Ignition lamp and charging query

[Concrete-crusher]

Hi I have been for a drive today of about 25 miles being a hot day I wanted to see how the new cooling system worked. All well there but

When I got home I noticed the ignition lamp glowing very slightly at higher revs , then when I measured the voltage I found 12.36 V at the battery with the engine running but 12.6 v when switched off. Lastly the ignition lamp is not illuminating when the engine is not running but does come on briefly when you switch off.

its probably obvious to a few who know but that's not me. Oh and the alternator felt really hot which I have not noticed before. Like lots of parts its not done many miles but is around 4 or 5 years old.

any ideas ?

thanks Steve

[Chancer]

Alternator diode failure, disconnect the battery before it discharges.

If you get a spark or a drop in terminal voltage when you momentarily reconnect the battery (ignition & courtesy lights off) it will confirm the above suggestion.

[MarkDa]

Yes. If you've got an alternator you should be getting nearer 14v when running.
Should repair - DIY kit for <?15 if happy with bearings (?7 more) but replacements are pretty cheap and readily available.

[jono]

I fitted new diodes when this happened on a fairly new (Ebay) alternator.

It went again after a hundred miles so I bought a new alternator for ?35 from a reputable parts factor and its been fine ever since.

In my opinion just buy a new unit, it's not worth the hassle and uncertainty fitting a new diode pack