help on 12 volt charging

Can i suggest you buy one of these battery testers, it may also indicate what is happening with the charging system as well. It worked really well on an issue i had on my car.


AUTOOL 12V Battery System Tester Health Checker, Charging Analyzer for Cars, BT360 Amazon product ASIN B071NS74YK
 
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 ?
Hi Geoff it's an ebl119 I have not looked at the fuses on this just, checked the meters on the car all seems well ... what I don't understand is how quick the voltage of the battery drops as above I disconnect the ehu batt showing 13.2 turn the key fires up no problem as I watch the meter voltage drop down then I turn it off
 
If the battery voltage is dropping quickly, then it could be either a duff battery, or a good battery with a bad alternator/wiring fault.

A battery with a shorted cell will look like it's charging OK, but when disconnected with no charging and no loads its voltage drops to about 10.5V.

A wiring fault, or possibly a faulty component, might draw a large current from the battery, causing the voltage to drop, and continue to fall. But the wire or component should get quite hot, so you would be able to tell from that.

Have I got it right, when you turn off the ignition key, the voltage stops dropping?
 
If the battery voltage is dropping quickly, then it could be either a duff battery, or a good battery with a bad alternator/wiring fault.

A battery with a shorted cell will look like it's charging OK, but when disconnected with no charging and no loads its voltage drops to about 10.5V.

A wiring fault, or possibly a faulty component, might draw a large current from the battery, causing the voltage to drop, and continue to fall. But the wire or component should get quite hot, so you would be able to tell from that.

Have I got it right, when you turn off the ignition key, the voltage stops dropping?
correct i am going to try to video the meter and post it on here
 
correct i am going to try to video the meter and post it on here
ok i hope this works 1 hour after this video with no ehu the battery has gone up to 12.7 volts

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Take a photo of the -ve starter battery terminal. I suspect you have smart charging and ecu controls the charge.
 
It looks like the alternator is having the opposite effect! Unless as noted above a smart charging system is taking all the juice to the leisure batteries. I'd still think any system should be putting 13-14v into the vehicle battery though as it needs quite a bit of heft to start the engine - that's about (except we can use it for hab if we can switch it over) all it does and it takes a lot out of it and so needs a good charge to get it back. Although it does seem to recover voltage-wise when the engine is off so it could be smart enough to know it does not need it, however, what seems to be a drain when it is running must be wrong surely, expand this scenario out and you have so low a voltage on the vehicle battery as to not be able to start again. Other idea is that maybe as smart charging system, it is deliberately sending a float voltage to a known good vehicle battery...:unsure:

I'm intrigued...

If ALL my batteries weren't in my shed on charge, I'd drive up to storage and check what mine does.
 
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It looks like the alternator is having the opposite effect! Unless as noted above a smart charging system is taking all the juice to the leisure batteries. I'd still think any system should be putting 13-14v into the vehicle battery though as it needs quite a bit of heft to start the engine - that's about (except we can use it for hab if we can switch it over) all it does and it takes a lot out of it and so needs a good charge to get it back. Although it does seem to recover voltage-wise when the engine is off so it could be smart enough to know it does not need it, however, what seems to be a drain when it is running must be wrong surely, expand this scenario out and you have so low a voltage on the vehicle battery as to not be able to start again. Other idea is that maybe as smart charging system, it is deliberately sending a float voltage to a known good vehicle battery...:unsure:

I'm intrigued...
me too it starts fine does its party trick as per video turn it all off no ehu etc come back after an hour and the battery is sitting at 12.7 ,, i did not think 2017 ducato had smart charging but stand to be corrected i will take a photo of the neg terminal and post it
 
If the starter battery was discharged a bit , not to much, (put lights on 5 mins ?) and then the van started I wonder if the readings would be higher to confirm alternator output is able to be as normally expected.

