Leisure Battery Discharging During Driving

bigtwin

bigtwin

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I seem to be having a problem with my leisure batteries discharging while I’m driving. I’ve observed this over the last 3 days as I’ve been driving (each day) south through France.

Symptoms:
After being on mains hook-up and having fully charged batteries prior to setting off on a 2 - 4 hr drive, the leisure battery voltage drops to about 12.2V by the end of the journey.

Observation:
With the engine running, the vehicle battery voltage shows (on the control panel) to be high 13V/low 14V. However the leisure battery voltage remains at 12.whatever.
Off hook-up, there is no indication on the control panel that there is any current being drawn from the leisure batteries (When loads are switched on, the panel shows an appropriate discharge current).

Questions:

  1. When the engine is running, should the leisure battery be seeing the same voltage as the vehicle battery?
  2. If the answer to the above is yes, is it possible that the fridge 12V heating element is being powered from the leisure batteries instead of from the alternator? *
  3. Any thoughts on a diagnosis before I start removing the driver’s seat To access the charger?
* To prove/disprove this ‘theory’, I plan to disconnect the 12V heating element before I start my next leg of the journey.

Ian

We have an Electroblok EBL 99 with an associated IT991-2 Control/Display panel.
 
Disconnect the EBL to reset it, reconnect then see the voltages.

1......yes, same voltage..
2..... Won't make any difference when engine running.... Its still getting power from the alternator.
 
Similar problem 3/4 years ago and was simply an aged leisure battery that was knackered and wouldn't hold its charge anymore.....as you said it was fine on EHU.
Like you, I also had a reading of about 12v and thought that this meant it was ok..........sadly not, knackered and time for a new one!
 
Thanks pappajohn.

pappajohn said:
Disconnect the EBL to reset it, reconnect then see the voltages.
Click to expand...

The voltage reading on the control panel is corroborated on a Fox-D1 display fitted when I had the solar panel fitted (10 years ago). Additionally, it’s evident that discharging has taken place as as soon as mains is connected, the charger is pumping 15A into the batteries (for some hours).
That being the case, do you still see merit in disconnecting the EBL to ‘reset’ it?

pappajohn said:
1......yes, same voltage..
2..... Won't make any difference when engine running.... Its still getting power from the alternator.
Click to expand...

1..... Obviously a problem there then. But it’s not obvious why this might be related to a discharge whilst travelling. Thoughts?

Ian
 
Phod's said:
Similar problem 3/4 years ago and was simply an aged leisure battery that was knackered and wouldn't hold its charge anymore.....as you said it was fine on EHU.
Like you, I also had a reading of about 12v and thought that this meant it was ok..........sadly not, knackered and time for a new one!
Click to expand...

It’s a brand new battery.

Ian

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Ian.........my guess it's the same outcome, brand new or not but as its brand new you'll be able to get it replaced FOC under warranty....Good Luck
 
Phod's said:
Ian.........my guess it's the same outcome, brand new or not but as its brand new you'll be able to get it replaced FOC under warranty....Good Luck
Click to expand...

The battery is fine. I did a controlled discharge test on it before I fitted it and verified it’s capacity.

Ian
 
I'll have a go at this ! My initial thoughts are that the habitation batteries have had it and no longer holding a charge. However, I think you need to establish if the hab/cab batteries are receiving a charge from the alternator.

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DBK said:
What's the voltage in the morning after a night on EHU? It should be something around 13.8volts.
Click to expand...

On hook-up it’s about 14.2V.
Off hook-up it’s 12.7 - 12.9V

Currently (?) it’s 14.2V after being on charge for 6hrs.

Ian
 
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PhilandMena said:
I'll have a go at this ! My initial thoughts are that the habitation batteries have had it and no longer holding a charge. However, I think you need to establish if the hab/cab batteries are receiving a charge from the alternator.
Click to expand...


bigtwin said:
The battery is fine. I did a controlled discharge test on it before I fitted it and verified it’s capacity.

Ian
Click to expand...

As indicated in my OP, the leisure battery isn‘t getting a charge from the alternator but that, in itself, doesn’t explain why it’s discharging during driving.

Ian
 
Lenny HB said:
If it's not the battery it's probably the split charge relay in the EBL & the fridge is flattening the leisure battery. If it's a tall fridge freezer they can take 14 amps on 12v.
Click to expand...

Yes, this was my thought too, so my plan is to disconnect the 12V element on the next leg of my journey.

Ian
 
bigtwin said:
On hook-up it’s about 14.2V.
Off hook-up it’s 12.7 - 12.9V

Currently (?) it’s 14.2V after being on charge for 6hrs.

