Battery Draw Down Question

Discussion about the OutBack Energy Cell Batteries
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outrigger999
Forum Guru
Posts: 105
Joined: Tue Oct 28, 2014 12:58 pm

Battery Draw Down Question

Post by outrigger999 » Mon Jun 15, 2015 11:55 pm

Hi Folks,

Can someone explain to me how battery strings are drawn down evenly? Is it basically that if each battery is healthy, that the internal resistance is roughly the same so the draw down happens evenly because of this fact? So if you have a bad battery in one of your strings, that will throw off the internal resistance of the entire string causing it to have an uneven draw down? If you have such a situation, what's the best thing to do to get them back in alignment (assuming that's possible)? These are AGM Outback RE200 batteries in case you're interested. I believe I have a bad battery but don't have the equipment to do all the testing. Of course I might need to just buy the right equipment however I'd like to hear from the community first what they would do to troubleshoot this situation. When I test my strings, one string is drawing down less then half the amps than the others.

Thanks for the insight in advance.

petertearai
Forum Guru
Posts: 397
Joined: Fri Aug 06, 2010 4:35 pm
My RE system: 2220 watt pv, fm80, outback fxr 2000 watt inverter. Shoto 12 times 2 volt exc400 lead carbon batterys 24 volt system victron battery moniter. optics RE
Location: NewZealand North Island

Re: Battery Draw Down Question

Post by petertearai » Tue Jun 16, 2015 2:04 am

Hi . Measure the voltage on each battery with no power being drawn into or out . Ideally disconnected . This should show you the problem battery . How many strings do you have ? . How are they connected . Getting parallel strings evenly connected can be a problem . Smart gauge http://www.smartgauge.co.uk/schems.html
Have good diagrams .
Looks like you have a amp meter , this is no doubt given you the clue as to which string the battery is in .
2220 pv. fm80. 12 times 2 volt exc shoto lead carbon 450 AH 24 volts. victron battery monitor. outback fxr 2000 watt inverter

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