I have a timer on my block heater so it only comes on for a little while. It's on my 93 7.3. Usually if it gets to be about 25 ish degrees out I do not bother plugging in. Below that I plug in for about 2 hours 2.5 ish and all is well. Once it hits single digits or the weather says it's for example 9 degrees actual but feels like -10 I plug it in for 4 4.5 hours. That seem pretty normal? I mean honestly I feel if i forgot to plug in on a temp like that it would probably start but absolutely hate it and I'd have to do a couple glow cycles. I usually glow about 7 seconds on 30 ish degrees and at 20 to 25 degrees I glow about 10 to 13 seconds and at like 10 or anything lower I would do about 18 seconds. And of it wouldnt start (which id be surprised) id let it sit for 20 seconds and do another 5 seconds. This is not plugged in. Plugged in I'd do about 5 to 7 seconds no matter what the temp because if it was warmer than 20 to 25 degrees it wouldn't be plugged in anyway. Also I have a manual glow system. Just seeing if what I do is normal or bad. Fortunately iv never had fuel gel (yet) I put about 4 ounces of Howes additive for every 5 gallons of fuel. Never an issue so far and it's gotten to about -15 for almost a week back in December. Anyway wat do you guys think?
Yup the block heater is about 800 to 1000 watts as measured with my watt meter. All those times sound fine for manual glow plug starting.
Plus we are all forgetting fresh batteries. I've battled getting my batteries back recharged after sitting for a while. With these diesel engines I do notice a difference with battery charge and starting time. A fresh battery turns the starter faster and seems to light the engine up quicker. Even slightly down on charge and there is a longer time to start with slightly slower cranking speed.
My solution, a 2 Amp trickle charger keeps the batteries fresh. As the temp drops so does cranking power. If you have to plug in the block heater, I think a 2 amp permanent charger under the hood attached to the batteries would help. Plug in the block heater and charger at the same time, even leave the battery charging all night. Not much power and it adds a little warmth to the batteries so you get more cranking power and speed on startup.
I also believe trickle chargers help extend battery life when batteries sit idle. prevents deposits from forming on plates.