Terrano Alternator/Battery problems

Sounds like alternaror to me. If you're still getting some charge it proberbly needs new brushes. Regards Bob
Where to next

Jimmy
never disconnect while running,It should be charging about 13volts when flat
I'd first check fan belt tension if your sure the battery is ok .Mick.

By the way ... an alternator will not charge a dead flat battery, you need to leave the slave battery connected for a few minutes to "excite" the alternator diodes!

With the engine off check the battery voltage with your multimeter, it should read around the 12 volt mark, start the engine and hold the revs up a little (don't rev the rings out of it, just hold them a few hundred rpm above idle) The voltage should now rise to around the 14 volt mark. If not you have a problem with the charging circuit. I'll assume it's not a broken drive belt :). Next check the wiring and connections between the battery and alternator. If no fault is evident then the fault lies in the alternator, most common fault is the regulator or brushes(most modern alternators have the brushes and regulator contained in one unit, not too expensive to change and see, depending on make/model of course. (my Bosch one was around $70 for this u beaut one that pumps out extra voltage under load) and they are a handy spare to carry in any case. If it's not this and you need an overhaul or exchange unit things may start getting pricey (as it always seems too with a 4wd :( )

My alternator died slowly charge dropped to 12 volts and took 10mins to get to 13v, not enough $600 later and all happy again.

PS Warrantee Ins company closed doors 1 month before realised alternator faulty.