Off grid house - Does anyone know how to find short circuits affordably?

[Listener2307]

Originally Posted by hapci534

I have an off-grid house, 6 batteries of 1350 Amp hours total feeding and inverter and then a grounded electrical box that supplies a conventionally wired house. Everything works fine… until a big rain comes. When rain hits, battery charge goes down from 80% to 0% in about 15 minutes. I see no arcing anywhere, no bursts of noise (though I don't visit the attic much) but the water is clearly causing some sort of slow discharge somewhere. Is there a way to track the issue down without spending half a grand?

During the recent big rain, I experimented by turning all the circuit breakers off, energizing lines one by one with no appliance running and watching the battery charge percentage change. Some lines lost 0% of charge. The longest line feeding my cable modem’s wall plug in the farthest corner lost 13% battery charge in 5 minutes. Cowabunga! But next day a 0% line also drained the battery. WTH, the short circuit moves around? Do circuit breakers / electric boxes go bad after several decades? I could really use some advice. Thank you

I would take apart the breaker box so that I could see everything.
It could be that insects, like ants, have moved into the innards (I don't know what your box looks like) and when it rains their filth causes a path to ground.
So for me, I would be prepared to vacuum out and chemically clean every surface connected to the main buss. If your various lines leave via a common conduit of some sort, I would suspect that, too.
Before I closed it back up I would replace all breakers unless they looked really clean.
That's how I would start.
Next I would start casting a jaundiced eye on my converter......

[Terryj]

Lets start with the basics or you could be chasing your tail on this. CAUTION: Before cleaning any corrosion from connectors remove the power from the source. DC amperage can and will kill you.
1) You have a battery bank that ( I assume) is being fed by solar panels or a wind turbine and these total 1350 aH, so the batteries are connected in parallel due to you suppling 12V to your inverter.
Question: Have you measured the voltage from your source, ie Solar Panels or Wind Turbine to the input on your batteries? Is it in specs as to the manufactures specs? How old are your batteries? How old are the solar panels or wind turbine? Are the connectors from your source to the batteries free of corrosion?

2) How old is the inverter? Have you check the connection from the batteries to the inverter, are they free of corrosion? Do you have only 1 line feeding the mains on your breaker box? If so is it free from corrosion? CAUTION: Disable the inverter before attempting to clean the mains in the breaker box.

3) You stated you turned off the breakers one at a time, if your having a voltage drain with the breakers turned off then the issue lies in the breaker box or the equipment feeding the breaker box, ie a bad inverter or a defective battery. Yes, it is possible to have a defective breaker in the off position, it could leak voltage into the line it is connected to.

Remarks: If your batteries are 5 years old or older they should be replaced, inverters used for household energy supply will take its toll on batteries in short order. If the batteries are going dead then they could build up sulfates on the plates and short out.

[hotzcatz]

If there's also a charge controller either as a separate unit or as part of the inverter, then batteries will last a lot longer than they used to.

[Arktikos]

Originally Posted by hapci534

I have an off-grid house, 6 batteries of 1350 Amp hours total feeding and inverter and then a grounded electrical box that supplies a conventionally wired house. Everything works fine… until a big rain comes. When rain hits, battery charge goes down from 80% to 0% in about 15 minutes. I see no arcing anywhere, no bursts of noise (though I don't visit the attic much) but the water is clearly causing some sort of slow discharge somewhere. Is there a way to track the issue down without spending half a grand?

During the recent big rain, I experimented by turning all the circuit breakers off, energizing lines one by one with no appliance running and watching the battery charge percentage change. Some lines lost 0% of charge. The longest line feeding my cable modem’s wall plug in the farthest corner lost 13% battery charge in 5 minutes. Cowabunga! But next day a 0% line also drained the battery. WTH, the short circuit moves around? Do circuit breakers / electric boxes go bad after several decades? I could really use some advice. Thank you

Any updates? If I recall correctly, your home is fairly new. Who set up your solar system?

Your panels should be going to a charge controller before inverter. Both the panels and the battery bank should have a breaker to shut them off/isolate from the load.

Several good suggestions already. First thing I'd do is check your wiring from panels to battery or charge controller, make sure no connections are exposed to the elements and that they are tight. Next, test voltage for each battery in the bank.

[lensam69]

Somebody should go check on this guy if we don't hear back from him soon...

[hapci534]

Thank you, I'm still working on the suggestions. I have three 80Amp charge controllers, each handling 4 solar panels, so there is quite a bit of checking involved. (And remaining...) So far there was no "dzzzt!" and I still have all my hair This house is actually quite old, it was built (and wired) in the 1970's.

The charger that converts generator output 5pm-10pm is an IOTA DLS-55/IQ4 combo with supposedly has 3-stage charging and some automatic de-sulfating function if I remember right.