Leisure Batteries.....

[Richp]

I know covered many times, but each thread has its own issues.
I have 2 new AGM batts fitted.
They charge fine on hook up, taking on amps and voltage in mid 14V.
When driving 4hrs plus, the G shows, but the voltage hovers around mid 12v and the amps draw around 0.2-4. negative.
At no point does the amps show a positive charge to the batteries.
Where on earth do I start fault checking please? Could it be as simple as a fuse? But which one, and where? Also, the previous leisure battery cooked itself under the seat, would that be down to a blown fuse somewhere. Appreciate any help anyone can give to point me in the right way.

 

[WelshGas]

I know covered many times, but each thread has its own issues.
I have 2 new AGM batts fitted.
They charge fine on hook up, taking on amps and voltage in mid 14V.
When driving 4hrs plus, the G shows, but the voltage hovers around mid 12v and the amps draw around 0.2-4. negative.
At no point does the amps show a positive charge to the batteries.
Where on earth do I start fault checking please? Could it be as simple as a fuse? But which one, and where? Also, the previous leisure battery cooked itself under the seat, would that be down to a blown fuse somewhere. Appreciate any help anyone can give to point me in the right way.

Check the large Brown 80 amp fuse under Passenger seat. It is a separate fuse holder, on the R hand side I think, and is in the Alternator/Split Charger circuit.

 

[MattBW]

That sounds like the bluemotion technology. I suspect all you are seeing is that your batteries are at the point of being charged as much as they can be, the system will then disengage. AGM batteries will only be charged to about 80% to allow for the regenerative braking and bluemotion tech capacity to go into .

Usually when it gets close it will drop to about 13.4 and then finally into the 12.7 region.

 

[Richp]

Check the large Brown 80 amp fuse under Passenger seat. It is a separate fuse holder, on the R hand side I think, and is in the Alternator/Split Charger circuit.

Thanks, just checked and that looks fine. So is there something next I should check?

 

[Richp]

That sounds like the bluemotion technology. I suspect all you are seeing is that your batteries are at the point of being charged as much as they can be, the system will then disengage. AGM batteries will only be charged to about 80% to allow for the regenerative braking and bluemotion tech capacity to go into .

Usually when it gets close it will drop to about 13.4 and then finally into the 12.7 region.

Is bluemotion only on newer models? Mines a 2012 SE

 

[MattBW]

Bluemotion was available in 2012, may need to check the logbook to be sure.

 

[MattBW]

What are your batteries voltages once you stop and are at rest?

 

[Richp]

What are your batteries voltages once you stop and are at rest?

At rest, engine off, 12.5V. I'm picking up that the alternator will only charge to 80%, which I assume is around 12.5V, so does this mean it's my ignorance to worry, and actually all is as it should be?

 

[TripleBee]

My batteries are always fully charged as I am lucky not to have BMT!
Maybe you can try to check the voltage while driving downhill for a long time. If the car goes into recuperation mode, it will first charge the starter battery, and when that one is full, it will start charging the leisure batteries (I guess).
At one point the leisure batteries must be charged, and this has to be displayed.
Worth to check, but probably hard to find the right place to really test this?

 

[MattBW]

At rest, engine off, 12.5V. I'm picking up that the alternator will only charge to 80%, which I assume is around 12.5V, so does this mean it's my ignorance to worry, and actually all is as it should be?

Just after switch off it should be a little higher but should settle down to aruond 12.5v. So it sounds about right, it should be around 12.5 if its bluemotion. If the voltage drops off from there though within say an hour without any use of power it may be an issue.

 

[Richp]

Following up, I've done some testing with a meter, the split charge relay works.
The engine battery is only showing 12.4v despite a 700 mile drive last week, so low, and may be on way out.
The engine battery charge increases to 13.6V with engine running, so I deduce the alternator is working.
Engine off. The input to the relay is showing 12.4V, as is the output, towards the leisure Batteries.
With the engine running, the input to the relay doesn't change, it remains at 12.4V and doesn't increase to the 13.6V the engine battery is showing (with alternator)
So the leisure batteries are not being charged when engine is running.
They Do charge on EHU.
So all I can think is that the engine battery is failing and not achieving sufficient charge for the power to divert to the leisure batteries, is there a module between the engine battery and leisure battery relay which stops any charge divert unless the engine battery is optimised for charge?
Thanks for any advice.

 

[Richp]

I add, my camper is not a blue motion

 

[MattBW]

Am I right in thinking you got this resolved now?

 

[Richp]

Yes, thanks to yours and others advice