Tony Whitley Posted June 3, 2014 Share Posted June 3, 2014 which is strange because my car has an alternator. A few days ago I noticed that the charging light stayed on for a while after starting the car unless the revs were above a couple of thousand. Otherwise everything is fine and I drove the 50 miles to Brands this evening and hurtled round the track without a care in the world. Setting off home I turned on my lights and had the charging light glaring at me. I turned off the headlights and it was OK on the parking lights as long as I kept the revs up. I hoped it might recover after charging for a while but though the red light stayed off for a short while when I put the headlights on it soon came back again. This is not a failure mode of an alternator that I'm familiar with - they either work or they don't. It's a relatively new (2 years?) Brise unit but they have a reputation for not lasting long on the Duratec. Any guesses before I take it to Burghfield Starter and Alternator Centre? Link to comment Share on other sites More sharing options...
Guest Posted June 3, 2014 Share Posted June 3, 2014 Tony, I'm not going to be much help with a fix but am interested to hear you've had this problem. I've got a nearly new (less than a year old) Duratec based car. Right from the off I've had problems with the car Drawing more current than the alternator is making at idle. With just side lights on its just about OK. With the headlights turned on, as soon as I get stuck in traffic and I'm idling then I'm on borrowed time. This happened to me on my trip back from the Caterham factory after I picked my car up. I assumed it was a one off but it's since happened to me again just this last BH weekend. It was raining so I had the hood on the car. With wipers on, headlights on and front heated screen on to stop the screen fogging up, the battery was dead after just 5-10 minutes when I inevitably got stuck in bank holiday traffic and was moving at a crawl. Jump started fine and with the car back on sidelights and with intermittent use of the wipers I was able to continue the journey. Not good though. I wondered if my alternator was just a bit weak but on hearing your account, I'm starting to wonder if the alternators are simply not up to the task or not being spun fast enough with the engine just ticking over. Can an alternator be made to spin a bit quicker at idle some how? I was going to give Caterham a call about it this week as my parts are still under warranty for the time being. Tom Link to comment Share on other sites More sharing options...
Markiebabes Posted June 3, 2014 Share Posted June 3, 2014 Does it have a diode pack/ rectifier ? If so can it be replaced ? Had similar on a car a few years back changed this and all good 😬 Link to comment Share on other sites More sharing options...
Markiebabes Posted June 3, 2014 Share Posted June 3, 2014 Tony Just found This might help ? 😬 Edited by - markiebabes on 3 Jun 2014 22:43:32 Link to comment Share on other sites More sharing options...
ECR Posted June 4, 2014 Share Posted June 4, 2014 You can fit smaller pulleys to alternators. This will make them spin faster at tickover to give more charge. BUT it also makes them spin faster at high revs and they are limited to about 18000 RPM from memory. Exceeding the maximum will lead to bearing failure. Depends how high you rev your engine Edited by - ECR on 4 Jun 2014 10:33:24 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 4, 2014 Member Share Posted June 4, 2014 To both of you with the charging problems: can you measure the voltage at the battery under all those conditions and let us know? Thanks Jonathan Edited by - Jonathan Kay on 4 Jun 2014 07:50:12 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 4, 2014 Member Share Posted June 4, 2014 Duplicate post Edited by - Jonathan Kay on 4 Jun 2014 07:50:01 Link to comment Share on other sites More sharing options...
revilla Posted June 4, 2014 Share Posted June 4, 2014 @ECR - Wouldn't you need a SMALLER pulley rather than a larger one? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 4, 2014 Member Share Posted June 4, 2014 Do people ever use slipping couplings on alternators to avoid the overspeed problem? As used to be done on engine-driven cooling fans. Jonathan Link to comment Share on other sites More sharing options...
Nigel Riches Posted June 4, 2014 Share Posted June 4, 2014 Check the resistance of the wire from the alternator to the battery, any more than a squeak of an ohm and a problem such as yours will occur. Check the voltage at the alternator output terminal with the engine running app 2K rpm, should be in the range 13.5 - 14.5 V and then check at the battery positive terminal, the voltage should be the same, if not the charging wire (usually brown in colour) is high resistance and should be replaced, or terminals checked for loose crimps etc. Also worth checking the voltage at the excitation terminal at the alternator end. If both are OK then it sounds like a rectifier / regulator fault. I take it the belt doesn't slip, all the battery connectors are in good condition, including the earthing from the engine to the chassis and back to the battery, earthing faults can cause some odd problems, also is the battery in good nick? Duff battery could be dragging to much out of the alternator. Some food for thought, have fun. Nigel. Link to comment Share on other sites More sharing options...
ECR Posted June 4, 2014 Share Posted June 4, 2014 Revilla Er yes ..... Link to comment Share on other sites More sharing options...
Guest Posted June 4, 2014 Share Posted June 4, 2014 Many thanks for all of the suggestions folks. I'll have a look at some of the points mentioned and get back with some results over the weekend. Link to comment Share on other sites More sharing options...
