T6 Beach leisure battery not charging

[Kayleigh]

Hi all, I don’t normally post for help, but the leisure battery on my T6 Beach does not seem to be charging from the alternator. I have looked through other threads but can’t find a definitive answer.

I checked al the fuses I can see under the passenger seat but they all look fine. There is something with 100 on the top. Is that another fuse? (photo attached).

The battery is used to power the interior lights, run a 5G router (about 6W) and charge the Ecoflow Delta 2 when the engine is running.

I don’t plug in to charge the battery as the alternator does a good job.

Just wondering what I should check next. Any help would be really appreciated!

I have attached some stats for the battery. The big drop off was when I was working from the van last Tuesday.

 

[WelshGas]

Hi all, I don’t normally post for help, but the leisure battery on my T6 Beach does not seem to be charging from the alternator. I have looked through other threads but can’t find a definitive answer.

I checked al the fuses I can see under the passenger seat but they all look fine. There is something with 100 on the top. Is that another fuse? (photo attached).

The battery is used to power the interior lights, run a 5G router (about 6W) and charge the Ecoflow Delta 2 when the engine is running.

I don’t plug in to charge the battery as the alternator does a good job.

Just wondering what I should check next. Any help would be really appreciated!

I have attached some stats for the battery. The big drop off was when I was working from the van last Tuesday.

View attachment 152350

View attachment 152351

View attachment 152352

View attachment 152353

Do you have the factory fit Mains charger and does it charge the leisure battery on EHU?

 

[Kayleigh]

Do you have the factory fit Mains charger and does it charge the leisure battery on EHU?

Thank you for the super quick response @WelshGas . I have just managed to find an adapter and plugged into the hookup. This is now what I am seeing (see attached).

 

[Perfectos]

What is the voltage of the starter battery (30 minutes after engine stopped) ?

The starter battery is prioritised over the LB. Just wondering if the Starter is fully charged ?

Have you checked the large clear fuse 80a centre right fuse In Your photo ?

Do you have a volt meter ? First principle would be to establish if the starter battery is being charged from the alternator?

 

[Californication69]

 

[Californication69]

Get a good working voltage meter and check the starter across both terminals to see what the actual V DC is.
Use the graph above.
Then start the engine and test the battery again, might need to put max charge on to get revs up or switch heated screen, and there was something else to get revs up to 1200rpm.
Then make sure alternator is providing 14.2v
Let us know

 

[Kayleigh]

What is the voltage of the starter battery (30 minutes after engine stopped) ?

The starter battery is prioritised over the LB. Just wondering if the Starter is fully charged ?

Have you checked the large clear fuse 80a centre right fuse In Your photo ?

Do you have a volt meter ? First principle would be to establish if the starter battery is being charged from the alternator?

I checked the starter battery voltage and it’s 12.97v but the van has been standing for 4 days. When I start the engine it goes up to 14.55v. Heated windscreen did not seem to make any difference. That’s on tickover.

I took the 80A fuse out and that’s fine. What is that one for?

 

[Kayleigh]

Get a good working voltage meter and check the starter across both terminals to see what the actual V DC is.
Use the graph above.
Then start the engine and test the battery again, might need to put max charge on to get revs up or switch heated screen, and there was something else to get revs up to 1200rpm.
Then make sure alternator is providing 14.2v
Let us know

Thanks. Yes the starter battery is pretty much 100% charged and the alternator is charging as well, so that’s all fine.

 

[Kayleigh]

Current leisure battery status with the engine running on tick over, heated windscreen on and still plugged in to EHU.

Unplugging from EHU and the battery was showing 12.65 but now 12.51 after a few mins. It is not being charged from the alternator.

 

[WelshGas]

I checked the starter battery voltage and it’s 12.97v but the van has been standing for 4 days. When I start the engine it goes up to 14.55v. Heated windscreen did not seem to make any difference. That’s on tickover.

I took the 80A fuse out and that’s fine. What is that one for?

