The two Interstate SRM-24
12 Volt batteries that came in my 2018 Flying Cloud 20FB were suspect from the get go. After removing them and attempting to charge them individually they would not take a charge. I have an Interstate Battery distributer close to my house with a service counter. I took them down there and they confirmed they were toast.
They were dated August 2017 and under warranty. I opted to replace them with Interstate GC2-ECL-UTL 6V deep cycle golf cart batteries. I had taken measurements of my battery box and was confident these would fit. These cost a little more than the warrantied group 24's so the pair cost me an additional $70 after the credit from the warranty was applied.
The two batteries fit in the battery box allowing the lid to close without any modifications other than removing the plastic tray in the bottom. My understanding is the newer Airstreams like mine have a deeper box than previous models.
I purchased the following:
1 foot 2/0 gauge wire with ring terminals on each end (welding supply) $8.00
2 ring terminals for 6 gauge wire $2.00
I connected a pos post on one battery to the negative post on the other with the 2/0 wire I had fab'd up creating a single
12 volt cell. The new batteries only had threaded posts(no large post to clamp to) so I cut off the clamp style terminals on the 6 gauge wire running from the trailer and replaced these with the 6 gauge ring terminals. I then connected these, along with the positive and negative leads from the converter (I think thats what they go), and the leads from the solar plug to the free positive and negative posts. There is also a wire from the power jack that connects to the positive post.
Everything seems to be working so far. We'll see how they last in the long run. With the updated battery box on my 2018 I was able to fit these batteries and use the factory clamp to hold the batteries in without modification of the box. I did have to slightly bend down the fuse on the top of the positive terminal connector going to the converter.
If my calculations are right I went from 92.6 pounds of batteries on the tongue providing roughly 160 Amp Hours (80AH usable to 50% depletion) of
12 volt power to 124 pounds of batteries on the tongue providing 225 Amp Hours (112.5 AH usable to 50% depletion). Total cost was around $80 with the warranty credit on the original group 24 12 volts.
The first photo is the original group 24's wired in parallel. The trailer main is wired to one set of posts and the converter is wired to the other set. Not sure why they did it this way.
The second photo is of the 6 volts wired in series.
Linear Mode
