Digital Battery Monitor

[Richard Noble]

I'm sure that we all have the idiot light battery monitor in our rigs. My question is has anyone found a didgital display that will utilize the existing wires to the idiot lights for a better way to monitor the batteries? I'd like to place a better monitor next to the idiot lights and not have to run new wires.

[BryanL]

The best bet is probably to just use a self powered digital voltmeter. There are panel meters that will provide a voltage and power themselves off of what they are measuring.

The key is to be able to interpret the measurement properly. That means measuring voltage only after the battery has been resting for a half hour or more (no significant charge or discharge) and compensating for the connections and wiring between the meter and the battery.

Note that battery voltage, if properly interpreted, is a good a measure for a battery bank state of charge. If you watch how it bounces when you fire up a load like the furnace or water pump, you can also get a good assessment of the battery's state of health.

After that, you get into having to install shunts and trying to count electrons. These types of battery monitoring devices provide a lot of fun and some impressive numeric displays but I'm not sold on their actual utility versus cost.

[Joe-K]

Another option if you really want to get rid of the idiot lights is to replace your battery monitor and tank monitoring system at the same time with a SeeLevel system. Then you'll have a digital battery voltage readout as well as the digital tank level display.

[Rick Long]

I installed 2 meters.... Sure is nice to know whats going on!

[Flagelpater]

Rick, Where did you get the meters? Also, any tips for the installation?

[Rick Long]

The meters are from eBay Blue LED Volt Meter DC 7V-15V Doesn't Require Power:eBay Motors (item 370285449749 end time Nov-05-09 09:05:15 PST)

Very important.. they MUST be self powered. Watch the description.. they have LCD and LED.. I wired directly to the batteries so I could check them even if the disconnects were engaged. You can use tiny wire... I used two twisted pair in the CAT 5 cable. (very easy to run)

I used a SPDT switch so I can check both house and chassis with the same meter. The AC 120V meter is of course to check generator/shore power.

Switch:

[Flagelpater]

Rick, I find the LED but can not find the LCD 120 Volt meter. Did you get it at ebay also? Thank you.

[Gary RVRoamer]

Here's a self-powered AC voltmeter from the same source

LCD Volt Meter AC 50-300V Doesn't Require Working Power - eBay (item 390114694051 end time Nov-05-09 18:56:02 PST)