Range Rover Classic battery not charging,what next?

1994 Range Rover Classic Soft dash 3.9efi

Where to check next?

Battery good and takes a charge from a charger no prob, HT leads,plugs, dizzy cap, rotor all new

Alernator replaced with a 120A unit, live (red cables) all good no stiffness and connections good.

Will run normally for a couple of weeks if used regularly but evetually struggle to start and battery goes flat.

All the above changed and lastly stuck an earth lead from battery -ve to chassis, straight from clamp to a cleaned point on chassis, did this yesterday so haven't checked drain but doing a quick warm up and then sitting in park with revs up a bit it still struggled with front and rear heaters switched on.

Thinking engine earth straps next, anything else on the list?

what voltage do you read across the battery at idle and at 2000rpm? its worth doing this test with no accessories turned on and again with everything turned on, heated screens, seats, headlights heater fans on max etc etc

kermit_rr said:

what voltage do you read across the battery at idle and at 2000rpm? its worth doing this test with no accessories turned on and again with everything turned on, heated screens, seats, headlights heater fans on max etc etc

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If a drop where am I looking next after all I have already done?

you said alternator replaced, but we need to confirm its 'good', being a replacement, new or not doesn't confirm this

What Kermit RR said..

Ascertain whether the alternator is working before anything else..

I'll say again, to fully charge a modern automotive battery you heed at least 14.5 volts from the alternator, 14.8 is better.
Check what you have across the battery with the engine at 2K rpm.
You need to check the earth strap from engine to chassis. A jump lead from the battery to the engine can be used to see if it improves matters.

Datatek said:

I'll say again, to fully charge a modern automotive battery you heed at least 14.5 volts from the alternator, 14.8 is better.
Check what you have across the battery with the engine at 2K rpm.
You need to check the earth strap from engine to chassis. A jump lead from the battery to the engine can be used to see if it improves matters.

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Cheers, that is kinda what I needed to know, I am 'assuming' yes I know never assume anything that my alternator is good, ran a new earth from battery to chassis but was wondering if the engine earth may be an issue, had this before on a Bentley Turbo R of same era, chased probs for ages then stick a jump lead from the engine to the chassis and solved instantly!!

I posted but didn’t read the above post...
Good to see it was solved...

Think he meant the Bentley was fixed.
Once you've checked the alternator out put is good by checking at the battery with the engine running then the battery needs to be properly tested.
How has it been tested so far?
Carry out a test for parasitic battery drain.

Is the vehicle being used primarily for short journeys as that will gradually drain the battery from the starting. Short journeys won't put much charge back esp if a lot of electrical stuff is being used.

Straun said:

If a drop where am I looking next after all I have already done?

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On RR.net there is an electrical troubleshooting guide to work through with acceptable voltage drops.

Grrrrrr said:

On RR.net there is an electrical troubleshooting guide to work through with acceptable voltage drops.

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Update folks as managed to get access to a bit more equipment, alternator is as I thought good, the battery is good (drop test etc done on it)
Moved the new chassis to -ve battery terminal earth over to one of the engine earths and this seems to be making a marked improvement, also cleaned up the engine to coil earth in a seperate job.
Ratae's point may be an issue, the vehicle is used for a lot of short journeys then called on once a month for longer journey, sometimes involving a caravan, have a trickle charger from another vehicle kicking about and may look into fitting this to the rangey!!

A smart charger from Lidl or Aldi for about £15 is a good investment, updating the alternator regulator to a 14.7 volt set point would also help.

Datatek said:

A smart charger from Lidl or Aldi for about £15 is a good investment, updating the alternator regulator to a 14.7 volt set point would also help.

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Have a laid up road legal Quadzilla buggy that had a trickle charger, quite a neat setup that could easily fit onto the rangey, as I have a caravn with an external socket sitting next to rangey thought it may be an option (and free!)
Cheers will have a look at an upgraded regulator, already upgraded the alternator to a 120A unit.