DIY Overland Solar Power

Posting in the off chance this is useful for anyone else. Utilizing a spare 24F battery, and various Amazon parts, I’ve rigged up a solar charging system that should power everything in camp.

Parts:

- waterproof 3W trickle charging solar panel (comes with ASE adapted alligator clips and cigarette male end).
- waterproof cigarette lighter charger with inline fuse.
- Atwood marine battery box.
- Marine terminal clamps.
- USB adapter with voltage display.
- Pack of 5 weatherproof ASE adapters.

I don’t like wiring anything not factory to my truck’s primary battery; there are too many stories of accessory electrical fires. This spare battery will live in the bed of the truck to power LED pod lights and various USB items at night while the solar panel tops off the 24F during the day via the cigarette charger while driving to the next camp site. Total cost less battery, $75.

 

I was thinking of something very similar with a battery i have laying around just to play with. I haven't really read into it cuz it hasn't been my highest priority. Why did you use a 3w charger? Can you use bigger? Sorry if these are basic or stupid questions.

 

I used a lower W trickle charger to avoid overcharging and damaging the battery.

 

Trickle charger will not keep up

 

What kind of charger would you recommend?

 

Can you help us understand the math using my battery as an example?

24F battery rated at 935 cranking amps and 130 minute reserve time. Let’s use a single 60 Amp LED pod drawing off the battery for 1 hour. If 130 minute reserve time is based on 25ah until the battery gets to 10.5V, does a 60a draw essentially cut the reserve time in half? And if the battery is run down to 10.5V at that point, how long would my 3.3W solar charger take to bring the battery back to 12.6V?

 

You mean 60 watts

 

Correction, 60W

 

Watt rating is per hour.

A 60w drain for 1 hour is 60w drain on the battery. So it would take your 3w charger 20 hours to fully recover that loss. And that's if the sun is strong and your panel is aimed directly at it.

Also, wattage is amps*voltage. Still on 1 hour basis. 25a/hour draw on 130 minute reverse is 54a total, or roughly 650watts total based of 12v. In theory, you could run that 60w pod for almost 11hours.

Aaaaaand if your battery has completely used the reserve, that would take your 3w solar a whole 216 hours to recover. That's eighteen, 12 hour days in full sunshine.

PS: electrical fires are usually caused my someone not wiring in a properly sized fuse (also not in the correct location, near the power source), and/or using too small of wire.

 

So outside of all the comments about how long it will take to charge and draw etc.....you really need to buy a charge controller. They are very inexpensive on Amazon and will save you the price of a new battery. They are designed to stop you from over charging your battery.
I've built a ton of these mini off grid kits and used to sell them as well. I just got finished installing a new set up on my camper last week and cannot stress the importance of a charge controller.
Here's one for $13 that would work for what you are trying to do...

20A Solar Charge Controller Solar Panel Battery Intelligent Regulator with Dual USB Port 12V/24V PWM Auto Paremeter Adjustable LCD Display

https://www.amazon.com/Controller-B...ge+controller&qid=1561879873&s=gateway&sr=8-3

 

Thanks for the education, guys. After this trip I’ll probably switch to a better panel and add the controller. For now I’ll try to use the battery as a back up source of power only.

 

You need a lot more than 3W.

Put one of these in the window as a sun visor and charger.

https://www.ebay.com/itm/Renogy-E-F...ortable-Dual-USB-Battery-Charger/382901359631