Confused about charging systems

Hi. I’m new to this, and I’m having some trouble understanding what I’ll need to use to charge my lithium batteries with both solar and the van’s alternator.

I’ve been reading everything I can find on the topic, but I’m unclear on whether I need a DC to DC charger, a battery isolator or a solar charge controller, and what kind of solar charge controller.

What I need to run daily is a gaming laptop used for communication and web application development for about 12 hours a day, a powered USB hub, I also have a 27" monitor that I’d like to use, but can work without. The not-all-day items I have are small heater when it’s cold and a drop in water heater element to heat water when I make coffee.

I’m working with an extremely tight budget, so I’ll be using components that no one here would likely recommend by name … there’s an 18 watt solar kit with everything but the battery at the Walmart site for under $100, that kind of budget. I’ll upgrade as I can, you can find it searching the site for “Pwtool 12V Monocrystalline Solar Panel Kit Flexible Solar System kit 30A Controller Connector Mono Solar Panel Power Station

I’ll need to position the solar panel at each stop, so this is really a short-term solution that will eventually become a backup.

So, what I want to do is to charge the batteries from the alternator when the engine is running and solar all other times. What is my most affordable option to set that up, with the understanding that I’m fine having to upgrade it within the next eight or so months if necessary?

Thanks in advance for your help and suggestions.

When I started, it was mass confusion after watching all the YouTube videos, then I found a website that made it all make sense. Check out this link: There’s everything from selecting a vehicle, through every step of a build…with diagrams, pictures, videos, links on where to get what will be needed, and they are great with answering questions. My van ended up being my Covid project. Then I didn’t like what I built…tore everything out except the solar, repurposed what I could, and added a few things.
It’s true that you will never be “finished”! Every trip, you’ll discover something you either don’t need, don’t want, want to change or want to add.

But, go check out and good luck!! Also, my build is simple. My solar is a 250 watt panel, mounted on the roof with 3M VHB tape 4950 under the z-brackets, covered with Eternabond for weatherproofing…advised by Hobotech, on YouTube, as I didn’t want to drill my roof. I bought my panel at San Tan Solar in Gilbert, AZ for $50. I initially had a 20A MPPT Epever charge controller. It didn’t work as well as I wanted, so it was replaced with a 30A Beleeb charge controller that made all the difference. My batteries are (2) 6V deep cycle golf cart lead acid batteries, wired in series for 230aH of power storage. Got the batteries at Batteries Plus. I have a 750 watt inverter that handles what I need. I did add a Keyline smart battery isolator to charge while driving. My batteries stay topped off most of the time. I built my system following the diagrams on gnomadhome. You can’t go wrong.

Good luck!!


I have researched this one as I wanted to do the same thing. You need a battery to battery charger. You can find one on Amazon.
A B2B charger is different than a solar charge controller or another charge controller.

So make sure to get battery to battery charge controller or charger.

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Not all chargers are created equal. So really depends on what you want the charger to do. If you just want to put a slow charge on the battery bank and you don’t have anything drawing on it, then those low amp controllers will work. If you have a fridge or want to use your alternator to charge your batteries from drained to full, then you need a battery to battery charger. That way it can handle the amps the alternator is putting out and also charges at the correct voltage for your battery. Not all batteries are created equal. They require different charging voltages and amperage’s depending on your bank size and type. Also keep in mind not to overload your alternator. You can put too much of a load on the alternator and cause it to fail early. Not so much of your trickle charging the battery bank but if your drawing a lot of current to charge a bank, then you may want to watch how many amps your alternator can produce vs how may your drawing vs how many the vehicle needs to run and charge its battery.

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