Answers to questions about RV Repair and Maintenance from RV expert Dave Solberg, author of the “RV Handbook” and the managing editor of the RV Repair Club. This column appears Monday through Saturday in the RV Travel and RV Daily Tips newsletters. (Sign up for an email reminder for each new issue if you do not already receive one.) Today Dave discusses running a roof AC on solar.
I have a 2004 Fleetwood Providence. What type of solar system would I need to use one AC and regular electric outlets to boondock for a week or so? I have 4 AGM 6-volt batteries now. Would I need to change them or get more? —Randy
Until just recently I would have said there is no way to run a roof air conditioner on house batteries through an inverter. Not only would it take a gazillion AGM batteries and a football field of solar panels, but the initial startup of the typical roof AC is too high.
Enter SoftStartRV™, lithium batteries, and high-watt solar panels. Once again I was reminded to never say never! At the recent RV Show in Hershey, PA, Keystone unveiled their new SolarFlex system that will be standard on all Keystone products.
The SoftStartRV has been featured quite extensively by RV Travel and especially by Mike Sokol. According to their website, it will reduce initial startup draw by 70 percent, so you can actually run two roof AC units at one time. It reduces both torque and startup power and reduces the thumping a roof air conditioner typically makes during the cycling on and off process. I’ll let Mike dive into the technical aspect, however. Check out the video in this article on installation.
It’s amazing how technology has changed, especially when it comes to RV batteries! With several companies getting their start in the marine industry, we see the migration into the RV world with high amp hours and more affordable prices. However, they’re still several times more expensive than traditional lead acid batteries.
Keystone has partnered with Dragonfly Technologies, that has been known for their Battle Born products the past few years. They offer a 270 amp-hour battery with battery management system, as you cannot just drop lithium batteries into your existing system without the proper charging system. Once again, Mike Sokol has some great information from Progressive Dynamics in a livestream here.
The difference is lead acid batteries can only be drawn down to about 50 percent, while lithium can be drawn down 95% or more. There are many more advantages to lithium batteries; however, I’ll refer you to Mike’s articles. While working with Zamp Solar, I was introduced to Expion Batteries, which the former owner of Zamp Solar had started up recently.
When I was traveling around the country for Winnebago training dealers, solar panels were a novelty mostly for the Blue Bird Bus owners. They were the size of a king size mattress and took forever to charge a single group 27 battery. Fast forward a few years and solar panels have gotten smaller, lighter, and more powerful.
This picture shows two 300-watt panels on the Keystone displayed at the Hershey RV Show. Keystone partnered with Future Solutions to develop a series of solar arrays that they use on various models. They offer 200-watt and 300-watt panels that can be combined to get more than 1200-watt charging power! So, it is important to understand the charging power available, amp hours of your batteries, and power requirements of your rig, as you will be using items that will draw power other than just the roof AC. You need to have the right battery management system.
Having said all that, the unit at Hershey had a Bluetooth monitor. The rep from Keystone pulled up the screen on his tablet that showed power consumption as well as projected battery/amp hours available. The unit with the roof AC running could last approximately 2.5 hours. And that was with three 270 amp-hour batteries
So, after all that, to answer your question. It can be done, but not for a long period of time and at a fairly high cost.
Read more from Dave here.
Dave Solberg worked at Winnebago for 15 years developing the dealer training program, as marketing manager, and conducting shows. As the owner of Passport Media Creations, Dave has developed several RV dealer training programs, the RV Safety Training program for The Recreation Vehicle Safety and Education Foundation, and the accredited RV Driving Safety program being conducted at rallies and shows around the country. Dave is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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