Leisure Batteries - how to know if they are fully charged

[Jabberwocky]

Hi, I have simple question but I don't seem to be able to find a simple answer. Sorry.
What should I see on the control panel when my leisure batteries are fully charged?
A) When on EHU.
B) When engine running.

Volts, % and amps charging

Thanks in advance.

 

[Palm]

100% is a good indication, low loading current i.e. < 1.0 A is another good indication

A fully loaded car battery has a resting voltage of 12.7 V when it is fully loaded everything below 12.0 V indicates the need for immediate charging. AGM battery's might have 0.1 higher voltage.
Resting voltage measured on a disconnected battery.

 

[Jabberwocky]

I ask because I saw something quite strange (I think).
12.7v, 100%, 0.2amps when engine off and no EHU.
Then with EHU 14.3v, 5amps.
Then with engine running (no EHU) 13.5v, 16.9amps.

 

[Palm]

Looks grate!
14.3 and 13.5 V is charging voltage, 5 and 16.9 A is charging current. The charging current will decrease overtime during a normal charging progress. It is miles of text on concerning Leisure batteries, charging and the control panel readings you can do.

 

[Jabberwocky]

Looks grate!
14.3 and 13.5 V is charging voltage, 5 and 16.9 A is charging current. The charging current will decrease overtime during a normal charging progress. It is miles of text on concerning Leisure batteries, charging and the control panel readings you can do.

It's just a little confusing when the LB's say 100% charged and I see such high currents of 5 and 16.9 when either I am on EHU or with engine running. I would have expected to see these much lower when I read the 100%.

 

[Palm]

Yes the charging current are expected to decline when the sensors in the charging system consider the batteries fully loaded. The difference in voltage can be different stages in the charging process or just different charging sources.

 

[AlanC]

If you are looking at the control panel straight after plugging in the EHU, then yes, a fully charged battery will register 14.3 volts with a current of 5 amps or so. But if the batteries are already full (charged by the alternator) and the charger senses this, the current will fall back to around 0.5 amp very quickly. The volts will stay at 14.5 volts as the charger is still connected and trickle charging the batteries while on hook-up.

As your van is a new T6 you may well have Bluemotion on it. This will prevent any of the batteries being fully charged while driving as it works by taking the alternator off load during acceleration to improve the fuel consumption. I believe the batteries can only achieve around 80% charge on these vans.
In this case all of the batteries will be charged when on EHU to bring them up to 100%. That may well take a short while.

I would be wary of the control panel display though. It is not a calibrated device so not giving an accurate reading. It is just an indication of the batteries condition.

BTW, the panel itself draws -0.2 amp when switched on, so do turn this off when you have finished camping.

Alan

 

[Pippa]

Hello all - was wondering if someone could give us some advice on a similar note.
Our main battery ran flat last night (ok - my fault I admit) - we got a jump start from a kind fellow camper and have then driven/left engine running for over 5 hours so we're hoping the main battery should be "ok".
The problem is the Leisure batteries - they were at 70% this morning and now having driven all that way they're at 60%. Nothing is on & no chargers/plugs left in sockets.
I was reading on another thread that mentioned the circuit breaker being on/off had an effect on their leisure batteries but not sure how that would work?
We weren't on EHU whilst away.
2016 T6 so the point about Bluemotion made above would apply to us - I just thought they might have got up to 80% rather than dropping to 60%.
Any thoughts?

 

[WelshGas]

Hello all - was wondering if someone could give us some advice on a similar note.
Our main battery ran flat last night (ok - my fault I admit) - we got a jump start from a kind fellow camper and have then driven/left engine running for over 5 hours so we're hoping the main battery should be "ok".
The problem is the Leisure batteries - they were at 70% this morning and now having driven all that way they're at 60%. Nothing is on & no chargers/plugs left in sockets.
I was reading on another thread that mentioned the circuit breaker being on/off had an effect on their leisure batteries but not sure how that would work?
We weren't on EHU whilst away.
2016 T6 so the point about Bluemotion made above would apply to us - I just thought they might have got up to 80% rather than dropping to 60%.
Any thoughts?

When you had the Jump Start where were the leads connected on your car?

Hopefully Red to Starter Battery +tve and Black Lead to an Earth Point or the Engine Block and NOT the Starter Battery -tve pole.



If not connected properly then the electronics that control Leisure Battery charging may be damaged. I would expect ALL batteries to have a reasonable charge by now. Having the engine on idle produces very little charge overall.

I would suggest plugging into the Mains for 24 hrs at least, or get everything checked by VW although they might charge for this.

The Circuit Breakers are only active on the Mains 230v circuit, nothing to do with charging from the engine.

 

[Pippa]

When you had the Jump Start where were the leads connected on your car?

