Wednesday, February 8, 2023


Ask Dave: How can I tell if my converter is charging?

Dear Dave,
I noticed that my house batteries do not seem to be charging when I am plugged into power in a campground or at home. I replaced them this spring and am wondering if the inverter/charger has gone bad, or could it be something else? How can I tell if my converter is charging? —Gregg, 2016 Winnebago Sightseer

Dear Gregg,
You did not include the model number so I looked up the specs on the 35G, which is one of the more popular Sightseer floor plans. It looks like typically all the models had the same brand, just the larger ones would have a higher amp model. According to the specs, that model has a 45-amp model and I assume it is a Magnatek. In this case, it is located under the bed.

However, since you indicated an inverter/charger, you must have the 36′ model that has a Dimensions Inverter/charger located in a lower compartment.

How to tell if your converter is charging

First, make sure the connections to the batteries are clean and solid.

Then start with a multimeter set on the 12V DC setting and measure the voltage of your batteries without being connected to shore power. They should be 12.6 volts or less, depending on their state of charge. Then plug the shoreline power in and see what the voltage is when the charger kicks in. The Magnatek converter is designed to go to 13.8 volts for 8 hours, as instructed by Winnebago, and then drop down to 13.2 volts as a maintain.

Typically, the Dimensions 2,000w inverter/charger would have a multi-stage charger and you could see up to 16 volts at an initial charge. I would suggest finding the owner’s manual and go to 7.2 on troubleshooting, and start by looking for a code on the display. If the batteries go below 10 volts, the inverter/charger would need to be reset. This is done by pressing the inverter and reset, on/off button three times. If the display is blank, it could be the in-line fuse.

There is a very good flowchart, as well. I would also suggest verifying there is 120-volt power going to the inverter and 12-volt power coming out. It could be bad batteries, as the charging portion will not kick in if the batteries are below a certain point.

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

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8 months ago

I won’t use a meter where you choose the range. Autorange only baby!

Yes follow the manufacturer TS guide but also remember voltage is not the only test.

Test the battery (ies) is good (resistive battery test Note; disconnect battery first).

If everything shows the right voltage the answer could still be a bad converter if the current is not correct.

To check current the output of the converter must be under load. A good way is read the current going to the battery if it is 50% discharged). A 36A or 40A converter should be putting up to 20A or more out. If it is 2amps or less then the convertor is bad or stuck in trickle mode.

Make sure the convertor is set for the correct battery chemistry.

You can check the inverter current by plugging in a know load 120volt device like a hair dryer. I like the dryer because you can test 3 ranges (fan, low, high).

Arrgh out of characters… See next

8 months ago
Reply to  TIM MCRAE


Use a clamp on AC ammeter (with the plug adapter) and check the current while on shore power (or your house}. Note the current on all 3 settings. Don’t use the high setting if the amps would exceed your inverter capacity (ie 2000 watts = 120volts x 15amps. I rounded up and down to account for losses and pf).

Now unplug shore power turn on your inverter and test the same device on an inverter outlet. The device should run fine and be drawing the same current as before, on each setting.

Last edited 8 months ago by TIM MCRAE
Glenn A
8 months ago

I would suggest using the 50 VDC scale on your meter. Otherwise, any voltage above 10 will probably be “off scale high”.

I’ve never seen a multimeter with a 12V scale. But, I haven’t seen everything.

Stephen Malochleb
8 months ago
Reply to  Glenn A

Most of the time there is a 20 volt setting for this use. Next step is 200 volts which you could use if you thought there was more than 20 volts.

8 months ago
Reply to  Glenn A

You’re right, but also wrong, there is no 50 VDC on digital VOMeters! I’ve only seem 2, 20, 200, 600DC Volts
My 2 cents

Glenn A
8 months ago

I guess it depends on the meter manufacturer.

Glenn A
8 months ago

Take a look at a Simpson 260.

Glenn A
8 months ago

Yes, I know a Simpson 260 is analog.

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