Ian
Click to expand...
Thank you although I think that makes things more difficult. :) After being on charge from EHU I think all is as it should be. So why isn't the battery being charged while you are driving and actually seems to be discharging?

How does it start in the morning, does the vehicle battery have some "oomph"?

Edit: I'm a slow typist and reader. :) I think Lenny's suggestion is probably more likely. :)

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DBK said:
Thank you although I think that makes things more difficult. :) After being on charge from EHU I think all is as it should be. So why isn't the battery being charged while you are driving and actually seems to be discharging?
Click to expand...

Needs some investigation.

DBK said:
So why isn't the battery being charged while you are driving and actually seems to be discharging?
Click to expand...

Possibly as Lenny HB has postulated.

DBK said:
How does it start in the morning, does the vehicle battery have some "oomph"?
Click to expand...

It‘s been starting fine; perhaps a little sluggish but then it’s been cold this last few days.

Ian
 
  • Thanks
Reactions: DBK
From my limited understanding of the wiring diagram for EBL 99 it seems to show that the absorber fridge runs from the Start Battery input rather than Leisure batteries.

Martin
 
funflair said:
From my limited understanding of the wiring diagram for EBL 99 it seems to show that the absorber fridge runs from the Start Battery input rather than Leisure batteries.

Martin
Click to expand...

Yes, that’s how it should work but I’m fearing that I have a fault that results in no charge going to my leisure battery and that my leisure battery is powering the fridge when I’m driving.

Ian
 
I had exactly this problem many years ago on an old KonTiki. The alternator output connection to the split charge relay, a simple double pole relay, was via a fuse and this had blown. The D+ connection from the alternator was still switching the relay when the engine was running but all this was doing, in the absence of any feed from the alternator, was connecting the leisure battery to the fridge. This flattened the leisure battery on even a moderate run. Replacement of the fuse cured the problem.

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Reallyretired said:
I had exactly this problem many years ago on an old KonTiki. The alternator output connection to the split charge relay, a simple double pole relay, was via a fuse and this had blown. The D+ connection from the alternator was still switching the relay when the engine was running but all this was doing, in the absence of any feed from the alternator, was connecting the leisure battery to the fridge. This flattened the leisure battery on even a moderate run. Replacement of the fuse cured the problem.
Click to expand...

Many thanks; any idea where the fuse was?

Ian
 
nabsim said:
Aren’t they usually near the Starter battery, big 50amp fuse with a smaller one on the side of it?
Click to expand...

Thanks; I’ll take a look when the weather is a bit nicer. ? ☔️

Ian
 
I think on the KonTiki it was under the drivers seat, but that was on a 20 year old MH (it wasn't 20years old then.) Not really helpful to the OP on a quite different vehicle though. If you can measure the voltage at the fridge and there is no increase with the engine running then it looks like this could be the problem.
 
Reallyretired said:
I think on the KonTiki it was under the drivers seat, but that was on a 20 year old MH (it wasn't 20years old then.) Not really helpful to the OP on a quite different vehicle though. If you can measure the voltage at the fridge and there is no increase with the engine running then it looks like this could be the problem.
Click to expand...

Thanks; I‘ll check that out tomorrow.

Ian

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Might be worth checking that the D+ to the EBL is OK, you should be able to check both battery inputs at the EBL unit if the access is any easier than at the battery end.

Martin
 
funflair said:
Might be worth checking that the D+ to the EBL is OK, you should be able to check both battery inputs at the EBL unit if the access is any easier than at the battery end.

Martin
Click to expand...

Haha! The EBL is under the driver’s seat!

Access requires lying on the floor between the two seats and probing your fingers under the seat while trying to shine a torch to see what’s what!

Alternatively it’s a case of trying to induce a hernia whilst lifting the driver’s seat off! ?

Ian
 
Reallyretired said:
I think on the KonTiki it was under the drivers seat, but that was on a 20 year old MH (it wasn't 20years old then.)
Click to expand...
On my 1999 Kontiki and 2001 kontiki there was a pair of 30a relays, one fridge, one split charge, both on the bulkhead next to the battery.
Nothing but empty space under either seat.
 
pappajohn said:
On my 1999 Kontiki and 2001 kontiki there was a pair of 30a relays, one fridge, one split charge, both on the bulkhead next to the battery.
Nothing but empty space under either seat.
Click to expand...
Mine was quite a few years older, and just had a single relay, hence the problem. As the OP doesn't have the same mh it may not be relevant, but would be a possible explanation for his problem.

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pappajohn said:
On my 1999 Kontiki and 2001 kontiki there was a pair of 30a relays, one fridge, one split charge, both on the bulkhead next to the battery.
Nothing but empty space under either seat.
Click to expand...
German vans with an EBL the relays are inside the EBL.
 

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