"It has to do with voltage under load."
maybe you should explain that -- to the Trojan battery company, who would disagree with the proposition that 7.5V will fully charge an 8V battery ... modern battery chargers have stages, bulk charge [current is sent to batteries at the maximum safe rate they will accept until voltage rises to near (80-90%) full charge level], absorption charge [steady high voltage, current drops as internal resistance increases], and float charge [maintenance trickle charge at
rated battery voltage, or 8.5V in this case], most 6V chargers can not achieve a float rate of 8.5V, although most could charge an 8V battery to 80-90%
I think some people who
think they understand electronics make stuff up, other folks with extensive electrical/electronics experience, who have to spend over $1,000 for a bank of batteries, and another $2,000 for an inverter/charge controller, not too mention the cost of PV panels, investigate the specifics to insure none of those are a frequently recurring cost
8V batteries are sold at Tractor Supply because they're tractor batteries, but even there it was the Ford tractors that benefited from them, and really only in the harshest winters, Chev trucks work fine on 6V if the proper cable sizes are used [#0 minimum, 00 preferably] rather than the standard 12V cables [#2, or even 3] found most places now, which is where "voltage under load" is relevant .... I don't think I've ever seen a "show car" with an 8V battery, although some rarely used trailer queen museum pieces might take that route, and no doubt they've adjusted the regulator and/or have an 8V charger at home
to
fully charge a lead acid battery, you want to charge to 2.4 volts per cell, an 8V battery has 4 cells, that means it needs a charging voltage of 9.5V - a 6V charger will not maintain an 8V battery, a 12V charger can be used on an 8V battery, if put on trickle charge [2-5amps] for maybe 30 minutes, then allowed to 'rest' 30 minutes - repeat until the 8V battery shows 9.5V while charging, and 8.5V after resting for 3 hours
but now this thread should go to the Electrical Forum
Bill
