Solar maintainer.

[fj12ryder]

The depth of knowledge about all things solar on this forum is formidable indeed. So I want to take advantage of a small amount of it.

Can a 10 watt solar battery charger keep an average RV 12 volt battery fully charged over the winter? The charger will be facing south, and not in the shade. And will it require a charge controller? And lastly considering the question what should I use to keep a single 12 volt deep cycle battery charged from mid-November to mid-March?

The toyhauler is in storage about 10 miles away. I've always pulled the battery, brought it home, and hooked it up to my Battery Tender. But this is a new-to-us toyhauler and I'm wonder if I need to move into the 20th Century. Yeah I know, but I'm always a step behind. 🙂

TIA

[fj12ryder]

Well, FWIW, I unearthed the ol' amp meter and checked the lines coming off the battery. With the OEM battery disconnect set to Off, the draw was 0.01 amp. With the OEM battery disconnect set to On, I had 2.2 amps of draw. More than enough to drain the battery fairly quickly I believe.

On our older Fuzion, the battery disconnect only disconnected major things, there was still enough of a draw, I never measured it, that it would drain the battery down in a week or two.

[RLS7201]

2oldman wrote:

RLS7201 wrote:
At first I questioned if 1.5 watts was enough but so far so good.

I doubt 0.1 amp for maybe a few hours/day would do much of anything. You may want to check the battery voltage and see if it is actually doing anything.

Doubt all you want but it does keep the battery topped off for over 3 months. Before the 1.5 Watt charger, the battery wouldn't start the truck after sitting for over 3 months. Now when we return home the truck starts. Next spring, I will take a voltage reading of the battery.

Richard

[fj12ryder]

pianotuna wrote:
fj12ryder,

five watts per 100 amp-hours of storage is the bare minimum. No need for a controller.

Thank you for the info.

[2oldman]

RLS7201 wrote:
At first I questioned if 1.5 watts was enough but so far so good.

I doubt 0.1 amp for maybe a few hours/day would do much of anything. You may want to check the battery voltage and see if it is actually doing anything.

[RLS7201]

I have this solar charger on the dash of my Pick Up all winter long while snow birding for 3.5 months. Been using it for about 6 years with no problem.
At first I questioned if 1.5 watts was enough but so far so good.

Richard

[pianotuna]

fj12ryder,

five watts per 100 amp-hours of storage is the bare minimum. No need for a controller.

[Boon_Docker]

frankwp wrote:
I've always disconnected the fully charged battery every fall & left it for the winter. In the spring, the battery isn't noticeably discharged. I just replaced the old battery at 11 years, but even so, it still had some life left in it.

I do the same. My pair of GC2's discharge less that 10% over the winter.

[frankwp]

I've always disconnected the fully charged battery every fall & left it for the winter. In the spring, the battery isn't noticeably discharged. I just replaced the old battery at 11 years, but even so, it still had some life left in it.

[Boon_Docker]

Go for the 10 watt unit. Just make sure one of the battery cables is disconnected over the winter.

[Crazy_Ray]

NO

[2oldman]

garym114 wrote:
Easiest way, charge the battery fully and remove the negative battery cable. The battery will fine, it will not freeze, the self discharge rate will be minimal.

this

[fj12ryder]

Thank you all for the information. Right now I'm leaning toward going with a cheap 10W maintainer. If I regret it, I will pass that along, and you all can say "I told you so". 🙂

[valhalla360]

As long as there aren't any parasitic draws, yes, a 10w panel should do fine.

Disconnect the battery from the rest of the system and directly connect the panel.

Self discharge can run down a battery over 6-8 months and lead-acid batteries are only happy sitting at 100% charge.

[wanderingaimles]

I have a spare group 27 rv marine battery that i leave out on my deck, it only gets used in power failures with an inverter. I have a small solar panel maintaining it and it has always been charged when needed. Which is only two or three times a year for Cpap and or refrigerator.