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connecting a ctek 5.0 to w211 main battery

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mike75

Active Member
Joined
Nov 27, 2014
Messages
67
Car
w211 e270 2003
Hi guys.I bought a ctek mxs 5.0 and I don`t know how to connect it to the main battery. Negative wire shoud go to the battery negativ terminal or it shoud go to the ground?
I read many forums and the opinions are divided.
Please advice. I don`t want to burn de BCM.
 
The ctek adapter cable is connected red to red terminal and black to black terminal on the battery, the plug connector from the ctek to your leads can only be plugged in one way so you cannot make that mistake and the unit would not power on if you had the wrong polarity. (i think)

I permanently connected the eyelet type connector to the battery for ease of recharging if that helps just leaving the cable connector visible by making a hole in the boot liner and pulling the cable through.
 
Thx. But I just spoke with a mb tehnician and he said to connect the negative terminal to the ground so that de bcm to be aware that the battery is charging and to be capable to redirect chraging to the small battery in the front.
 
I fitted the ctek leads to both front and rear batteries permanently to make it easier to maintain and charge.

Blackc55 is an MB tech
 
I've always presumed that connecting the leads to the charging points in the engine compartment will charge both batteries. Am I correct? If so, the OP could use those unless he plans to keep the car in storage over the winter.
 
mike75 said:
Using the same charger?
Click to expand...

Its very rare that i recharge the front maybe once a year, the rear much more often as that's powering lots of systems on the car, so to answer your question i charge each individually.
 
I don`t want to be rude but I have another question. The car must be in sleep mode when I connect the charger to the main outlet? While the battery is charging can I open the door? It may be a stupid question but I am a novice.
 
mike75 said:
I don`t want to be rude but I have another question. The car must be in sleep mode when I connect the charger to the main outlet? While the battery is charging can I open the door? It may be a stupid question but I am a novice.
Click to expand...

No and yes.

There is no such thing as a stupid question, forums are here to help others.
 
Hi All,

If you are ever wiring in a connector for a battery charger, please do ensure it is fused on the +12v side as near to the connection to the battery as possible. That way the fuse protects the wiring (saves it melting/catching fire) should the wire get damaged - which is more likely since its likely to be an un-secured connector (i.e flapping around tucked away under some piece of carpet).

I strongly advise a decent branded (CTEK, or the Mercedes own one, (which for mine is a CTEK in disguise) or Optimate are ones I would suggest).

I had a customer turn up with a cheap halfords one the other day. The fuse was on the ground side. Which is very very stupid as the live wire would just melt and catch fire if the live wire got damaged on any of the bodywork (which of course is ground).

Richard
 
richard said:
Hi All,

If you are ever wiring in a connector for a battery charger, please do ensure it is fused on the +12v side as near to the connection to the battery as possible. That way the fuse protects the wiring (saves it melting/catching fire) should the wire get damaged - which is more likely since its likely to be an un-secured connector (i.e flapping around tucked away under some piece of carpet).

I strongly advise a decent branded (CTEK, or the Mercedes own one, (which for mine is a CTEK in disguise) or Optimate are ones I would suggest).

I had a customer turn up with a cheap halfords one the other day. The fuse was on the ground side. Which is very very stupid as the live wire would just melt and catch fire if the live wire got damaged on any of the bodywork (which of course is ground).

Richard
Click to expand...

^^^^ Agree

And if the OP wishes to leave permanently as i did

Comfort Indicator Eyelet M6 for CTEK charger - XXX9046 | Allbatteries.co.uk
 
I recently bought the CTEK 7.0 from Amazon. I missed their last lightning deal on the 5.0 and so when this hit £70 I thought early Xmas pressie for myself :). It is normally £87.50 and recent lightning deal brought it down to £74ish so at the moment it is even cheaper!

Will be trying it out on the weekend but have read nothing but good stuff about them so don't expect any issues.
 
Am sure I used the m8 for the battery at the front, think that was a 10mm retaining bolt for the terminals, and the m8 for the rear?? not that i can look as the car is now gone, may have done a bit of fettling with a needle file as is the way when you originate from gods county:D

or did i machine down the bolt fit the eyelet then rebuild with liquid metal and re thread:doh::D
 
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