alternator problem (cooking battery)

[mickanic]

Hi, I own a 1993 325i se 24valve auto 4-door saloon.
It all started about three weeks ago when I broke down, prior to that every time I revved the engine or used the kick down, the radio switched off… then came back on after a short while, anyway. I’ve had no problem starting the vehicle, battery very good, all in all, no problems at all. On the day I was on a fairly long run, when I notice a very strong smell, I thought it was the exhaust cat playing up, stopped looked round the car, nothing amiss, then two miles up the road, dash lights started to flash then no power, and car ground to a halt, everything was dead. Lifted the bonnet… no smell, open the boot.. very strong smell of acid, the battery was very hot (cooking) I disconnected it, and closed the boot for half-an-hour, for it to cool down.
Had to be recovery back home, next day checked it out, put in new battery and checked the charging rate, ok but alternator was noisy, replaced it, everything was fine until a few days ago, the battery light on the dash came on while driving, stopped the car, with the engine ticking over, battery light went out and battery charging 14.4v but if I rev the engine very slowly up…. to 2,000 rpm the battery light comes on, not charging (checked with a volt meter) then if I release the throttle and blip the throttle the light goes out and charges the battery. Sorry it is a tad long winded, but trying to give you all the info as poss. any question please ask.
Any ideas would be great, is there a relay that controls the amount of charge to give to battery from the alternator, apart from the alternator itself….
Thanks Mick.
[email protected]

[91HO305TPI]

have you replaed battery that got cooked?
your alt is obviously not charging of idle, and nothing eles controls alt output i would warrinty
alternator if posable and replace batt if not allready done.

[mickanic]

hi, thanks for replying. I replaced the cooked battery with a new battery.
I have ordered a new alt today, should be here tomorrow. One thing that did happen both times is that i was using the kick-down. As i said before that the radio turned off while using the kick-down then came back to life. This time i'm again using the kick-down and batt light stayed on........ seems like problems arise when using the kick-down, ideas more than welcome, Mick