We’ve been getting poor battery life in the trailer (basically only used to run the electronics while the trailer is in storage, because we’re usually on shore power while we’re actually camping). The AGM batteries are only supposed to have a ~5 year lifespan, and I suspect they’ve gotten below the 50% charge level a few times, which damages them. When we took Tourtoise in for its *cough* annual *cough* maintenance, we asked them to check them and quote us for a lithium upgrade.
Both 6V batteries failed their load tests. The shop wanted $1,500 for the lithium replacement, with two 100 Ah batteries at $600 each. I’ve been looking at doing this myself, and that just seemed unreasonable.
Instead, I ordered a single 200 Ah battery for $400. The review sites that I looked at recommended getting simple batteries without bluetooth monitoring and adding monitoring elsewhere if needed, so I also got a Victron SmartShunt for about $80.
Installing the battery itself was pretty easy. The battery compartment is under the bed, so I removed that, unplugged the old batteries, moved them out of the way (HEAVY), and dropped the new battery in place.
Installing the SmartShunt was similarly easy. I picked a spot where the wires would reach and screwed it in to the side of the battery compartment. It showed that the battery was at 100% charge, which was surely not the case. I had to tweak some settings in the Victron app.
Next up was setting the battery charger to charge a Lithium battery at the proper voltage, rather than an AGM battery. I had a heck of a time figuring out how many chargers were actually in the trailer. I’d watched some videos where all they do is change the settings on their Victron charger, but I was under the impression that that was only for solar charging, not for shore power charging.
I had forgotten the PIN for the Victron charger, so I ended up removing a drawer and cramming myself into the cubby to unscrew the device to read the sticker that the docs described as being “on the back”. In fact, the sticker is on the top of the unit, and I could have photographed it with careful phone placement and no unscrewing. Oops.
With that PIN recovered, and everything screwed back into place, I was able to set the solar charger to Lithium settings.
More internet digging helped me figure out that yes, there is a separate charger for shore power. It is a WFCO power center. The actual charger part of it is under the fuse panel, hidden behind a screw-on plastic panel. The model supposedly auto-detects whether the battery is a lead-acid or lithium battery based on how it responds over several charge cycles. I did not have time to run the battery through several charge cycles before returning it to storage, but I found some forum posts about forcing the unit into Lithium mode by using a jumper. After trying that, I was able to get the unit to change from the green status LED (lead-acid) to the blue (Lithium).
As I suspected, the battery was not at 100%. I had to charge it on shore power for 6-8 hours before I saw the charging current drop from ~9A to virtually nothing.
I had previously built a cellular voltage monitor, which I reinstalled downstream of the SmartShunt. The SmartShunt claims that it is drawing ~100mA of current, which the solar should easily replace, even in the trailer’s covered parking spot.
