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Industrial Solar Trickle Charger Recommendations

Where I work we have a little bus we use to take college students on field trips. (I call it “the short bus,” but it hauls honor students most of the time.) It’s about the size of a small class C motorhome. It has a Ford diesel chassis and it has three batteries.

Unfortunately, the bus doesn’t get used very often, and it frequently won’t start when we need it. It sits parked in a lot with no nearby access to an electrical outlet, so I am considering a solar trickle charger. With the solar panel laid on the dashboard, it should get enough Florida sun to provide charging power, especially in the morning (it faces east).

With a budget of about $200 can anyone recommend a solar trickle charger that can handle three full-sized truck batteries?

Tomorrow I’m going to jump-start the bus and figure out if any of the 12 volt outlets inside the bus are live when the key is not in the ignition. If one of the outlets is always live, that will make my job of hooking up the charger easier, but if they aren’t live, I will have to remove the battery cover and install a cable on one of the batteries.

I’ve taken a quick look at solar trickle chargers on Amazon, but I’m wondering if any of you have had good or bad experiences with any particular brands or models of industrial solar trickle chargers.


i’ve been very happy with this Schumacher panel. I use it in my Dodge B250 camper van:

They also make a model SP-400 panel with 4.8 watts, but in Florida that might actually cook your batteries and require a charge controller. Even with 3 batteries I would try to SP-200 first and see if it can keep up. It definitely won’t need a charge controller and won’t risk frying your batteries.

A simple 12V solar charger will only work if the three batteries are hooked up in parallel. Also, how often is the vehicle used, and how long is it run? Perhaps a simple disconnect switch would do the job, but that would mean there is some kind of excessive parasitic loss which should be investigated.

I might spring for the “Battery Tender” solar charger with the electronic controller, 5 watts:

@NYBo, I know the batteries are wired together, but I don’t know if they’re wired parallel or in series. I’ll post a picture tomorrow. The periods of use and disuse are pretty random. It can sit for a couple days or it can sit all summer unused. It is used for local field trips two miles away and it is used to take students to conferences 300 miles away.

@texases, I’m liking the look of the solar Battery Tender, and if I add a couple accessories (links below), it might make my job a lot easier. I’ll just need to figure out a way to run the wire out of the battery compartment so I don’t have to remove the compartment cover (under the stairs) every time I hook up the charger.

Thanks to all!

The battery’s have to be wired parallel. If you wired the battery’s in series you’ld end up with 36 volts.


That saves me the trouble of posting a picture. Thanks!