rossyb53 · Nov 21, 2013

My batterys been going flat overnight so thought id do a test to see if its draining power when the ignition is off. I took the negative off the battery and stuck a voltmeter between the negative terminal on the battery and the negative cable. 12v was shown when the ignition was off. Im guessing this means somethings draining power. :frown: I removed all the fuses one by one to see if the voltage dropped, but it didnt. So i removed the wires off the alternator and the volts droped to 0v. Does this mean my alternators draining the power when the ignitions off or have i totally got the wrong end of the stick?

Cheers

damanic · Nov 21, 2013

you want to read amps not volts if completing a circuit with the multimeter. How to Measure Amperage: 6 Steps (with Pictures) - wikiHow

Anything more than 30mA and you have a parasitic drain issue.

rossyb53 · Nov 21, 2013

Cheers ive corrected my mistake and it reads 27ma when alternaters connected and goes to 0 when i disconect alternater.

Jonnyb1990 · Nov 21, 2013

How old is the battery and in what condition are the earths ?

trax · Nov 21, 2013

rossyb53 said:
Cheers ive corrected my mistake and it reads 27ma when alternaters connected and goes to 0 when i disconect alternater.

are you disconnecting the alt from the alt side?

a fried diode can cause a drain if it's deffo the alts fault

rossyb53 · Nov 21, 2013

Batterys brand new and ive cleaned all the earths up so there all ok. Yes disconecting the alternator by removing all 2 wires from the back of it

trax · Nov 21, 2013

rossyb53 said:
Batterys brand new and ive cleaned all the earths up so there all ok. Yes disconecting the alternator by removing all 3 wires from the back of it

just out of randomness, reconnect it all, then test with W wire (if you have it) removed and d+ (warning) removed

rossyb53 · Nov 21, 2013

Not got a W wire or a d+ Ive only got 2 wires going to the alternater. The main battery wire B+ and a thinner wire with a spade conector on which i cant see a marking on the alternator saying what it is. Im not the best when it comes to electrics

trax · Nov 21, 2013

rossyb53 said:
Not got a W wire or a d+ Ive only got 2 wires going to the alternater. The main battery wire B+ and a thinner wire with a spade conector on which i cant see a marking on the alternator saying what it is. Im not the best when it comes to electrics

hopefully that will be d+, it links to your dash light and is required for the alt to work properly

if you unplug the thin one and turn on your dash then you will not have the usual bat light.

i doubt it was that, i was just curious.

discomania · Nov 21, 2013

rossyb53 said:
Cheers ive corrected my mistake and it reads 27ma when alternaters connected and goes to 0 when i disconect alternater.

You don't have an issue then. 27mA is nothing.

rossyb53 · Nov 21, 2013

cheers for the help, im guessing my alternators wired up wrong. Ive only recently bought the 90 and its had a 300tdi engine put in by the previous owner. Ive just been too look at it again and both the wires are brown, one goes to the B+ and the other brown one goes a spade connecter with no markings on it. Ive got no battery light on dash and had a look at alternator and found the D+ has no wire going to it. I think i might have to take it to someone who knows what there on about cause electrics are not my strong point

trax · Nov 21, 2013

rossyb53 said:
cheers for the help, im guessing my alternators wired up wrong. Ive only recently bought the 90 and its had a 300tdi engine put in by the previous owner. Ive just been too look at it again and both the wires are brown, one goes to the B+ and the other brown one goes a spade connecter with no markings on it. Ive got no battery light on dash and had a look at alternator and found the D+ has no wire going to it. I think i might have to take it to someone who knows what there on about cause electrics are not my strong point

don't sell yourself short.

he's right 27mA isn't a large load. say you have a 70ah battery and if it loses 30ah it wont start.

(30/0.027)/24=46.3 days standby

i'm wondering if your alt is working properly.

stick the wires back on where you found them and place your multimeter measuring the voltage of the battery. start her up and see if the voltage has risen. ideally 14.4 (but probably just below or above) with a little bit of revs.

if so, then alls good. if not then that's the issue. you aren't charging the battery.

if it isn't charging, stop the engine, use your multimeter and see if the two brown wires on the alt output 12v. if so, they are from the starter/battery and should go to B+.

next, you need to wire the dash light to d+. see if any other wires are knocking about. do your know what your original engine was? At the worst, remove your defender dash and trace the wire into the bulkhead and see where it goes.

post back

edit: 87 defender you have, so 2.5 na. check that thin brown wire to see if it has a yellow stripe. if so that's the dash light. stick that one on d+

rossyb53 · Nov 21, 2013

Cheers trax, I think ive got to the bottom of the problem with your help. pulled off aload of insulation tape and found the yellow and brown thin wire. Ive connected the 2 thick brown wires to the B+ and the yellow and brown thin wire to the d+. Ive now got a battery light on the dash

Started her up and the voltage of the battery has risen to 13.9v so its charging. Gunna take it a good run in a moment to charge battery then leave it over night and see if it starts again tomorrow. Hopefully all is sorted now. Thanks for the help mate

trax · Nov 21, 2013

rossyb53 said:
Cheers trax, I think ive got to the bottom of the problem with your help. pulled off aload of insulation tape and found the yellow and brown thin wire. Ive connected the 2 thick brown wires to the B+ and the yellow and brown thin wire to the d+. Ive now got a battery light on the dash Started her up and the voltage of the battery has risen to 13.9v so its charging. Gunna take it a good run in a moment to charge battery then leave it over night and see if it starts again tomorrow. Hopefully all is sorted now. Thanks for the help mate

good job! see you don't need no autoelectrician

no probs, it might take a good run to recharge it.

i'd probably take the battery indoors and stick it on a trickle charge overnight. it's good for the battery to do that every now and again.

rossyb53 · Nov 21, 2013

You was right

thanks again you've saved me some £'s

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