I have 2 12v 12ah lead acid batteries from an old scooter. They say they are 20 hour batteries on them. does this mean I can draw a maximum of 6 amps from them?
- posted
18 years ago
Maximum current draw from a battery
Loading thread data ...
- Vote on answer
- posted
18 years ago
The exact wording would be interesting to me. . .
If you need them to last for 6 hours, yes. Otherwise, no.
- Vote on answer
- posted
18 years ago
The normal method of calculating the ampere-hour rating of a battery is to determine the current which will fully discharge the battery in
20 hours - that is probably what the "20 hour" label on the battery refers to.Since the batteries are rated at 12 Ah, you can theoretically draw 0.6 amps for 20 hours, 1.2 amps for 10 hours, (or any combination of current and time that equals 20) before they are fully discharged - however, if you discharge a battery significantly faster than the 20 hour rate, you will get fewer total ampere-hours out of it than its rating suggests.
The maximum current you can draw will depend on the internal resistance of the battery, but will be much higher than the AH rating might suggest. A car battery might be rated at 60 AH, but will easily deliver a few hundred amps (for a short time) while starting the car.
-- Peter Bennett, VE7CEI peterbb4 (at) interchange.ubc.ca new newsgroup users info : http://vancouver-webpages.com/nnq GPS and NMEA info: http://vancouver-webpages.com/peter Vancouver Power Squadron: http://vancouver.powersquadron.ca
- Vote on answer
- posted
18 years ago
You can draw a huge amount of current for a brief time from a good 12 volt 12 ah lead acid battery. It is impossible to say, from the specs given, exactly how how huge, but *way* more than 12 amps. As an example, an automobile battery rated at say 60 ah at 12 volts can provide cranking current of well over 400 amps.
Ed