Help with C-LiFePO4 battery

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Mettleramiel
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Help with C-LiFePO4 battery

OK, so I got this PHET battery for free from work the other day //img227.imageshack.us/img227/3617/dsc03031s.th.jpg). Looking online, it appears to be 24v 10ah C-LiFePO4. Now, I need a little help with it.

First off, I would like to test it to see just how much capacity it has. At work, we have what is called an "Alphabat" made by Emrol. It's a load tester for deep cycle batteries. Basicly, you input the rated AH, and the machine puts a constant load on it until the battery is dead, then it gives the battery a percentile grade based off of the rated AH. Problem is, I don't want to drain the batteries too far and destroy them as I know can be done with LiFePO4. Does anyone know what would be a good voltage cut-off?

The other problem is that I don't have a proper charger, how can I go about charging the battery (just for testing purposes) without over or undercharging. If you look at this picture, I took her apart and I can't see any BMS //img52.imageshack.us/img52/3050/dsc03030np.th.jpg). Don't I need one or is it just hidden from me? I have 12v automotive chargers and 24v SLA chargers on hand.

Last question, I know lots about SLA's, but I'm a complete newbie with Lithium. Currently, I have 48v20ah of SLAs on my scooter, from what I understand, 48v10ah of LiFePO4 should give me about the same range? I ask because if that's the case, I can get these 24v10ah batteries from work for $400CAN with a 3 year warranty, so adding the one I already got, I think that would be a pretty good deal. Personaly, I'd rather wait for another free one to come in, but I've been waiting for this one for 2 years. Thanks for the help!

proton
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Re: Help with C-LiFePO4 battery

strange no bms..
you'll need one, or, use a cell meter to monitor the groups in the pack, to stay above 2.4/2.5v each group
I have a 24V 5A lifepo4 charger if u need one
www.falconev.com

The LiFepo4 BattMan www.falconev.com

procrastination inc
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Re: Help with C-LiFePO4 battery

that looks like 8 cells in series, 4 parallel. Nominal 24V, must be about 2,5AH cells. ( I just looked at the full size pic... forget those cell counts )

Surely there is a low voltage cut off some where in the pack. Though I imagine it will cut of on "high" current too.

The Radio Control guys use a nice little charger, I Max B8 that could look after this pack. You would have to tap in to the battery to fit a balance plug and they are a bit expensive but I think worth it if you work with packs under 24V. I have an old B^ that I use alot.

Now these have a discharge function that will run the pack down to the end and monitor each cell as it goes. It displays the mAh discharged. I have seen 33000mAh in a deep cycle lead acid, so it should handle 10Ah easily. This charger also balances cells on charging.

mf70
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Re: Help with C-LiFePO4 battery

I can get these 24v10ah batteries from work for $400CAN with a 3 year warranty,

If I were you, I'd head down to the Purchasing Department with a plate of cookies (or equivalent) and become someone's Good Friend. Whoever is supplying this battery will also have both a data sheet and a charging system. The charger is probably overpriced, but the data sheet will tell you how to treat them.

Then you wander over to Engineering with a second plate of cookies and see how your company treats these batteries. Where's that test article that isn't needed anymore?

Mark

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