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The usual recommended charge rate for most lead-acid batteries is 1/10 of the rated amp-hour capacity. So a 5 amp charger would be about the right size. Now for the rest of the story:
The more discharged the battery is, the slower you want to charge. Within large limits (self discharge rate), you can't charge too slow. If time is not a factor, I would recommend a 1 amp charge. It'll take 2-3 days to fully charge, but the battery will be healthier.
Having said that, the amp-hour capacity is a good rough guide to charging time. If you're charging at 1 amp, the battery should reach full charge in 20-60 hours, depending on depth of discharge and such. The low current involved means that you won't hurt anything by leaving the charger on for the whole 60 hours. After charging, top up the cells with distilled water as necessary (shouldn't need much).
Charging at 5 amps, you'll want to take it off charge no more than 8-10 hours after start. The best way to check is look for a voltage of above 13.2 volts across the terminals. This means that the battery is as charged as it will get, and you are now hydrolizing the water in the electrolyte instead of charging the battery.
An excellent way to limit the current throughput of a big battery charger is to put a 12 V (or 6v, if that's your flavor) light bulb in series with the charging circuit. Smaller wattage lightbulbs result in a lower maximum current. This will make nearly anything into a 'float' charger that can be running unattentded for several days before you plan on starting your HMV.
-Rad Davis
Gavin Broad <invest@portsmouth-mann.com> wrote:
Gentlemen,
At 5 amps, for how long should one charge a 12 volt, 50AH battery, assuming
it has been run very low?
Thanks as always.
Gavin
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This archive was generated by hypermail 2b29 : Mon Feb 21 2000 - 18:15:06 PST