Possible to read 12 volt battery health at stereo wire?

[cvin]

I had a friend wire in some usb and 12 volt plugs off the stereo power

Wondering if i plug a cheap digital meter into one of these plugs if it would give correct reading on my 2 batteries??

[xrated]

It would be close, but the problems I see are twofold.
1. You should never wire in a 12V accessory plug into a stereo power supply circuit. That circuit is probably fused well below the rating of just one of the accessory plugs, much less a couple.
2. You are talking about a "cheap" digital meter which sometimes can be 5% or more off from the actual voltage, so don't depend on the reading to be dead on. Plus, that circuit that feeds the stereo system probably has pretty small wire, and most likely a voltage drop from the battery to the plugs.

[cvin]

Thanks for the feedback

The guy that did the mods for me is really good and i am pretty sure i remember him telling me there was plenty of power on the wire.... seems like he checked it and gave me a number...

Anyway i will watch it and see if it gets hot at all etc
It definitely has not tripped any fuses and it seems to be running everything fine

I figured the digital meter on there would not be super accurate, will try it and see how it goes
Maybe if i keep an eye on it i can get an idea on how the batteries are going up and down in charge boondocking

[Ductape]

I did this tapping into a 12v light circuit in the entertainment center cabinet. I used an inexpensive meter off of Amazon. Mine is very accurate when compared to my multi-meter on the batteries. I mounted mine in the side of the entertainment, so that I can glance at it through the screen door, since we are always outside. If I spent a lot of time indoors I might mount it differently.

[cvin]

Ran the tv off this line last nite and no issues, it did not even get warm