Lifepo4

[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]

Originally Posted by aaannndddyyy

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]

Originally Posted by Syman

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]

Originally Posted by Syman

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]

Originally Posted by 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

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]

Originally Posted by Syman

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]

Originally Posted by Syman

.... 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]

Originally Posted by Footie

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]

Originally Posted by Syman

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???.