That is correct, and my post was to show that even a FASS would drop a little.
When the grid heater turns on it draws current from the batteries, and that affects everything else connected to them.

 

Just a quick update.

Last week when I was driving home (about 35 km), when I accelerated more than a tiny bit the fuel pressure light came on and I couldn't go over 80 kph on the highway without the light coming on.

Made it home, replaced the pump (with the garage door half open at about
-20C) and now the light doesn't come on. I believe the light is triggered when pressure is 4psi or less.

Also the charge recovers faster and the Check Gages light doesn't stay on as long. The fuel pump must've been drawing a fair bit of current too.

Thanks for the help!

 

Sorry I didn't mean to like steal away from your observations, silly me

But thanks for the info.

My truck to does the same but no biggy, and my batteries are going on 9 years old. Turn the key to on and my voltage goes up to around 10, once started it will go to 14.5 lets say, grids come on, drops to 11ish if i remember correctly...