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Nov 11, 2011 10:32:41 GMT
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Since the citroen owners forum is full of rich smug guys who never have to fix anything themselves, I'd rather come here with my problems  The symptoms: - Voltage drops when I use any electrical equipment (headlamps, heater fan, etc.) - Need to rev the engine for it to charge properly (above 2,5k) The facts: - I fitted an internally regulated alternator of a ford sierra twin cam - new regulator and brushes - everything checked and cleaned inside the alternator - new + and - cables to and from battery/alternator - smiths dash voltmeter but also a regular DVM - Charges just fine at 13,5V-14,2V with no load - Starts everyday directly on LPG (!) I already know why I need to rev the engine, because on my citroen the alternator is run of the camshaft and on the ford from the crank, so it's only turning at half speed. But when I'm driving along at 3k rpm, the alternator surely should generate enough current to power the feeble headlights? But still, is there something I can do to make the alternator charge at a lower rpm? The power draw question still stands, only the smallest draw (12v cellphone charger) will drop the voltage to around 12V and continues to slowly drop (meaning I'm emptying the battery!) Strangely enough, I can drive the car all day and night without truly running out of power? I've checked the dash meter against my DVM and even thought it's very slow, it does finally indicate the right voltage.  |
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Last Edit: Dec 14, 2011 13:13:19 GMT by joostvdw
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stealthstylz
Club Retro Rides Member
Posts: 14,960
Club RR Member Number: 174
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Nov 11, 2011 10:38:15 GMT
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Do these need the alternator light wired up to work? IIRC some alternators do.
Only way to speed the alternator up is to fit a smaller pulley or drive it from the crank.
Matt
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Nov 11, 2011 10:39:02 GMT
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If your alternator is only rotating at half speed due to being driven from the camshaft i would have thought putting a smaller pulley on the alternator would increase the rpm & keep the charge rate up.
I know companies like Merlin Motorsport can supply different sized pulleys as i have bought pulleys from them in the past when i was working as a race car builder!
Hope this helps ........
Tim.
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1974 Chevrolet C20 Camper Special Pickup Truck 2002 Fiat Multipla oil burner SOUTHWEST SWAPMEET southwests best car parts selling page on facebook for retro/custom/classic www.facebook.com/groups/249875865097198/ |
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Nov 11, 2011 12:20:17 GMT
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stealth: Yes, it needs an alternator light, it is connected and working, driving it from the crank is not possible due to the strange engine layout of the DS.
I actually fitted the slightly smaller pulley of the original externally regulated alternator, but that made no discernible difference. Are alternator pulleys a universal fit or do I need a specific one for a sierra twin cam? It needs to be a double V belt at least.
What is the internal difference between an alternator driven from the camshaft and one driven from the crankshaft?
Could it be that the alternator light is not working 100%? I mean, it lights up, goes out when the alternator starts charging, but could it cause the alternator to charge at half capacity if it wasn't working properly?
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Nov 11, 2011 12:35:35 GMT
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Well, I can confirm that something is wrong, I just stuck the meter on a sierra twincam at tickover (800rpm) and put the lights and the heater on full - battery voltage is steady at 13.5v.
Have you tried a different battery?
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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Nov 11, 2011 12:44:02 GMT
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Thanks for going out and sticking a meter on it for me No, I haven't tried a different battery, it's a bit of a strange battery with the poles reversed to what's normal. So I would have to buy a new one, which is because of this pole thing a special order and thus very pricey  Since it's a carburettor model, with only very simple electronic ignition, shouldn't the alternator be able to power it even without a battery? I always assumed simple cars don't even need an battery as long as the alternator is good. |
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Nov 11, 2011 12:59:33 GMT
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No, quite the opposite. An alternator requires a battery of the correct working voltage to function correctly. Running one with no battery at all will destroy it. PS, it was no bother, I'm driving one so it was just outside  |
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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Nov 11, 2011 13:09:52 GMT
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Also, try the following test on your battery - Measure the voltage across the terminals with ignition off, then put the headlamps on and watch the meter - it should stay steady at just over 12v and not drop quickly.. if it doesn't, it is a faulty (or flat) battery. Charge it, try again... still the same, dead battery.
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To get a standard A40 this low, you'd have to dig a hole to put it in |
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Nov 11, 2011 17:32:11 GMT
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You also need to check the wiring and connections of the main wire between the alternator and the battery and also between the alternator/battery and the fuse box (or whatever passes for the main power distribution board on a DS) as a corroded wire or poor contact could also cause this kind of problem and could also lead to the point of high resistance getting hot and letting the smoke out.
One further check would be the earthing of the alternator to the engine and engine to chassis.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Nov 11, 2011 21:46:07 GMT
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Echoing the above I would say check all your connections and carry out voltage drop tests on your earth points.
