My new trailer is now three years old. Not so new anymore. Frankly, I've made so many changes Airstream would hardly recognize their trailer anyway, so what's one more, which is to cycle out the stock Interstate Group 24 batteries and modify the battery box to accept larger capacity batteries. I've been reading much about the lithium batteries and their advantages, frankly think they're great. I was almost starting to go that route when reality hit, the work to redo all the existing wiring, the complexity, and then there's the price tag. Ouch. I need a new truck, my son is in graduate school ($$$), I just spent a lot on a new Trek road bike..... Maybe later.
In reality we are mostly weekenders and long week'rs. I never imaging full timing, but can imagine some long duration camping. If I'm hot, I'll probably pay to stay in RV park to plug in, but mostly stay at National and State Parks. Might boondock some, but I like to travel to tour, to experience different places and people.
So decided to go old school, lead acid battery upgrade. On my trailer the battery box is outside. No need for AGM's. I'm intrigued by the Trojan T-165 260 amp hour battery (130 usable). Not sure this is what I'll get but I know I need to modify the stock battery box as its only 10" deep and cannot hold any normal 6 volt (golf cart) battery.
Knowing this would require welding, and to make this even more adventurous, since I've never welded before, I bought a Harbor Freight welder figuring this should be just fine and of course I can do this. What a disaster. As I practiced with this new welder I discovered I could not make a weld to save my life. So what to do? Ahh.. watch a YouTube video. I learned the welder uses AC current and DC is what's required for decent welds. So after modifying the welder by rewiring and adding a rectifier and large capacitor to bridge the sine gap I ended up with a decent DC welder that works okay. After practicing on various metal bits I think I'm ready.
My stock Airstream 2013 external battery box was 10" deep. Most 6 volts are 11" to 12" tall. Their other dimensions are okay for the existing battery box. Using a straight edge I figured I could lower the battery box up to 3" and still remain in line between the jack and lowest point on the spare tire. The idea here is a object on the road over a hump would still clear the modified box if it cleared the spare tire. Since I've never dragged the jack nor spare tire, I figured this drop should be okay. I decided to drop 2.5" just to be safe.
Major tools used, a grinder with a cutoff wheel and sanding disk. A Sawsall with metal blade. My modified welder. Here's some photo's.
In the above photo I've cut the bottom off the battery box. No going back now!
Not trusting my welding skills I embrace a hybrid approach. I cut four 1/8" steel straps extending the bottom 2.5", securing it all with 3/8" bolts. I then weld them solid, including the bolts and nuts.
View from top.
Viewed from underneath.
To be fair, butt welding thin steel sheet is hard. I managed to weld enough to get complete connectivity along the length, but not 100% all the way. Burn through spots were hard to avoid. Ended up running a paste of JB Weld to fill in the gaps. After it cured I sanded it smooth.
After sanding and paint this is the finished result. Not too bad. You too can do this this with enough persistence. Just don't set your front yard on fire as I did when grinding off excessive weld splatter.