alternator? voltage drop when heaters on and lights?

[supercharged spaniel]

i checked the volts on the battery/alternator earlier this year but am concerned mine my be on its way out? 

if i have the lights on and the heaters and turn the lights off then the heaters speed up?  if i rev the car from idle the lights become ever so slightly brighter?  now i havent got my volt meter to check the voltage yet so ill do that but is this nomal?  i just feel like ive never noticed it before if its normal or not...anyone?
cheers

[supercharged spaniel]

well ive just checked it as i found my multimeter.  Turns out with everything on, heaters, lights, main beam, wipers, rear screen, fogs..11.8volts?

this means alternator change doesnt it? anyone know how much a new one is through vag?  aprox?  its probably exchange too?  what about changing it?  fairly easy?

[vwmk3jon]

changing the alternator means the charger getting in the way! Most arsehole place that VW could find to put it!

Mines doing the exact same thing as yours although its never failed to start on me and this is the 2nd alternator!

[supercharged spaniel]

well mine starts ok i suppose although not as responsive as its been ovr the last few years but it defo shouldnt be as low as that from the guides on the forum so im gonna change it...just hunting around to get one thats the problem...for a decent price anyways.

[SamG40]

I took mine to a local place that rebuilt it, came back good as new and cost around £50, although of course I had to wait a while for it, depends if you can cope without the car or not.

[supercharged spaniel]

i cant really thats the problem ive got...

[Dan]

I priced one up the other week, £140.53 + VAT, exchange.

[scotsjohn]

well ive just checked it as i found my multimeter.  Turns out with everything on, heaters, lights, main beam, wipers, rear screen, fogs..11.8volts?

 I'm assuming thats at idle, if so that's probably OK. What are you getting at a couple of thousand revs?

[hayesey]

11.8v isn't ok, it needs to be a good 13+ volts across the battery terminals or the ecu will get the hump about it.

[supercharged spaniel]

its around 13 ish with the lights off but ive noticed the car seems a little twitchy when trundling along with the lights on...must be this voltage drop...is this the ecu 'taking the hump'?  gonna sort an alternator out soon me thinks

[scotsjohn]

Might just need the commutator ring cleaned and a new brush set. Pretty straightforward if it wasn't for the alternator location.

[katabatic]

Hi supercharged spaniel (and others!),

I had this problem quite severely when I first bought my present g over two years ago (engine would stall with almost any elec, load on). I bought a brand new alternator (Lucas one) - no difference. Bought a new VAG one - no difference. Removed Clifford alarm - no difference.

Changing every sensor on the engine, the plugs (new Bosch platinums), a new coil and beefing up the earthing to the engine block and the tickover is a lot more stable and stronger(!) although the problem is still there; the engine is still not happy sitting in traffic with headlights on, for instance. I think it is just something to accept when running a tuned car - I turn the headlamps off if sitting in traffic and on again when moving again. She always starts first time as well!