Hello all and thanks again in advance. I have found some suitcase style solar panels that get great reviews on Amazon and am considering pulling the trigger as they would work well for my intended use. They come in 40w, 80w, and 100w. I hope to charge up my single AGM (31) after daily use. We don't have or want a TV nor do we use other power hungry electronics when we camp. The furnace running at night does most of the damage. I converted to LED lighting. We are weekend warriors and dry camp in state and NP's a lot. It would be nice to. It have to run the generator when we dry camp for three days at a time. So, the panels get bigger and heavier of course as the power increases. I like the idea of the 40w panel as it is easily stowed and light weight. Could a 40w panel re-charge a group 31 AGM (half depleted) in a day with a decent amount of sun? I know these questions are hard to answer with so many variables. I have read so much about solar panels that my head hurts now. :)

Jbrowland wrote:Could a 40w panel re-charge a group 31 AGM (half depleted) in a day with a decent amount of sun? I know these questions are hard to answer with so many variables. I have read so much about solar panels that my head hurts now. :)At 100ah, 50% depleted is 50ah. 40w panel = 3amps, at best. 50/3= 17 hours.It will take a couple of really good days, at least.

Thanks. That's close to what I guesstimated as well. Looks like the 100w is likely a bare minimum huh? Hmmm. I wish I was a little more handy. Just installing two 100w panels on the roof sure would be better and not much more expensive, if I could do it all myself.

Those are good panels, good company. Consider that panels mounted on top mean you have to park in the sun. Works for some locations not for others. In many areas if you park in the sun so the panels work well then you have to run an air conditioner and end up with no gain. A 100w setup in full sun will give you 50AH in just less than 8hrs. Any solar will at least cut down on your generator use.

tonymull wrote:Those are good panels, good company. Consider that panels mounted on top mean you have to park in the sun. Works for some locations not for others. In many areas if you park in the sun so the panels work well then you have to run an air conditioner and end up with no gain. A 100w setup in full sun will give you 50AH in just less than 8hrs. Any solar will at least cut down on your generator use.Great points and beyond my minimal DIY experience, why I chose the portable option. State parks and NP's have a lot of tress and such.

So, the panels get bigger and heavier of course as the power increases. I like the idea of the 40w panel as it is easily stowed and light weight. Could a 40w panel re-charge a group 31 AGM (half depleted) in a day with a decent amount of sun?NO..not enough powera grp 27 at half charge is down about 50 amp hoursthe 40w is going to charge at Maybe about 2.5 amps , it would take over 20hrs tocharge to fullit would extend your battery use during the summerit would not do much to help you in cold weather, with the furnace use at night"Any Charging" is a help,but consider at least 100wthis would give you about 5.3amps chargingif your a weekend camperand start out with a fully charged battery, this will help you thru the weekendbut you need to fully recharge the battery when you get home from camping

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westend
Explorer
Jul 03, 2016
I'd suggest to buy one of these 100 W Grape solar panels, a length of MC4 wire (can be had online for cheap), and an inexpensive solar charge controller. The panel can be mounted or you can leave it tilted as a portable system. The wiring is about the same or at less skill level as wiring a home stereo. If you want the panel to be carried as a suitcase, screw a handle to one side of the frame. I'm guessing you'll be into this for around $175 when it's all done.
2oldman
Explorer II
Jul 03, 2016
Jbrowland wrote:
Looks like the 100w is likely a bare minimum huh?
Yeah, even 100w is just getting by. For short durations and light loads, carrying a spare battery may be a better choice. Charge when you get home.
MrWizard
Moderator
Jul 03, 2016
So, the panels get bigger and heavier of course as the power increases. I like the idea of the 40w panel as it is easily stowed and light weight. Could a 40w panel re-charge a group 31 AGM (half depleted) in a day with a decent amount of sun?

NO..not enough power
a grp 27 at half charge is down about 50 amp hours
the 40w is going to charge at Maybe about 2.5 amps , it would take over 20hrs to
charge to full
it would extend your battery use during the summer
it would not do much to help you in cold weather, with the furnace use at night
"Any Charging" is a help,
but consider at least 100w
this would give you about 5.3amps charging
if your a weekend camper
and start out with a fully charged battery,
this will help you thru the weekend
but you need to fully recharge the battery when you get home from camping
Jbrowland
Explorer
Jul 03, 2016
tonymull wrote:
Those are good panels, good company. Consider that panels mounted on top mean you have to park in the sun. Works for some locations not for others. In many areas if you park in the sun so the panels work well then you have to run an air conditioner and end up with no gain. A 100w setup in full sun will give you 50AH in just less than 8hrs. Any solar will at least cut down on your generator use.

Great points and beyond my minimal DIY experience, why I chose the portable option. State parks and NP's have a lot of tress and such.
tonymull
Explorer
Jul 03, 2016
Those are good panels, good company. Consider that panels mounted on top mean you have to park in the sun. Works for some locations not for others. In many areas if you park in the sun so the panels work well then you have to run an air conditioner and end up with no gain. A 100w setup in full sun will give you 50AH in just less than 8hrs. Any solar will at least cut down on your generator use.
Jbrowland
Explorer
Jul 03, 2016
Thanks. That's close to what I guesstimated as well. Looks like the 100w is likely a bare minimum huh? Hmmm. I wish I was a little more handy. Just installing two 100w panels on the roof sure would be better and not much more expensive, if I could do it all myself.
2oldman
Explorer II
Jul 03, 2016
Jbrowland wrote:
Could a 40w panel re-charge a group 31 AGM (half depleted) in a day with a decent amount of sun?

I know these questions are hard to answer with so many variables. I have read so much about solar panels that my head hurts now. :)
At 100ah, 50% depleted is 50ah. 40w panel = 3amps, at best. 50/3= 17 hours.

It will take a couple of really good days, at least.

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