Some cold morning voltages for you
Discussion
My car's starting to struggle since the cold weather's arrived. I only do small journeys to work, and the battery light on speedo/rev counter is almost continuously illuminated.
So this morning, I decided to investigate.
To charge a 12V battery, you need somewhere between 13.2V & 14.4V going in.
On cold start tickover I'm getting 13.1 rising to 13.2V as the car warms up, barely enough to charge the battery, but just about doing the job.
However
The hot air to clear the windscreen drops it down by .1V
The headlights drop it down by a further .25V
And the heated rear screen drops it down by a fairly heavy .6V
In short, with those three going, on tick over the battery is getting murdered.
Getting the revs up, will obviously solve the problem, but it's not always an option.
Time for a trickle charger me thinks
So this morning, I decided to investigate.
To charge a 12V battery, you need somewhere between 13.2V & 14.4V going in.
On cold start tickover I'm getting 13.1 rising to 13.2V as the car warms up, barely enough to charge the battery, but just about doing the job.
However
The hot air to clear the windscreen drops it down by .1V
The headlights drop it down by a further .25V
And the heated rear screen drops it down by a fairly heavy .6V
In short, with those three going, on tick over the battery is getting murdered.
Getting the revs up, will obviously solve the problem, but it's not always an option.
Time for a trickle charger me thinks
Pretty much the same with a lot of old school cars (not drive by wire throttle, decent controlled idle).
When all the gubbins is on and driving a short journey the battery will always take a pounding.
My old Astra only had to drop the Idle by 100 revs/min and the Alternator would pretty much stop.
You'll find this problem affects you more if your idle is already pretty low.
When all the gubbins is on and driving a short journey the battery will always take a pounding.
My old Astra only had to drop the Idle by 100 revs/min and the Alternator would pretty much stop.
You'll find this problem affects you more if your idle is already pretty low.
RUSSELLM said:
My car's starting to struggle since the cold weather's arrived............ On cold start tickover I'm getting 13.1 rising to 13.2V as the car warms up, barely enough to charge the battery, but just about doing the job.
Does the voltage increase with revs once moving along?If not then your altenator is probably on it's last legs.AlVal said:
can anyone reccommend a good brand of trickle charger that would be suitable for the cerb, and have some kind of setup that makes it easy to plug in and unplug when parking in the garage
The award winning 'CTEK' brand are probably the best out there at the moment imho,the xs800 is purely a trickle charger(maintainer),and the 3600 model is a combined 3.6a charger and maintainer which automatically decides at which rate to charge.You could hadwire one in the car,or use a cigar lighter adapter if you want it to remain portable.Using a trickle charger isn't really fixing the heart of the problem that is the alti doesnt turn fast enough on idle. With that in mind, it must be possible to fit a different pulley onto the alti so that it spins a bit faster on idle? Perhaps one off another car, or even a special machining job?
The AJP Griff said:
RUSSELLM said:
My car's starting to struggle since the cold weather's arrived............ On cold start tickover I'm getting 13.1 rising to 13.2V as the car warms up, barely enough to charge the battery, but just about doing the job.
Does the voltage increase with revs once moving along?If not then your altenator is probably on it's last legs.A quick blast up & down the motorway on A Saturday seems to put enough charge in the battery to give me a week of cold starts.
BCA said:
Very useful stuff, thanks, dads recently fitted a voltmeter to the Cerb (where the clock was) and his early morning readings on it led him to wonder if the battery was giving up - this has put his mind at ease.
Thanks Russ.
Where did you get the voltmeter from? Does it match the rest of the dials? Thanks Russ. Toadusmodus said:
BCA said:
Very useful stuff, thanks, dads recently fitted a voltmeter to the Cerb (where the clock was) and his early morning readings on it led him to wonder if the battery was giving up - this has put his mind at ease.
Thanks Russ.
Where did you get the voltmeter from? Does it match the rest of the dials? Thanks Russ. RUSSELLM said:
To charge a 12V battery, you need somewhere between 13.2V & 14.4V going in.
On cold start tickover I'm getting 13.1 rising to 13.2V as the car warms up, barely enough to charge the battery, but just about doing the job.
However
The hot air to clear the windscreen drops it down by .1V
The headlights drop it down by a further .25V
And the heated rear screen drops it down by a fairly heavy .6V
In short, with those three going, on tick over the battery is getting murdered.
For comparison reasons, I've just checked the voltages on my old Rover.On cold start tickover I'm getting 13.1 rising to 13.2V as the car warms up, barely enough to charge the battery, but just about doing the job.
However
The hot air to clear the windscreen drops it down by .1V
The headlights drop it down by a further .25V
And the heated rear screen drops it down by a fairly heavy .6V
In short, with those three going, on tick over the battery is getting murdered.
Cold start (tick over rises to 1300RPM), 14.7Volts.
The Lights, heated rear screen & fan all use .1 of a volt each. So with all of them on, you get 14.4 volts...... versus the paltry 12.15 volts off the Cerb.
Apparently that alternator is off a Land Rover.
I'm going to hazard a guess, that the Land rover must have been spinning it around a hell of a lot quicker than the Cerbera does.
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