Reply
 
Thread Tools Display Modes
Old 04-04-2015, 05:19 PM   #1
Senior Member
 
Bianchina3's Avatar
 
Join Date: Apr 2015
Location: Chicagoland..Da Bears
Posts: 119
Adding a solar charger for batteries.

I am interested in adding a solar charger to my unit to charge/maintain my batteries. I have two 12 volt batteries and the purpose is to keep them maintained when not in use. Maybe a second purpose would be to charge them up a little during the day, but not expecting much.

The question is does it matter what size panel you buy? Assuming that you get a smaller on can you get bigger if you want. At what point, wattage wise, does it switch from maintaining to charging?

Thanks.

Ed
Bianchina3 is offline   Reply With Quote
Old 04-06-2015, 03:47 AM   #2
Member
 
Join Date: May 2014
Posts: 36
I have 2 deep cycle 6 volt batteries, 2nd year since newly installed. I use 1.5 watt solar panel I mount on TT tongue. It maintains the charge at 13.4 volts when stored. I tried a 4.5 watt earlier and it over charged the batteries. Just remember to check water levels in the batteries. Good luck


Sent from my iPhone using Forest River Forums
10Boomer is offline   Reply With Quote
Old 04-06-2015, 05:33 AM   #3
Senior Member
 
Join Date: Feb 2012
Posts: 1,101
It really does depend what you want to do. If you just want to keep a disconnected battery charged a 5w panel with a basic charge controller will work. The charge controller would just disconnect the panel from the battery at a set voltage so it doesn't over charge it. If you want something that will have different stages then you need a mppt type controller and a larger panel. If you want to charger your batteries then you need at least a 60W panel.
__________________
Ontario

Vibe 6501
1 Prospector Canoe
2 Mtn. Bikes
4 Hiking Boots
Happy Vibe is offline   Reply With Quote
Old 04-06-2015, 06:47 AM   #4
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 22,818
Quote:
Originally Posted by 10Boomer View Post
I have 2 deep cycle 6 volt batteries, 2nd year since newly installed. I use 1.5 watt solar panel I mount on TT tongue. It maintains the charge at 13.4 volts when stored. I tried a 4.5 watt earlier and it over charged the batteries. Just remember to check water levels in the batteries. Good luck


Sent from my iPhone using Forest River Forums
This is why a solar charge controller is needed to replace battery capacity lost.

Small panels without integral controllers can overcharge because current will always flow when the panel in in partial to full sun; whether the battery can handle the influx or not.

Your 1.5 watt panel is producing 13.4 volts at (.112 amps) 112 milliamps (1.5 watts) in full sun; less current if not. That is about what parasite draw plus internal loss is; so capacity remains about the same when the panel is connected. Much more continuous current than that will definitely overcharge and ruin the battery over time as you discovered.

A solar charge controller will reduce charging current to a trickle as the battery fills; a good one will also vary voltage output based on battery condition, like your camper's staged converter, to "make hay while the sun shines" and efficiently recharge a partially discharged battery.
__________________
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW
Herk7769 is offline   Reply With Quote
Old 04-15-2015, 10:10 AM   #5
Senior Member
 
Bianchina3's Avatar
 
Join Date: Apr 2015
Location: Chicagoland..Da Bears
Posts: 119
After doing some more research I have determined that what I want to do is to use the batteries during camping and then be able to charge them slowly over course of a week or two. If I need a quicker turn around, like camping two weekends in a row I can pull the battery and charge them at home.

I know I need a controller but the question stands for the panel. Does this additional info help narrow the panel size?
__________________
Ed and Jennifer Bianchina
2014 Dodge Ram 1500 Crew Cab
2011 Puma 2011 26 RLSS

Bianchina3 is offline   Reply With Quote
Old 04-15-2015, 11:17 AM   #6
CJM
Member
 
Join Date: Aug 2014
Posts: 53
There is a ton of information that is needed to size panels correctly. . I see a lot of misinformation on forums, and a lot of wasted money as well. My advice to you would be install a panel on your roof. 50-100 watts. Chase the cable down the fridge vent, Mount a charge controller in the back of the fridge ( go with a sealed charge controller, yes they exist), and tie into the DC Side of your panel. There is better, ways to install, that can maximize your DC out put, but this will give you your desired result with pretty good recovery time, for the best dollar for dollar result. . Do not buy these parts from an RV dealer. Buy on line or find a reputable electrical supply vendors. Panels should be at or about $1/watt. Basic charge controller about $60.
CJM is offline   Reply With Quote
Old 04-15-2015, 01:15 PM   #7
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 22,818
Quote:
Originally Posted by CJM View Post
There is a ton of information that is needed to size panels correctly.
Therein lies the nut.

Existing battery capacity in Amp Hours; the amount of that battery capacity you use per day; the amount you would like to replace each day of available/usable daylight; and how low you are willing to discharge your expensive deep cycle battery(s) will determine the wattage you will need on the roof.
__________________
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW
Herk7769 is offline   Reply With Quote
Reply

Tags
solar, battery

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.



All times are GMT -5. The time now is 05:54 AM.