CTEK Battery charger / neg connection question...

[AlexMac]

I've just bought a CTEK MXS 5.0 to help maintain the battery during winter (lots of short journeys with high elec demand). I'm going to fit the permanent direct connector to make it all a bit neater and wondered if anyone else has done so on a B7 (Tfsi). If so, what did y'all do about the neg side of things?

CTEK's literature and currently held opinion seems to be NOT to go direct the the battery negative clamp. But I'm not sure that this is actually a problem. Obviously I'm aware of the hydrogen+spark risk on connect/disconnect, but surely this is negated when using the CTEK 'Comfort Connect' fittings anyway.

I'm also aware that if there's a battery monitoring system fitted via the main vehicle earth lead, you would effectively bypass it by connecting direct to the battery, but AFAIK the B7 wasn't fitted with one.

Besides that, the only other thing I can think is the risk of a voltage spike damaging things (which may be damped out by earthing further from source?), but isn't that a throwback to the analogue and VERY early electronic systems of yesteryear?

Very happy to be corrected on any of the above, and also interested what points other people have used for their negative connections in this application.

Any thoughts chaps & chappesses.......?

 

[olliecampbell]

We always fit them contected directly at work. I've also had one connected to my Impreza for about 5 years without any problems


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[AlexMac]

Cheers Ollie, made sense to me but nice to have someone confirm real world useage.

Interestingly I found this quote from CTEK themselves:

Q. Why do you have to connect negative to ground and not to the battery?
A. All CTEK chargers observe the directives that apply in the EU. All battery chargers whatever the brand must be approved in line with the same standards. Many more basic chargers can cause the battery to emit a significant amount of oxy-hydrogen gas and also generate a spark when connecting. This represents a major risk of injury and it is therefore stipulated that the first terminal should be connected away from the battery in order to reduce the risk. A CTEK charger is spark free, has a minimal amount of gassing and can therefore be connected directly to the battery. However, we do not recommend this for approval reasons.

So I'm now totally confident that unless installing on something with battery management, direct connection is fine.

 

[rum4mo]

I always connect across battery +ve and body main earth point, and I'd suggest that is the only way you consider connecting it especially if you have a charge monitor lump at the battery -ve terminal.

Edit:- now on my B8 S4, the battery is in the boot and has a charge monitor lump on the earth lead, so for me the simple way is to connect between the +ve jump start point under the bonnet and the chassis main local earth point.

 

[45bvtc]

As connected on my RS3 for 7+ years now and no problems:

Similar on my A1 and TT.

Note: I re-engineered the connection as I found the CTEC ones inconsistent during charge.