Battery load or battery leak?

[jimthom]

My Bluesky solar controller is showing a -.3amp battery drain, this is a concern on a steel boat. I was worried that I had a DC negative leak. This leak could only come from my house batteries since there is no connectivity with these circuits and the engine electical system.

I was hoping someone could confirm my premise that this -.3 amp is an unknown load rather than a leak.

Premise is based on lifting the boat from the water there was no sign of electrolysis (particularly apparent with copper-base anti-fouling); the display was still showing a -.3 amp discharge.

I think the display would show 0.0 amp if it is a leak, as once the boat was removed from the water there wouldn't be place for the DC negative to leak to. Boat is on isolated stands.

Thank you,
Jim Thom

[Zil]

DC can only "leak" from battery to battery, not away from the hull. Have you tried disconnecting circuits?

[noelex 77]

It is probably the self consumption of the controller.it is also possible it has drifted out of calibration. Its hard to measure these low currents accurately with something that will also read high currents.

Try turning everything off and measure the drain direcly at the batteries. A clamp on multimeter is ideal. You can use an ordinary multimeter by disconecting one of the battery leads and inserting the meter in series. Be careful most will only measure a maximium of 10A so make sure you have not left anything on.

If there is a drain double check everything is really off (stereo memory circuits etc). Then try turning on each circuit breaker and checking there is still no load (providing nothing comes on automatically)

[djmarchand]

0.3 amps isn't very much. It could be as simple as having incandescent indicator lights (yes I know, some are leds, but some are incandescent) on the DC panel. Smoke/CO2 detectors are another culprit.

David

[The Garbone]

The memory (always hot) on my FM stereo/mp3 player pulls .25Amp.

[jimthom]

Thanks to everyone for their help. My OP was a little misguided as I realize the Blue Sky could never measure a leak; it only relects what is going on within the circuits. I did use an ampmeter in series with the hull and battery terminal and it indictacted 1.1 microamperes.

I was more concerned about the possibility of a dc leak than an unknown load as I have seen what electrolysis can do to a steel boat and I'm going back into the water tommorrow. I'll systematically suss out the mysterious -.3A later and hope the solar panels can keep up with it in the meantime.

Cheers,
Jim