testing batterys
Submitted: Saturday, Dec 18, 2004 at 13:56
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Member - Brian (WA)
Hi all. Just checked my deepcycle batt. two multi meters, one read 12.60 one
12.57. I then checked it with a hydrometer.and got readings of between 12.80
and 13. in each cell. what would be the state of chagre? the hydrometer is about
12yrs old can these go wrong.
cheers brian
Reply By: Mike Harding - Saturday, Dec 18, 2004 at 14:30
Saturday, Dec 18, 2004 at 14:30
You really cannot rely on the voltage of a battery to accurately reflect it's state of charge.
This link gives good info. on using a hydrometer:
http://www.uuhome.de/william.darden/carfaq4.htm#hydrometer
Mike Harding
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Reply By: Magnus - Saturday, Dec 18, 2004 at 22:12
Saturday, Dec 18, 2004 at 22:12
Check out the download at this site to be confused a little more. There are various State of Charge tables available which will give an indicator of the charge in your battery.
Magnus Home page
Hydrometer readings are the best, but you need to know other factors for them to be accurate eg Temp, how long at rest etc. There is plenty of info available on the net on this subject including the one already referred to.
I use the SOC tables in
camp to keep an eye on the battery in my CT.
Cheers
Magnus
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Reply By: Member - Jeff M (WA) - Monday, Dec 20, 2004 at 11:56
Monday, Dec 20, 2004 at 11:56
Also Brian, it depends on how good your multi metre is! Some of these cheapies are so far out they're dangerous IMHO.
I've got a couple of reasonabally cheapies but I have tested them against my brother FLUKE and they are very close @ 12vDC (which is what I use it for 99% of the time) so am happy with them, however a mate of
mine's cheapie (from supercheap) is 0.5 of a volt out @ 12vDC. That's a fairly big marigin of error, especially when you are testing for voltage drop etc.
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