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Discussion Starter · #1 ·
Hi all,
Hoping you are all well.
Been reading a lot of forums about 12v batteries failing and preventing the car "starting". I know there are the jump lead points under the bonnet, but with so much time on my hands, I thought I would have a proper go at finding the illusive 12v battery. For those that don't know, its in the boot.

The jury was / is out about the type, size and whether or not it can be charged via an external charger.

I have a CTEK charger that I use on the Wife's Mini. She doesn't use it much, and the car is now over 6 years old, and still has the original battery, so i guess this charger does something right !
The 12v battery is located under the large plastic tray / bin thing to the left of the boot. Its a wiggle and lift type affair to remove it, but it really doesn't put up too much of a fight. Once uncovered, I was looking at a fairly normal car battery.

I unplugged the car charging cable first, then hooked the CTEK charger up, directly to the + and - terminals, set it to "Re- condition mode" and away it went.

Photos attached of what / where.

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It usually takes a good few hours to work its magic, so I will report back later. Fingers crossed there are no warning lights !
Cheers
 

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Discussion Starter · #2 ·
I forgot to add, I will add the fly lead to the battery terminals, so I can just clip the CTEK charger on without having to remove the plastic panel. I will run it off the battery, and up so it comes out where the small access panel is to get to the light cluster. Will post more photos as and when. Will make it a lot easier in the future.
Cheers
 

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Looks like the same charger I got earlier in the year younger through lockdown. Very interested to see how it affects the car. Did a fair bit of research when I got mine and it turns out regular boost of the battery on an ICE car offers better mpg as the fuel pump/spark etc has more power behind it.

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I forgot to add, I will add the fly lead to the battery terminals, so I can just clip the CTEK charger on without having to remove the plastic panel.
A smart plan as long as the extended terminals are heavily insulated to avoid a loose spanner in the boot shorting across and toasting the car. But it also raises another point. Many modern cars now have a gizmo in series with the live lead from the +terminal that sends signals to the central 'brain' of the car. If that suddenly detects a jump from, say, 12v to 14v when a charger is attached it can cause it have a benny and result in a visit to a dealer to reset the computer. I have read of a couple of such events. It has also been a long time recommendation to apply a charger, or jump leads, to the positive terminal but the negative to a metal part of the cars' chassis rather than the negative terminal. Something to do with H2 given off by a 12v battery and avoiding a local spark to possibly ignite it.

On the subject of the use of a smart charger/conditioner, I would agree that a monthly connection over quite a few hours can extend the life of the 12v battery considerably. But also avoids the common experience of a dead battery locking people out of their EV and causing a recovery visit. Not sure if this is also a problem with a PHEV though because the 12v topping up may be handled by the usual alternator/regulator system on the ICE and therefore a much more robust system.
 

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Discussion Starter · #5 ·
Yeah, I checked for sharp edges where the cable routed up, and there was enough thread on the battery terminal screws to allow me to just add another nut, so there is no risk of loosing connection, and throwing error messages. So now I have the charger fly lead accessible via the left hand rear light cluster flap. I hooked it through the cars wiring loom, ready to go !
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I actually experienced a flat battery, quite exciting, alarm went off, could not lock car doors, loads of error messages saying fault in lots of subsystems then completely dead. Had to call out VW assistance, AA man didn’t know what to do and had to wait for VW engineer the next day.
Since then I have charged the battery several times with a CTEK charger using the terminals under the bonnet with no problems.
 

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Yeah, I checked for sharp edges where the cable routed up, and there was enough thread on the battery terminal screws to allow me to just add another nut, so there is no risk of loosing connection, and throwing error messages. So now I have the charger fly lead accessible via the left hand rear light cluster flap. I hooked it through the cars wiring loom, ready to go !
View attachment 137434 View attachment 137435
Has previously pointed out, it is recommended that the black negative terminal of the smart CTEK unit, is connected directly to the body shell of the car and not the terminal post of the battery itself.
I have the quick connect CTEK loom permanently connected to the battery of my car.
I feel it is much safer method than using the standard crocodile clamps that can be prone to spring off !.
Not a good situation.
 

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Has previously pointed out, it is recommended that the black negative terminal of the smart CTEK unit, is connected directly to the body shell of the car and not the terminal post of the battery itself.
I have the quick connect CTEK loom permanently connected to the battery of my car.
I feel it is much safer method than using the standard crocodile clamps that can be prone to spring off !.
Not a good situation.
I always used the posts under the bonnet that are there for the purpose of charging the battery, but then I only did it when the car was left for holidays etc.

The battery on the Golf GTE was a lot more involved to get to though, the Passats is in a sensible place.
 

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Discussion Starter · #9 ·
Has previously pointed out, it is recommended that the black negative terminal of the smart CTEK unit, is connected directly to the body shell of the car and not the terminal post of the battery itself.
I have the quick connect CTEK loom permanently connected to the battery of my car.
I feel it is much safer method than using the standard crocodile clamps that can be prone to spring off !.
Not a good situation.

Hi,
I used the eyelets on the charger fly lead, and screwed them to the terminals. Wouldn't have risked it with the crocodile clips - like you say, could easily ping off.

Cheers
 
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Hi,
I used the eyelets on the charger fly lead, and screwed them to the terminals. Wouldn't have risked it with the crocodile clips - like you say, could easily ping off.

Cheers
CTEK recommends that you connect the negative terminal eyelet direct to the body shell of the car and NOT directly to the battery post.
Here is a video produced by CTEK themselves which covers this point.

 

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I located my very own battery today and found it only produced 12.17V !

A bit low!

So can I directly plug the battery charger to the battery? I was of the impression that charging the battery while it's sitting in the car is not a good idea. And which one of the cables mentioned in the first post is the car charging cable?

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Discussion Starter · #12 ·
Hi,
When you say " which one of the cables mentioned in the first post is the car charging cable? " I do not know, I just clipped the charger crocodile clips directly to the battery terminals.
 
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