strongy Posted January 14, 2003 Share Posted January 14, 2003 I am just about to replace my alternator for the third time in as many months ☹️ (overcharging at high revs). Are these re-con units any good (have I just had a few lemons?)or is it just false economy, what are the Caterham supplied units like and does anyone know what price? All experiences greatly received. Cheers Strongy Link to comment Share on other sites More sharing options...
Nigel Riches Posted January 15, 2003 Share Posted January 15, 2003 Strongy, you may just have been unlucky, I got the alternator on my x-flow from Lucas as a reconditioned unit and it's been fine for over 7 years, it cost more than from the motor factors, but then it may well have lasted longer, who knows, how do you know it's overcharging at high revs? out of interest, when the alternator is "excited" and supplying current to the battery, the voltage should be approx 14.5v, when no loads are switched on, there should be about 1v potential higher than battery volts when all loads are applied, ie, (engine off ) battery volts no load = 12.5, all loads on voltage (engine running approx 2000rpm)= 13.5volts. hope all this tripe has been of some help, I only found out all this stuff as I had a problem with my 20 year old Toyota, regards and keep it on the blackstuff, Nigel 1982. 5 speed, clamshells. B.R.G / Ali. The True Colours. Link to comment Share on other sites More sharing options...
Casbar Posted January 15, 2003 Share Posted January 15, 2003 I've had a few problems with Alts. 1st one lasted for 7 years, second one for a year after a couple of 2 day failures. 3rd one, been on the car for 6 months, although it took another failure to get this one. I think the problem is on a normal car, the alt doesn't rev to 7000 plus very often. I work on the theory that a recon unit from a motor factor costs about £45, and if it fails within the year, I get another one free. I don't think spending £70 plus or more on Caterham or race one means you will get one that lasts. Link to comment Share on other sites More sharing options...
Nigel Riches Posted January 15, 2003 Share Posted January 15, 2003 Another thought on overcharging, what is your crankshaft pulley to alternator pulley ratio?, if you have a standard pressed steel pulley on the crank and the regular small alternator pulley there is a chance that the alternator will be driven to fast, as far as I know, (thats old fashioned for AFAIK, for the text tossers) the steel crank pulley is smaller, thus reducing the drive ratio, somewhere there must be a formula for this, I have the steel crank pulley and need at least 1700rpm to get the "alt" warning light to clear after starting, once fired up and charging she idles at about 1000rpm and no alt warning showing, so must be ok??? Nigel. 1982. 5 speed, clamshells. B.R.G / Ali. The True Colours. Link to comment Share on other sites More sharing options...
Anthony Posted January 15, 2003 Share Posted January 15, 2003 Hi Strong, My x-flow has not travelled any great distance but I did put a small dia front pulley on it ( from Burtons if I remember correctly ) which seemed sensible and cheap precaution given the horror stories I was told about the pulley go pop at high RMP. It is a std Lucas unit which I got from SPR from recollection. Showing my age here, but pulley was c. 26 GBP from Burtons. Might help save your alternators Link to comment Share on other sites More sharing options...
strongy Posted January 15, 2003 Author Share Posted January 15, 2003 Phew, who would have thought an alternator would be so complicated. I think that it is overcharging, because ign lamp comes on at high revs (5000) {it used to be 6500 rpm and was almost a makeshift change up light, but as you can see light is now on at lower rpm and I suspect it will just get lower} I must confess I havn't measured output at battery terminals, I just assumed that diodes were overheated and knackered. On the topic of the pulley - outer diameter is 60mm and was from the valeo unit, I will swap this onto the recon unit. Any more input would be much appreciated before I put an order in with the folk at Caterham. Thanks for your help. Strongy Strongy - go on, wake the neighbours. 😬 Link to comment Share on other sites More sharing options...
strongy Posted January 17, 2003 Author Share Posted January 17, 2003 Having tinkered a bit more traced fault down to a loose connector on the alternator, off to buy some new spade connectors now. Strongy Strongy - go on, wake the neighbours. 😬 Link to comment Share on other sites More sharing options...
Super_Rich_Bernie Posted January 17, 2003 Share Posted January 17, 2003 General solution to a failed alternator seems to be to replace it, however with two cars in the past I stripped the old unit, fitted new brushes and diodes and in one case a bearing, cleaned up things up with cellulose thinners and bolted it back together. Cost was minimal and they both proved reliable thereafter. One of those was charging at low revs and failing at high revs. The other failed altogether with blown diodes. Worth a try given a decent recon will be the best part of £100. I suspect that cheap recons don't replace the windings anyway. Jonathan Link to comment Share on other sites More sharing options...
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