Tony Whitley Posted June 8, 2014 Author Share Posted June 8, 2014 Reporting back: Battery volts: Before touching the car 12.25 (6 month-old Odyssey PC680) Cranking 9.5 approx, spins over happily Tickover rising from 13.0 to 13.7 Sidelights 13.5 Headlights 12.8, falling continuously Mains 12 Alternator light goes out at 14 Headlights + revs 13.8 (thus the alternator light stays on) That's the easy bit. Having taken #1 primary off to get at the alternator connections I find 50R on the green wire through the ignition to battery. No green wire found on the connectors so I have to strip the loom to,trace it. Green wire is spliced into a red one and thence into two small white ones at the connector while the red one is spliced into a green/red one and then brown/yellow at connector. I think we can see where this is leading, at this point I remember being told "Freestyle: great engineering, really bad at electrics". However, end to end both wires are a fraction of an ohm. Now I know which wire on the body loom connector I find 50R from there to the battery which later rises to 190 and open circuit. To be continued... Edited by - Tony Whitley on 8 Jun 2014 11:03:24 Link to comment Share on other sites More sharing options...
Tony Whitley Posted June 8, 2014 Author Share Posted June 8, 2014 The big red one from the alternator is spliced into two big brown ones at the connector and also reports small fractions of an ohm. Link to comment Share on other sites More sharing options...
Tony Whitley Posted June 9, 2014 Author Share Posted June 9, 2014 I did find that the spade on the ignition switch was loose which might explain the open circuit except that the car has not shown any sign of it. I struggle to use that to explain the steady 50R I was seeing when I first checked from alternator to battery. The insulation on the wire to the alternator was a little cooked so I replaced it. On the road this morning it settled down to 14.2 V (after running with the charging light on for a few hundred yards). As soon as I switched the headlights on it dropped below 14 V and the light came on. So, several hours work and it's no different 😔 Link to comment Share on other sites More sharing options...
andy_h Posted June 9, 2014 Share Posted June 9, 2014 Are you sure the lights circuit isn't the problem, ie they are drawing much more than they should and hence the alternator can't cope? Link to comment Share on other sites More sharing options...
Tony Whitley Posted June 9, 2014 Author Share Posted June 9, 2014 I had that thought but it also takes a while before the charging light goes out after starting the engine, suggesting the alternator can't supply enough amps to do anything much more than keep the engine running. As if I had a dynamo... Link to comment Share on other sites More sharing options...
SJD Posted June 9, 2014 Share Posted June 9, 2014 .....perhaps you do have a dynamo like I do 😬. Link to comment Share on other sites More sharing options...
Guest Posted June 11, 2014 Share Posted June 11, 2014 Right so i've finally managed to sneak out to the garage for half an hour this evening to take a look. I've yet to look at the resistance of the charging wire to the alternator but intend to do that tomorrow evening as the car is jacked up and I can finally get at the alternator from underneath. In the meantime, some interesting readings: 12.7v @ battery (engine off) 13.8v @ battery at idle 13.5v with sidelights on (LED based sidelights), falling all the time. Had reached 12.7v within approx 2 mins, still falling so switched lights off With lights off, battery voltage started rising again. So it would seem that I can't even turn the sidelights on without their being a net loss overall. My only other observation is to do with the size of the pulley. Its 3" diameter (approx 7cm) which to my eye at least looks quite large compared with alternators i've seen fitted to other cars. Does this seem large? It certainly wasn't spinning very fast with the engine at idle. I'm going to attempt to have a more thorough look tomorrow and try and take some of the readings mentioned in Nigel's earlier post where I can. I've had a look and I have a single large brown cable that goes from the starter motor and on to the alternator. I'll be checking that first I think. Edited by - TomWoodis on 11 Jun 2014 21:33:03 Link to comment Share on other sites More sharing options...
CharlesElliott Posted June 12, 2014 Share Posted June 12, 2014 LED sidelights?? Can you measure the current the lights are drawing? Link to comment Share on other sites More sharing options...
Guest Posted June 15, 2014 Share Posted June 15, 2014 Hi Charles, Yes the side lights have been replaced with LED based bulbs instead (recent change on my part) So I've had a bit more time to play with this and take some further readings as suggested. I started by looking at the positive wires running to the battery from alternator. This had resistance of 0.2 ohms so barely any resistance so looks fine. I rewrired it all back up again and started it, took some more readings: 13.2v at idle (fast idle with engine cold) - volatage rising slightly 12.9v at idle (once warm and revs dropped a bit) - voltage pretty stable This is with no other electrics turned on. These figures seem low to me, anyone care to comment? By my reckoning, if I turn anything on whilst at idle then I'm running the battery flat. With sidelights on it dropped to 12.7v and appeared to be dropping slightly over time. Once the car had got properly warm ticking over in the garage, the fan kicked in. With just the fan on, the voltage at the battery was showing 12.2v! I also did the comparison that someone mentioned previously comparing voltage at battery compared to voltage at terminals of alternator. The figures were within 0.1v volts of each other so seems like the circuit is good. Maybe I've just got a duff alternator? Anyone else with a Duratec able to test voltage at battery at idle with the cooling fan on by way of a comparison? Thanks Tom Edited by - TomWoodis on 15 Jun 2014 18:54:50 Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted June 15, 2014 Member Share Posted June 15, 2014 Have you cleaned and reconnected all the earth connections already? Jonathan Link to comment Share on other sites More sharing options...
Tony Whitley Posted August 13, 2014 Author Share Posted August 13, 2014 Reporting back: the alternator eventually died completely, the fault was the field windings breaking where they connected to the regulator. It's the second one to do this, caused by the field windings coming loose within the alternator casing. So much for paying a hefty premium for a "quality" product. I presume the "dynamo" effect was the first wire breaking, meaning the alternator couldn't supply full power. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted August 13, 2014 Member Share Posted August 13, 2014 Did you send it back to Brise for the diagnosis? Jonathan Link to comment Share on other sites More sharing options...
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