Welp, the electical gremlins keep peering their heads with the heffalump.
2 years ago, the heffalump was shipped to Bellingham, WA where it sat in grey weather for a couple of week. So there wasn't much solar harvesting. When I went to go pick it up, the 2 starter batteries were flat so they were replaced. Over a period of about 1 year, one of the positive terminals leaked fluid and caused corrosion. That was was cleaned up several times with a mixture of baking soda/lime/water. The problem persisted and over the past 2 years, I've replaced a positive terminal about 3 times and also swapped batteries. The cable was cut back, cleaned, and soaked in the same solution a few times.
Last week, I ended a work shift early in the morning to find that the batteries were dead. I carry a Truck PAC 3000 and tried jumping it to no avail. When the autopart stores opened up, I secured 2, AGM batteries, and again repeated the process of cleaning, replacing terminals, and added electrical grease.
This past week, I monitored the connections and didn't see any corrosion. I previously added a dash gauge to monitor voltage. When the truck is on, it's reading between 26=27v.
This morning, I woke up to flat batteries again. I arrived here on Friday. Moved the truck on the lot yesterday, it's been parked since. I hooked my jump pack that was fully charged and it drained it within seconds. I'm now reading 8.6v. I'm wondering if I've got a parasitic draw somewhere. But I'm not sure where to look since the truck's system is so simple and doesn't have a modern ECU. The lights are off. Nothing on the dash was left on. Currently in Issaquah, WA at a friends farm.
Any input/help would again be appreciated. :-/