Series 3 charging issue

Blackerstone · Dec 20, 2023

Grateful for any advice on a battery charging problem on a 1972 series 3. The ignition warning light doesn’t illuminate but I’ve got power at the bulb holder and at the alternator brown yellow wire coming from the warning light. I’ve checked different bulbs that are known to be working, could it be an issue with the bulb holder?

tottot · Dec 20, 2023

More likely issue with alternator. Have you checked alternator is working? Should read 14v at the batt when motor running.

Blackerstone · Dec 20, 2023

The battery voltage does drop when running, it’s recently had a new rectifier and regulator. I’ve checked the diodes with a multi meter and I get a reading of 1368 one way and nothing the other.

kermit_rr · Dec 20, 2023

There should be 12v at the small wire on the alternator when ignition is on, not running

Blackerstone · Dec 20, 2023

Thanks, Yes I’ve got 12v there with the engine off but the warning light isn’t illuminated.

kermit_rr · Dec 20, 2023

If you take that small wire off and earth it then the bulb should light up.
If it does then you must have an alternator issue.
Try a jump lead directly from the alternator body to the negative terminal on the battery

Blackerstone · Dec 20, 2023

I tried that earlier and the bulb didn’t illuminate. That’s what I can’t understand, I’ve got power at the bulb and it’s passing to the alternator even without a bulb in place but when I put a bulb in it won’t light

kermit_rr · Dec 20, 2023

Then the wire could be damaged, able to carry enough to light up the volt meter but not enough to light up the bulb

Blackerstone · Dec 20, 2023

That would make sense, I was thinking it might be the bulb holder but if it’s taking the power in and out it should be ok. I will take a look at the wiring, thanks for your help.

kermit_rr · Dec 20, 2023

It could be anywhere along the line including the holder. Be methodical

Blackerstone · Dec 20, 2023

Thanks again for the advice. Does the alternator need to sense the resistance of the bulb to start charging? Just wondering if I might have a wiring and an alternator problem.

kermit_rr · Dec 20, 2023

The alternator needs a voltage applied to energise it. I don't know the threshold but I'm guessing it's not getting enough if the bulb isn't lighting
Does the horn work? That should be connected to the same post on the ignition barrel

Blackerstone · Dec 21, 2023

The horn does work but I would describe it as being “dull” even though the battery is reading 12.55 volts with the multi meter.

Gun7354 · Dec 22, 2023

Ive just had this me self......it was the rectifier on the alternator. The build did light up though when i put an earth on it. I suddenly had no ignition bulb light and all charging stopped. New alternator cured it.

Rich

Gun7354 · Dec 22, 2023

Series 3 - No charging light - Me old thread

Blackerstone · Dec 22, 2023

Gun7354 said:
Series 3 - No charging light - Me old thread

Thanks for this really helpful. Think I’m going to start with a wiring and earth check first. Suspect it’s wiring and the alternator although the recitifier wasn’t changed that long ago.

Blackerstone · Dec 22, 2023

Gun7354 said:
Ive just had this me self......it was the rectifier on the alternator. The build did light up though when i put an earth on it. I suddenly had no ignition bulb light and all charging stopped. New alternator cured it.

Rich

Thanks Rich, it’s the bulb not lighting when earthed that’s got me puzzled. I’m going to start with a check on the build wiring and earths then change the rectifier in the alternator I think.

boguing · Dec 22, 2023

It was the bulb wire on mine and I vaguely remember that it was broken somewhere on the engine side of the bulkhead.

tottot · Dec 24, 2023

mahour3g said:
Not exactly sure, but have you noticed it dying much faster recently. It could be the battery on its last legs and the watch is just rejecting charge from it. If not it’s either a serious hardware issue (probably unrepairable) or a glitch in the software in which case you could fully reset it. Anyway good luck and if it doesn’t work just take it to the apple store

What! This is a series Land Rover we are talking about, does not know what software is and never will

steve2286w · Dec 27, 2023

Sounds like another BoBism clone

Series 3 charging issue

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