How To Trouble Shoot If batteries Are Getting Charged

You can be suspended from this forum for not owning a voltmeter.

To me, it is risky to travel without an alternate charging source, even a rather puny one. Risking trip on a converter made in Hungdong China just isn't worth it...

Vulcan Rider wrote:

CA Traveler wrote:

Take the batteries to a auto store for a free load check. Mark all cables and take pictures first.

It is NOT necessary to remove batteries for a load test.....IF the parking lot at the auto store is big enough to get in and out easily.

Portable charges work great when the battery is fully charged. The OP doesn't know if his battery is charged and it needs to be charged and then tested which a good tester will do. That's likely to be a in store test unless he has an alternate charger.

CA Traveler wrote:

Take the batteries to a auto store for a free load check. Mark all cables and take pictures first.

It is NOT necessary to remove batteries for a load test.....IF the parking lot at the auto store is big enough to get in and out easily.

If you don't have a voltmeter handy, you can do a quick check by turning on a (12V) incandescent light in the RV and then plugging into shore power while watching its brightness. It should get a little brighter when the converter comes on. Some LED lights would also, but not all—better ones have a regulator built in that keeps the voltage at the LEDs constant. (Simpler ones just use a current limiting resistor, and those would change brightness with changing voltage.)

If you have a really old converter, it's possible that the battery charge line is a separate one from the main output, in which case the test above could be misleading. You would also be well served to replace it with practically any newer converter; many of them had very very limited battery charging capability, only a few amps, and provided quite unclean 12V power to the rest of the RV. Chances are that you don't have to worry about that unless you have a vintage RV.

I do this all the time with my battery bank especially when camping off the power grid where my batteries are very important for a succesful camping run. I have a three meter battery monitor panel which looks at BANK1 and BANK2 and reads their DC VOLTAGE level. My third meter reads the DC CURRENT either being pulled from the battery from the various loads in the trailer or the reverse of that when being charged by the on-board converter/charger.

Looking at these meters I can tell if the charging circuit is connected or working and when not hooked to shore power or generator I can get a pretty good idea what my battery banks state of charge is. Of course i am looking for the 12.0VDC point which is very close to the 50% charge state where I don't want my battery banks to get below.

The batteries at fully charged if your 12.6-7VDC. They are at 50% charge state if you read 12.0VDC...

This handy chart shows the approximate charge state of the batteries based on the DC VOLTAGE reading. Of course the absolute way to determine this is to do a HYDROMETER check. Approximate charge state levels works fine for me.


You can use a multimeter as suggested above to accomplish the same thing.

Batteries are just too expensive for me to not keep a close watch on them. They are the heart of my OFF-ROAD camping...

As stated above if you are reading 13.6VDC or higher depending on the charge mode the converter/charger is then you know your on-board converter charger is charging the battery bank when you are on shore power or running from a generator.

Pretty easy daily routine if you have a digital readout battery monitor panel installed. Watching the trailer OEM Percent of CHARGE meter is useless as this meter will read any level you want to see seemly by how you hold your head haha... I have found everyone I have looked at to be almost worthless... This is great idea but you need to have digital meters installed to really know what the charge status is of your batteries.

my battery monitor panel looks like this...




You can see the OEM Percent of Charge status meter in this photo and for most of the time it reads FULL or NOTHING... That doesn't work for me haha..

You can purchase a battery monitor meter system from various vendors with the BOGART ENGINEERING TM2025-RV model probably the most popular.


Roy Ken

Great Info. here! Thanks! As soon as it quits raining we will see what we have.

To test converter functionality, measure, first, (from one battery terminal to the other) the voltage of the battery at rest with converter not powered. Second, measure voltage again with power to the converter.

The first measurement should be 12->12.7 DCV. The second measurement should be >13.2 DCV, likely > 13.6 DCV.

If your battery is now low and you have been connected to shore power for some rime, check the inline fuse or circuit breaker that is close to the battery. These are sometimes attached to the frame or tongue, occasionally inside a junction box. Without that circuit breaker closed, no power can reach the battery from the converter. Some breakers have a small reset button.

Buy a digital voltmeter - $5 at HF. Battery voltage should be 13.4+ when charging. If not a sealed battery check the water level.

Take the batteries to a auto store for a free load check. Mark all cables and take pictures first.