Little-Acorn

It's a 4500mAh, 9.9V 30C LiFePO4 battery from Turnigy. 3S, 2P. Similar to a 30C LiPo, except these don't catch fire, puff, or explode. Hobby King has them in Hong Kong, I have one on order now, but Gawd knows when it will get here.

Link to it at:
http://www.hobbycity.com/hobbyking/s...dProduct=10310

The voltage is higher than a 7-cell NiMH or 2S LiPo, but lower than a 3S LiPo. I've used LiFePO4 batteries on electric bikes, and they are far more powerful than the alternative (Sealed Lead-acid batteries) that are sometimes used. I hope to find that they have the same power-providing abilities as a LiPo, though it's hard to compare them directly because the voltage is different from LiPo's. Hopefully my Slash 4x4 will be faster with this 9.9V LiFePO4, than with a 2S (7.4V) LiPo, though it probably will be slower than with a 3S (11.1V) LiPo.

The nominal voltage of a basic LiFePO4 cell is 3.3V, while the voltage of a basic LiPo cell is 3.7V, hence the difference in battery pack voltages.

Many people have found that their car is faster with a 2S LiPo (7.4V) than with a 6-cell (7.2V) NiMH, even though nominal voltages are almost exactly the same, because the LiPo can deliver a lot more current than the NiMH. I'm hoping that this LiFePO4 battery will have the same current-delivering capability as the LiPo, and make the car just as jumpy... more jumpy, in fact, since the voltage is higher than the 7.4V 2S LiPo. But probably not as jumpy as an 11.1V 3S LiPo, since that voltage is higher still.

This LiFePO4 is rated at 30C, meaning a 4500mAh battery should be able to deliver 135 Amps continuously. Hobby King claims it can surge to 40C for 10 seconds, meaning 180 Amps(!). I guess I'll find out soon if it's true.

Anybody tried one of these?

BuggyKing

iTrader: (17)

I havent but know about of people who do and like them. The only thing is they do not have a hardcase. So just be careful and get them punctured.

Duster_360

iTrader: (21)

Few of the guys in Monster Truck forum have run them. They apparently need a breakin, these are not the orig a123 type cells which didn't need breakin (a123 patented that forumla), like 20-30cycle breakin period. Don't discharge more than 50% and don't charge at more than 2C during breakin. The Protek LiFes say not to charge at more than 1C during breakin. These also seem to have the rep of puffing for no apparent reason.


One of the lipo testers on RCG had one puff on him...

shanty140

iTrader: (5)

+1

I have seen two of these batteries puff and they were only had like 5-10 cycles on them.

kufman

iTrader: (6)

I had the 2S version and it puffed on the 4th cycle. I set my cutoff too low because I didn't know they needed to be broken in. A123's are better batteries in my opinion.

Buzzerbro

iTrader: (9)

I bought one of these for my Traxxas Rustler VXL and they are great when new. Tons of current. After about 5 uses it would no longer take a full charge and over time its capacity decreased. Now after about 20 cycles it has puffed.

I also have the 2S version and they are still holding a good amount of capacity however they have swelled slightly.

By the way, I was not aware of a breakin procedure when I first got these so they may have contributed to there poor performance.

Duster_360

iTrader: (21)

Thats what the Protek instructions tell you - that without breakin, they will not live up to expectations.

"NOTE: Brand new LiFePO4 batteries have been found to fail prematurely if they are deep discharged below 3.26V per cell (below 33% capacity) too early. A break-in period of 20 cycles is currently recommended. While testing has shown that this battery can be charged at up to 3C rates, it is recommended that this battery not be charged at rates higher than 1C to maximize the lifespan of the battery. Additionally, LiFe batteries should not be discharged below 2.5V per cell to avoid pre-mature failure and maximize battery life span."


Somehow its not surprising that Turnigys LiFes don't come with any warnings or instructions....