help on 12 volt charging

pagey

pagey

Joined
Aug 22, 2007
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essex
Funster No
145
MH
2017 sunlight t69s euro6
Exp
since 1999
ok 2017 ducato 130 no output from the alternator to the engine battery but no ign warning light on ? i have checked with 2 multimeters both showing 12.5 v at the battery engine running,any ideas on where to start to find the problem tia
 
Check the 50a fuses by the batteries and work around the other fuses😊
 
I've never come across this problem but if there's a break (fuse etc) in the alternator to battery wiring then the warning light may go out as the alternator is working as it should but nowhere for the current to go.
Warning light usually come on if the alternator itself is damaged
 
Check the earth leads that go from the engine to the body/chassis and also the battery to body earth connection, you may need to remove clean and replace the connections. You could also use a jump lead as a temp. earth lead between the engine and the starter battery earth (-) and see if the charging improves
 
all fuses in the battery area are ok , earth leads spotless with no corrosion are there any other fuses that control charging ?

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Is the starter motor a bit sluggish in operation ?

If so, this could indicate a bad earth between engine block/chassis and affect alternator output.
 
Try and see what the voltage is between battery 12 + and engine, using the engine as a ground.
 
hi no the starter is spinning as usual
 
NicM said:
Try and see what the voltage is between battery 12 + and engine, using the engine as a ground.
Click to expand...
its the same at 12.5 volts
 
Are you able to get at the alternator wiring connections to check they are ok , also I think that the main alternator output may be linked to the starter battery via the starter motor main lead connection and may be worth a look at.
If you do have a jump lead you could also try a temp. connection between the alternator body and a good earth to eliminate a poor alternator earth..

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GeoffnDee said:
Are you able to get at the alternator wiring connections to check they are ok , also I think that the main alternator output may be linked to the starter battery via the starter motor main lead connection and may be worth a look at.
If you do have a jump lead you could also try a temp. connection between the alternator body and a good earth to eliminate a poor alternator earth..
Click to expand...
hi i will try that in the morning as its raining here and i will have to jack it up first. this is a strange one on me ,i have yet been able to find a wiring diagram
 
If the fuse is ok, I would suspect the voltage regulator is not putting out full voltage. Built into the alternator and fairly easy to swap out
 
just noticed that yours is 2017, so possibly a smart alternator, which complicates things
 
GeoffnDee said:
When you say no ignition light can you confirm you mean it is not coming on at all.
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it comes on when i turn the ign on then goes off when i start it up

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If a diode or diodes fail in the alternator you will be getting some a/c voltage output and a drop in dc output depending on the alternator you should not get more than 50 to 100mv a/c any more and the alternator will need repair or replacement.
 
Has it got a smart alternator?

If so 12.5V is fully charged so switch on headlamps etc and see what the volts are take a few readings 10-15mins apart

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RandallC said:
Has it got a smart alternator?

If so 12.5V is fully charged so switch on headlamps etc and see what the volts are take a few readings 10-15mins apart
Click to expand...
hi its not a smart alternator but thanks
 
update i mistyped the voltage at the start thread the battery is at 12.37 volts on ehu and only 12.05 as i take it off ehu and start it up the meter reading drops to 12.1 and then drops quickly (30) seconds down to 11.8 and will go down further but i turn it off. so i am thinking the battery is finished what do you think?
 
You said the engine spins over just fine, so can't see the battery being totally goosed.

Geoff
 
i will go and investigate further

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Are you measuring the voltage at the battery or straight on the alternator?
If at the battery and at the alternator it's over 14v that would point to a wiring or earth fault.

Have you checked your meter against another one to make sure its ok?

If the battery is low best not to try starting the engine as you could take out the Airbag ECU.
 
pagey said:
it comes on when i turn the ign on then goes off when i start it up
Click to expand...
This suggests the alternator is at least "excited" and "should" be pumping out 13 - 14v DC to the vehicle battery. If it's not, as seems to be the case, then it could well be (as has been said) a bad earth at the alternator or battery and/or a broken regulator on the alternator.
 
Lenny HB said:
Are you measuring the voltage at the battery or straight on the alternator?
If at the battery and at the alternator it's over 14v that would point to a wiring or earth fault.

Have you checked your meter against another one to make sure its ok?

If the battery is low best not to try starting the engine as you could take out the Airbag ECU.
Click to expand...
Voltage measured at the battery only 12.05 when off ehu for a few mins then drops down I have not measured the alternator output only at the battery also I have used 2 meters
 
pagey said:
Voltage measured at the battery only 12.05 when off ehu for a few mins then drops down I have not measured the alternator output only at the battery also I have used 2 meters
Click to expand...
Sounds like it could be the battery dragging the alternator output down.
 
You say that you are only getting 12.37v when on EHU , which also seems to be low , is your PSU a Schaudt EBL one , if so which model.
Also are you able to check your meters on another battery to double check their readings ?

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Last edited:

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