Michael Hoskinson wrote: > I have a question about buddy pairing batteries. I have 16 free > Hawker 26 Ah batteries,, and 10 Panasonic 17Ah, for a 96 volt pack. > The Hawkers are used, but the Panasonics are unused, though 2 years > old. I was planning to buddy-pair just the Hawkers for my test pack, > but I'm wondering if I can incorporate the Panasonics too.
Buddy pairing identical lead-acid batteries is fairly trouble-free. Voltage and internal resistance change with state of charge in such a way that they tend to settle out at the same state of charge, and share the load in proportion to their amphour capacity. Buddy pairing non-identical batteries is quite a bit more problematic. Differences in temperature, age, and type of battery mean they will NOT generally be at the same state of charge at the same voltage, and will NOT share the load equally. So, you would need some kind of monitoring and charge management system to detect and correct imbalances between the batteries. This could mean measuring their individual voltages and charging them individually as needed to maintain balance and warn you of excessive discharges, or an automated system to do it. Otherwise, you're going to find one of the pair going dead and failing while the other one still has charge left. > I plan to use one of the 17Ah Panasonics for a 12 volt auxiliary > battery, charged with the DC/DC converter. (Please steer me right > if this is not a reasonable idea). This is perfectly reasonable, as long as the DC/DC converter's voltage, current, and the time it is applied are reasonable for the battery. Remember that DC/DC converters are NOT battery chargers. -- Lee A. Hart Ring the bells that still can ring 814 8th Ave. N. Forget your perfect offering Sartell, MN 56377 USA There is a crack in everything leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
