Trickle charging - confusion over where to connect to

[gaby]

Originally Posted by MrM83

Thanks for the detail. I remain surprised Volvo aren't more explicit with warnings around not charging via main battery in light of the above.

I find the instructions in the manual clear and explicit, they leave no doubt as to where and how to charge the battery.
If I don't understand certain instructions in the manual, I try to find out the why, before doing it in some other way.

[MrM83]

I was a victim of a botched software update at my cars last service, which Volvo claimed was due to the 12v battery charge being "too low". It was a real pain and caused a number of features not to work until the software update was correctly implemented, incidentally after I charged the 12v battery directly using my CTEK trickle charger.

My experience and Volvo's feedback seems inconsistent with the hybrid battery keeping the 12v battery topped up as I charge my car regularly and drive on electric as much as possible, but I, and Volvo, may be wrong.

But this is why I have an interest in maintaining the state of my 12v battery. Driving around with various features being defective is not ideal. My comment around explicitness is to do with detail in the manual. If anyone can point me to the online manual reference for a 2021 T8 with regards to trickle charging (and separately how to put the car in neutral if the battery is dead), I would be grateful.

Sure, the instructions are explicit when they exist. I havent managed to find them in the online manual for my year of manufacture, nor when I have had a cursory look for other years. I have searched and I would have hoped I could have found them, but having not, I created this thread.

As a result of comments in this thread I am left in absolute doubt as to what I should be doing. I would welcome someone to point me in the right direction should they be so inclined to look.

[Mad Malc]

If your car has the specific 'charging posts' then it seems obvious to myself that you should use them.
As for getting the car out of gear, I would ring Volvo customer service for their input.

[MrM83]

With regards to "charging posts" under the bonnet, are they not there for convenience, since the battery is tucked away in the boot? For me its actually more convenient to use the battery directly due to cable run lengths.

[nu11eaf]

Originally Posted by MrM83

With regards to "charging posts" under the bonnet, are they not there for convenience, since the battery is tucked away in the boot? For me its actually more convenient to use the battery directly due to cable run lengths.

There could be a one way charging system that charges both starter and stop start batteries from the under bonnet connections but if you charge using the main battery posts only that battery gets charged.

[Basill]

Originally Posted by nu11eaf

There could be a one way charging system that charges both starter and stop start batteries from the under bonnet connections but if you charge using the main battery posts only that battery gets charged.

I believe there is a risk of damage to the battery management if the underbonnet terminals are not used for charging, jump starting etc.

[MrM83]

I posted a thread earlier about my car giving me a warning / error saying 12v system service needed.

Last night I trickle charged my XC90 T8 using the points under the bonnet. This morning it was showing as fully charged on my CTEK.

Still the warnings persisted all day today.

I’m planning on disconnecting the negative battery terminal for a while to see if that clears it, but before I did so I connected my CTEK to the battery in the boot. To my surprise it was low; 2 dots on the CTEK which is what the front was showing the night before. So the plot thickens.

Either I have an issue with a connection between the front battery and the rear battery….. or trickle charging the front has no bearing on the back….

I’m now charging the rear battery and will be interested to see if my issues go away tomorrow….

[davidwf15]

on my MY2023 XC60 B5P (mild hybrid) I understood that the 48V battery starts the car using the starter-generator system....if that is correct then how could it be jump started if ever needed using the 12V terminals under the bonnet ?
Does the 12V system also charge the 48V battery?

[LRS]

Originally Posted by davidwf15

on my MY2023 XC60 B5P (mild hybrid) I understood that the 48V battery starts the car using the starter-generator system....if that is correct then how could it be jump started if ever needed using the 12V terminals under the bonnet ?
Does the 12V system also charge the 48V battery?

From my understanding you’re correct – the 48v battery is used for ‘starting’ and is part of the starter-generator circuit. Exactly how you would jump start the 48v battery, I’m not sure. The 12v system is used for the majority of electrical components and I believe is charged from the 48v system through the DC/DC Converter.

There was an interesting article about the issues being experienced in e-LCV fleet vehicle 12v systems because of the reliance that the 12v battery has on the DC/DC Converter to charge it. https://www.gbnews.com/lifestyle/car...-draining-vans

Looks like the 12v battery system is being identified as a potential big problem area for Electric, Hybrid and Mild-Hybrid vehicles.

[davidwf15]

Hmmm..interesting indeed .....I also wonder why, if the 48V battery relieves the 12V system of so much load, the 12V battery is so BIG.. . ..it wouldn't look out if place on a bus 😁......that link seems to be the opposite problem where the 12V battery.dies