Alternator problems!

[puddock]

Hi,
Can anyone help me? Last week when I was driving around, the battery light on the dash was flickering and later on, while Rohan was picking me up from a night out the car decided to cut out! Cue, me pushing the car into the car park slightly inebriated and in 4inch heels!
At first we though I needed a new alternator but when Rohan went out on Friday (first day without rain!) to take out the alternator he noticed that the little cable that runs out of the alternator seemed to have too much tension on it,after cleaning the contact on the cable and trying to take the tension off the wire he put the spare battery on the car and it started up no problem and after leaving it running for a while, he took it a run along the motorway for 20mins and the battery light stayed off.

However, when I came home from work and we started the car again the battery light was back to flickering but when he was fiddling about with the cable it was going off as normal. The connection seems a bit loose so we were going to take the connector off and extend the wire so it wasn't pulled and put a new connector on the end. As we don't know what the wire actually does, we don't know if it will fix the problem or if its just something to do with the dash light. Any ideas?
Thanks, Katie

Sent from my HTC Desire S using Tapatalk 2

[Dollywobbler]

Hi Katie. This is one of those jobs where you really need a multimeter. They can be bought for less than a tenner and are essential to trace electrical faults. An alternator works by taking in power via that small wire, then it effectively gets boosted by the alternator. If that small wire comes off, then there will be no alternator output. At least, that's my understanding of it... (I still regard electricity production as a black art!)

[Rommel]

Hi Ian,
I'm going to reterminate and slightly lengthen that cable as I am fairly sure that this will solve the problem.
Next cable will be a slightly more involved job, as it's speedo cable time!

Rohan

[Dollywobbler]

Given the cost, I think I'd be tempted to replace the dashboard bulbs while I was at it. I've got binnacle removal down to a fine art now. It's not too bad once you've worked it all out. The binnacle is held in place either with two 11mm nuts or plastic wing nuts. I've no idea when they changed over.

[citronut]

an alternator will produce current even with no wires connected to it whilst being spun,

the thick wire is live all the time as it goes straight to the positive terminal of the battery,

first thing to do is make sure all the wires/connectors are in good order and nice and tight

regards malcolm

[puddock]

Thanks Ian and Malcolm, dependent on weather Rohan will probably have another look at it today. He thinks there may be a break in the wire further down which could be a pain! But still cheaper than a new alternator I suppose!


Sent from my HTC Desire S using Tapatalk 2

[Birotor]

Malcolm's point is very valid! The alternator MUST be connected to 'the battery' when the engine is running. There are ways round this but only relevant in very specialised circumstances eg The battery can be replaced by a 'dummy load' in competition vehicles AND where external electrical switches are fitted so that Marshalls can turn off the engine after an accident (red switch with lightning flash label adjacent) the switch in the off position isolates the alternator output and directs it to a resistor connected to EARTH. Non competition look alike switches often used as anti theft devices do not have this and should not be put to off with the engine running.

[puddock]

Thanks for all the help everybody, turns out a new alternator was required in the end anyway! Glad to report that Beazley is finally back on the road!

Sent from my HTC Desire S using Tapatalk 2