacks of 8 cells, laid side by side, with the BMS stuck on top. The basic stack of cells would measure about 300 x 135 x 40, with the BMS bringing the thickness up to about 55mm.

Jeremy

[Syman]

I will let you know how i get on. If i buy one it will be next month. When i get paid. LOL
Unless anyone wants to buy me one! I would tell all my ebike matts