So after my alternator bearing failure I got a recon Bosch one, didn't get chance to fit it yesterday so today was the day!
Finally got my viscous fan off then old alternator out of the car, the battery had drained down to the point that the key fob wouldn't open the car but I hadn't locked it anyway.
New alternator fitted jump from the brother in laws golf and then a quick trip round the block, all good seems to be charging
Bonnet up check fluid level that's ok top hose is warm bottom hose not so? heaters are blowing warm so looks good, I then hear the engine start to hunt up and down plus the charge warning light is on and off same time as the engine hunting also the voltage rises and falls in time with the engine, if it's revved it makes no difference still pulses the dash lights and the battery warning
It takes about a minute for the fault to appear, am I missing something obvious.
Has my old faulty alternator killed my battery or is this recon one faulty??

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Something prevents the alternator putting out a charge for the first minute or so, to assist the engine to start, that's why there is a delay... Probably the BECM

I'd check the wiring carefully as it could be a poor connection or indeed the new alternator maybe faulty, unlikely though as they tend to test the rebuilt ones more than the new ones... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

stan wrote:

can you fill your car profile in so we know what you have...

Think I'd try removing the battery, (well, disconnect it anyway) fully charge it overnight and see what happens, low voltage can pull all sorts of problems and the voltage was low when you jumped it....

Remove battery from charging in the morning, leave it an hour and check the voltage, should be around 12.6V if not the battery could be toast...  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Battery already out of the car not sure why the voltage was still falling after car turned off, will see if I can borrow a charger do it over night.
Thanks for the help  2004 4.4V8 Vogue
BMW 330CD
BMW523i
Escort Mexico MK1
1974 airportable series 3

I've just replaced my battery..prior to replacement my idle.was up and down and it would do it with anything under 1000rpm..thought I had a bad sensor somewhere then replaced the battery and it stopped it instantly..i think the car does it if voltage is too low..mine would drop from 12.5v to 9.5v in hours after a charge....

Dave 67 wrote:

not sure why the voltage was still falling after car turned off

Battery on charge all night disconeccted at 6.15 this morning just checked with a multimeter at7.15 still sitting at about 13.1V.
Will leave it off the car today check when I'm home later, then reconnect see where we are!!
It's only an 88ah battery not sure on OE fitment but most batteries seem to 110ah that people are fitting? 2004 4.4V8 Vogue
BMW 330CD
BMW523i
Escort Mexico MK1
1974 airportable series 3

i replaced last month at dealers and was replaced with 110ah 88 seems a lot to small

The 110amp is for the diesels, yours will work fine for now, if you have to change it there is an argument that the additional few quid for the bigger one is worth it...  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

So update!!
Had the battery off the car on charge all night off this morning left all day on the side in the garage, checked it when I got home very little voltage drop all day so little in fact it was nothing.
So battery back on the car start up round the block a home only about a mile all the seats in the front on and both screen on, no battery warning light.
Get home meter at the jump start points alternator pushing just over 13.5 volts out rising occasionally,turn off engine and battery sitting at 12.5 with bonnet up doors locked.
Oh might have sorted this, drive the 4 miles to the train station to collect the wife battery light comes on just as I get to the station
Get home turn the car off get the meter out and it's sitting at 12.2 volts 🙈🙁🔫
So in the morning when the engine and alternator a cold I will drive round the block at home see if the alternator charges till everything heats up.
Starting to think it is breaking down when it gets hot? 2004 4.4V8 Vogue
BMW 330CD
BMW523i
Escort Mexico MK1
1974 airportable series 3

Just wanted to say thank you to the people who replied with advice, especially Haylands for his time and advice.
This is now sorted, after looking at every possibility I came to the conclusion that the Bosch factory recon alternator was faulty. So this morning pulled it back out of the engine and took it back exchanged it under warranty, came home fitted the new one started the car up and it has run, charged flawlessly all day.  2004 4.4V8 Vogue
BMW 330CD
BMW523i
Escort Mexico MK1
1974 airportable series 3

Always good to get an issue like this resolved even if it has cost some extra coolant  FFRR MY06 facelift With TDV8 Alloys Zeros/ATR's
Mantec Sump Guard, Rigid Load liner, MY10 BT upgrade.

Result, pleased you got to the bottom of it, that is rare to have a recon failure as they are tested by a real person... must have been a Friday one...!!!! Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-