RV Straight Talk with Jeff Johnston​

Can I Hook Up my Car Battery Charger AND the RV Charge Line?

Q: This week, Eileen from Bar Harbor writes, “My RV’s converter does a really slow job of charging my 12-volt battery. If I hook up a car battery charger, do I need to disconnect the RV charge line from the converter to avoid damaging the system?”.

A: Greetings and welcome to RV Straight Talk, where I’ll try and answer your RV technical and at times not so technical questions. You can submit your questions by email to jeff@rollinontv.com, or by simply going to our website at rollinontv.com and clicking on the RV Straight Talk link.

Leave everything connected, Eileen. You won’t hurt a thing. When you have a battery connected to two different sources of charging power, say for example one is 12.3 volts at 3 amps, and another is 12.5 volts at 8 or 9 amps. They do not combine to create 24 volts. A system like this, the battery will more or less select the highest of the voltage and amp inputs, and that’s the one that it uses for its charging line or charging power. So, you have the two sources connected, your converter is a lower amperage source. The car battery charger is higher amperage and higher voltage. It’s gonna work– it’s gonna be the one that the battery uses for charging. So, it works great. I do that all the time, and it’s a pretty common practice among RVers because a lot of those older RV chargers take an awfully long time to bring a battery up to full snuff. I hope that explains it, Eileen.

Many RVers use a standard car battery charger for faster, more effective
RV battery charging. It’s a good idea that works well.

Email me your shipping address, Eileen, and we’ll make sure you receive one of these classy Rollin’ On TV coffee mugs. Ceramic, hard to spill.

And don’t forget, if you have an RV tech question, send it in and I’ll get you a straight, honest answer. If we use your question on our website or the TV show, we’ll send you a Rollin’ On TV mug just like this one or very similar. We regret we can’t personally answer every question we receive, but we do answer the ones we use on the show or the website. That’s it for this week, and thank you for watching.