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R.S. Autotech. Servicing/Repairs/Diagnostics.
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Nov 17, 2011 15:02:31 GMT
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Well, I fell for the oldest trick in the book... When I went out just now to have a measure at the different points and connections, the battery was flat, or at least too flat for the car to start. So a pair of jumpers cables and a spare car later, it was charging (the jumper cables are too flimsy to start the citroen from) and since I was bored I started measuring resistance (I would've liked to measure voltage drop, but without the engine running it was no use). After some mucking about, I discovered that there was a 6 ohms (!) resistance between the negative battery post and the negative clamp and at the positive side there was 4 ohms resistance! Well, that sure explained a lot  Cleaning the terminals (which didn't look remotely bad or oxidized) gave me 0,0 ohms between the negative clamp, terminal, alternator, chassis and engine block. And 0,0 ohms between the positive terminal, clamp and B+ post on the alternator. Sadly, I still couldn't get the car to start, so I haven't actually tested if the problems went away, but I have a good feeling about this Battery is on a charge right now, but I won't be able to go back at it before monday. |
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Nov 17, 2011 20:28:52 GMT
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Yes, should have thought of that - especially since I had exactly this problem with my A6 back in the spring. Battery lives under the rear seat so everything looks clean, but inside the battery terminals was a layer almost like a clear varnish. A quick scrape and clean doubled the cranking speed and all sorts of electrical weirdness went away.
Only noticed because I happened to touch the positive clamp when attaching the jump leads and found it very hot.
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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Nov 26, 2011 18:28:43 GMT
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So I had some time today to thoroughly measure it Put the freshly charged battery in it and fired right up on LPG (always a relief ) At first it was charging at 14,1V so I was really happy and thought I had sorted the problems, but turning on the lights made it drop to 12,6V and turning on the heater, high beams and spotlights made it drop to 12,0V before I raised the idle which made it indecisive whether it would charge or not.. Driving around town with dipped beams on it almost reaches 13V but when I slow down to idle it immediately falls to 12V or lower. The engine is properly grounded, all connections under the hood are checked and double checked but it's still not working as it should I just thought of 1 thing left to check, I don't know if the voltmeter on the dash is directly connected to the battery or through the dashloom (and thus crusty old connectors and fusebox). If it's the latter, that would explain the drop in voltage when I turn on the lights... Mmm, food for thought... |
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will930
Part of things
Decked K11 Micra - RetroRunner Mk2 Golf
Posts: 521
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Nov 26, 2011 18:35:50 GMT
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sure just drive the car, with everything on and keep checking the voltage on the battery its self, as the voltmeter may be reading wrong, always worth a try, or drive around with a spare battery and if it dies and wont start then there is something wrong! then use the spare to jump start it!
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I just cant drive round in it with the volt meter dancing all over the gauge, so I stuck a amp meter on it today and was mystified by the results; it gives of a slowly oscillating positive and negative current of about 10 amps?! I'm fairly sure this can't be right? It should read the same as the current draw which is with the lights off almost nothing, right?
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what does the voltage on the actual alternator terminal and casing read?
is the alternator grounded to the block well? With the lights on and the engine running, put the probes of your multimeter between the alternator casing and a good ground (Try both the battery negative and a decent chassis ground if you can.
Are you completely rid of any of the external regulation system? I.E the main terminal from the alternator goes directly to the battery positive?
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Dec 13, 2011 16:02:55 GMT
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Cobblers, it's 13,5V all round, but it drops rapidly when I turn on the lights or when the engine rpms get low. The external regulator is completely cut out and the new alternator is wired in with new wires and clamps. So today I went to an alternator expert and a befriended mechanic (those are the best!). The first confirmed that running the alternator on the cam with a large pulley like on the DS is NOT a problem! He said he could take it in and do some measurements, but not today. After that I went to my mechanic and told him the same story. He then remembered a while back he had a car with similar symptoms having a bad diode inside and that the only remedy was to change it out. It also had a power drain (because of the this blown diode) making the alternator only put out a couple of amps but drawing almost equal amounts (!) Long story short, he had another alternator laying around and gave it to me to see if that would solve my problems It's actually smaller, which is nice, and uses almost the same mounting points as I already had, shouldn't be too hard to fit it then! |
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Dec 14, 2011 13:12:58 GMT
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Fitted and wired the alternator today and succes! 13-14volts of constant charging, idle with lights on What did we learn; bosch alternator parts over very interchangeable (I swapped regulators and pully to fit it) but more importantly, even if you think you know electronics and even if you think you've measured all the internals, you won't know for sure if it's any good unless you bring it to a specialist to have it tested. Or swap it out of course Thanks for the advice and help! |
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