I’ve noticed on regular occasions that many drivers give their truck one last start before turning in for the night. They strike the engine up, give it a minute or so idling, then switch it off till morning.
WHY?
I can only assume they think they’re putting some charge back into the battery ready for the morning.
A 13ltr + lump takes a hell of a lot of amps to fire up, so I’d doubt 2 mins of idling will put back in anywhere near what they’ve just taken out starting the bugger.
Or am I missing the point totally here?
Could be using the kettle or microwave.
You’re right, I think drivers think it’ll help keep batteries topped up but also right that starting takes up so much power you’ll end up with less power in the batteries after a minute or two idling
It’ll take at least twenty minutes of fast idle to charge batteries.
goshow:
WHY?
Coz they know ■■■■ all about modern engines
Tractor units typically have a 13Kw starter motor but it only takes a second or two to get the engine running, and a 200 Ah alternator will replenish that lost charge in less than a minute.
Harry Monk:
Tractor units typically have a 13Kw starter motor but it only takes a second or two to get the engine running, and a 200 Ah alternator will replenish that lost charge in less than a minute.
But only at a fast idle. Alternators on vehicles are typically geared to give output at running speeds, not tick over. Hence why most narrow boats have a large(r) pully to run the alternator, as their engines spend most of their time at, or just above, idle.
I’ve started up before getting into bed but only for the air con to cool the cab a bit in hot weather.
I assumed they were checking that it would fire up and they hadn’t already killed the batteries while cooking tea.
Me first raggedy arsed car transporter was a bloody old Iveco wag n drag with a coffin nailed to the back of the day cab (that leaked, they all do that sir 
) in winter if i’d used the night heater for more than an hour during the evening no way would the thing start, not able to use it once lying in state in the coffin, cos same problem, so yes i’d have to to run the engine for about 15/20 minutes just before i got in bed, even then it was touch and go whether it would need a jump start in the morning, no telly none of that stuff, no room for a bloody telly 
Bodgit and Scarper operated and maintained.
Had similar touch and go cold start issues with many Volvos over the years up to and including FM’s, left for a long weekend without switching off at the mains, yep jump start it is.