Lifepo4

[semmel]

Please be careful, (technology or type of product)

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]

ThunderPower TP6000-5S3PL battery

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]

£150 !!!!

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: http://www.pedelecs.co.uk/forum/electric-bicycles/1193-tongxin-k-nano-motor-project-17.html ) 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]

will the battery deliver 33AMPS plus?

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]

thanks

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]

thanks again

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

 

[aaannndddyyy]

Hi Syman I texted ping the other day (22/4/2008) about getting one of these batteries, he replied
“For now, we don't have more 36v10ah for you. Because recently we are short of LiFePO4 cells. So, we have to save our remaining stock for ebay auctions. I think the lack of cells will last about 4-7 weeks. The price is 239usd+70usd shipping fee to UK, directly transaction through PayPal. If you still want the pack, please let me know. I will inform you as soon as we have plenty of cells.”
Ebay prices are rising due too the many bids on each indivual battery, it looks like you will have too order in advance if you don’t what a bidding war.

 

[Syman]

Hi see there are Li Iron Phosphate (lifepo4) 36volt 10amp batteries on EBay for around 250 pounds with charger plus delivery, eBay UK Shop - PingBattery: 36V LiFePO4 Batteries, 48V 24V Battery, Electric Bike Scooter that’s in the same price bracket as NiMh and li-ion manganese . lithium iron phosphate (LiFePO4) batteries, or nano lithium-ion batteries as they are sometimes called, are the newest generation of rechargeable batteries on the market.
There are three types of lithium ion cells based on different cathode materials. They are lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate types. Although lithium cobalt oxide cell has the advantage of high energy density, it suffers from safety concerns. Lithium manganese oxide cell has been evaluated for the application on high rate due to the better safety characteristics. However, its high temperature performance is the major drawback and experience from a lot of members on this forum a short life cycle. While Lithium iron phosphate cell has the best safety characteristics, long cycle life (up to 2000 cycles). It is very suitable for high discharge rate occasions such as EV.

How many people have one of these batteries? I think there need to be quit a few people buying these batteries befor they should be trusted. How Easy is it to post a good review of something your selling! I am not saying anyone on here is the seller, but that sort of thing has happend in the past. 2000 cycles!! Every other batterie like this says 300 cycles. Why?

 

[john]

How many people have one of these batteries? I think there need to be quit a few people buying these batteries befor they should be trusted. How Easy is it to post a good review of something your selling! I am not saying anyone on here is the seller, but that sort of thing has happend in the past. 2000 cycles!! Every other batterie like this says 300 cycles. Why?

I think the number of cycles is referring to the chemistry, LiFePo4 as opposed to other lithium chemistries, which have been tested by other suppliers (A123 I think). It remains to be seen whether this supplier's product lives up to the same cycle life.

It could be that as their reputation is established then their price goes up?

 

[aaannndddyyy]

How many people have one of these batteries? I think there need to be quit a few people buying these batteries befor they should be trusted. How Easy is it to post a good review of something your selling! I am not saying anyone on here is the seller, but that sort of thing has happend in the past. 2000 cycles!! Every other batterie like this says 300 cycles. Why?

Here are a few places too look for answers.

Endless-sphere.com • View topic - Duct Tape E-Bay Lifepo4s???

Batteries and Chargers | V is for Voltage Community

plus this forum .

 

[Syman]

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

I dont think your reply is right. I have looked at the spec and the only do 10 amps not 40amps. This battery is no good for any bikes that need a lot of power. Though they say they can do 40amp bursts they will NOT run at 35amps or 40amps for any lenth of time.

 

[aaannndddyyy]

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?

PingBattery LiFePO4 are rated at 2/C continuous and 4/C for short busts, so if you require a continuous 33 amps you will need a minimum 17 amp battery, I would suggest one of the 20amp batteries which will cope with your requirements without putting a strain on the cells or bms.

 

[Jeremy]

Syman,

You can choose to disagree with me if you wish, but I do actually run a bike with a 36V 10Ah Ping pack, so can discuss it with the benefit of first-hand experience.

The cells are rated at 2C continuous, as has been mentioned, but will quite happily deliver at around 4C without any problems. They stay cool, even at 4C discharge rates, in fact. I tried the battery on my Crystalyte motor last week, just as an experiment. This motor pulls around 35A from the pack at full throttle. The pack coped with this load without a problem, although the BMS did limit a couple of times.

Several people on the Endless Sphere have happily run the cells at up to 4C or more and not had serious problems. The cell weak points are the connection tabs, not the chemistry. These are fairly fragile and one ES member managed to burn through a tab when he took the BMS off and pulled 50 or 60 amps from a small pack.

I am not sure where you are getting the information that states that these packs are only OK for 10A. It certainly is not mentioned by Li Ping in his data, to the best of my knowledge.

Jeremy

 

[Footie]

.... 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 ....

I don't see where your getting the 10Amps limit from either.
Your not confusing amps with amps hours are you?
When I ordered my LiFePO4 battery from ping (36 volts, 10 amp hour) I told him my main fuse was a 25 amp so he set the BMS for a continuous discharging current to about 25 amps.
I have ridden up some monster hills, including some that stopped me dead and I had to walk - not once has my battery cut out under load.
.

 

[Syman]

I don't see where your getting the 10Amps limit from either.
Your not confusing amps with amps hours are you?
When I ordered my LiFePO4 battery from ping (36 volts, 10 amp hour) I told him my main fuse was a 25 amp so he set the BMS for a continuous discharging current to about 25 amps.
I have ridden up some monster hills, including some that stopped me dead and I had to walk - not once has my battery cut out under load.
.

I have found some one that has tested the battery. Load test on pingping 36v10ah battery | V is for Voltage Community
I think it say it all. Dont buy these batteries if you need any power!!

 

[aaannndddyyy]

I have found some one that has tested the battery.
I think it say it all. Dont buy these batteries if you need any power!!

Syman.
Let's get this into perspective,you do not own one of these batteries you ask questons then dont listen to the people who are using these batteries, have found one negative post amongst hundreds of positive ones on a different forum,so now feel qualified to give advice???.