BMS, ac charger, Solar charger for 24v LIFEPO4

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witzgall
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BMS, ac charger, Solar charger for 24v LIFEPO4

HI all;
I am new to the forum, and new to LIFEPO4 battery technology. Jumping right in, I just bought into the group buy from evcomponents for 8 x 40ah cells. This will be used as a battery pack to power a Torqueedo electric outboard motor. The battery that comes with the motor is 10ah, this with I will have 4x the capacity.

I need to identify a BMS and charging methods/devices. For the BMS, I would like to find a solution that is reasonably priced, handles a variable voltage, and does not bleed off voltage as heat during cell balancing. Solar charing is an option for this, using a 60w Kaneka panel: http://www.affordable-solar.com/kaneka-60-watt.solar.panel.ika-gsa.htm

this puts out 60 volts. A BZ products MPPT50hv charge controller, which is settable to 12-24-48 volts, would provide the juice to the BMS.

On land, I could use a 120v charger as well. Perhaps a 15ah?

Anyone use this BMS? http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2480
Looks nice, except are those aluminum blocks shunts? The info on the web page is sparse.

Any help and insight would be nice.

Chris

reikiman
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Re: BMS, ac charger, Solar charger for 24v LIFEPO4

I'd say those aluminum blocks are heat sinks .. you'll note that there are transistor-like-objects bolted to the front of them. There are 16 total, or two of them per cell. I'm guessing this is a darlington transistor style BMS and hence relies on shunting power as heat during balancing.

witzgall
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Re: BMS, ac charger, Solar charger for 24v LIFEPO4

Yep, that is what I meant - heatsinks for shunting (is that the right terminology - shunting?).

THe reason I am interested in finding a solution that does not bleed of excess voltage as heat is efficiency. If I setup solar charging, getting the most efficient charging possible makes sense, as the power used is of a limited supply.

Is there anywhere I can read that is a good primer on LIFEPO4 charging and balancing?

Chris

KAE
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Joined: Wednesday, May 27, 2009 - 13:17
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Re: BMS, ac charger, Solar charger for 24v LIFEPO4

If you would like to order an active balancing (energy transfer) BMS board, I may be able to put one into my next order that I should be recieving in about 2 weeks. With 8 cells I'm assuming your running a 24V system, your charge voltage should be about 29.2 volts so running a 60V or 120V charger could seriously damage your batteries. An energy transfer BMS for 8 cells with a 50/150amp discharge rating will run about $90. Use the contact page at Kennedy Alternative Energy or contact me here if you have any questions. I have already placed the order so you must let me know soon if I am to modify it in time.

Feel free to let me know any other questions you might have.
There are other BMS available with lower discharge ratings and somewhat lower price depending on your system, however this is what I would recommend.

-Joseph Kennedy

Kennedy Alternative Energy
http://www.kennedyalternativeenergy.com

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