Ok, I live in sunny So.Cal. (sorry nor-easters, don't hate the playa') and when our lovely sun isn't blocked by the smoke and soot from raging wildfires I could see the benfits of having a solar unit on the roof.

My question is, are these things practical? Are the one's that supposedly "trickle charge" the batteries by plugging them into the cig lighter useful? Is that even possible?

Don't need an engineering answer but I didn't think that plugging something into the 12v socket could charge the coach or engine batteries.

Hi gwbischoff,

The typical 1 to 3 watt chargers that lay on the dash provide between 0.1 and 0.25 of an amp to the starter battery. It doesn't sound like "a lot" but in Northern Climates it is enough to warm the battery very slightly, and that can make a huge difference when the weather is -10 C.

Roof units are better for extending the number of hours you can use the cabin batteries . About the smallest unit one can find is a 68 watt Unisolar. On a good sunny day that will crank out about 4 amps. More than enough to take care of "parasitic" loads and put a few amps into the battery. This may extend the life of the cabin batteries because they won't get totally discharged when the RV is in storage.

If one is actually camping and using power for lights, etc. a much bigger system can be a good investment. I'd love to have 500 or 600 watts of solar to "play with" but costs for such a system are in a ballpark of 6,000.00 for parts. The rule of thumb is still in the area of ten dollars per watt.

My own current system has two ancient 15 watt panels giving me 2.5 amps in full sun. Just enough to keep my batteries in tip top shape but not really enough to do much more. I'd just love to add another several panels and as they drop in price that may happen. (Or if I get "lucky" on Ebay).

If I really want to "charge" my starter batteries I have a cable with two male cigarette lighters on it. I plug one end into the cabin outlet--and the other into the dash cigarette lighter. This allows my solar system to "feed" the starter batteries. I do this when I'm starting in cool temperatures (read below freezing) as a "poor man's" way to strap all the batteries together for starting. Probably with the size of the wire I can't do much more than 8 amps--but that's still 8 amps that my starter batteries don't have to produce when I run the glow plugs on my diesel.

For extremely cold weather I run my generator--and use it to power the block heater, the converter for the RV and a 1500 watt heater. I place the "jumper cable" into the sockets which means the converter will charge the starter batteries too (and warm them)--and come back in 3 hours to start the RV. I've done this at -30 C and so far have never had to get a "boost".

Thanks for your reply.

I'm just amazed that you're actually able to charge your battery by plugging it into the cigarette lighter. I had no idea it was that simplistic.

At what point to I need a charge controller or are they always a necessity?

I have a gas generator too, but wherever we go there's plenty of sun and it seems like a waste.
It would also be nice not to have to worry about it while in storage.

I'm looking at something like this:

http://www.campingworld.com/browse/skus/in...it/skunum=31283

Hi gwbischoff,

15 watts for that price is on the high side. I see that the kit includes a charge controller. That's always a good thing. Here is the same kit on ebay.

http://cgi.ebay.ca/Sunforce-15W-Solar-Pane...1QQcmdZViewItem

I'm not sure a single 15 watt panel would take care of parasitic loads. It would be fine during the day time--but remember those loads don't disappear at night. So one needs a big enough system to put a few amps into the batteries just for "insurance".

If you are serious about solar I'd really recommend unisolar panels as they are more or less "unbreakable". Labor costs will be the same so get the highest wattage you can afford.

Depending on how many total amps your batteries are you *might* get away without a controller with a single 15 watt panel--but you *might* also fry your expensive battery bank. A charge controller is a very good idea particularly the MPPT style. Get a very big controller--then as time goes on you may wish to add more panels. A dollar paid now will save you a bunch later.

This was all great information.

Thank you.

IMHO, in order to obtain a solar system for the simplest duties, more money is spent than you receive in benefits. In other words you do not get your monies worth. Again just my opinion.

I'm not looking to run the A/C or the microwave off of it. I know I'd need to cover the roof with panels and then some. But if I can put one up there and get an extra day's worth of lights or fans or the radio while dry camping it would be worth it, for me.

For instance, we try to go to Yosemite every year and there are no hookups on the Valley Floor campgrounds. Four days is just about the limit (without running the generator). If I could get another day out of the batts, that would be enough for me.

Sorry, was just my opinion.

My experience has been this - a solar charger that costs about the same as a battery is only good for keeping the battery charged while it is not being used. I have 2 batteries - when I get back from a trip I will charge one in the shed using a 110 charger, then swap the batteries. I leave the second one in the shed charging and use the solar charger to keep the one on the camper up to speed. This charger in no way does any kind of job when the battery is being used for fans, lights, etc., it will only trickle to the battery. Swap the batteries after about 4-5 days of camping and keep going strong.