Hopefully Red to Starter Battery +tve and Black Lead to an Earth Point or the Engine Block and NOT the Starter Battery -tve pole.
View attachment 33163


If not connected properly then the electronics that control Leisure Battery charging may be damaged. I would expect ALL batteries to have a reasonable charge by now. Having the engine on idle produces very little charge overall.

I would suggest plugging into the Mains for 24 hrs at least, or get everything checked by VW although they might charge for this.

The Circuit Breakers are only active on the Mains 230v circuit, nothing to do with charging from the engine.

Thanks - can't recall how the jump leads were connected. May have to take it into VW - the Leisure batteries weren't perfect before this anyway.

 

[AlanC]

This is the second time this diagram has been posted recently and I am at a loss to understand why, when jump starting a vehicle engine battery, it is necessary to connect the -ve cable to an earth point on the body or engine.

Given this is connected directly back to the battery -ve pole using a substantial 6mm cable, the two places are at the same potential, ergo the same.

Can someone please explain why this is being pushed as a correct method to jump start an engine.

Many thanks

Alan

 

[WelshGas]

This is the second time this diagram has been posted recently and I am at a loss to understand why, when jump starting a vehicle engine battery, it is necessary to connect the -ve cable to an earth point on the body or engine.

Given this is connected directly back to the battery -ve pole using a substantial 6mm cable, the two places are at the same potential, ergo the same.

Can someone please explain why this is being pushed as a correct method to jump start an engine.

Many thanks

Alan

It’s in the VW handbook 2015 Page 444/5

 

[BillyCasper]

When you had the Jump Start where were the leads connected on your car?

Hopefully Red to Starter Battery +tve and Black Lead to an Earth Point or the Engine Block and NOT the Starter Battery -tve pole.
View attachment 33163


If not connected properly then the electronics that control Leisure Battery charging may be damaged. I would expect ALL batteries to have a reasonable charge by now. Having the engine on idle produces very little charge overall.

I would suggest plugging into the Mains for 24 hrs at least, or get everything checked by VW although they might charge for this.

The Circuit Breakers are only active on the Mains 230v circuit, nothing to do with charging from the engine.

Does this mean you can’t use a Suaoki type portable starter battery with a Stop/Start engine? No black cable with clamps at both ends and no donor engine block to attach to? Sorry if question is dumb, I don’t really understand electricity.


Sent from my iPhone using Tapatalk

 

[Ian Robinson]

My understanding from having jump started many an old banger over the years is that the last connection often causes a significant spark - flooded cell batteries can generate enough hydrogen to explode - so you make the last connection away from the battery on the engine or another good earth connection to avoid a face full of hot acid. My T5 now has an AGM battery so risk of explosion is probably lower - but why risk it when there are plenty of good earth points under the bonnet away from the battery. I was not aware of electrical damage to systems, but vehicles are certainly a lot more complicated these days!

 

[WelshGas]

Does this mean you can’t use a Suaoki type portable starter battery with a Stop/Start engine? No black cable with clamps at both ends and no donor engine block to attach to? Sorry if question is dumb, I don’t really understand electricity.


Sent from my iPhone using Tapatalk

Vehicle with Flat Battery then connect the Suaoki red lead to +tve Battery pole and the Suaoki black lead to a Bolt etc on the engine block, NOT the -tve pole of the battery.

The 2nd Diagram is for the situation where the helping vehicle ALSO has Stop/Start.

 

[BillyCasper]

Thanks! Yes, I should have read more carefully, the case in point is if the supporting vehicle is Stop/Start.

Vehicle with Flat Battery then connect the Suaoki red lead to +tve Battery pole and the Suaoki black lead to a Bolt etc on the engine block, NOT the -tve pole of the battery.

The 2nd Diagram is for the situation where the helping vehicle ALSO has Stop/Start.

 

[WelshGas]

Some more information regarding WHY you do not connect the Black -tve lead to the Flat Battery -tve pole.

 

[BillyCasper]

A follow on question, the leads on those portable battery packs are very short. Can you attach the black cable to any bolt in the battery compartment like those holding body panels or the battery tray? Or, should I carry a longer black cable to reach over to the block?

 

[AlanC]

Sent from my iPhone using Tapatalk[/QUOTE]

Some more information regarding WHY you do not connect the Black -tve lead to the Flat Battery -tve pole.
View attachment 33171

Thank you WG, useful information.

Alan

 

[altvic]

Vehicle with Flat Battery then connect the Suaoki red lead to +tve Battery pole and the Suaoki black lead to a Bolt etc on the engine block, NOT the -tve pole of the battery.

The 2nd Diagram is for the situation where the helping vehicle ALSO has Stop/Start.

On my camper VW make it difficult to attach black lead to black negative terminal as you can see on the photo. There are plenty of places bolts to attach the crocodile clip of the negative lead when jump starting.zoom in to see.