Are Tenergy LifePo4 batteries any good?

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lehula
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Are Tenergy LifePo4 batteries any good?

I have been cruising around ebay for LifePO4 batteries because I want to build an electric skateboard. I came across some Tenergy batteries. http://cgi.ebay.com/3-2V-10Ah-Lifepo4-Lithium-Iron-Phosphate-Battery_W0QQitemZ260390761948QQcmdZViewItemQQptZLH_DefaultDomain_0?...

The shape of these batteries appeals to me because I'm building a skateboard. Also, of course the price. The cheap price of these batteries makes me question their integrity. I wrote the seller, asking if these are just chinese junk batteries, but I never got a reply. Has anyone used these Tenergy batteries. Let me know what you think of them. Thanks.

Also, any suggestions on my electric skateboard building, would be appreciated. I going for a 36 volt 800 watt build I think.

dogman
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Re: Are Tenergy LifePo4 batteries any good?

An 800 watt skateboard is big enough to need a good lifepo4, not just a few cheap cells in a small amp hour size. To have the pack last, you should use something that could drive a similar wattage bike. Usually this means about 10 ah of cells unless you are using more expensive stuff. If it is for short rides, then you might want to look at higher discharge rate lipoly, found in the hobby stores for helicopters and such. That way you can still have a small pack, lotsa power, and less money going out. The downside is having to charge carefully, in a place that won't burn down. They have fireproof bags for that though.

Edit, Just back from the site, actually those aren't bad looking cells. I was thinking you were looking at cells in the camera size. You'd need 12 of em, a bms, and a charger that goes to the right voltage. Don't even think of no bms. It might be easier to just order the same thing, assembled, with a charger and bms from high tech bikes, or pingbattery. At 8 pounds, you could easily carry it in a backpack.

Be the pack leader.
36 volt sla schwinn beach cruiser
36 volt lifepo4 mongoose mtb
24 volt sla + nicad EV Global

Nigel
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Re: Are Tenergy LifePo4 batteries any good?

Hi,

I would recommend 10Ah Headway cells (12 of them) + BMS rated at 30Amps constant 50Amps peak .... or at least 15AH (20 is better) pack if you are using smaller 3Amp cells paralleled up ....

The standard BMS's that come with some of the smaller skateboard LiFePO4 packs don't last to well due to the high current drain the skateboards have.

Example: I run 36V 20Ah LiFePO4 packs in my boards and the BMS's have to cope with 25-30Amps constant, and 50Amps peak (when you're climbing a hill). With some of the 10Ah packs, the standard BMS's have the constant set at 20Ah and the peak set not much higher at 35Amps (approx).....also, they have a low cell group voltage cutout (when one of the groups of cells ... most 36volt packs have 12 series) drop too low, which happens under high current drain .... a couple of good hill climbs and they cut out everytime (I know from experience). And once they start cutting out 9/10 of the cheaper BMS's don't recover, ie you end up bridging the BMS to get them to work again :(
I've used 10Ah, 12Ah, 15Ah and 20Ah packs in my 800watt boards ..... and the only ones which have delivered constant results have been 10Ah Headway cells, or at least 15Ah packs (if you are using 3Amp cells), but either way the BMS's have to be sized properly :)

Hope that helps

Cheers
Nigel
www.greenskate.co.nz

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