Correct way to connect a CTEK charger

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Dave Richardson

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Plymstock Plymouth
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W176 A class 180 cdi
Just after a few thoughts.

Is it better to connect Ctek charger leads directly to the battery terminals or on to the jump start terminals under the bonnet.

I'm tending to go with the jump start terminals so as to protect possibly damaging the SAM unit.
Thoughts Please

Dave
 
Hi Dave.

There’s another, recent, thread on battery charging where members have been charging by connecting directly to the terminals on their cars with no issues. I’ve recently charged my battery using jump terminals as that’s how it tells you to do it in the owners manual, plus it saves taking the fan duct out.

check your owners manual but both will do the trick.

Al
 
I do mine on battery and have always done on numerous cars with no issues.


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Is it better to connect Ctek charger leads directly to the battery terminals or on to the jump start terminals under the bonnet.

It doesn't make any difference, so if the battery terminals are hidden, why bother using them when Mercedes left remote connections with easy access?
 
Depends on where the car is located and where the battery lives. My SLK is in the garage so secure, but the battery is under the bonnet which I cannot close as the metal edges would cut the wires. My s204 lives in the driveway and the battery is in the boot, the tailgate will close over the extension lead wire so I can put a charger or conditioner on, with the charger and extension reel inside the boot, and close the tailgate/lock/alarm the car, and the big rubber tailgate seal protects the cextension reel cable.
 
I thought If you have an AGM battery, you should attach a charger to the remote points under the bonnet.
That way the ecu knows the battery state of charge. ?
This appears to be the case for BMW. If you connect directly to the battery terminal you bypass the ecu
 
I thought If you have an AGM battery, you should attach a charger to the remote points under the bonnet.
That way the ecu knows the battery state of charge. ?
This appears to be the case for BMW. If you connect directly to the battery terminal you bypass the ecu and the car can lose track of the State of Charge
 
Anything with stop/start I use the provided connectors, not the battery terminals, so the BMS can see what has gone on.

Cars with no stop/start just attach CTEK comfort connectors permanently to battery.
 
Genuine question, if the engine is of and all electrics are asleep how will the ecu/bms know whether the increase in battery charge had come direct to the battery or through the posts? Wouldn't the ecu, on wake up, check and register the battery state of charge as a matter of course?
 
Genuine question, if the engine is of and all electrics are asleep how will the ecu/bms know whether the increase in battery charge had come direct to the battery or through the posts? Wouldn't the ecu, on wake up, check and register the battery state of charge as a matter of course?
Modern cars never sleep, they are watching and listening to you all the time.

Even my 2004 SL starts purring as soon as I unlock a door.
 
Modern cars never sleep, they are watching and listening to you all the time.

Even my 2004 SL starts purring as soon as I unlock a door.
This... :)

With stuff like keyless entry, collision alerts, anti-theft systems, remote data transfer to sat-Nav systems and so on, the modern car is never 'off'.

To answer the question though, I don't know for the Mercedes. On my Mazda, I have the Ctek fly lead connected directly to the battery terminals. But it doesn't have stop-start etc..
 
My Ctek's connect directly to the battery terminals, I have a Ctek comfort connector permanently connected which shows the battery charge state via red, amber or green flashing LED's.
 
Mercedes themselves connected my CTEK directly to the battery terminals on my CLS55..
 
For me, the direct connection is far more convenient than using the jump start points in the engine bay since I park my care nose into the garage.

If you are worried about the SOC, connect the positive charging lead directly to the positive terminal of the battery and the negative charging lead to the 'body' of the car (as per CTEK instruction). That said, as already mentioned, I cannot imagine the ECU monitoring the SOC when the engine is switched off. Otherwise, the drain current will be a lot higher than a few mA if the processor is running all the time causing the battery to drain within a few days not weeks.
 

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