I am watching the voltage start to sag a bit in my truck, but I have good faith that I’ll make it to five o’clock. The sun angle is declining now that it’s almost four o’clock and the skies have clouded up. But my battery bank is full and my laptop is fully charged, so I think I won’t go dark for another hour. #trucklife
I used to think that it was the starting and accessory batteries 🔋 with their different charge depth fighting that was causing the starting battery to loose charge when both batteries were connected in Big Red. But it turns out after reading on the internet, the relay that connects them is quite power hungry, pulling 400mA per my volt meter or about six watts whenever the relay is live. Doesn’t sound like much but six watts adds up over time. It takes a fairly powerful electromagnet to securely latch the relay when live to ensure that it doesn’t bounce loose on rough roads or have poor contact leading to arcing ✨ and burnt contacts.
The electricity use is fine and not possible to prevent unless I replaced the relay with a latching relay of some sort. Not a big deal when the big olf alternator is putting out 135 amps but something to consider with the solar panel that only puts out like 2 amp in the winter and maybe 5-7 amp on a sunny summer day. Also definitely something to consider when I eventually have an off grid property of my own.
Today was a bad day to test a relay that opens based on solar power. Worse sun angle of the year, shortest daylight of the year, and it’s a cloudy day. But it’s all hooked up and ready to go.