Technical Battery not charging

[nigelvan]

I have a x250 3.0 2007 Citroen, after going on a trip this weekend (2x 45 min drive) I noticed the van was starting a bit more difficult and checked the battery voltage in the back (where the DC-DC charger for the leisure battery is, leisure battery disconnected at the moment) and it only indicated 12.2V. The DC-DC charger is connected directly with the fuse panel mounted on the positive terminal of the starter battery. When measuring under the bonnet at the indicated jump start point I get 14.8V. So it seems the alternator is running fine. Also no battery charging warning light on the dashboard.

I'm thinking about a loose connection or wire damage somewhere. Are there any weak spots in the charging circuit of the x250? I probably should start looking in the battery compartment and check for blown fuses or wire damage. How can I identify the cable coming from the alternator?

 

[Communicator]

The battery warning lamp, is really an alternator warning lamp, so as alternator is OK, no lamp.

When testing from the jump start point, where is your meter negative connected, engine block or chassis? I suspect to the engine block.

A common fault on x250's is deterioration of the engine block earth strap, but this is usually indicated by several alarms, with no obvious cause.


You can check for a faulty earh strap, by connecting a jump lead between the engine block (lifting lug?), and a clean chassis earth point.

 

[nigelvan]

Thanks, but the strap was replaced by the previous owner, as it's obviously new. I measured on the chassis, not the engine itself.
Good to know the warning light tells only about the alternator. The ECU probably sees the 14V so no problem.

 

[Communicator]

The attached eLearn file was posted a few weeks ago, and I saved a copy out of curiosity, as my vehicle is an x244.

It seems that the alternator is connected to the starter teminal B. The starter has two linked terminals A, & B. Terminal connects to the jump start point, and then to a CAL4 fuse at the battery.

I am also attaching another "lifted" photo of an X250 battery with battery isolator on negative pole, ignore this device. The starter/alternator connection will be the large right angle lug, connecting to the large CAL4 fuse.

 

[nigelvan]

So if I understand correctly, the starter and alternator share the same thick cable to the battery? I'll start by checking the fuses and connection on the board then. Seems very weird because starting is no problem at all. So I'll double check my measurements from last weekend the coming days and get back here with the results. Thanks for your help so far.

 

[rayc]

Any help? B099 is the battery terminal fuse board, A020 is the starter and A010 is the alternator. What voltage do you get at the feed to the DC-DC charger at the battery terminal fuse board? Is the voltage arriving at the DC-DC charger in the rear any different?

 

[Communicator]

So if I understand correctly, the starter and alternator share the same thick cable to the battery? I'll start by checking the fuses and connection on the board then. Seems very weird because starting is no problem at all. So I'll double check my measurements from last weekend the coming days and get back here with the results. Thanks for your help so far.

1.Yes according to the drawing, cable is shared.

2, May I suggest that you start by checking the voltage directly accroos the battery terminals?

3. Yes it does seem weird, as "starting is no problem at all", conflicts with your original post on this thread.

4. Confirming readings is usefull, when previous results are confusing.

5. You have not stated that your vehicle is a motorhome, based on having two batteries, I will make that assumption. As well as the B2B, does it have a split charge relay (often integral with proprietry 12V system, CBE, Schaudt, etc,) Has this split charge relay been disabled, when the B2B was installed?

6. Your feedback is appreciated.

 

[nigelvan]

Hi Communicator & rayc, sorry for the confusion.
It is indeed a converted van with a lithium battery in the back charged by both solar and a Votronic DC-DC charger. Right now, the lithium battery is disconnected. So no connection between starter and leisure.
Here a my test results from today:
- started with 12.1V across the terminals
- Had a rough start, little energy in the battery left after my lasts starts
- After start 12.4V across battery terminals
- At the jump start point: 14V
- Shut down the engine and attached a trickle charger at the jump start point
- Trickle charger puts out 14.4V, at the battery 13.3V
- Resistance between engine and chassis: 44ohm
- I'll check the ground connection between engine and chassis later, but there seems to be a resistance somewhere further down the line causing a voltage drop.

 

[Anthony489]

Hi nigelvan

The resistance between engine/gearbox and chassis should be extremely small, more like 0.002 ohms. I suggest you re-check your measurement. Bear in mind that a normal ohmmeter can give a false reading if there is any existing current flow in the circuit being tested, so you might need to disconnect the main battery whilst testing.

 

[nigelvan]

Hi Anthony, Thanks once again for your help.
I'll disconnect the battery and measure again.
In the meantime I found a little cable that the seller told me he put in because there was a bad mass, I didn't pay attention at the time because I didn't know anything about engines back then (I still don't, but I try). He did this because the engine's idle rpm was unstable back then, so he put the cable in and this fixed it (the throttle body was dead as well...) When I remove this cable the problem indeed comes back. This makes me suspect this little cable is the only good connection between engine and chassis, handling all the high current between battery and alternator/starter.

image:

link to image: https://photos.app.goo.gl/fWPLBdKyjiUDiANd7

I'll disconnect the battery and will start checking different points for resistance. I checked the strap again and it is indeed new but the bolts are quite rusty...

 

[Communicator]

Hi Communicator & rayc, sorry for the confusion.
It is indeed a converted van with a lithium battery in the back charged by both solar and a Votronic DC-DC charger. Right now, the lithium battery is disconnected. So no connection between starter and leisure.
Here a my test results from today:
- started with 12.1V across the terminals
- Had a rough start, little energy in the battery left after my lasts starts
- After start 12.4V across battery terminals
- At the jump start point: 14V
- Shut down the engine and attached a trickle charger at the jump start point
- Trickle charger puts out 14.4V, at the battery 13.3V
- Resistance between engine and chassis: 44ohm
- I'll check the ground connection between engine and chassis later, but there seems to be a resistance somewhere further down the line causing a voltage drop.

