Having a problem with charging - just changed the engine, back on the road for a couple of days, and the battery went flat 15 miles from home. Breakdown brought me back, charged the battery with charger overnight, charged up fine ( battery is Bosch, less than a year old). Started up fine, but charge warning light is glowing dimly. Tightened aux belt, still the same replaced alternator with one off the new engine (I had used my old alternator which worked fine before the engine blew). Exactly the same result - lamp glows but not at full brightness.

Any ideas guys (and gals!)?

Earthing problem? Loose nut on power cable for alternator?

Coincidence and the alt is shagged, did you have to wire in an additional bulb to make the charge light go off if it happens to be an led? Maybe that bulbs blown??

The alt wont be charging the battery if that lamps on mate.

Just a couple of ideas to try.

Cheers

Rich

[Edited on 28/5/11 by RichardK]

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Originally posted by stevegough
Having a problem with charging - just changed the engine, back on the road for a couple of days, and the battery went flat 15 miles from home. Breakdown brought me back, charged the battery with charger overnight, charged up fine ( battery is Bosch, less than a year old). Started up fine, but charge warning light is glowing dimly. Tightened aux belt, still the same replaced alternator with one off the new engine (I had used my old alternator which worked fine before the engine blew). Exactly the same result - lamp glows but not at full brightness.

Any ideas guys (and gals!)?

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Originally posted by RichardK
Coincidence and the alt is shagged, did you have to wire in an additional bulb to make the charge light go off if it happens to be an led? Maybe that bulbs blown??

The alt wont be charging the battery if that lamps on mate.

Just a couple of ideas to try.

Cheers

Rich

[Edited on 28/5/11 by RichardK]

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Thanks for all the info, I had pretty much come to the conclusion that the alternator was ok, and that it was a bad connection somewhere. However, I wondered if there was something obvious I was missing elsewhere.

As 'spiderman' has said, I don't need to put a second bulb in (I'm using 'bright 6' and the charging was fine before the engine swap.

On the first start up with the new engine, the charging light was on full initially, then after a few mins running, it dimmed down - I put it down to the battery being quite discharged through the fortnight's lay - up.

I will run through the testing sequence (I have already partly done this - but it isn't easy - access is a bit tight - see the pic!)


Description

I'll let you know what the problem was - when [ and if!] I find it.

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Originally posted by stevegough
As 'spiderman' has said, I don't need to put a second bulb in (I'm using 'bright 6' and the charging was fine before the engine swap.

I wouldn 't discount that as it ias a very simple test. Unless someone corrects me, BRIGHT 6 use LEDs so if a LED with drop resistor is used instead of a charge light lamp (i.e. filament bulb), it will supply 1/10 of the current a filament bulb would supply. I have home made LED lamp with a ressitor in parallel to increase the current tyhat is needed to self-excite the alternator.. Disconnect your charge lamp and using a wire connect to 12 V via a small bulb the alternator and run engine. It is a 5 min test.

On the first start up with the new engine, the charging light was on full initially, then after a few mins running, it dimmed down - I put it down to the battery being quite discharged through the fortnight's lay - up.

^^^ Strange .... alternator earthing is done via the body - check that there is clean metal between it and bracket and engine (scrape any paint off), then check earth strap from engine to battery. If you have jump lead, then clip on to battery earth and alternator body/bracket and give engine a whizz. That too is a 5 min test.

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Check all the earths and alternator cables for loose/poor connections and for any trapped wires. Put a volt meter accross the battery then try a jump lead between the battery -ve and alternator body as a quick check for main earth.

It is worth trying a test lamp from charge light connector (disconnect the existing wire) to +ve and then start and check charging to check that circuit is exciting the coils as if the problem is a trapped or poor connection it could have been OK when you first re-started but then failed.

I'll put my 10p on a shagged battery. What odds are you guys offering?
Cheers!

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Originally posted by 02GF74

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Originally posted by stevegough
As 'spiderman' has said, I don't need to put a second bulb in (I'm using 'bright 6' and the charging was fine before the engine swap.

