Is it normal to worry about winter charging for a remote lithium bear fence?

You're right to worry about the charging cutoff, but it doesn't mean your fence goes dead the second it hits 32 degrees. LiFePO4 batteries will still **discharge** at temperatures way below freezing, often down to -20°C or lower. The internal BMS (Battery Management System) only blocks the incoming charge from the solar panel to prevent lithium plating, which would kill the cells. Since your fence and scale draw such low current, a 100Ah battery can easily run the system for two or three weeks without a single drop of solar input. The self-heating batteries usually need a significant amount of current to kick in—often 5 to 10 amps—and your 50W panel is only going to put out about 3 or 4 amps under perfect conditions. In the winter, you'll be lucky to get half that. It's unlikely you'll ever trigger a built-in heater with that setup. Instead of relying on a heater, a better move is to **insulate the battery box**. I’ve used 2-inch rigid foam board to line a heavy-duty plastic tote. It won't keep it warm forever, but it traps the small amount of heat generated by the BMS and slows down the temperature swing enough to catch a few hours of charging during the warmest part of the day.

If you're really concerned about months of deep freeze where the sun never warms the box above freezing, you could look for a battery specifically rated for low-temperature charging or just stick with the lead-acid plan. But with a 100Ah capacity and a tiny 0.3A draw, the lithium will likely outlast the cold snap anyway. Just make sure your charge controller is actually compatible with lithium profiles so it doesn't try to run a high-voltage equalization cycle, which can trigger the BMS to shut down entirely. One thing to watch out for with that DIY scale is **temperature drift** in the load cells. When the metal in the scale shrinks in the cold, your weight readings will start bouncing around. You might want to build a software offset into your code or just accept that the winter data is going to be a bit noisy untill things thaw out in the spring.

I ran into this exact issue with my setup last year. One thing people miss is the grounding. When the ground freezes solid or you get a foot of dry snow, your fence won't bite even if the battery is full. I ended up burying a ground plate way deeper than usual and added a 'hot-cold' wire system where every other strand is a ground wire. That way the bear hits both and gets zapped regardless of the soil. As for the battery, I just buried my insulated box about a foot deep in the dirt. The ground stays way warmer than the air and kept my LiFePO4 from locking out the charger most of the winter.

If you want to stop stressing about the heater not kicking in, just grab a Battle Born BB10012H. It’s thier heated 100Ah model and the internal heating element is designed to work even with lower-current solar setups becuase it prioritizes warming the cells before taking a charge. I’ve seen them survive brutal mountain winters where cheaper brands just stayed dormant for months. It’s a bit more cash upfront, but way better than hauling lead-acid blocks every November. Plus, their BMS is bulletproof compared to the generic stuff. You won't have to worry about the bear fence going cold.