Checking 12V from outside the rig

Hmm, I leave my batteries in the RV all winter - not plugged in to shore power. I do check the voltage every month or two and would plug in or use a charger if it was low.

Just use your battery cutoff switch to stop all draws from the batteries.
When you want to use the RV, switch it back on.

RVng/camping is complicated
Towing is complicated
Leveling is complicated
Running fridge is complicated
Using toilet is complicated
Dumping tanks is complicated
Maintaining tires is complicated
Using TVs---getting OTA channels is complicated

Now storing is complicated.

WHY do we put ourselves thru this :B

I would get a really cheap volt meter- the kind with lights instead of numbers- unhook all but the over 13 volts light. If the light is on, it's charging, if it's off, it isn't, but the battery will still be OK.

What is the purpose of leaving the television powered on all winter? It's certainly not needed for the television, and I don't think the RV is lacking for entertainment during its hibernation.

The voltage drop for a remote voltmeter is going to be negligible because the current flowing to it is negligible. This is double the case if you only connect the sense lines and power the voltmeter with a battery or wall wart or something...but even without, you're looking at maybe 0.1 or 0.2 volts maximum.

Not really sure what problem you're trying to solve. Why would your battery stop charging? Pop a breaker? Converter fail? Somebody unplugs your shore cord?

Assuming there isn't a big 12V parasitic load, it will take quite a while for the battery to self-discharge to the point where it will freeze.

Until I get the solar mounted I bring my batteries home, make sure they are completely charged and then put a charger on them once a month when I exercise the generator.

Another thought...stop worrying about it. There are plenty of other things to worry about. RV'ing isn't and shouldn't be as complicated as we make it.

Or, bring the batts inside for the winter and go sit by the fireplace and relax.

Any sort of light left on would only make the problem worse. If your converter was charging your battery your light would be on. When the converter stopped for whatever reason the light would still be on but now battery powered. It would drain the battery down and finally go out. You would then know your battery was dead but that isn't much help.
In order to monitor the battery you would need to use Jim's idea of extending the leads on a voltmeter. There wouldn't be any voltage drop because there's no load so no need to worry about that.
Here's my idea: turn off the TV, I'm not sure why you want it on anyway. Disconnect the battery and bring it inside. Put it on a trickle charger somewhere that you can see it regularly.
Or, even simpler, don't bother with the trickle charger. I take my boat batteries out in the fall and let them sit in the garage all winter. In the spring I reinstall and they start the boat fine. The last set of batteries lasted 7 years like this.

JiminDenver wrote:
How far? It would be cheesy but I'd just extend the leads on a cheap voltmeter into the house. there would probably be voltage drop but you could gauge that to just make sure the battery was staying up. Bt the time you noticed a light not being on, your battery would be dead.

X 2

Here's one that should work. Just extend the leads directly to the battery or attach a male 12 volt connection & run it through a window into the coach 12 volt receptacle.

VOLT METER

Porch light would be good or a work light. Or better yet install an LED marker light where you can see it.. (Or a regular marker light).