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Old 08-14-2018, 12:31 PM   #1
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connecting solar battery to battery...

We have a 2011 Rockwood Mini Lite, and we'd like to use a 5v flexible solar panel to keep a trickle charge on the battery this summer...and maybe through the winter here in upstate NY.
We're looking at a Renogy 5w flexible panel, but it has a usb port. How do you connect this to a 12v deep cycle battery? If someone knows of an adapter, I have no clue where to find it. Any help would be appreciated!
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Old 08-14-2018, 12:36 PM   #2
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Hi,

There probably is an adapter of some type you could find to do this.

Five watts is unlikely to do a lot for you, but give it a go if you like.

FWIW.

Rich Phillips
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Old 08-14-2018, 07:13 PM   #3
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Sorry to send back a negative, but by the time you try to "convert" 5v DC up to 12V, you'd lose half of the current. Places like Harbor Freight make 14v panels specifically for this BUT there is the downside that it's NOT regulated and could boil out the battery over time - (at least in theory any non-regulated input is a hazard). You also need at least 13.6 v to charge a 6 cell lead-acid automotive battery and ideally 13.2 to keep it "on float". Lastly is that Winter with the sun so low, there is a lot of atmospheric interception and the total "insolation" or sunlight per sq meter drops off so you probably would not generate even the 5 watts you might get in summer with the sun directly overhead. And then the theft factor if unattended....
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Old 08-14-2018, 07:41 PM   #4
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A 5W panel will not even cover the parasitic draw of the items in the RV.
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Old 08-14-2018, 08:44 PM   #5
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5 watt, not 5 volt I hope regardless it is a waste of time for such a small amount of solar.
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Old 08-15-2018, 02:57 PM   #6
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Rule of thumb

A rule of thumb for lead acid batteries is that you can charge them continuously at 1% of the Amp hour capacity. So, if you had 160 Amp Hour (typical pair of Group 24 batteries) you could charge them at 1.6 Amps without issue. Left alone the batteries will lose about 10-20% of the capacity per month or even worse, if you have a pair of 12V batteries and one of them has a bad cell, it will take the good battery down with it over time.

So how do you get 1.6 Amps? Get a small Battery Tender (brand name) and hook it up and leave it on. If no house power in the area, then get a minimum of a 40 watt solar panel with a charge controller. In winter months maybe boost it to a 50-100 Watt panel to compensate for clouds and snow?

On my TT batteries I use the Battery Tender hooked to a time that runs about 6 hours a day. Came through the winter in great shape.

Like others who have commented, 5 watt panels are a toy and won't even maintain a small motorcycle battery.
There are great folks on this website with a boo-gillion years of RV experience.
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Old 08-15-2018, 06:31 PM   #7
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I have a mini lite as well. I have 2 Costco 6 v batteries that I remove during the winter months and store in my garage. I check them every month but they don't lose that much charge. I just put my plugin battery charger on them every couple of months to top them off.

During summer travel season I keep them charged with a Renogy 100 W solar panel that I mounted on a water proofed sheet of 1/8" plywood (can't roof mount on the lites), a Renogy solar controller, and a Victron 700 battery monitor. I guess I have about $350 tied up in all of it. We have gone 4 days without sun running almost everything without running the batteries down to 80%. They recharge in about a day of good sun light.

Solar is the way to go on the road, but home just take them out and plug them in.
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Old 08-15-2018, 06:41 PM   #8
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Quote:
Originally Posted by Ilovemywife View Post
5 watt, not 5 volt I hope regardless it is a waste of time for such a small amount of solar.

USB = 5Volt
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Old 08-15-2018, 06:45 PM   #9
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Quote:
Originally Posted by mlleelise View Post
We have a 2011 Rockwood Mini Lite, and we'd like to use a 5v flexible solar panel to keep a trickle charge on the battery this summer...and maybe through the winter here in upstate NY.
We're looking at a Renogy 5w flexible panel, but it has a usb port. How do you connect this to a 12v deep cycle battery? If someone knows of an adapter, I have no clue where to find it. Any help would be appreciated!

It's never going to work, the applied charging voltage must be higher than the battery voltage and anyways with a 5 Volt 5 Watt panel the output is nothing.
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Old 08-15-2018, 07:35 PM   #10
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Quote:
Originally Posted by mlleelise View Post
We have a 2011 Rockwood Mini Lite, and we'd like to use a 5v flexible solar panel to keep a trickle charge on the battery this summer...and maybe through the winter here in upstate NY.
We're looking at a Renogy 5w flexible panel, but it has a usb port. How do you connect this to a 12v deep cycle battery? If someone knows of an adapter, I have no clue where to find it. Any help would be appreciated!
Greetings mlleelise, the Renogy 5w flexible panel with a USB connector is designed for charging things like a smart-phone. A 5-watt panel will charge a phone, but very slowly. You need something bigger for maintaining a 12-volt battery in good health. Without going into technical details, UT_Grandpa who already posted in this thread (http://www.forestriverforums.com/for...ml#post1901074) already covered it: You need a larger panel.
I think your desire to augment your Mobile Palace with a solar charging system is very wise, but regrettably you need to purchase something much bigger. I'd recommend minimally considering something like the Renogy 50 Watt 12 Volt Solar Starter Kit (https://www.renogy.com/renogy-50-wat...r-starter-kit/). However, since this pushes the budget up substantially, it might be wise to learn more about solar and the benefits of augmenting your Mobile Palace with solar supplemental energy.
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Old 08-15-2018, 10:20 PM   #11
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5W solar works

Hi, use Pulsetech Solar Pulse Maintainer Battery Charger 5Wt to charge and keep "clean" 12V battery while using a battery disconnect. Works well to maintain battery while in storage. Is removable when not needed. In sunny CA so solar a good option.
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