Solar trickle chargers

[John McDonald]

I may be storing our car for 10 months without access to electricity. I want to know of any experience you have with small (5 or 10 watt) car dash solar panels and controllers. Success? Failure? Brand and size?


The car will likely be stored in Deming, NM from March through December under an extra tall carport, so with plenty of daylight if not direct sun except for an hour or so each day.


Cheers John

[John DL]

I use a 10 watt solar charger/maintainer from Battery Tender. Works well. No issues. Switches to trickle charge when battery is full to maintain. Uses “smart” battery program protect the battery. I found the 5 watt to be too low power. I got mine a few years ago and that model is no longer made. But Battery Tender still makes newer models. Amazon carries these and other brands.

[herons]

Originally Posted by John DL

I use a 10 watt solar charger/maintainer from Battery Tender. Works well. No issues. Switches to trickle charge when battery is full to maintain. Uses “smart” battery program protect the battery. I found the 5 watt to be too low power. I got mine a few years ago and that model is no longer made. But Battery Tender still makes newer models. Amazon carries these and other brands.

What size solar panel would you pair with the charger for a 12v battery?

[John McDonald]

Originally Posted by John DL

I use a 10 watt solar charger/maintainer from Battery Tender. Works well. No issues. Switches to trickle charge when battery is full to maintain. Uses “smart” battery program protect the battery. I found the 5 watt to be too low power. I got mine a few years ago and that model is no longer made. But Battery Tender still makes newer models. Amazon carries these and other brands.

Thanks.
I’m using a 5 watt panel here in Duluth MN and it seems to put out a grand amount of .08 amp!! Yes that’s .08 not .8!
I’ve used the plug-in battery tender for many years and it worked great. So I’ll check out the solar combo.
Thanks again.
John

[John DL]

Originally Posted by herons

What size solar panel would you pair with the charger for a 12v battery?

If you are asking about a simple battery maintainer I use a 10 watt model. This will maintain a charged battery. It will not charge a low or partially discharged battery. If you are asking about charging a battery for boondocking I use a 100 watt panel

[John McDonald]

Your first response was all I needed.

[Marv]

Your cigarette lighter may be disconnected from the battery. I believe you can get a small solar panel that connects through the diagnostic port, which is live all the time.

[John McDonald]

Originally Posted by Marv

Your cigarette lighter may be disconnected from the battery. I believe you can get a small solar panel that connects through the diagnostic port, which is live all the time.

Yes, I have a device that plugs into the OBD2 port that I attach the solar panel to. Some vehicles USB and cigarette lighter ports are only available when the ignition is on.

[Mike_L]

I use a diesel tug to tow my trailer but little else. It may sit for months without use. It has two 1100 amp batteries. I use a 10 watt solar panel placed on the truck's dash and connected to the cigarette lighter to keep the batteries charged and it works well.
I've also used this panel to recharge an RV battery but it took about a week to fully charge it. The charge controller regulates the power to the batteries, preventing overcharge.
Some vehicles draw a small amount of power from the battery continuously. The solar panel should put out more power than the vehicle consumes, otherwise disconnect the battery from the vehicle (remove at least one battery cable) and connect the panel directly to the battery, not through the cigarette lighter.
You can also remove the battery from the vehicle and charge it at home to keep it topped up.

[John McDonald]

Originally Posted by Mike_L

I use a diesel tug to tow my trailer but little else. It may sit for months without use. It has two 1100 amp batteries. I use a 10 watt solar panel placed on the truck's dash and connected to the cigarette lighter to keep the batteries charged and it works well.
I've also used this panel to recharge an RV battery but it took about a week to fully charge it. The charge controller regulates the power to the batteries, preventing overcharge.
Some vehicles draw a small amount of power from the battery continuously. The solar panel should put out more power than the vehicle consumes, otherwise disconnect the battery from the vehicle (remove at least one battery cable) and connect the panel directly to the battery, not through the cigarette lighter.
You can also remove the battery from the vehicle and charge it at home to keep it topped up.

Is your controller separate from the panel?
( I have two 130 watt solar panels for the trailer and they of course require a separate controller.) But the 5 and 10 watt panels advertised on line as “battery tenders” or “maintainers” or some other verbiage like that don’t give any specs that guarantee they really have a controller as part of the panel. I have my doubts that they are legit.
I understand the panel or controller also need a dios to keep the current from reversing at night and draining the battery towards the solar panel.

[Mike_L]

Originally Posted by John McDonald

Is your controller separate from the panel?
( I have two 130 watt solar panels for the trailer and they of course require a separate controller.) But the 5 and 10 watt panels advertised on line as “battery tenders” or “maintainers” or some other verbiage like that don’t give any specs that guarantee they really have a controller as part of the panel. I have my doubts that they are legit.
I understand the panel or controller also need a dios to keep the current from reversing at night and draining the battery towards the solar panel.

I got this as a birthday gift from my kids a few years ago. It came with a separate charge controller with lights to show "charging" and "charged". The charge controller has a diode to prevent reverse current flow. I think any charge controller used to charge a 12 volt battery will work.

[Darrell in Al]

When you get one make sure to get a quality brand solar charger that monitor's the battery's condition. Last year I had one on my 4 wheeler battery, it boiled the battery dry over charging it. The "Battery Tender" brand I didn't have a problem with on one of my Jeeps battery. It was my fault on killing the battery I should have been checking it better.

[John McDonald]

Thanks all!
I do need a separate controller for my small solar panel (just like I do for my two 130 watt panels).
The companies that advertise their “dashboard” 5 and 10 watt panels as “battery maintainers” are being deceptive - surprise surprise!
I’m going to checkout Home Depot as mentioned by someone here, but now I don’t see that response above.
Cheers John

[Larry C Hanson]

Hello John,

For camping in my Trillium I use a 150W panel and a
BlueSky Solar Boost 2000i When I store the trailer I use
the same controller with a little 'old' 10W panel. The
little panel does a fine job of maintaining the battery.

Uncle Larry

[John McDonald]

How many and what types of batteries does it maintain? And how much sun does the panel get in the winter? In other words, where is it located? In what state?
Thanks. John

[Larry C Hanson]

OK John,

Battery maintained is a Trojan deep cycle 130AH (SCS225).
Panel is on the tongue of the trailer facing due south.
It gets plenty of AZ sun ... Latitude is 34N. Elevation about 5200'

Uncle Larry

[John McDonald]

Is the battery disconnected from the trailer so no phantom loads (propane detector, circuit boards of furnace, frig. ….) are taking amps out of the battery?

[Larry C Hanson]

Yes John.

In the power center/charger I installed there is a fuse on the
battery circuit. I pull that fuse so no phantom loads. The solar
charge system goes directly to the battery so it is not affected
by the disconnection.

Larry

[John McDonald]

Thanks.