house voltage drop

[busshawg]

This is probably normal but would like to put the question out there. My house batteries drop close to 1 volt over 24 hours when nothing is on. Is this just because the system has voltage thoughout it? I did install a master switch last night so I can shut the house sytem down before the power hits the fuse panel. Just wondering if there is something I should be made aware of due to teh voltage drop.

Grant

[WEC4104]

Grant:

If the one volt drop only happens during that first 24 hour period, it sounds pretty normal to me.  Generally, when the battery charging system (alternator, inverter, etc.) is shut off, the battery voltage begins dropping slightly and it takes a number of hours to settle in on it's "at rest" voltage.

The question is: "Does it drop another volt the next day, and another the next day, etc?"   If it does, this would indicate a phantom load, or possibly an issue with the battery itself.  Just having voltage in the wires in the bus shouldn't create a drain, it has to be doing something. That can include clocks, thermostats, refrigerator control boards, and all sorts of stuff people don't think about.

The master switch you installed should be a help in pinning things down.  Fully charge the battery, then turn the switch off to completely disconnect it from the bus.  Start recording the voltage over a few days. You might see the normal voltage drop slightly the first day, but then it should level off and be consistent for the next few days.   After confirming that it stays level for 2-3 days, throw the master switch to "on".  If you start seeing the daily drop in voltage, you have an electrical load somewhere.  Pulling individual fuses and re-running tests could help you isolate the guilty ccircuit, or you could use an ammeter.

[busshawg]

Thanks , makes sense to me.

[JohnEd]

Grant,

Everything WEC said.  Also, you will need to let the battery sit for some time after you remove the load to be able to accurately measure the state of charge by measuring the bat voltage.

John

[Utahclaimjumper]

Also you need to know that the average lead-acid battery looses 1 to 2 percent of its charge per DAY under normal circumstances.>>>Dan

[busshawg]

all very usefull info, thanks again