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madscientist267
Apprentece
7 Posts |
 Posted - Sep 16 2008 : 2:44:01 PM
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I would look into balancing if you're going to have that many batteries in series. Thats a total of 78 2V cells, and as any one (or more) of which begins to have different SOC or SOH (due to snowballing imbalances), you'll ultimately end up with a really nice set of paperweights suitable for nothing more than holding down the library of congress.
Depending on your use case, you might want to consider something more resembling smaller, individual chargers for each battery (or at least pairs), each with their own regulation. The better the balancing, the longer the lifespan of the entire bank.
There are other benefits to running individual chargers; the least of which is that a single component failure somewhere doesnt require a single expensive replacement (bridge, transformer, etc).
Either way, you're right; you will need a bit of power to charge them all, but if you go with individual chargers, the only thing you'll really need to make sure is 'beefy' is your mains feed.
One other note - depending on exact chemistry, 14.5-14.9V is ok for cyclic use, provided the time is limited, and the temperature of the batteries monitored. If you intend to have them waiting on standby, you should allow them to float much lower, somewhere between 12.9 and 13.2. At higher voltages and temperatures, cells gas excessively and plate warping can become a problem, ultimately destroying the batteries.
Speaking of gassing - This many batteries on charge (and even discharge depending on rate) produces serious amounts of gas even during NORMAL charge - Hydrogen accumulation becomes a very important consideration. Don't do it in an interior space without significant amounts of ventilation, unless of course you don't really value the structural integrity of the interior space in question, and anyone anywhere nearby. :)
Steve
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If it aint broke, fix it anyway; there's always SOMETHING wrong with EVERYTHING. |
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Car Battery Charger
