Battery charging question

JohnCalifornia · Apr 21, 2023

Hi , if I charge the main car battery under the bonnet with my CTEK charger will it also charge the leisure battery’s at the same time?

Sad · Apr 21, 2023

I wouldn't have thought so...

dspuk · Apr 21, 2023

No and why? Just plug your Cali in. EHU charges the leisures to, I believe, 80%, then moves to charge the starter as needed. It is year dependant but the later years for sure do. Hard to tell you if yours does as it just says “looking to buy”.

JohnCalifornia · Apr 21, 2023

I’m more thinking if I don’t use the Cali for a few weeks I’ll put the main battery on a trickle charge so it doesn’t drain so it will start with no issues. I’ll try it and see what happens

westfalia · Apr 21, 2023

No
But if you charge the leisure batteries it can trickle charge the starter
battery, depending which van you have.
Can't have it both ways.

dspuk · Apr 21, 2023

JohnCalifornia said:
I’m more thinking if I don’t use the Cali for a few weeks I’ll put the main battery on a trickle charge so it doesn’t drain so it will start with no issues. I’ll try it and see what happens

If you don’t use it for a few weeks and need to trickle charge you have a different issue.

VW recommend to plug in once a month via EHU if you don’t use the Cali. Just do that. You’re overcomplicating it TBH.

JohnCalifornia · Apr 21, 2023

Ah right I didn’t know that the EHU will also charge the main battery too if it needs it.( model year depending) I’ve just got the Cali so learning new things each day. Have you any idea what model year this does this feature?

dspuk · Apr 21, 2023

JohnCalifornia said:
Ah right I didn’t know that the EHU will also charge the main battery too if it needs it.( model year depending) I’ve just got the Cali so learning new things each day. Have you any idea what model year this does this feature?

Which Californias (trickle) charge the starter battery?

So what year of Californias do charge the starter battery?

vwcaliforniaclub.com

Steve1 · Apr 21, 2023

JohnCalifornia said:
Hi , if I charge the main car battery under the bonnet with my CTEK charger will it also charge the leisure battery’s at the same time?

No, because if it did then starter would also be drained by using the leisure batteries risking the van not starting. There is a big relay under the seat that only joins the starter to leisure when the engine is running.

JohnCalifornia · Apr 21, 2023

Interesting …. I assume mine will charge up the starter battery too. I’ll get my voltmeter out and try it tomorrow

westfalia · Apr 21, 2023

What kind of California do you have and what year?
I'm hoping its not a 2013 beach without any hook up socket

JohnCalifornia · Apr 21, 2023

Ha ha it’s a 2019 Ocean and I think it’s got the EHU……

JohnCalifornia · Apr 21, 2023

Steve1 said:
No, because if it did then starter would also be drained by using the leisure batteries risking the van not starting. There is a big relay under the seat that only joins the starter to leisure when the engine is running.

Is this the split load relay? I think this relay works on voltage . It should activate when voltage is above 13v I think then shut off when below 13v thus not using leisure battery power. When a battery charger is applied to the starter battery it should put over 13v into it and should activate the split load relay thus also charging the leisure batteries. I did a micro van conversion during the lockdown and fitted a similar system so I know for sure that the leisure batteries got charged up along with the starter battery when the charger was fitted to the starter battery.

Steve1 · Apr 22, 2023

JohnCalifornia said:
Is this the split load relay? I think this relay works on voltage . It should activate when voltage is above 13v I think then shut off when below 13v thus not using leisure battery power. When a battery charger is applied to the starter battery it should put over 13v into it and should activate the split load relay thus also charging the leisure batteries. I did a micro van conversion during the lockdown and fitted a similar system so I know for sure that the leisure batteries got charged up along with the starter battery when the charger was fitted to the starter battery.

In a conversion it often works on voltage sensing as you mentioned because that's an easier way of doing it without hacking into wiring etc. In the factory fitted California version the relay is controlled by the ECU directly and I am pretty sure it will only turn on when the engine is running irrelevant of voltage on the starter side.