Sunday, Jul 27, 2014 at 20:59
Remember any state of charge readings need to be with the battery in a resting state and at a known and corrected temperature.
If the battery is under charge or under load the state of charge readings will be misleading to say the least......for any sort of meaning the battery needs to be rested at least an hour before measurement...no load no charge...for real accuracy think in terms of 4 pluss hours.
remember a battery is not a bucket and state of charge by measuring voltage is an estimation.
Also temperature has a great influence on battery performance and measurement.
Lead acid batteries are happiest at arround 25C.....higher they suffer from life shoteninmg effects, below that their capacity to deliver drops rapidly till arround 0C that will typically produce bugger all.
If you want to get some sort of idea of these influences, you need to go to one of the better battery manufacturer sites that show a full spec seet for their batteries ( not most car battery sites).
There you should see curves for state of charge corrected for temperature, battery capacity V temperature and a whole pile of other stuff.
You have a bank of 4 batteries..are they 4 x 12 volt batteries all in paralell or are they 4 x 6 volt batteries in series paralell.
either way, from time to time it is wise to seperate the batteries and apply an "equalising" charge and
check the condition of the batteries individually.
You can do some basic tests with a decent voltmeter....but for anything realy meaningfull you need to
test the batteries under load with some sort of loading battery tester like a battery analiser or a carbon pile ammeter.
I realise most people don't have these lying arround.....but most good battery shops should have them on hand.
ONE big trap with battery banks is wiring them all from one end of the bank......even though the connecting straps are heavy, the battery nearest the lead in will do most of the work and have a shorter life than the rest.
so it is wise to wire positive from one end of the bank and negative fromthe other end of the bank....with a 2 battery bank it more or less stops there.
if you have 4 batteries in paralell it is wise to rotate the batteries from time to time inners to outers.
paralall battery banks most certainly need attention and maintenance if anything other than a short life is to be expected.
Remember the basic design life span of a lead acid battery is two years.......improved technolgy can extend this quite a bit as can carefull attention.....but the basic design life span remains.
remember also..with apprpriate abuse the life of a typical battery can be reduced from up to 5 years to a matter of weeks.
cheers
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