I have been considering getting a solar panel for maintaining our 2 12v deep cycle batteries when parked at home.i usually back the TT in behind our garage and plug in the 30 amp shore power cord into a 20 amp 110 outlet with adapter to charge and maintain the batteries which has worked fine.i would like to park the TT in our back yard which would place it a good distance from the garage. solar panel would be in full sun all day unless its cloudy. the TT already has a solar connector wired.We do not dry camp or boondock but do have a residential fridge that we always load the night before camping and leave it running while on the road so the batteries do get used.wondering if a single 100 watt panel would be enough for charging and maintaining the 2 batteries while at home. i found this on amazonRenology 100 watt 12v panel with controller included in the kit169.99 (expandable to 4 panels )looking for thoughts or advice

As long as the fridge is off, the 100 watt panel will keep the batteries charged just fine.

I use a 30-watt Renogy solar panel and controller to keep my 4 6-volt batteries charged when stored over the winter near Seattle. I connect the charge controller's output directly to the batteries, and use the battery disconnect switch to remove any possible current draws. It works great!Note: I put the solar panel on the roof in the fall and remove it in the spring.

What are the amp-hrs of the batteries and what is the draw of the fridge? Storage: it would be simpler to disconnect the battery.Fridge the day before: Good chance it kills the batteries before you leave. That's where you need to check the amp-hr and draw. Don't plan on using more than 50% of the rated amp-hr if you don't want to damage the batteries. Probably simpler to run some extension cords for the day before. As long as you aren't running the air/con, household extension cords should be fine even for pretty long runs.

valhalla360 wrote:What are the amp-hrs of the batteries and what is the draw of the fridge? Storage: it would be simpler to disconnect the battery.Fridge the day before: Good chance it kills the batteries before you leave. That's where you need to check the amp-hr and draw. Don't plan on using more than 50% of the rated amp-hr if you don't want to damage the batteries. Probably simpler to run some extension cords for the day before. As long as you aren't running the air/con, household extension cords should be fine even for pretty long runs.last year to test how the batteries would do powering the fridge.not sure of the official draw from fridge but last summer in 90 heat with ac not running the fridge ran late afternoon till next morning off the batteries showed 12.5 volts after maybe 18 hours. (nothing but fridge running and other parasitic draws) i didn't want to discharge batteries below 50 percent.

100 watts is way more than you need to maintain your batteries. There are plenty of trickle chargers in the 7-10 watt range that would serve your purposes.

Solar panel question for 12v battery charging | Good Sam Community

red31
Explorer
Jun 01, 2018
dpgllg wrote:
Not to hijack this thread but my 5th wheel is prewired with the Furrion plug to connect a Furrion solar panel. I can't afford the $300 for the Furrion right now and only want this to maintain a fully charged battery.

Is there a way to use the Furrion connection with a Renogy panel for example?

Thanks!

Dave

http://www.rv-project.com/projects/solarconn.php
dpgllg
Explorer
May 31, 2018
Not to hijack this thread but my 5th wheel is prewired with the Furrion plug to connect a Furrion solar panel. I can't afford the $300 for the Furrion right now and only want this to maintain a fully charged battery.

Is there a way to use the Furrion connection with a Renogy panel for example?

Thanks!

Dave
austinjenna
Explorer
May 30, 2018
This is what I have been using for several years to keep the 2 batteries charged while parked in my backyard. Works perfectly.
The batteries are disconnected during storage.

I do the same when its in the storage lot. I have a battery disconnect switch to the fiver and a 100w panel and morning star 30 amp controller which keeps the batteries always topped off.
red31
Explorer
May 30, 2018
something like this will convert the mc4 to SAE
https://www.renogy.com/renogy-mc4-to-sae-adaptor/

if the polarity is reversed just rewire the connecton at the battery.

Solar will maintain and provide temperature compensated maintenance voltage for you batteries.

The connection to to the two 12v batteries should be the same as the supply to the RV, charge and discharge connect to the same place.
valhalla360
Navigator
May 29, 2018
sgfrye wrote:
valhalla360 wrote:
What are the amp-hrs of the batteries and what is the draw of the fridge?

Storage: it would be simpler to disconnect the battery.

Fridge the day before: Good chance it kills the batteries before you leave. That's where you need to check the amp-hr and draw. Don't plan on using more than 50% of the rated amp-hr if you don't want to damage the batteries. Probably simpler to run some extension cords for the day before. As long as you aren't running the air/con, household extension cords should be fine even for pretty long runs.

last year to test how the batteries would do powering the fridge.

not sure of the official draw from fridge but last summer in 90 heat with ac not running the fridge ran late afternoon till next morning off the batteries showed 12.5 volts after maybe 18 hours. (nothing but fridge running and other parasitic draws) i didn't want to discharge batteries below 50 percent.

If you are just going to turn it on 18hr early, skip the solar and disconnect the battery until you are ready to cool the fridge down, then flip the battery switch on.

Unless you have another use, it would be a waste to add a solar system. If you are concerned one of the little 10w trickle solar panels could be wired direct to the battery to keep it up when disconnected from the trailer systems but not really needed.
sgfrye
Explorer
May 29, 2018
time2roll wrote:
For the effort I would still go 100 watts. Yes the 30 might be fine. Yes the 7-10 watt might be fine if battery is fully disconnected and just to maintain a full charged battery. With 100 watts you can arrive with a low battery, close up the RV and the battery will be fully recharged in a couple sunny days. No more effort to mount a 100w panel vs something smaller.

Yes you must get polarity correct. Pretty sure the ZAMP is just a common SAE 12v connector available at most automotive or electronic supply stores. Make your own pig-tail adapter to connect as needed.

At this low power you can connect to one battery if that is easiest. Best is positive to one battery and negative to the other same as you main RV cables should be attached.

Thumbs up
sgfrye
Explorer
May 29, 2018
red31 wrote:
there are adapters for the zamp solar ready plug
https://www.youtube.com/watch?v=LShSQeddlgk
There are also mc4 to sae adapters

You nailed it. Thank you
time2roll
Nomad
May 29, 2018
For the effort I would still go 100 watts. Yes the 30 might be fine. Yes the 7-10 watt might be fine if battery is fully disconnected and just to maintain a full charged battery. With 100 watts you can arrive with a low battery, close up the RV and the battery will be fully recharged in a couple sunny days. No more effort to mount a 100w panel vs something smaller.

Yes you must get polarity correct. Pretty sure the ZAMP is just a common SAE 12v connector available at most automotive or electronic supply stores. Make your own pig-tail adapter to connect as needed.

At this low power you can connect to one battery if that is easiest. Best is positive to one battery and negative to the other same as you main RV cables should be attached.
red31
Explorer
May 29, 2018
there are adapters for the zamp solar ready plug
https://www.youtube.com/watch?v=LShSQeddlgk
There are also mc4 to sae adapters
2oldman
Explorer II
May 29, 2018
12v side of life.