How To Use An Accurate Voltage Panel Gauge For Diagnostics.

The most important thing with a battery voltage meter is to know what is NORMAL for your system. It does not need to be calibrated to some military standard as long as it gives REPEATABLE readings. You want a permanently mounted meter, some place where you will see it multiple times a day.

• Know what is normal voltage when the batteries are fully charged and there is no load. (Immediately after a battery comes off of a charger the voltage is ABOVE normal. It will take some time (10-20 minutes ?) with no load to return to normal)
• Know what is normal voltage when your solar is putting out a good charge.
• Know what is normal voltage when you converter/inverter/charger is adding power.
• Know what is normal voltage when you inverter is on. (This will change over time.)

Once you know what is normal, then you will know what is ABNORMAL and can dig into things more !

Do you consider tenths of volts enough resolution for a panel meter?

My Trimetric battery monitor is connected to both banks and gives accurate battery voltage displayed to 0.1V resolution. The monitor has millivolt resolution for determining power usage.

My Monaco installed gauges are designed for the salesman to claim what a great battery monitor the rig has. The dash gauge can be used to determine that the alternator is charging the chassis battery.

The Trimetric display or any battery connected voltmeter can indicate the battery status IF you know about how much the house loads are. ie A large draw drops the battery voltage which will rise after the load is turned off. I have 3 charging sources for both banks: charger, alternator and solar.

Most electrical problems are better served with a portable DVM to isolate to the source or maybe a test light. DVMs typically have a long response time and a analog meter has better transient resolution. Beyond that an oscilloscope would be required.

Chris Bryant wrote:
Do you consider tenths of volts enough resolution for a panel meter?

I do. I consider this 'information' vs 'data'. Too easy these days to get buried in data and lose track of the basic information.

If I see 14.2+ volts by mid morning and 13 in the afternoon I know my solar is working and the battery is fine for the next overnight.

Chris Bryant wrote:
Do you consider tenths of volts enough resolution for a panel meter?

I don't. Not if you want to use it to monitor your batteries.

There is a large difference in battery SOC between 10ths of a volt.

But if you're using an actual battery monitor like a Trimetric, then I'm not sure why you would have a separate voltage meter at all.

Yes a portable DVM is best used for trouble shooting

A Reliable panel meter and knowing what's normal, is vital for knowing when it's time to go trouble shooting

Instead of waiting until suddenly there is no power or not enough power

in order not to flood the thread I'll limit this response to one tight area.

A five digit meter..

You glance at it. You find the least significant digit rapidly descending, then the 2nd to least significant. Maybe flipping the tenths downward every ten to fifteen minutes. It's sunny outside and you have solar panels.

Would you have seen this with your 3-1/2 digit meter?

Now starts the process of your analyzing. You know how often you gaze at the meter. What now?




You gaze at the meter and just the opposite is occurring. The voltage reads a full half volt below float voltage and the least significant digit is gaining. How does this affect your monitoring habit? I'll put this in real world terms -- the second meter is in your bedroom. And you don't necessarily have to have solar panels. Let's blot out the obvious like the heater fan. The main monitoring panel is 17' distant. Course A and then course B with and without shore power...

I have a DVM (from Amazon) hooked up to the battery box and wired
directly to the batteries. I walk past it several times per day
while I'm camping and a quick glance shows what is going on.

If by mid-afternoon the voltage is > 13.0, I know the solar is working
and I have enough for the evening. If the voltage is 12.8 or below
then I may have to top up the batteries with the generator.

I have 1 solar panel hooked up during storage (with the battery
disconnected from the TT) and as long as I see > 12.8 then I know
that the batteries are topped for the next time I want to go camping.

bpounds wrote:
But if you're using an actual battery monitor like a Trimetric, then I'm not sure why you would have a separate voltage meter at all.

Agreed. My rig came with a charger/inverter volt meter on the remote panel and a idiot light voltmeter and the dash voltmeter displays the chassis battery. None of these are connected at the battery terminals but all are perfect for the salesman.

The Trimetric came later and is connected directly to both battery bank posts.

CA Traveler wrote:

bpounds wrote:
But if you're using an actual battery monitor like a Trimetric, then I'm not sure why you would have a separate voltage meter at all.

Agreed. My rig came with a charger/inverter volt meter on the remote panel and a idiot light voltmeter and the dash voltmeter displays the chassis battery. None of these are connected at the battery terminals but all are perfect for the salesman.

The Trimetric came later and is connected directly to both battery bank posts.

I was thinking trailer, since that's what I have. My bad. I can see the need for a dash voltage meter, plus whatever happens to be back in the coach.