Solar charging vehicles

This is where it all started. The problem I was running into was trying to keep all the batteries in all the vehicles I have charged. This isn’t a problem for most people I’m sure but most don’t have over 20 cars, trucks, tractors, mowers, etc to deal with.

Like most people I started out using various battery chargers. But between lack of outlets, limited amount of battery chargers and a poor memory as to what I had charged last and when this didn’t work out very well. I lost numerous batteries to nothing more than forgetting to charge them. It doesn’t take very many instances of letting a battery drain down too far to render it permanently dead or unusable. I had actually never even considered a battery being damaged by letting it run down. Heck I had run down a few hundred batteries at this point and all seemed to charge up fine in the past. But what I didn’t realize back then was the fact I was killing the batteries by letting them drain down all the way.

After getting into the solar setups I soon realized I didn’t know squat about batteries. Up till then I figured if it showed 12 volts on a 12 volt battery it was “full”. Anything over that was just icing on the cake. Sure I looked for 12.something as a rule but I know they didn’t stay at 13 volts after sitting a bit so 12.something must be fine… right? WRONG.

As you can see from this chart below full isn’t just 12 volts.

Battery Power Levels

But worse than that 12 volts is actually less than 50% of the battery. Since I learned that you never really want to go below 50% that means at 12 volts with no load on it the battery isn’t fully charged its actually technically DEAD. Scary huh?

So I needed to charge the batteries in my cars and such regularly enough that they stayed above 12.06 volts with no load on them. Since most vehicles with computers drain the battery constantly to some extent and I have a bunch of vehicles with computers and car stereos (which also drain the battery over time) this would actually turn into a full time job just keeping them charged. From moving cords around and swapping battery chargers every day this could easily end up being a nightmare. The less I drove a vehicle the easier it was for me to forget it was even in the yard let alone keeping it charged. My super duty truck was the first target. Being a diesel it doesn’t crank very well if the batteries are not at their best and I paid over $300 EACH for the two batteries in it. Since that’s over $600 in batteries you can see why it was the first on my list to take care of. So how to solve this delima?

My first knee jerk reaction to solve my problem was to put a normal or even a trickle charger on each vehicle. Well my super duty did not charge well in the past with a trickle charger so that probably wouldn’t work out so hot in the long run not to mention I would have to have over 20 of the things to keep everything charged. That’s a bunch of money. That doesn’t even include the cost of drop cords to reach the various vehicles with some runs being 100 foot or more. Priced drop cords lately? They actually cost more than the battery chargers…. But even if I was willing to buy a charger for each vehicle anything over a very small trickle charger actually causes more damage than not charging the battery at all believe it or not. Leaving a normal battery charger on a battery for long periods actually boils the acid out of them. So now I have a chance of roasting my $600 plus batteries even if I leave a charger on them 24/7. So what was my solution?

Enter Solar !


Alabama has some wonderful sunny weather for the most part so solar seemed like a good way to solve my problem and it did.

I purchased a 30 watt solar panel from amazon. Its made by windy nation. The picture above makes it look huge. Trust me its not. The tiny center top panel in the large picture up top is the 30 watt panel I bought to charge the vehicles to start with. As you can see from the specs below it only puts out 1.67 amps in full sunlight.



8I also purchased a sansonic duo solar controller. These controllers allow you charge two batteries at one time.


Click the picture above for a link to the amazon page I bought it from.

Solar Duo Controller

In my case I was using it to start with to charge the dual batteries in the super duty on the first battery connector of the charger and the other connector was attached to my corvette. So every day when the sun came up the super duty truck and my corvette got charged.

The controller is a pwm controller. This stands for pulse width modulation. Basically it turns on and off every so many seconds. This is actually a very gentle charging method that is very safe for the batteries. The other type of controller like I have on my house solar system I purchased later is a mppt controller. These controllers a very expensive compared to the pwm controllers but they do a much better job of charging a battery or bank of batteries back up in a short period of time. Which basically is useless on a maintainer setup like you want for cars and such. So just get the pwm.

The 30 watt panel just felt weak to me for charging things so I later added a 100 watt renogy panel. The new panel I wired in parallel with the 30 watt panel thus giving me 130 watts. Now THIS setup will CHARGE a battery not just maintain it. But over time I realized I really just needed the 30 watt since 2 amps is enough to bring a battery back up even if its a bit weak it just takes longer. The Renogy panel I bought was a mono crystalline panel which I will cover in the house solar setup in more detail but lets just say it puts out more than the poly crystalline panels. The 30 watt is a poly and the 100 watt panels are mono. So between 70 more watts and the better quality it was night and day difference wise between them. But with that said the 30 watt poly turned out to be just fine for my vehicles charging needs.

Ok now I had a solar setup and I could charge two vehicles at once. For most people this is all you will need. So I was into this for the following.

$60 solar panel

$50 solar controller

$30 in wire to connect it all

So for $140 I had something that was 100% reliable, zero maintenance and cost nothing to run. Pretty happy with it so far. But this still left me a ton more vehicles to charge…

This could get kind of expensive at $140 for every 2 vehicles. For instance lets say I had 24 vehicles to charge (there are actually more but this is for calculating) that’s 2 charged per setup so that’s still 12 setups at $140 each so $1680 to charge the vehicles… NOT

What I came up with cost $10 per vehicle to add to the system. What I did was order a bunch of these :


Clicking the picture above links to the 24 volt timer I bought. The 12 volt version can be found by clicking HERE

Its a 12 volt timer with 20 event programming. It runs on 12 volts charging its internal battery for its clock and memory and can switch 12 volts on and off. Using one of these on each vehicle allowed me to cut in and out vehicles on given days. This allowed the one controller and panel to charge all my vehicles. Since I knew it could charge two batteries at once on one lead for my super duty which had two batteries in parallel from the factory.

I also added an indoor display to the duo charger to I could monitor what was happening. It looks like this.

mt1meter mt1meter-with-charger

Click the pictures above for a link to the amazon page I bought it from.

This shows the display beside the charger. The display came with a 50 foot cord but that wasn’t long enough to reach the house so I ordered a rj45 100 foot cord and a connector union. The plan was to connect the two cables together and then bury the cable under my driveway. It turns out the network cable was long enough by itself so I just used it instead.

With the display connected I can monitor each battery’s voltage, amp hours charged and solar panels voltage, amps charging and amp hours charged.

Update – 12/27/2016

I just added another panel to the 12 volt system. I went with a Renogy 30 watt panel since it is a monocrystaline panel vs the poly I had already. When it arrives I will update how it performs vs the poly I have now.


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