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alternator testing
beaver34 - 30/5/11 at 11:51 AM

hi all,

whats the best way to test an alternator to see if its charging?

item in question is in my 73 vw bay camper van, light is not on the dash at all and used to be, volt gauge was showing lower than normal also, first time on the road since engine rebuild so seems alittle strange as it was new last year

thanks

rusty nuts - 30/5/11 at 12:32 PM

Have you got a multimeter? Put the red t6o battery positive+ and the blaqck to negative- start engine and take a reading, should be getting around 13.5v to 14.5v , if not check the output at the alternator . Could be thew regulator faulty? If its a 1600 then I always find it quicker to take the engine out to fit an alternator than trying to do the job in situ

steve m - 30/5/11 at 12:33 PM

with the engine ticking over, you should get a voltmeter reading of about 13.8 - 14volts across the battery

beaver34 - 30/5/11 at 01:00 PM

quote:
Originally posted by rusty nuts
Have you got a multimeter? Put the red t6o battery positive+ and the blaqck to negative- start engine and take a reading, should be getting around 13.5v to 14.5v , if not check the output at the alternator . Could be thew regulator faulty? If its a 1600 then I always find it quicker to take the engine out to fit an alternator than trying to do the job in situ


read just under 12 with multi meter on, i checked wiring but there is nothing to heck really it has an earth then live to battery and feed to light at front, it is internal regulator unit, its just strange as its 2 years old and done about 3k miles, it is a 1600 but on twin carbs so no messing with them, id rather not pull the engine if im honest as it has extra coolers and all them oil lines to sort, is it worth getting it reconditioned? might be cheaper than buying another outright

carlknight1982 - 30/5/11 at 01:53 PM

see if the brush pack is removable, try a new pack in it if so

try bedfordshrie auto electrics, they will post to you hell i have them send stuff to wakefield regualr for work

Chippy - 30/5/11 at 04:11 PM

quote:
Originally posted by beaver34
hi all, item in question is in my 73 vw bay camper van, light is not on the dash at all and used to be, volt gauge was showing lower than normal also, first time on the road since engine rebuild so seems alittle strange as it was new last year
thanks


I think that the first thing to do is find out why your charging light isn't coming on, lamp blown, brocken wire, if the alternator isn't getting an exciter current then it wont charge. HTH Ray

beaver34 - 30/5/11 at 04:15 PM

I wouldn't think that the alternator would my charge even if the light is blown? It's abit of a nightmare as it runs the lenght of the van Wight the rest of the loom in tr chassis rails if I remember rightly

Chippy - 30/5/11 at 10:17 PM

The alternator will not charge with the light blown, or the wire broken. When you turn on the ignition the warning light must come on, this shows that the alternator is being supplied an exciter current, you have to put some power into the alternator for it to start charging, once it is the light will/should go out due to the power being fed back up the wire so putting the light out. HTH Ray

02GF74 - 31/5/11 at 03:47 PM

raymond is right about the lamp.

to check this is the cause, as per the other alternator post on here, I suggest doing the same, which is:

take a long piece of wire, attach one end to positive of battery, connect a small 12 v bulb to other end of wire. to other end of bulb connect another wire and connect this to the alternator .

the lamp should come one,

run engine and watch as it magically goes out .... if it doesn;t the alternator is not giving out any output.

beaver34 - 31/5/11 at 07:17 PM

quote:
Originally posted by Chippy
The alternator will not charge with the light blown, or the wire broken. When you turn on the ignition the warning light must come on, this shows that the alternator is being supplied an exciter current, you have to put some power into the alternator for it to start charging, once it is the light will/should go out due to the power being fed back up the wire so putting the light out. HTH Ray


thanks, never though it would work like that! anyway blow bulb ill order a new one and some spare as there all the same


thanks guys