72v 12.8Ah (60 Amp) pack from Batteryspace

Now that they've started selling 24 cell LiFePO4 (and LiPo) BMS's, Batteryspace.com now has a 72V LiFePO4 pack for sale (as well as several other smaller sizes). The BMS they are using limits it to 60 Amps discharge, and it looks like the continuous discharge rate is around 50 Amps (based on the specs of the cells, they could use the 100 amp BMS they have, but that would be cutting it a bit close).

The price works out to $1.40 per Watt Hour (not including shipping or charger).

The size is also not bad either: 12.5" x 4.3" x 5.5"

http://www.batteryspace.com/index.asp?P ... rodID=4990

They are also selling some LiiMnNi3 cells (some in hard packs with screw terminals).

http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=1437

Anybody know the quality of their lifepo4's? Doesn't seem like to bad of a deal with that 60 amp discharge and 12ah. It would cost me more to do it in A123s and I still have to build it. Not a bad charger at 6 amps but the link takes you to the 48v charger.

So those are 48 6.2 ah cells in the pack in the pic? That sure beats 18650's where you have about 300 spot welds. Theoretically that pack would run a clyte 5304 on 72volts. Buy it and let us know for how long. The trouble with this stuff, is it can take years to know if it really lasts for thousands of cycles in the real world. We are a legion of beta testers. Most of us on ping packs are still under half the expected cycles.

Just got back from a look, WoW, they really improved thier lifepo4 offerings! Looks like you can get good chargers too without waiting for shipping from china or paying a ridiculous price. Lotsa decent looking individual cells, including ones that may be similar to pings. Nice. This is the stuff we've been waiting for, real avaliability and enough competition to drive prices down. If it comes, we'll build it.

Looking some more on the 72v pack, its 60 amp cutoff, not 60 amp continuous discharge, a bit of difference... I don't see a c rate spec on the cells inside, but I do see there are 96 of em. Still a lot better than several hundred 18650's but not as nice as a big prismatic to my mind. Assuming these cells can take 2c and last, you'd be pretty ok with a 20 amp controller, Just like you might with a ping, but I still like the idea of a bigger pack to run a 5304. Or a better cell if these are 2 or 3 c type. looking more... I only see a 1 c test, so once again, we get to see for ourselves if we exeed 1 c. Still looking some more, I see other cells with clearly better c rate, and three times the price, so I'm gonna say that these don't compare with A123 or PSI, but maybe compare with Ping for discharge rate. Better buy two packs for a big motor, but $2500 ouch! I guess we're still waiting for a price drop on the cells.

With the cells they used and the configuration (24S4P, 3.2 AH), the continous discharge rate would be around 50 Amps. Max discharge rate would be just over 100 Amps (without cutoff) - according to the datasheet for the cells.

However, the dataseheet is a bit conflicting: They have both a "recommended continuous and maximum" as well as "maximum continuous and maximum" rates

http://www.batteryspace.com/prod-specs/4796.pdf

I could not handle those prices!

I'll take my $0.18/wh konions any day (that isn't even including the extra cells I have laying around for other projects).

tostino said:

I'll take my $0.18/wh konions any day (that isn't even including the extra cells I have laying around for other projects).

Click to expand...

Yeah.. :? If I had the money though I would never build a custom pack. It's an exercise in extreme patience. At least you learn about the inner workings of stuff along the way though. I really wish someone offered a turnkey and affordable 20s Lipo charger. *sigh*

So what's the cycle life at 60 amps? 1000 cycles or 10? I'm confused, if the pack is 72v 12.5 ah isn't the 1c rate 12.5 amps? So what's the cycle life gonna be at 5 times the tested rate? The other cells, that sell for about $40 look like the good ones. I wish I was rich so I could afford to be the tester of this stuff.

From those discharge graphs it looks like you shouldn't really go over 10 amps per cell so with 4 parallel it looks like 40 amps continuous would decent. There is some major voltage sag on those cells.

you can build your own 48V 20Ah cell from prismatic cells for 900 bucks!

Or buy from ping for about 700. They seem to spec out about the same. Still, its an improvement for batteryspaces offerings.

Weight specs look good. Shipping is only $12 which helps but still makes it more than Ping but, if it really can throw the amps, I might give it a torture test. Do you think you could put one of these (actually the 48V 10 aH) in parallel with a Ping? I'd use it both as a short trip battery to torture it and in parallel (x2 if I like it) with a 20aH Ping. 40 aH @ 48V w/5303 = 60+ miles @ 25 MPH average...