true or false

[clarkie2772]

hi all best wishes for the season

someone told me that if you put your headlights on for 20 secinnds or so before you start your engine this has a positive effect on the battery and serves to warm it up aideing ignition ....... is there any truth in this or is it just waffle

all the best marc

[simonr]

No - I think they were winding you up.

If your battery is marginal and it's 50/50 whether it will have enough juce to start the vehicle, running the lights for 20 sec will just make it a certainty that it will not start.

I can see that a battery will deliver more current while warm - but I think the effect of this will be marginal. It will heat up a similar amount in the first couple of seconds cranking. The flip side to this is that as batteries heat up, their effective capacity reduces (which is why they are often cooled in electric vehicles). Thus, your cranking time will be further reduced!

Running your headlights after it has started will make the engine heat up a little quicker though.

Si

[JimAttrill]

Running your headlights after it has started will make the engine heat up a little quicker though.

Si

By putting a bit more strain on the engine and therefore generating more heat? Must say this is the first time I have heard this one.

Rather like going downhill offroad with the aircon on as the engine braking is greater.

[clbarclay]

My experiance is batteries appear to have more power left in them if left for a while. I first came across this with model cars.

It also happened the last time I was off road. 2/3rds the way through a winch recovery my engine stalled and there wasn't enough power in the battery to restart it. After a while of faffing about to get a 90 within jump ead length and riging up

[nobber]

sounds like waffle to me , to warm the engine up though i usually drive with the handbrake half on.

warms the engine up in no time.

[western]

to warm the engine up though i usually drive with the handbrake half on.

not a good idea as it will overstress the transmisson too,

[Les Henson]

No - he was serious, the friction produces a lot of heat, which sets fire to the handbrake. In no time at all your bum is nice and toasty.

Les

[sotal]

I've heard the put your lights on theory before, it was in relation to older vehicles such as series LR's and the recommendation was to put your sidelights on for 10 seconds before starting if you haven't started for a while.

I think the theory was it warmed the battery up a little and reduced the 'shock' to the battery.

The peson suggesting it suggested newer vehicles didn't need this as they use the battery a litlle bit all the time. Even entering the vehicle on a newer vehicle switches on a courtsey light for 10 seconds.

No idea if it's true or not but I leave my series weeks sometimes without starting and I never follow this advice. I just jump in and start it up. The glow plugs come on first which would warm the battery up if neccessary. I'm still on my first battery.