Nothing really new, just a recent scare.

So far this winter, things are going well. I’m looking to source some new spark plug wires and spark plugs for the chassis, trying to eliminate a serious mis-fire. And to stop blowing unburnt fuel out the exhaust. The Onan starts better the colder the air temperature. Running the generator for an hour in the morning and the same in the evening is keeping the battery pack in a good state of charge, this morning we were showing 80% of full charge after an evening of movies and light and a night’s worth of heat.
I keep track of the battery health by checking the battery voltage on a regular basis. The scare we had recently was mostly due to the way I check the battery voltage. checking the battery resting voltage follows a few simple rules. One the reading only counts after the battery has been resting for at least 3 hours. Second, the batteries can’t be asked to supply a significant amount of power while the voltage is being read because their internal resistance will cause a false reading. So I take a voltage reading first thing in the morning after the furnace has been off for 15 minutes. The world isn’t a perfect place and as long as I’m consistent in my measurements I achieve a usable number.
Well I scared myself last week. I hadn’t been paying much attention to the care and feeding of the batteries, trusting the generator 2-hour runtime and the automatic control of the PD 3-stage charger to tend to matters for me. As it turned out things weren’t as bad as I first thought, but at the time the voltage reading indicated that the batteries were at less than 50% of charge. Yeah, I panicked. I put a load on the system and took the voltmeter and started checking for bad connections, and shorts. Eventually while lying on my back under the chassis and finding voltage readings at 60%-80% of charge I had one of those Homer Simpson D’oh! moments. I check the battery voltage at the 12V socket in the kitchen. My laptop was plugged into the 12V socket in the writing desk, drawing on the same line from the battery. You might not think that’s very much current but charging my laptop draws 5A of current. Battery voltage is measured on 0.01 volt increments and 0.1 volt is a big change in battery state of charge. Unplugging the laptop and giving the batteries 1/2 hour’s rest showed a better state of charge. Still not where I hoped to be but not as bad as things first looked.
Next I took over control of the three-stage PD charger, setting the charger for bulk mode after bringing the generator on-line. That doubled the charging current and after several days of doing that I left the charger on automatic this morning since the batteries, after doing their duty for the night were showing 80% state of charge. So unlike our start last winter, we’re getting by on 2-hours of generator run time out of 24 and we can easily get by with 1-hour of charging if I don’t mind running down the battery pack.
Next up, insulating the holding tanks.

About Art

55 years old. By training, ability and experience I am a master toolmaker. My most recent projects include designing and building a process to grind a G rotor pump shaft with four diameters and holding all four diameters within plus or minus 4 microns of nominal. This was an automated process using two centerless grinders refitted to my specifications using automatic load and unload machines plus automatic feedback gauging. I also designed and built an inspection machine to check for the presence and size of a straight knurl on a hinge pin using a vision system for non-contact gauging.
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