I wouldn 't discount that as it ias a very simple test. Unless someone corrects me, BRIGHT 6 use LEDs so if a LED with drop resistor is used instead of a charge light lamp (i.e. filament bulb), it will supply 1/10 of the current a filament bulb would supply. I have home made LED lamp with a ressitor in parallel to increase the current tyhat is needed to self-excite the alternator.. Disconnect your charge lamp and using a wire connect to 12 V via a small bulb the alternator and run engine. It is a 5 min test.

thanks for that, I see your point, but to get to the bright 6 wiring, I first have to unbolt and remove the dash - that takes about an hour! - And as I've said previously, it was working before I changed the engine, so I don't think messing with the charge-feed / indicator lamp is necessary.....yet! Instead, could I run a wire (tempoarily) straight from battery to the exite terminal on the Alt?

On the first start up with the new engine, the charging light was on full initially, then after a few mins running, it dimmed down - I put it down to the battery being quite discharged through the fortnight's lay - up.

^^^ Strange .... alternator earthing is done via the body - check that there is clean metal between it and bracket and engine (scrape any paint off), then check earth strap from engine to battery. If you have jump lead, then clip on to battery earth and alternator body/bracket and give engine a whizz. That too is a 5 min test.

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Originally posted by v8kid
I'll put my 10p on a shagged battery. What odds are you guys offering?
Cheers!

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Originally posted by v8kid
I'll put my 10p on a shagged battery. What odds are you guys offering?
Cheers!

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Originally posted by adithorp
Check all the earths and alternator cables for loose/poor connections and for any trapped wires. Put a volt meter accross the battery then try a jump lead between the battery -ve and alternator body as a quick check for main earth.

It is worth trying a test lamp from charge light connector (disconnect the existing wire) to +ve and then start and check charging to check that circuit is exciting the coils as if the problem is a trapped or poor connection it could have been OK when you first re-started but then failed.

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right, I've just spent a couple of hours on it to no avail....

1: replaced the alternator with my own.
2: doubled up the Heavy duty +ve feed with one from battery to alt.
3: doubled up the exiter wire from a connection halfway along (not dismantled dash - YET).
4: bat voltage (13.45 engine off)
5: bat voltage (13.08 engine running) - bright 6 glowing slightly.

6: no change with any of the above extra wires in place.

7: checking feed to halfway point on the exiter wire is showing a possible problem:
..........with ign off, voltage at the feed is nil.
..........with ign on, is shows 6.5 volts, when you start the engine, this goes up to 13.0
..........is this showing a possible poor feed to the exiter for the electromagnets in the alt?



I am in the garage with my laptop, going to try and put a heavy duty earth directly alt body to battery now (as a few of you suggested). Then I'm thinking of stripping the dash out to get at the bright 6 wiring.

Watch this space - more suggestions are very welcome

Does that mean my 10p is at risk?

Fault finally located! All you guys who said earth fault on the alternator to engine - that's what it was!!!

I had cleaned the alt earthing wire, but reconnected it wrongly! DOH! This short red wire went from the top alt bracket to the manifold bolt. When I changed the engine (and each time I changed the alt) I reconnected it to the washer above the insulated bush on the other end of the alt bracket - so I was effectively earthing the inlet manifold to itself - He! He! what a plonker!

Seriously, lots of kudos to you guys for trying to help me, I didn't need an auto electrician - just a psychiatrist!

Cheers, and thanks to you all.

Good Good, looks like i might visit next week after all lol

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Originally posted by Ben_Copeland
Good Good, looks like i might visit next week after all lol

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Originally posted by v8kid
Does that mean my 10p is at risk?

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Do you accept postal orders?

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Originally posted by stevegough
I had cleaned the alt earthing wire, but reconnected it wrongly! DOH! This short red wire went from the top alt bracket to the manifold bolt.

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Originally posted by 02GF74


Can't say I understand that since alternators make the earth contact via the body so no need fo any extra wires .... but then I do not know exactly whcih make/model you are using. Seem to recall it is Lucas - not come across Lucas alt needing separate earthing ut then I do not know details of every model.

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