Last August, I teased that there was one more significant Silver Subie mod, but I never got around to documenting it. Since then, I did a full engine overhaul, new clutch, new brakes, new radiator, etc.
I wasn't happy with depending on the car battery for overnight use, but I couldn't justify a dedicated "house" battery, or so I thought. Shortly after getting home from the weekend trip with the tent addition, I was "blessed" with a CPAP. Now I had an excuse! The CPAP provider was less than helpful about running it on batteries, so I reinvented the wheel, so to speak.
If it were just current uses for the Subie, I could have gone with a smaller battery, but I needed it to have enough capacity to support our annual river trip as well. My design criteria was to have enough capacity for the CPAP for 10 nights or to comfortably handle the computer and 12 volt fridge (one can dream, right?) in the Subie.
I ended up selecting an LiFePo4 50 Ah battery from GoWesty.com. They import this battery for "house" battery applications in VW Vans. The physical size and weight were excellent, and the price was better than I would have expected.
I lose some space in the kitchen box, but that's a small price to pay for the convenience!
The battery is charged from a Renogy 20Amp DC-DC Battery Charger. This provides the charge curve that the LiFePo4 battery needs. This charger lives under the driver's seat.
The charger can be turned on/off from a switch that fits into a blank spot on the console. Since I only use the battery on overnight trips, the charger is turned off for everyday use of the Subie.
With the car installation finished, I built a water (and sand) resistant box to house the battery and control panel.
It's one more thing that gets loaded in the canoe, but the system worked well and lets us do those extended float trips that we love. It's been a win-win solution.