Electrical issues

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ritmo
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Re: Electrical issues

Post by ritmo » Tue May 13, 2014 6:37 pm

Right! I had been an idiot. Immobiliser off and there's life!

Alternator still not charging though. Seeing 12.5volts with engine running.

I wonder if I have the alt wired incorrectly as suggested by Electrokid. Anyone know where the smaller wire goes?

Really pain in the ass getting to the alt.

Just trying to get a picture of current wiring.

ritmo
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Re: Electrical issues

Post by ritmo » Tue May 13, 2014 6:39 pm

I have main cable on B+ smaller cable on d+ :s

ritmo
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Re: Electrical issues

Post by ritmo » Tue May 13, 2014 9:58 pm

Well, no joy yet.

I cleaned and checked the ground cable to the gearbox. All looked fine and after cleaning showed 0 ohms.

Cable from +battery terminal to solenoid to alternator all fine and also showing 0ohms.

100 ohms measured between negative bat terminal and D+, but showing 8volts which someone suggested was about right.

Cleaned and checked connector block and all other connections under battery, all seemed fine. Right mess of cables all over the place though. Not sure if its all todo with the alarm. Messy!

I can only think that maybe this alternator is faulty. Seems unlucky as it was behaving much the same as my original alt. I have a spare valeo alt which doesn't fit Betty, but maybe I will be able to Frankenstein the electrics off the back of it to the fitted one. Pain in the ass to have to get in to the alt area again. Radiator out etc.

Will update. Thanks for everyone's suggestions.

ritmo
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Re: Electrical issues

Post by ritmo » Tue May 13, 2014 10:00 pm

One last thing. I remember the C5 valeo pulley is a little smaller than the original. Should run faster though. So can't imagine it's caused a problem.

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electrokid
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Re: Electrical issues

Post by electrokid » Wed May 14, 2014 10:52 am

I have main cable on B+ smaller cable on d+
That should work fine. Even alternators that need a small amount of current to get under way take that current from the bulb connection so providing the bulb in the dash comes on with ignition and without the engine running then everything is wired up ok. Some cars have an additional resistor wired across the bulb so that it all still works ok if the bulb goes - 330 Ω is typical and if you want to retrofit one make sure it is a 1 or 2 watt resistor - theoretically it could dissipate around 0.6 watts for a short peroid so it could briefly get warm. (Or do what I used to do when building valve amplifiers - tack solder components upside down so that if they overheat they just melt the solder joints and fall off :twisted: )

Measuring ground cable connections with an ordinary meter is a good start to make sure there's a connection but a visual check and removal of anything that might get in the way such as a layer of paint or rust is essential - with earth strap connections you're aiming for milliohms - not ohms.

It does sound as though the alternator is duff though - Where in London are you and is the car here or in Glasgow ?

Some alternators can be damaged if they are run without the battery connection - there are sometimes protection diodes built in but they are not always successful.

Not sure what you are measuring re 100Ω / 8v on the D+ ? Hopefully that's 100Ω static and 8 volts when running ? If there are volts on the points you are measuring then that will screw up any attempt to accurately measure ohms.
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ritmo
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Re: Electrical issues

Post by ritmo » Wed May 14, 2014 2:14 pm

Ok more clues, thanks.

I'm in Glasgow, as is she. Just popped out and turned ignition on. Battery light is not illuminating (as I remember it used to before engine starts). Suspicion back on the wiring?

Measuring 100ohms and 8v with ignition on but engine not running.

Will measure milliohms later, but I did remove earth from gearbox, cleaned contacts and also clean both +\- battery clamps.

Having no problems at all starting now by the way.

Dashboard off and check more cables?

Thanks!

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Re: Electrical issues

Post by KevR » Wed May 14, 2014 3:02 pm

When my alternator was dying, one of the clues was the dash light didn't illuminate when I turned the key on. As I said before, give the alternator a tap or two while the engine's running. If it starts charging, it's almost certainly brushes/slip ring.
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Re: Electrical issues

Post by ritmo » Wed May 14, 2014 3:11 pm

Will do this after work. Are they not brushless? Thanks

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Re: Electrical issues

Post by KevR » Wed May 14, 2014 4:00 pm

The original BX one wasn't brushless, can't say for your C5 one though.
1990 BX TZD Estate ('the grey one', 1991 BX TZD Estate ('the white one'), 1982 2CV6 Charleston (in bits), 1972 AZU Serie B (2CV van), 1974 HY72 Camper, 1990 Land Rover 110 diesel LWB, 1957 Mobylette AV76, 1992 Ducati 400SS, 1966 VW Beetle, 1990 Mazda MX-5, 1996 Peugeot 106D, 1974 JCB 2D MkII, 1997 BMW R1100RS, 1987 Suzuki GSX-R1100, 1978 Honda CX500A, 1965 Motobecane Cady, 1988 Honda Bros/Africa Twin, 1963 Massey Ferguson 825, and a lot of bicycles!

ritmo
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Re: Electrical issues

Post by ritmo » Wed May 14, 2014 5:48 pm

Kev. Used your technique. The alternator hasn't started charging, but the light does come on again now before engine ignition. Also interesting. Battery low on volts again today after a 6hour charge yesterday. Don't know why would have lost so much over night.

I guess I need to get out the alternator and replace the brushes then.

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Re: Electrical issues

Post by citronut » Wed May 14, 2014 6:29 pm

i have not heard of the tap trick with alternators, usually applies to starter motors,

do you have an auto sparks local to you, you could maybe take your selection of alternators to them to have them bench tested

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electrokid
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Re: Electrical issues

Post by electrokid » Wed May 14, 2014 8:06 pm

Sorry - I didn't express that very well - if there is a voltage on 2 points that you are measuring then switching to ohms and measuring again will produce a meaningless reading. And your meter will not measure milliohms - just not capable of it. What you have already done with the cleaning should be fine.

To measure milliohms you would need four point measurement...

http://www.allaboutcircuits.com/vol_1/chpt_8/9.html

but don't worry about it !
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ritmo
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Re: Electrical issues

Post by ritmo » Wed May 14, 2014 8:07 pm

Whacking it definitely seems to bring up the battery light again. So now a search for valeo brushes. It's an A13V165.. WOW! Why so many different alternators?!

I'll try get hold of a replacement slip ring, brushes and regulator and hope that'll sort it... Then onto the other issues :D

Thanks again for all suggestions.

ritmo
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Re: Electrical issues

Post by ritmo » Wed May 14, 2014 8:11 pm

Yes, good point. I mixed up my memory of my multimeter. The degree of measurement goes up the way.. 20Kohm etc.

Will have a read up on 4 point measurements, cheers.

I wonder if anyone has just done a full rewire of their BX? If they're all as messy as mine is, I would expect someone would have. Didn't really bother much with cable management in the 80s?

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Re: Electrical issues

Post by ritmo » Wed May 14, 2014 8:18 pm

electrokid wrote:Sorry - I didn't express that very well - if there is a voltage on 2 points that you are measuring then switching to ohms and measuring again will produce a meaningless reading.
Right you are. And I'm mistaken, I was measuring ohms when ignition off and volts when ignition was on.