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Help With Draining Batteries

Sam B

Dec 22, 2016
2
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Dec 22, 2016
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Hello Guys! For a project, I need to drain a large 12V battery down to 11V (but not below) at a constant load of 24A in order to condition the batteries for maximum performance. I have a few ideas on how to do this, but thought I would ask the pros for some advice and probably some criticism (be gentle):
  1. Put the battery in series with a massive resistor and a heatsink and attach a voltmeter in parallel with the battery to monitor its voltage.
  2. Find a Voltage regulator and heatsink large enough to cope with this kind of power and attach a volt meter in parallel with the battery.
  3. Hook the battery up to some big halogen lights and do aforementioned with the volt meter.
  4. Do any of the above with a way to automate the voltage monitoring process.
Any advice is welcomed :)
Regards
Sam B
 

cjdelphi

Oct 26, 2011
1,166
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Oct 26, 2011
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1,166
How complex?

How about putting the wasted energy into something useful, yeah good question lol

24amps is a lot of current (24*12) 288 watts, maybe use two or three or four peltier (thermo electric) devices, eg to cool your beer on waiting for it to reach 11v

(Opamp/voltage comparator/micro controller to determine 11v and cut out the current)
 

duke37

Jan 9, 2011
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Jan 9, 2011
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5,364
No pro here.

Bulbs for a load would be the best since you do not have to supply a heat sink.

A voltage reference and a comparator to turn off the load would be simple to implement. A timer connected across the load would give battery capacity.

A switch would be needed, this could be done by one or more fets but a fat relay may be more suitable.
 

Bluejets

Oct 5, 2014
6,901
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Oct 5, 2014
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6,901
As Duke says, you will get approx 8amp load out of each 100w auto headlight bulb.
Current will change as voltage drops though.
If it's a comparison reading over several discharge periods then time record would be fine so long as you drop out the discharge at a given voltage..
 

Sam B

Dec 22, 2016
2
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Dec 22, 2016
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2
Thanks for all of the replies, I thought the lights would be the best option, just wanted a second opinion. I will probably do that and hook up a pass-through hall effect sensor to an arduino or raspi to monitor voltage.
 
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