Checking voltage regulator

[Edward92]

Broke down the other day because my battery wasn't charging, was told by the RAC guy that it was either the voltage regulator or the generator, how can i test them to see which it is?

Cheers, Eddie

[bmcecosse]

First check - is the fan belt tight? Was the red light on in the speedo? Has it been coming on/off for some time ? How long had it been on - how long did you drive like that?? So - to check the dynamo - take the fan belt off, take the wires off, join the two terminals together with a long piece of wire and then touch that wire onto the non-earthed terminal of the battery. If the dynamo runs as a motor - it's fine. But the most likely result is that the dynamo needs new brushes - an easy fix!

[Edward92]

Only had the car a little over a week, the red light did come on the other day, what does this indicate and thanks for the advice

[bmcecosse]

Like ANY Red (or Orange) light - it tells you to STOP DRIVING - right away ! In this case - it tells you that the dynamo was not charging...... As long as the fan belt is still there (that's the immediate roadside check) you can drive on to get home - but you MUST minimise electrical consumption, certainly no heater, no headlights, no side lights (if possible), no wipers. And then you may be able to make it home before the battery runs flat. Surely the 'RAC man' should have fixed the problem for you ?? Or did he just give you a jump start and send you on your way ? He didn't sell you a new battery by any chance ? There was a scandal a few years ago where they were on a bonus scheme to sell batteries - and were Fired if they didn't sell a minimum number!!

[Edward92]

He just said to look at the Voltage regulator/generator as one of them wasn't working properly, I wasn't using anything electrical because i set off to go home at about 7 in the morning and turned the lights out and it just killed the car! He put a replacement battery in my car while charging mine in his van on the way home and just switched them again when we got back to my house

[bmcecosse]

Oh well -that's actually pretty good service ! Well done RAC.