It’s the fuse between alternator supply and split charge relay.

 

[Californication69]

I checked the starter battery voltage and it’s 12.97v but the van has been standing for 4 days. When I start the engine it goes up to 14.55v. Heated windscreen did not seem to make any difference. That’s on tickover.

I took the 80A fuse out and that’s fine. What is that one for?

That’s good, starter and alternator working
So with engine off, what voltage on lesuire ?

 

[Californication69]

Sorry just saw 12.65 then 12.5 while engine running.
What’s the makeup of lesuire ?
Standard AGM one ?
So should be getting 14.2 from alternator too.
Use the voltmeter and not the Victron stuff.

Sounds like split charge relay stuck.
Switch everything off and try tapping with an implement to see what happens.
Might be stuck open ?

 

[WelshGas]

Current leisure battery status with the engine running on tick over, heated windscreen on and still plugged in to EHU.

Unplugging from EHU and the battery was showing 12.65 but now 12.51 after a few mins. It is not being charged from the alternator.

View attachment 152357

View attachment 152358

If the 80 amp fuse is definitely OK then next you need to check the 100/125 amp fuses in the fuse box located next/ underneath the engine battery.

 

[WelshGas]

@Kayleigh
This is the fuse box SA.

On the VW Transporter T6, the SA Fuse Box (Fuse Holder A) is located in the engine compartment, inside the electronics box (E-Box) directly underneath the vehicle's primary starter battery. [1, 2]
Because it contains high-power, heavy-duty strip fuses (which feed the main vehicle systems, alternator, and starter motor), it is tucked away for protection. Accessing it requires removing the main engine battery. [1, 2]

How to Access the SA Fuse Box
To reach this fuse holder safely, you will need to follow these steps:

1. Disconnect the Battery: Always disconnect the negative (-) terminal first, followed by the positive (+) terminal, to prevent short circuits. [1]
2. Remove the Battery: Undo the battery retention clamp/bracket and lift the heavy battery completely out of the engine bay. [1]
3. Open the E-Box Cover: Underneath where the battery sits, you will see a plastic electronics box (E-Box). Release the clips or screws securing its cover to reveal the heavy-duty SA fuse links/busbarunderneath

 

[Kayleigh]

@WelshGas Thank you for the detailed information. I have got to the fuses and this is fuse SA3. It looks okay to me I think.

 

[WelshGas]

@WelshGas Thank you for the detailed information. I have got to the fuses and this is fuse SA3. It looks okay to me I think.

View attachment 152374

View attachment 152375

View attachment 152376

It does look OK. Checked with a multimeter?
If the 80 amp fuse checks out then the next item to check is the Split Charge relay under the passenger seat. The 80 amp fuse should identify it.
If that is OK then the only thing left is the wiring.
For the split charge relay you will need a multimeter. With engine running the voltage input from the 80 amp fuse connection should be the same as the engine battery.
Also the output should be the same. If not then the relay is not connecting engine battery/alternator to leisure battery.

 

[Kayleigh]

Thank you @WelshGas
Checked all then fuses with a multimeter and they are okay.

Now with engine running and heated screens/lights and heating on I checked the relay.
Input side is 13.7
Output side is 12.97
Across the relay is .72
Starter battery is 13.7

 

[WelshGas]

Thank you @WelshGas
Checked all then fuses with a multimeter and they are okay.

Now with engine running and heated screens/lights and heating on I checked the relay.
Input side is 13.7
Output side is 12.97
Across the relay is .72
Starter battery is 13.7

When you measured the output side was that with the Leisure battery connected?
If so can you measure with leisure battery disconnected?

 

[Kayleigh]

Is that with the 80a fuse removed or physically disconnect from the battery terminals?

 

[WelshGas]

Is that with the 80a fuse removed or physically remove from the battery terminals?

Yes, removing the 80 amp fuse or disconnecting the leisure battery, either will do.
Then the output from the relay should be the same as the input voltage.