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If the starter battery was discharged a bit (put lights on 5 mins) and then started I wonder if the readings would be higher to confirm alternator output is able to be as normally expected.
i will go and try that now
 
Something else to consider, on some engines the glo plugs stay on for a while after the engine starts which will show as a voltage drop on your meter, if you listen carefully you may here a click as the relay shuts off and you will see the volts come back up again.
 
Take a photo of the -ve starter battery terminal. I suspect you have smart charging and ecu controls the charge.
 

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I have smart charging with shunt on -ve starter battery. The ecu receives info from bms that’s fed by the shunt, and I see quite often on idle 12,4v and alternator does not charge. It has stop start to. And it will not disable itself, unless battery is really low. The bms takes in account voltage drop and knows the amount of energy left, despite reading 12,2v.
 
If the starter battery was discharged a bit , not to much, (put lights on 5 mins ?) and then the van started I wonder if the readings would be higher to confirm alternator output is able to be as normally expected.
tried that geoff it was showing 12.7 v then went down in tenths to 11.4 then i panicked and turned it off 5 mins later its back up to 12.7

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Doi you have a loop back from leisure side like battery master? It may be taking charge from there?
 
Doi you have a loop back from leisure side like battery master? It may be taking charge from there?
hi no none at all i managed to post a photo of the neg terminal
 
With no EHU or solar or anything else charging it, and no loads, what does the battery voltage settle down to?

I think the next stage is to use a clamp meter, to see if there is any amps flowing from the alternator to the starter battery. Don't use a standard multimeter, it needs the wire disconnecting to send the flow through the meter, and that's definitely a bad idea with the alternator wire. Maybe pappajohn (post#3) is right on this one.
 
I can’t see nothing on that pic. Google smart alternator battery sense, and see what I mean, it has a shunt on the battery post. This is to eliminate you have/don’t smart charging.
 
I know you're getting a lot of advice, which is probably a bit confusing, but please try running your engine for longer maybe 5 to 10 minutes and watch what happens to the voltage, my mitsubishi used to go down to 11 volts whilst the glo plugs were on but would come back to 13.9 once they were off, glo plugs put a big load on the alternator hence the voltage drop.

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tried that geoff it was showing 12.7 v then went down in tenths to 11.4 then i panicked and turned it off 5 mins later its back up to 12.7
I suppose that the fuel pump , ECUs etc. would account for the dropping voltage when running without any input from a faulty alternator or a lack of connection from it to the battery (either + or -) . When you switch off the ignition , after a very short period , the battery returns to its unloaded voltage which then increases , if put on on EHU , due to a trickle charge via the EBL119
 
I suppose that the fuel pump , ECUs etc. would account for the dropping voltage when running without any input from a faulty alternator or a lack of connection from it to the battery (either + or -) . When you switch off the ignition , after a very short period , the battery returns to its unloaded voltage which then increases , if put on on EHU , due to a trickle charge via the EBL119
yes geoff once the engine is turned off it climbs backup to 12.7 volts if i connect the hook up it charges then but only a trickle
 
I wonder if there's a diode gone in the alternator which is letting current flow back to it ?
 
To be honest it's all getting beyond me now I set out this morning to have a look at the alternator I know where it is but age and atheritis put a stop to that what with a drive like Brighton beach and little chance of getting it jacked up it was a no no
 
I can’t see nothing on that pic. Google smart alternator battery sense, and see what I mean, it has a shunt on the battery post. This is to eliminate you have/don’t smart charging.
The pic shows up on my PC. The negative post has a lever clamp with a braided metal strap to the bodywork, plus a couple of brown wires attached onto studs with nuts. No shunt, relay or anything else.

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UPDATE started it up this morning let it run watching the multi meter gradually go down give it a boot full at 11.8 volts and walla 14.5 volts on the meter, i wished i knew why but i am glad it seems ok now fingers crossed thanks for the help and replies (y)
 
It's the glo plugs dragging the voltage down because of the amount of current they draw.
 

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