Alternator charging issues

Hi Guys,

any help or ideas are appreciated,

Alternator isn't charging the battery,and after having the dash lights flickering and then battery light coming up on dash i basically figured the alternator was buggered and i replaced it with a new one as well as a new battery for good measure.

so i put the new one in and still not charging the battery. basically my thoughts are is the new alternator faulty out the box or does the computer have a way of regulating the voltage output from the alternator and now the computer is now playing up.

i checked all fuses and nothings blown so I'm a bit confused as to what could be a reason??

First thing, check your earthing.

From experience. I had my engine rebuilt .... Got the truck back and the battery kept going flat. I replaced the battery. No change, so I replace the alternator thinking it was stuffed.... After near a $1000 of replacing parts I find the bloody mechanic did not screw in the earth wire that went to the engine.

Re connect it and all good.

So, first thing before replacing everything, trace your earth wires back to the body and engine and ensure they are in good nick. If in doubt, go down yo super cheap or Repco an buy a half meter battery cable and put another earth line to your engine directly from your battery.

Seriously, it may be as simple as this
Kindest regards
Rainsey


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If it's not the earthing it might be the serpentine belt slipping and not driving the alternator if the tensioning mechanism is not working right.

I had our Patrol 140k service a few days ago after just buying it 2nd hand. I asked my mechanic about the belt squeak at startup. He said that as the belt seemed in good condition the belt tensioner may be the issue. He said it's not an issue at the moment but if starts squeaking longer I may need to see if this needs replacing.

Kkperth,

Sorry but not wanting to hijack this thread but I found another reason for the squeak on startup and possibly why some belts slip and hence no charging is glazing on the pulleys.

My mechanic last service took my pullies and gave them a very mild sand blast which took the glase of the surface.

No lip no squeak


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Sorry make that no slip no squeak


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have you put a Multi Meter across the back of the Alternator ?
X 2 on the bad earths

Yendor may be the person you seek

thanks for the follow up guys,

in reconnecting the new Alternator, i noticed to the original there were 2 black wires joined to a single terminal onto the back of the alternator yet the new one doesn't have anywhere to connect this to. do we know what these do? i did run the car with the wires on the alternator and without and no difference so not sure what they are meant for

i run the multimeter over the alternator at the rear and was only getting a reading of 1.6 so im wondering why if its a new alternator the why would i be getting such a low Reading? if the reading was high i would presume a problem back to the battery but seeing as its from alternator a mystery.

i did have a thought about the belt slipping, but cant see or hear any evidence of it happening,there is no squeaking or anything.
ill try replacing the earth wire from battery, i did look over the earth wires and no signs of damage but it was dark so ill look again.

thanks again guys

What model Patrol and engine do you have?

Does the battery warning light come on in the dash when the ignition is turned on? does it go out when the engine is running?

Was the engine running when you got that 1.6 volt reading at the back of the alternator? what was the reading across the battery?

Have you check the fuse/s?

Also check the wires in the two pin plug at the alternator. Make sure the wires haven't broken near the plug.

Quote:

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Originally Posted by Yendor

What model Patrol and engine do you have?

Does the battery warning light come on in the dash when the ignition is turned on? does it go out when the engine is running?

Was the engine running when you got that 1.6 volt reading at the back of the alternator? what was the reading across the battery?

Have you check the fuse/s?

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I'm driving 2001 GU ZD30

The battery light comes on and stays on when the car has been started along with the sub tank light and even the ABS light was on for a bit. The tacho lights don't show up at all i'm not sure if the globes are blown or wiring has melted somewhere, but when the car is running the little light behind the clock in the dash is on but when i switched the headlights on they disappeared altogether.

as for the readings the car was running when i took the alternator reading and got the 1.6 volt at the same time car running i was getting around 11.2 at the battery. im told it should be around 13.5 to 14?

im going have a look at all wiring again but when i replaced the unit all the wiring seemed to be fine even at the switch..


Yendor do you know if the two wires joined together at the back need to be attached to the replacement unit as on the standard? these no power running through them so it may just be another earth?

Cheers

and i checked all the fuses i could find, pop the caps of in engine bay and checked under dash and no blown fuses

Quote:

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Originally Posted by jaseb13

I'm driving 2001 GU ZD30

The battery light comes on and stays on when the car has been started along with the sub tank light and even the ABS light was on for a bit. The tacho lights don't show up at all i'm not sure if the globes are blown or wiring has melted somewhere, but when the car is running the little light behind the clock in the dash is on but when i switched the headlights on they disappeared altogether.

as for the readings the car was running when i took the alternator reading and got the 1.6 volt at the same time car running i was getting around 11.2 at the battery. im told it should be around 13.5 to 14?

im going have a look at all wiring again but when i replaced the unit all the wiring seemed to be fine even at the switch..


Yendor do you know if the two wires joined together at the back need to be attached to the replacement unit as on the standard? these no power running through them so it may just be another earth?

Cheers

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The voltage reading at the back of the alternator should be the same as across the battery regardless of if the engine is running or not. It sounds like you have blown the main 100amp fuse near the battery.

Did you disconnect the battery when changing the alternator?

If the wires are large black wires, yes they need to be connected to earth. On the top alternator mounting bracket there is a threaded hole that I normally connect them to. Just find yourself a suitable bolt. You might also need to cut the tape from the harness to get some extra length in the black wire if they don't reach. These black wires won't stop the alternator from working.

Quote:

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Originally Posted by jaseb13

and i checked all the fuses i could find, pop the caps of in engine bay and checked under dash and no blown fuses

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Double check the 100amp fuse with a test light. Make sure it has power on both sides.

The wire runs from this fuse to the alternator, you did reconnect the large white wire under the 10mm nut on the alternator?

Quote:

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Originally Posted by Yendor

Double check the 100amp fuse with a test light. Make sure it has power on both sides.

The wire runs from this fuse to the alternator, you did reconnect the large white wire under the 10mm nut on the alternator?

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i just double checked 100amp and its fine, all the wires have been reconnected as per previously (except for those two black wires)

I've been reading about an exciter wire or something of this nature, have you heard of this??

Quote:

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Originally Posted by jaseb13

i just double checked 100amp and its fine, all the wires have been reconnected as per previously (except for those two black wires)

I've been reading about an exciter wire or something of this nature, have you heard of this??

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What is the voltage reading on the large white wire at the back of the alternator now?

The exciter wire is one of the two wires in the 2 pin plug at the alternator I asked you to check before. You need to have battery voltage in the white wire first.

great news!! so after checking over all wires, checking power in switches traced it all back to the nut that is inside the fuse box next to the 100amp fuse which connects to the other 100amp fuse and then goes back to the battery..the nut was LOOSE!! thats why i was getting power but very minimal due to bad connection

tightened all up cleaned all terminals and now getting full charge and every things back to normal..feel bit stupid about it all but i suppose its the little things..

i did get a new battery and alternator out of it but probably due for replacing anyway..

thanks heaps for the help appreciate it