So got into work bright and breezy to set off in my (2017) Daf 18 ton this morning.
The weekend shunter thought it would be a good idea to leave the ignition on and so the battery was flatter than a very flat thing.
No problem… half an hour later the workshop had it up and running.
My question was to the techs. How long do I need to drive for, to be certain that it will start by itself?
He reckoned 20 minutes…
I left the engine running at my first two drops…
and no doubt I won’t be invited to the next Health and Safety / DVSA. dinner dance…but I didn’t fancy being stuck …
I’d like to think it won’t happen again but…
Anyone any ideas how long you need to drive to be safe the battery has enough juice from completely drained ?
I have heard the figure of 20 minutes before, obviously if it’s a dark cold morning and you have every available device, lights, heater fan, heated mirrors, seats etc. switched on it will probably take longer.
Twenty minutes will top charge the batteries enough to start the truck after a brief stop but you will need to run the truck at normal speed for at least three hours to fully recharge them. However, if the batteries have been flattened completely then they are possibly now toast.
Have you not got a battery gauge on the instrument panel,keep an eye on it.
bobbya:
Have you not got a battery gauge on the instrument panel,keep an eye on it.
That won’t tell you anything other than the top charge on the batteries, not the depth of charge. You could run the engine for 30 seconds and then turn it off and the gauge would show 24.6 volts.
Harry Monk:
bobbya:
Have you not got a battery gauge on the instrument panel,keep an eye on it.That won’t tell you anything other than the top charge on the batteries, not the depth of charge. You could run the engine for 30 seconds and then turn it off and the gauge would show 24.6 volts.
It does show the state of the batterys though doesn’t it??
I have a device that plugs into the cigarette lighter that shows the charge state of the battery.
When a Stralis (*spit) that I once drove had flat batteries, the fitter who started it said to run it for ten minutes with EVERYTHING switched on. Now that surprised me, but he said the alternator works harder and puts more charge into the batteries under load. Anyone else heard this?
20 mins is plenty
I’m going to miss the slave lead, and knowing every vehicle has a slave socket.
If it’s only ignition left on then it would have been a slow drain and even possible they weren’t totally discharged. But by now you know weather their chardged or not. A bank of new 2017 battery’s should be still capable.
Twoninety88:
When a Stralis (*spit) that I once drove had flat batteries, the fitter who started it said to run it for ten minutes with EVERYTHING switched on. Now that surprised me, but he said the alternator works harder and puts more charge into the batteries under load. Anyone else heard this?
Yes and should also do the same when jump starting …
When someone left the lights on in the cab of my merc over the weekend it took 3 days for the battery level on the dash to show it as full.
surely there must be something flatter than a flat thing out there,lol
Thanks for the responses …
20 mins seems to be the consensus…useful to know for a future flat battery drama