Voltage Fluctuations

[adaml]

Battery Guru's can you help with this dilemma?

I have a 12v system, 500A/hr, bog standard car batteries as I can get these free.  I added two more to my bank but noticed a strange thing.  Good wind this weekend and turbine was putting out 10A plus.  Watching the volt meter the voltage reading was dropping as the amps going into the bank was increasing.  I would have thought this should have been the other way round.  One battery may have been on the way out and was hot to touch so I removed this but this phenomenom still persists.
Is this just the bank equalizing or is there a more fundamental problem/error?
Any input as always very much appreciated.

[DamonHD]

It might have been the other way round, ie the battery voltage was decreasing for some reason by itself (eg internal short) and that was allowing more amps to flow into the battery (greater voltage drop from the source).

I'm not saying that's what was happening, but I think it might get in the way of finding the answer to assume a particular direction of causation, if any.

Rgds

Damon

[wooferhound]

Where is it exactly that you are measuring the voltage ?

[adaml]

Thanks for the response guys.
I have a digital volt meter that is connected at each end of the bank.  I was also checking each battery with a mulit-meter, this was what led me to believe that on of the batteries in the bank was on the way out, plus the fact it was gassing and very warm to the touch.

[Rover]

Is it possible your metering equipment is wrong? Especially whatever you are using for curent monitoring.

Please give us the voltaget hat you measured. If it was above 13.5  V, the gasing at 10 amps in is expected.

What are the condition of the batteries? age? last time you looked at electrolyte level ?
Do you have a dump controller? any kind of controller? .. Have a controller between the turbine and the batteries?

[adaml]

Yes, I have a Ghurd controller on my bank.  Bank voltage was about the 13.28 mark.  I disconnected all batteries and tested each individually with a multi-meter.
I have never tested the electrolyte levels, no equipment to do this.  I do try to check that the water in the batteries is properly covering the plates.  Batteries are approx three years old.  I have never let them fall below 12.6v and they do not see that much use.