Alternator / Charging System

[UKWolf]

After getting the batteries checked - one down, one on its way - I've also found out that the altinator / charging system is only giving about 13.6 volts which is down on the 14.2 that it should be giving.

Anyone any ideas what to check to find out what the problem might be?

Many thanks in advance

[paulh]

If you still have the duff battery connected it will pull the alternator voltage down, see what its like with only the good battery connected.

[The Mechanic]

Try this.

Get yourself a relatively inexpensive hand held voltmeter from some where like Halfords for approx £7.00 (you may find them cheaper else where).

Locate the main (red) feed wire on the back of the alternator. Set your meter to 20V DC scale, place one (the red) probe from the meter onto the terminal connector (the feed wire) and the other probe (black) to a good earth. Start the engine and run it at idle...note the voltage reading which might be something like 11-12.5 volts. now rev the engine (not too much but to approx 2,500 rpm) and not the voltage reading...should be around 14-15 volts. Let the engine idle and re-check voltage at idle which should now be about 12.75 -13.00 volts. this will prove your alternators serviceable.

Many things can affect alternator output voltage, apart from poorly performing batteries. The drive belt may be loose or worn so that the belt is bottoming out (touching the bottom of the v pulley). The regulator may be lazy and reguire a good jolt (engine revs) to make it wake up and actually regulate. The brush pack may be excessively worn or be sticking causing a number of problems one of which will be poor charge rate and excessive arcing on the slip rings. Corossion is another area that needs to be checked, terminals, wiring and battery lug/clamps.

If you have to buy a pair of batteries try to get some that have matching production numbers/dates, in this way their performance will be roughly the same and no 'fighting' will occur ( one stronger than the other taking current away from one of the pair)

Hope this is helpful to you.

[MattF]

That alternator sounds like it's working fine. Wouldn't worry about it.

[kiowa]

the voltmeter on my stereo always reads about 13.6 so i wouldent worry to much bud

[Bludger]

Same thing happened with mine. Halfrauds said the alternator was shot and quoted me £300 to replace it. I changed the belts myself, fired it up and it charged beautifully.

i did have to change one of the batteries, but when I check it occassionally, it's always charging at about 13.

Check your belts and then re-test it.

Dave

[UKWolf]

Thanks guys

New batteries were fitted before checking charge rate, belt is tight but I'll check its not bottoming. I'll dig out the multi-meter (haven't seen it for about a year - god knows where it is) and do the other checks.

Amazing the differnce the new batteries made fired up almost as soon as I turned the key!!



Cheers once again

[The Mechanic]

Way you go pal!

So thats that, sorted then !