Another trick I've found to help prolong the battery while dry camping is to leave the water pump off, and only turn it on when I need the pressure built back up. It seems that the last bit of pressure the pump needs before cutoff will really drain the battery. I've noticed after installing some fans that the batteries don't last as long as they used to, so I try not to use them too often.

No worries, Butch.



Another trick I've found to conserve battery life is to leave our kids home!

Also works with the electric bill. Get the kids out of the house. When they're home I can use our electric meter as an extra fan to cool the house!

I had 3 110 watt panels on my roof of my old unit. I used to store it outside and there was no electric at the storage facility. I loved my solar panels and I had a 22 am hppt controller too. I could make power and I added an extra 2 batteries as well. I was pretty good to go and could ark use power and then start up and drive out again and not use the generator. Not that I was self sufficient and did not need the generator but it did keep the unit charged in storage and kept the batteries fully charged and gave a bit of help when boondocked and not runnign the genset. I have a friend who had 12 panels and he was pretty much good to go for a long time though he still needed the generator.

GW,

I stumbled across this link this morning. You might find it useful: http://www.ccis.com/home/mnemeth/12volt/12volt.htm

Thanks for the info.

I think I'll wait 'til I'm sober to read that one...

Actually, I found it to be very easy, understandable, and informative to read. One of the best ones on the topic I've read so far. One that I didn't have to grab a double after reading it and wondering what the heck it was I read.

Click to view attachment

Solar is BS. when it comes to electricity. OK for water and heating but not electricity. Go to northerntool.com and get a clip on pole mounted 400watt wind generator for about $375. 400 watts at 12 volts is 30 ampres! Wow! Sun doesn't shine at night but the wind does blow! Even at half the capacity you are doing real good economically. Basicly it works like a GM alternator with a built in Voltage regulator mounted on a pole and driven by a fan blade. It also follows the moving wind directions.

Investing $400 in solar gets you nothing. What you get is bout 1-2 ampres that only works during the daytime and if they ever quit working you are out the money. Any electric surge, over charging your batteries from another source while hooked up, wind,water and don't forget Hail will void their 1 year warranty so obviously solar is a bad direction to go. Power companies use wind never solar.
ALSO FOLKS, If you are using AC generators to recharge your batteries, you probably are wasting lots of feul do to poor design. Did you know that an AC generator requires it's motor to run a constant full speed(usually 3600 RPM's to creat any electricity at all? Where as a 12 Volt DC generator or alternator will produce it's necessary 12 volts consistently even at idle speeds? (They should make a small bumper mounted 12 Volt DC generator with a variable throttle to run more eficiently. Thought about making one with the honda GX 50 Motor. Revs to 7,800 RPMS and weighs 9 LBS).

This means that if you have a 4,000 watt AC generator running, you are only dumping out fuel at a crazy rate of 0.7 Gal per minnute because even if you have a huge charger you still are only using about 360 watts max of the 4,000 you produced. (90% Waste factor here simply because you are using an AC charger over a DC charger)

Very poorly designed! Go buy a micro-sized generator and only use your large on-board generator when running roof air etc. Consider however that your converter box usually only trickle charges about 3-10 amps.

Here is my configuration.

I have 6 very large deep cycle batteries(I got used for $120.00(ask me where to get them at that price)) and I can apply 60 12Volt DC amps to them and they will not cook. I can push it at 90 amps. At first I started out with a portable charger (Best charger in the world is th Black and decker 40amp smart charger at Mills Fleet Farm for $93.00) I mounted it directly in the battery compartment and wired it to an exterior outlet. Later I added a Minkota MK460 4 bank on board boat battery charger
(SAFETY ALLERT!! Only Digital smart chargers can be mounted near batteries safely)[u]
Now I am considering going to a Iota http://store.solar-electric.com/bach1.html 90 amp and then possibly adding 2 more batteries. Under this configuration, I could run about a month on dry camping or a week using heavy furnace, 2 TV's, lights, music etc), then use a 1000 watt portable generator to recharge everything in 6 hours using a 90 AMP charger, would consume about 1/2 gallon of gasoline, costing about a dollar fifty a week, where as using the House generator with the house converter and only 1 or 2 huose batteies I would consume about 8 gallons of gasoline costing about $30 a day. LIKE THAT?? See these specs?
http://www.campingworld.com/browse/skus/in...el/skunum=25320

Folks, it's all about battery size and heavy charging capabilities when it comes to going green.

BTW, if you ever need a new electric water pump, they (Northerntool.com)sell them not for $250 like RV stores do but rather $59-89. I converted my 2.8 GPM to a .75 GPM and changed all my faucet areators and shower head and now I get onboard water tank lasting 3 times longer or can travel with
less water (weight) etc.

Hi,

Consider a kipor generator instead of the honda--quieter and cheaper.

Do you have a url for the "clip on" windmill? I can't find it at Northern Tools.