Maximize Solar Power on a Small RV - [Connect DC to DC Charger to Trailer Batteries]

In this video we discuss:
1. How to use a battery switch to isolate solar panel arrays of different wattages so that they can both connect to the same charge controller.
2. How to connect a Renogy DC to DC Charger with MPPT from the towing vehicle to the trailer battery bank using a detachable connection.
3. How we use a battery switch to control where we send our DC to DC charge from our towing vehicle, to either a 50Ah LFP battery that runs our ICECO Fridge/Freezer, or our trailer battery bank.
The biggest reason that you might want to use a portable solar panel in addition to your rooftop solar panels is so that you can keep your RV in the shade during the summer months. The portable panel on an extension cord can reach out into the sunshine while the rig remains under the tree canopy.
Since we have 200W on the roof, we could not plug our 400W Lightweight Portable panel into the same charge controller at the same time. The differing wattages will negate the efficiency of the larger panel, so we installed a switch to isolate which solar array is charging our system.
See our review of the Renogy 400W Lightweight Portable Panel - • Renogy 400W Lightweigh...
The second switch is used to control which battery is being charged by our 30A Dual input DC to DC charger. We can charge our 50Ah LFP battery which runs our 12V ICECO Fridge /Freezer, or our 200Ah LFP battery bank in our trailer. This is especially helpful during the colder months when the fridge doesn't need to run that often, and the solar gain is low. While driving we can increase our battery state of charge by 20% for each hour driving.
Products Highlighted:
1. 400W Lightweight Portable Solar Suitcase - renogy.sjv.io/...
2. 30A Dual Input DC to DC Battery Charger - renogy.sjv.io/...
3. VL45 - Single Zone Fridge Freezer (For 12% off ICECO Cooler / Freezer, use our AFFILIATE LINK [icecofreezer.co...] and PROMO CODE [CANLIFE] at checkout!)
4. Extension Cables (single) - renogy.sjv.io/...
5. Battery Switch (1, 2, Off) 12-48V 200 - 600A
6. 15A In-line fuse switch
If we've helped you find something here, please be sure to purchase your Renogy gear through our affiliate link, renogy.sjv.io/L... and use promo code "CANLIFE" to receive an additional 10% off your Renogy order. This gives us a small commission and helps us keep our content free to all!
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Disclaimer: Most of the videos we make include affiliate links and paid sponsorship, this helps keeps our information free and us on the road (11 years and counting!).
This video is intended to help users plan, organize, calculate, and install a personal DIY solar powered electrical system. We, Shari & Hutch (Freedom in a Can, LLC), are neither professional electricians nor solar installers; we are educators who have learned to install our own system and to empower others to do the same. If you have questions, reach out in the comments section and we'll get back to you.
If you need further assistance beyond our advice, consult a solar professional or certified electrician. Electricity is dangerous, so do your homework, take it one step at a time, and good luck!

[@FreedomInACan]

BIG NEWS!!! Use CANLIFE promo code at Renogy checkout to save an additional 10% off most products -- even on SALE items! Use this affiliate link: renogy.sjv.io/LPEyNY Promo code CANLIFE valid in the United States, Canada, Germany, Australia, and the United Kingdom!

[@SCOTT-vm5nj]

Awesome, thanks for this. Is there a video about building your bike rack? I’d like to do that to my Scotty. Thanks 😮

[@FreedomInACan]

Thanks for the comment! This has been a huge benefit for our full-time life. We do not have a video about the bike rack. We had our local metal shop (folks who do custom welding, install snow plow mounts, etc.) fabricate & install a 2" receiver for a bike mount insert to the bottom of the trailer. So we could also take the rack and insert it into the truck. A year later, we had them reinforce it the mount and it's worked great ever since. Send me an email at [e-mail] and I'll send you some photos.

[@solidoaksrvtrail6588]

Do you have another video that explains about the efficiency of the 2 different solar arrays and why you’d need to swap? We have 400 W on the roof and want to get a 200 to 400 W suitcase. If they were both at 400 W it wouldn’t be an issue to go through the same 50 amp charge controller? We have an external input that goes through the same controller. Thanks!

[@FreedomInACan]

Hey there, thanks for the question. While we don't have another video, we just wrote a blog concerning this issue -- freedominacan1957.blogspot.com/2024/05/summertime-strategies-for-staying-cool.html#:~:text=System%20Integration%20Options,a%20few%20ways%3A Concerning your issue. How many panels do you have on the roof? I'm guessing 2 x 200W. So when connecting all of your panels together, roof and portable, they will need to be similar wattages. If you want to simply go through the same controller, use a 200W portable. Or you could have a separate controller for the 400W portable, (see our review of the Renogy 400W Lightweight kzbin.info/www/bejne/mnXKpGyIltaIoaMsi=mQX0D4-50Sc0dKwI), or lastly do the hack we showed in this video to isolate your panel arrays so that you won't loose the efficiency of the 400W. And if you want to go with Renogy, be sure to use our affiliate link: renogy.sjv.io/LPEyNY and promo code "CANLIFE" for 10% off. All the best, and let us know if you have any further questions.

[@solidoaksrvtrail6588]

@@FreedomInACan Thank you!!

[@Mr_SynergyPerformance]

I was under the impression that is was bad for the panels to be left disconnected from any load if they can be producing output. Maybe that’s an older methodology, but it has made me pause to rethink some design features of a solar setup. But, if they can be left disconnected (as long as they don’t short) that simplifies some things for me. Can you shed any insight on that?

[@FreedomInACan]

@@Mr_SynergyPerformance Thanks for the great question. It is my understanding that the risk of leaving panels illuminated, but disconnected, is more about an unplanned shock (wires not plugged into a circuit in the off position) rather than any damage to the panels. But let me ask our engineer friends at Renogy and get back to you with more specifics and reasons. Sound good?

[@FreedomInACan]

Sorry for the long delay in returning to your question. When you disconnect the solar panels from the charge controller, they are no longer in a circuit. So, they will produce a voltage when illuminated but no current, because there's no place for it to go, just like turning off a switch to an outlet. The only danger is if there's a potential for a short circuit when suddenly something unwanted causes the voltage to become a circuit, i.e. you. But with proper MC-4 connections and switches, there's no harm. Make sense?