Battery shock!

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bigwow

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Just arrived at the boat, after 2 weeks away to find my battery meter showing 29amps. The bank is 400! The only thing left directly attached to the battery is the Stirling charger, but not pluged in at the mains as 240 unpluged. All 12v switched off. Anyone any idea what has happened, will the battery charger, wired in but not live have drained the batteries?
 
You mean it shows a net draw of 29A? You can be pretty certain it is not right! Firstly if anything were drawing that you would know about it and secondly it would flatten the batteries in hours.

perhaps there is a poor connection or some corrosion at the shunt - either that or the meter itself is faulty
 
I would tend to think the meter is correct.
29 Amps in two weeks is 2Amps per day, so we have a leak of milliamps something not uncommon. To make sure I would disconnect the negative pole and put the multimeter across the terminal and pole measuring Amps. You might read something around 80 milliamps. Switching off the circuits which are on, you end up to the leaky one –hopefully.
 
bigwow said:
It was showing 29ah when it is usually 400ah so the loss is 371ah with main switch off
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If, as you said, the only thing left connected to the batteries is the Sterling charger, then it's likely that the charger is faulty and has discharged the batteries. Disconnect the charger from the batteries, recharge the batteries with another charger, then leave them to see what happens.
 
I'll do that, trouble is I'm on the boat now for a week so no other charger available here. Stirling seems to think batteries full so is only producing a 2 amp float. Battery is now up to 119amh 29%
 
bigwow said:
It was showing 29ah when it is usually 400ah so the loss is 371ah with main switch off
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What is/was the voltage? What happened when you started charging them up? How long did it take to get the reading back to 400, (or how high did it get before the charge fell to only a few Amps?).

Were the batteries genuinely flat? Dim lights, inverter beeping a low voltage warning, etc.?
 
bigwow said:
Stirling seems to think batteries full so is only producing a 2 amp float. Battery is now up to 119amh 29%
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Obviously the battery isn't full. The Sterling charger has probably gone to float on a timed basis. Disconnect it from the mains, then reconnect it, and it should start bulk charging again.
 
jimking said:
Are you sure that the meter is zeroed correctly? If the batteries appear normal then it just might be a meter calibration problem.
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Meter has been fitted and calibrated for about 4 yrs, I don't think the problem is the meter, I've switched the charger off then on and it's putting in 7 amps, not good but better than 2, I think it's time for a new charger!
 
Probably worth checking the battery voltage. Disconnect the charger - put the batteries under a small load and wait a while, then check the voltage.

If the voltage is >12.5 you are fine and the battery monitor is wrong, if the voltage is lower (12-12.2?) then the battery may be telling the trut
 
bigwow said:
Meter has been fitted and calibrated for about 4 yrs, I don't think the problem is the meter, I've switched the charger off then on and it's putting in 7 amps, not good but better than 2, I think it's time for a new charger!
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Whats the chargers max Amps? Mine is 70A so, when it is only pushing 7A into my 330Ah bank, they are pretty close to full. In fact, when they are depleted, (voltage 11.8 or so), it runs at 70A for a long time - 2 or 3 hours?

If your charger has a capacity of only 7A, or 10A, then the story is different.
 
If the main switch was off, then the BEP monitor would not have been active and could not have monitored the use of current to give its 'guess' at remaining capacity. I would still suspect a misreading.
 
After disconnecting the charger put a load on the battery for a few minutes. Then measure the voltage with a volt meter not the battery monitor. That voltage reading will be very telling.
 
Keith-i said:
If the main switch was off, then the BEP monitor would not have been active and could not have monitored the use of current to give its 'guess' at remaining capacity. I would still suspect a misreading.
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Battery monitors are usually wired so that they're constantly powered, in order to maintain the memory.
 
pvb said:
If, as you said, the only thing left connected to the batteries is the Sterling charger, then it's likely that the charger is faulty and has discharged the batteries. Disconnect the charger from the batteries, recharge the batteries with another charger, then leave them to see what happens.
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The bilge pump should be connected as well - any signs that may have been running?
 
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