Hi Nigel,

1. As you already appreciate 12.1V is too low a resting voltage for the starter battery.
2. Again 12,4V is too low to charge the battery efficiently.
3, Is the 14,4V output of your trickle charger, from the label, open circuit, or on load?
4. It is not practicable to test earthing resistances on the ohms range of a multimeter. You are trying to measure a small fraction of an ohm. For an illustration assume a low starter current of 100A passing through a resistance of 0.1 Ohms. Applying Ohm's Law you would get a voltage drop of 10V, which is obviously impracticable.

I agree with you intention to check the engine earth strap. Make sure that mating faces are free from corrosion, and if available apply a smear of vaseline or similar to prevent moisture ingress. This connection is in both starting and charging circuits. I have read of a strap which allowed starting, but caused spurious alarms during normal running. Odd.

Also may be worth checking the starter battery earth lead, for elimination. However I understand that there is a procedure to be followed, before disconnecting.

 

[jimboy]

Hi Anthony, Thanks once again for your help.
I'll disconnect the battery and measure again.
In the meantime I found a little cable that the seller told me he put in because there was a bad mass, I didn't pay attention at the time because I didn't know anything about engines back then (I still don't, but I try). He did this because the engine's idle rpm was unstable back then, so he put the cable in and this fixed it (the throttle body was dead as well...) When I remove this cable the problem indeed comes back. This makes me suspect this little cable is the only good connection between engine and chassis, handling all the high current between battery and alternator/starter.

image:

link to image: https://photos.app.goo.gl/fWPLBdKyjiUDiANd7

I'll disconnect the battery and will start checking different points for resistance. I checked the strap again and it is indeed new but the bolts are quite rusty...

Looks like poor earth. What you should do is multi earth the old girl. Thick lengths of earthing cable from earth battery terminal to engine various places you can get to, and on to body. Make up these yourself, an easy upgrade. I’ve done this on various vehicles I’ve owned.

 

[nigelvan]

Hi all, I think it was the strap after all. There were toothed washers (don't know the correct english term) between the connector of the strap and the chassis point.
The rough idle that came back after removing the small cable posted in previous message is now gone.
I get 13V at the battery and 14V between + and engine. After shutdown battery drops to 12.6V so alternator is definitely putting a charge in. I guess a 1V voltage drop is expected over a 2m cable run...

 

[Anthony489]

Hi again

When these X250 vehicles were built in the factory, they had a braided earth strap to link the engine/gearbox to the body (look under the air filter). There is a second earth cable from the body to the negative post of the battery, inside the battery box. So all the hundreds of amps of current returning from the starter motor goes via the strap to the body, through the body for a short distance, then via the cable back to the battery. This all works fine, but because of this arrangement, the strap, the cable and all their connections must have a large cross section and sound connections to give an extremely low total resistance.

Over time, connections can corrode. There is a particular problem with the strap which is braided to make it flexible, and exposed to damp under the bonnet. Corrosion builds up inside the crimp lugs, raising the resistance between the braid and the lug for some if not all of the copper strands. You can take it off and look at it, and it may appear fine. You can tug on the ends and it all appears firm. You can check it with a multimeter and it may read zero. The trouble is, you need (say) 0.001 ohms, and "zero" on your multimeter could actually mean 0.01 ohms or 0.1 ohms which are not nearly good enough.

Replace the strap with a good new one, with clean bright connections, and you will restore performance to factory spec. There's really no need to start adding extra straps in different places. If you find that a second (parallel) strap makes ANY difference when it's connected/disconnected, it simply means that the first strap isn't doing it's job properly.

 

[jimboy]

Hi all, I think it was the strap after all. There were toothed washers (don't know the correct english term) between the connector of the strap and the chassis point.
The rough idle that came back after removing the small cable posted in previous message is now gone.
I get 13V at the battery and 14V between + and engine. After shutdown battery drops to 12.6V so alternator is definitely putting a charge in. I guess a 1V voltage drop is expected over a 2m cable run...

Hi, if you multi earth as I suggested, you will have no more bother, in doing this you will make good the electrical system.

 

[nigelvan]

Thanks guys, I retested and now I get equal voltage (14.3v) on both battery and between positive terminal at the fuse box and engine.
Although, when starting rpm is unstable again and voltage low, until I rev once. Then everything is stable. Maybe my alternator clutch (I suppose it has one to make starting easier) is wearing out too...
The strap is brand new, shows no sign of corrosion, looks like shiny new copper, but there were these toothed washers underneath, probably put there because the strap spins when tightening the bolts. These little teeth probably don't create a good connection.
I will see how it behaves in the future, at least now I know how to fix it.

 

[rayc]

Although, when starting rpm is unstable again and voltage low, until I rev once. Then everything is stable. Maybe my alternator clutch (I suppose it has one to make starting easier) is wearing out too...

I had a 2015 Ducato 130bhp which had a slow starting alternator. Normally first start of the day and thereafter ok. It needed the revs raising to 1000+ to get it going.
Google 'altenator slow to excite' for interesting reading

https://www.fiatforum.com/ducato/420476-alternator-trouble-worse.html

 

[nigelvan]

Yes this is indeed the same behaviour with mine. Only when engine is cold, just tap the accelerator and the alternator kicks in. Interesting read indeed. Thanks!