yes if you just let the engine tick over, it will never charge the battery, slightly increase the revs, that should put some zip in the blighters… 
It will charge at idle provided the alternator light has gone out, but admittedly will charge faster if revved slightly.
Incidentally, if any Merc drivers don’t how to set fast idle for warm up and or battery charging, just ask & we’ll tell you.
Driveroneuk:
It will charge at idle provided the alternator light has gone out, but admittedly will charge faster if revved slightly.Incidentally, if any Merc drivers don’t how to set fast idle for warm up and or battery charging, just ask & we’ll tell you.
I just pull the cruise,limiter,exauster brake stick up
Regarding the comments about surge damaging the ECU.
I went to a local company yesterday to pick up my cutting gear for wheels clamps and while i was looking around there was a 24volt ani surge thing that you put on your batteries while jumpstarting, it’s designed to protect your ECU for the very low price of £4.99.
limeyphil:
Regarding the comments about surge damaging the ECU.
I went to a local company yesterday to pick up my cutting gear for wheels clamps and while i was looking around there was a 24volt ani surge thing that you put on your batteries while jumpstarting, it’s designed to protect your ECU for the very low price of £4.99.
also when you’re welding 
N2N Transport:
(unless you leave ■■■■ in the fridge)
I suppose your fridge is as good a place as any for hiding your ■■■■. 
BAILEY:
bugcos:
Have been told that running the engine for 15-20 mins does nothing really as it has used that much power starting it, is this truetotaly untrue as it will charge from running it,s like a car same thing will never over charge unless faulty alternator most car,s run at 13.6v max is about 14.v and i mean max so no it does help just starting it for about 10/15 min every few hour,s
The manual for my VW van said that the energy used to start the engine was about 30 seconds worth of idling. Which means you saved money by swiching it off for stops of over that. Pretty sure the same is true of a truck, the figure may be longer, 2 or 3 minutes at most, but not 15 minutes.
When I am running my inverter or laptop dropper, I run up the engine for 10-15 minutes at a fast idle if the voltage drops below 24.5v. Not had a problem yet, even with some slightly tired batteries.
N2N Transport:
As for battery isolators I always turn mine off when I am parked over a weekend etc. its good practice anyway (unless you leave ■■■■ in the fridge)
I hope that’s a spelling error and not some other pastime i know nothing about. 
limeyphil:
Regarding the comments about surge damaging the ECU.
I went to a local company yesterday to pick up my cutting gear for wheels clamps and while i was looking around there was a 24volt ani surge thing that you put on your batteries while jumpstarting, it’s designed to protect your ECU for the very low price of £4.99.
We used to carry those in case we had to have any repairs done enroute. But pray tell me about this and does it really work?
If you have a flat battery, you can plug an ABS lead from another truck into the socket and go for a cup of tea, when you get back the truck will then start from the power leached across.
I can just see the frazzled abs lead with the melted plastic sticking to the cat walk if someone forgot to unplug it before trying the start.
In theory might work, would need at least 30 mins me thinks.
Is there a device on the market that can show you how much power is left in the batterys.
I woke up in my Daf XF yesterday to find I had flattened the bats.
If some sort of warning or alarm came on I could have started up.
I carry jump leads but the problem could have been avoided if there was an indication of some sort. The Star ship enerprise has warning systems for everthing why can a Daf.
Those battery packs are £600.00 for a truck.
isn’t it dangerous to have someone (■■■■) in a fridge?
We should be able to hook up at services like campers do at campsites!! They charge the earth to park at MSA’s anyway!!
There is a device that connects to the battery terminal that is supposed to trip to leave enough power to start the engine. I can’t remember what they’re called or whether they have a unit capable of taking high truck amps.
Very weird…
When I come in on a Sunday, my batteries say usually about 23.8v. When I wake up in the morning after leaving the fridge on all night and watching dvd’s the display can say as low as 22.8v. Always starts first time every time.
Starting your engine when it’s as low as 24.4v? That’s what mine says five minutes after turning the engine off!
There are lots of companies that market retro-fit battery management systems.
These monitor the voltage & automatically disconnect the battery if the voltage drops below a pre-determined level for more than a minute or 2. Hence “saving” the remaining power for an engine start.
Priority low drain circuits such as tacho & maybe one interior light can remain supplied.
Just Google “battery management” or “truck battery management.”
Very Good!! 
Always keep your ■■■■ in the fridge as it stops them from spoiling!!
Wheel Nut:
If you have a flat battery, you can plug an ABS lead from another truck into the socket and go for a cup of tea, when you get back the truck will then start from the power leached across.
Nice one Malc, would the ‘donor’ vehicle need to be running?
Driveroneuk:
There are lots of companies that market retro-fit battery management systems.
These monitor the voltage & automatically disconnect the battery if the voltage drops below a pre-determined level for more than a minute or 2. Hence “saving” the remaining power for an engine start.
MAN gave me a ‘ballpark’ figure at the weekend for this type of system. £650
this is a fantasticly funny post!! ■■■■
Steve-o:
Very weird…When I come in on a Sunday, my batteries say usually about 23.8v. When I wake up in the morning after leaving the fridge on all night and watching dvd’s the display can say as low as 22.8v. Always starts first time every time.
this is like a bhp/torque thing, a car can have 500bhp but only 200NM of torque try and make it tow a 20ton trailer and it will fail.
i learnt this the hard way on a breakdown when i worked for scania, a truck wouldnt start, checked batteries first found over 24v so changed the starter to find it still wouldnt start!!! put my jump lead on and it fired straight up.
lesson is get your batteries drop tested not just volt tested.