battery needs a 13.5 charge to charge it. If your charge says 12.XX, its not charging the battery.

The power port can handle quite a bit of current depending on the fuse rating. even at 5 amps, your looking at 50Watts. You couldnt fit a 50watt solar panel on your dash.

 

ebay the plug for a couple buxs

 

It's in float mode. It will maintain 12.6 now because that is the desired voltage for an automotive battery at rest. If the battery calls for a charge it will increase the output. I've seen the panel put out 14.8v after I use the winch.
At 12.6 volt, 5 amp is 63 watt.

 

I have one of the small ones from Harbor Freight on an old diesel tractor and it is great, starts every time now instead of the battery always being dead. Three caveats: there is no parasitic draw on the battery in the tractor, the solar cells are located outside with no windshield etc obstructing them, and it is connected directly to the battery.

If you can, mount any solar charger outside as the windshield will block a significant portion of the correct wavelengths from reaching the cells, plus all solar cells are inversely efficient as temperature rises: the hotter it gets (such as in an enclosed cab) the less watts it can put out. In extreme temps it may not put out much if any. Also, hook directly to a battery instead of the cigarette lighter, as we are dealing with low voltages so you want the absolute shortest path to reduce losses associated with the length of wire.

 

my trickle charge applies .5amps... seems to work just fine, may take a bit to get there if it needs a bunch of charging. As long as the path is as direct as possible, loss over lenght will be minimal.

 

I have one on each of my trailers, including my dump trailer. They are there to keep the batteries at full charge, not full recharging, which every battery manufacturer will state is necessary to extend battery life as long as possible. They have done well for the 10 years or so I've used them, but I probably need to race them every 5 years or so. Pick them up when they are on sale and then they are a very useful item.

 

Mark: you may want to have two different set-ups, especially thinking a larger one for your fifth wheel if you dry camp like us. I have a triple 12V house battery set-up on our new-to-us motor home. I'm setting it up with two 144W x 24V New Old Stock Uni-solar stick-to-the-roof panels (wired in series) run through a Morningstar MPPT charge controller, which will step the high voltage down to charge the 12V house batteries. I haven't decided on which Inverter I'll install yet. While we have a quiet Diesel Genset on the MH, when we are dry camping we like to disturb the neighbors as little as possible.

For the starting batteries (and l have equipment all over the place that need battery charging -- running cords is a pain), here's what I did:

I watched ebay for a NOS Uni-solar flexible 12V panel. They were built mainly for sail boats/marine so often they are listed there. I scored an MBC-525 and it was slightly used so got it for like $25 -- this is a 22W unit that will easily sit across your dash held up to the window by a sunscreen (it is a 15" x 50" unit with 6 SS gromets for holding it down, hanging it, etc. and it's fully weatherproof). Then I got a Morningstar SunGuard 4 PWM controller for like $29 delivered off Amazon. I soldered twin pole connectors on the in and out of the controller so I can use a cigarette lighter adapter, battery clamps or permanent mount battery charge cables (mostly what I plan to use) -- anything you want to put a mating twin plug on, really.

So for less than $60 I have a solar charger that I can put on the horse trailer, the Bobcat, the Kubota, or any vehicle and move it around easily WITHOUT running any more dang extension cords!

Hope this helps...

 

Exactly, it would (barely) keep a single batt from self discharge. Particularly with the parasitic or vampire loads inherent these days. A really huge solar panel would do better, but would be expensive.

 

Thanks for all the ideas/tips guys! Lots to mull over to decide what to go with. I'm just skeptical on if these systems(5-7 watt) are really enough to offset parasitic load and keep the batteries up. First thing I should do is put a meter on it to see what the parasitic load is I suppose. Then I know if it'll offset that load at least. I checked a year or so ago, but I don't remember what it was. I just remember it was really small, but so are these systems.


I agree, this should be 2 different setups. Initially I was thinking this might work for the camper too while in storage to keep the batteries charged up. It wouldn't charge anything from scratch or even make a dent in the typical draws from using the camper! But, it wouldn't be needed if I put a decent solar system on it in the first place as that would keep the batteries charged while in storage. I am toying with the idea of a 200 watt, give or take, system for the camper to keep the batteries up to negate a good portion of generator run time. We have a Honda 3000, the really quiet one, but I, like you, don't like bothering neighbors any more than I have to. I haven't really started down this path other than just looking around to see what prices might look like.

 

I agree that the small starting battery solar chargers likely won't do much for our twin batts., that was why I started looking for something w/o a glass top and hard frame and had more umph. There are other thin film flexible solar panels out there that are more efficient than what I have, some you can roll up or fold up. My solution was a lot cheaper is all.

Ditto for your camper: I knew of Uni-Solar from a panel I had for my driveway gate, and they were ahead of the pack in their day with thin film, multi-layer solar cells that actually look at different spectrums of light, so they make power even under tree cover and on cloudy days. Downside is they went out of business during the crash and you can only find NOS, and they take up more real estate on your roof. The ones for the RV are different from what I used for your original query on starting battery charging. The RV ones are of the PVL series and come with an adhesive backing so it is peel-n-stick to your camper roof. Lowest profile you can get and they are super durable. I got my two on eBay and I was patient and found them for about $170 each, but since they are 24V, you have to run a MPPT type of controller that tends to be more expensive, but I will have approx 576 watts at 12V They are 18' (feet) long but just 16" wide.

We can take the RV stuff off-line if you want any more info on that...

Look for the MBC-525 and see what you think -- pretty trick for the money...

Good luck!

 

Looks like I might have a small issue to deal with too. I have .2-.3 amp parasitic draw with nothing running or plugged in. I do have a Prodigy P2 brake controller, with a couple of red lights that never go out. So that is some of it, maybe most of it. At first I had a 1.2amp draw. I was like what the... then I realized I left the dome light on when taking out the meter. Where are you guys at with parasitic draw? And what should I expect it to be?

diesel_dan, thanks for the info on the solar panels for the camper! I like that option a lot. I found some on ebay for buy it now at around $180. I'm in the middle of selling the old 5er and getting a new one It hasn't arrived at the dealership yet. got a sweet deal on a new one Once I get my hands on it, I'll be able to figure out what will work and what won't. If you don't mind, I might PM you to pick your brain for lessons learned if we decide to put a solar system in it or not.

 

Gotta wait for the computers to go to sleep and make sure the hood light is out

Josh

 

How long do you have to wait on the computers?

 

At least 15 minutes, 30 minutes would be better.

Josh

 

I only waited a minute or two, so that is probably where the draw is from. I'll check it again.