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lazy alternator?


scotty

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I find that when driving around the voltmeter on the dash reads about 13v. When the engine is idling it drops to about 11v. If I use the headlamps while driving the gauge drops from 13v to about 12 - 12.5v. As my S3 is only used every couple of weeks (or less in the winter) I have invested in a trickle charger to keep the battery topped up (the imobiliser was draining it).

Prior to the trickle charger, even quite a decent journey (30 mins) was not really charging the battery (post a jump start). I thought that would be enough to completely replenish it.

The battery is less than 6 months old so I don't think that is the problem, although it has been drained almost flat by the imobiliser several times.

Are these symptoms indicative of an alternator reaching the end of it's useful life? I'm guessing that is the problem and if so is there a reccomended replacement (more modern/efficient?) Also - how hard is that to do? Bloody tricky I'm guessing!

Any advice appreciated,

Scotty

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Hi Scotty,

I'm no electrical expert and can only speak from experience. My standard alternator charges fine and I have a good 12-12.5V reading when driving with the heater on full whack and the headlights on full beam (my lamps have been wired so that all 4 are on main beam). With everything off the gauge is easily point in the 5 o'clock direction.

I understand that if the battery runs completely flat then it will never regain it's full efficiency so I would invest in a new battery. I'm sure someone here will tell you how to check if the alternator is doing it's job properly!

Good luck,

Pete

Pete '79 S2

LEW Miss September 2009

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Try connecting a volt meter to the battery terminals with the engine running, when you rev it up the volt meter reading should increase if it doesn't it's knackered, like mine is at the moment.Apparently they are the same as an xjs. A recon from SJ IS ABOUT

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I had the same issues on my S3 Turbo and recently had the alternator rebuilt. It's good that you added the trickle charger but it may be to late for the alternator. The way it works has been described to me this way. If you battery has been run down from the lack of driving and you start and run the car, the alternator is forced to work harder to recharge the battery while the car is running. So what often happens is with the extra load the alternator overheats and over time goes bad. When the tech rebuilt my alternator he found that the internals had overheated so bad that the insulator (plastic.. covering all the internal electrical bit) had melted.

It's pretty simple and straightforward to remove the alternator. Climb inside the boot, it's on the top right hand side of the engine, close to the firewall. The alternator is supported by a triangle bracket and the tensioner. On the top of the alternator is a long bolt with a 13 mm nut on both ends. Loosen the end against the alternator (you will have to hold both end to keep the bolt from spinning. Remove the nut and washer. Then slacken the bolt on the tensioner and push the alternator towards the ground to slacken the belt. Take the belt off of the pulley on the alternator and then remove the bolt on the tensioner. Now go back to the long bolt and with a wrench push it towards the back of the car to shorten up that end of the bolt. Move the alternator forward and take it out of the car.

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I had the same issues on my S3 Turbo and recently had the alternator rebuilt. It's good that you added the trickle charger but it may be to late for the alternator. The way it works has been described to me this way. If you battery has been run down from the lack of driving and you start and run the car, the alternator is forced to work harder to recharge the battery while the car is running. So what often happens is with the extra load the alternator overheats and over time goes bad. When the tech rebuilt my alternator he found that the internals had overheated so bad that the insulator (plastic.. covering all the internal electrical bit) had melted.

It's pretty simple and straightforward to remove the alternator. Climb inside the boot, it's on the top right hand side of the engine, close to the firewall. The alternator is supported by a triangle bracket and the tensioner. On the top of the alternator is a long bolt with a 13 mm nut on both ends. Loosen the end against the alternator (you will have to hold both end to keep the bolt from spinning. Remove the nut and washer. Then slacken the bolt on the tensioner and push the alternator towards the ground to slacken the belt. Take the belt off of the pulley on the alternator and then remove the bolt on the tensioner. Now go back to the long bolt and with a wrench push it towards the back of the car to shorten up that end of the bolt. Move the alternator forward and take it out of the car.

post-154-1171135580.jpg

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Don't forget to remove all tools, fasteners, etc; so nothing gets caught in the timing belt!

Goes for any job in the engine bay. Never hurts to err on the side of caution.

On a separate note, what types of alternators are used on the various Esprits across the pond?

Lee

Edited by Esprit Aviation
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I had a deal on my car when, if I put the heater fan on, the voltmeter would drop right down when I was at idle. At first I though it was a problem with the fan. Then, when I went to fit a rubber boot over the alternator connection the wire came straight out of the eyeley on the back of the alternator.

Fitted a new cable and it's been fine ever since. I would check that first as it's easy.

S4 Elan, Elan +2S, Federal-spec, World Championship Edition S2 Esprit #42, S1 Elise, Excel SE

 

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