Battery charger question.

[sc_rufctr]

I have a CTEK battery charger and I always disconnect the battery from the electrical terminals of the car before hooking up the charger.

The question is. Am I being pedantic or overly cautious by disconnecting the battery before using the charger?

I've searched and done some reading and the consensus seems to be that it doesn't make a difference either way.
But there's a possibility that the diodes inside the alternator or the car computer could be damaged by the charger.

What say ye?

[Bill Douglas]

My car is also a SC and I just hook up the CTEK and leave it. And a friend of mine who knows everything just hooks it up and leaves it too. I've found all that "conditioning" stuff it does really has worked. The battery seems happier and spins the engine up faster since I got the thing. I've left it on and not driven the car for two weeks on one occasion, so it works for me.

[patz]

What is the output? 1.5amps? I have a pigtail mounted to the terminals and hangs out thru the hood. Plug it in walk away.

[Hugh R]

The only up side of disconnecting that I can see is if you reverse the charging then you just eff up the battery, not the car.

[sc_rufctr]

Just an update. I've been using the charger with the battery still connected to the car terminals.
No issues although I'm reluctant to leave it connected and charging when I'm not home.

Thanks for the input.

[Deschodt]

Originally Posted by sc_rufctr

Just an update. I've been using the charger with the battery still connected to the car terminals.
No issues although I'm reluctant to leave it connected and charging when I'm not home.

If it helps, I've had a long hood in storage for over a year now (I use it, but it sleeps in a warehouse), it's ALWAYS on the maintainer/charger (connected the charger leads to battery terminals, I just plug in the charger now). It was also in storage the year before that before I moved... So 2 yrs on those things 24h/day. You can probably relax... As long as you use proper equipment (charger/maintainer) I don't see how it could hurt the car. It's not like max amps charger on a dead battery forever, those modern chargers just stop charging when the battery is good... Everything electrical still A-OK !

[aigel]

I never worried about disconnecting the battery when charging it. Never had any issues correlated to this practice that I know of.

On the 993 after biting the bullet and installing a nice oddysey battery a couple years ago, I installed a trickle charger that remains plugged in when the car is parked in the garage. Works great.

G

[wdfifteen]

I would consider the environment the car is kept in. If there are bugs or rodents that would chew wires I would definitely disconnect the battery before long term storage. I've momentarily hooked my maintainer up backwards a couple of times with no damage to the car , battery, or the maintainer.

[aigel]

Main reason for a maintainer for me is to keep the brains alive in the 993. Otherwise, every time battery is disconnected it needs to relearn and set all the OBD2 codes. So, disconnecting the battery is a big no-no, unless it cannot be avoided.

G

[Crowbob]

There should be no problem if the CTEK charger is what they call a 'smart charger'. 'Smart' means the voltage output of the charger adjusts itself to the charge state of the battery. If the battery is very low, the smart charger pumps more volts until the battery reaches about 80% capacity (around 12.6 or so volts). Once the battery is at 80% capacity the charger output drops and becomes a maintainer vs. a charger. When the battery is full, a smart charger will also up the volts every once in a while to 'burn off' the plates. At no time will a 'smart' charger over charge (i.e., cook) a battery reducing its lifespan in terms of charge cycles and its ability to hold voltage. In addition, there are usually some very low phantom voltage draws such as the clock or the radio memory that will drain a battery in long-term storage and slow the recharge rate when the battery is connected to the car while charging.

Short answer: if it is a smart charger you're good to go leaving it plugged in and the battery connected to the car. Any time a battery is drawn down to below about 50% (approx. 12.2 volts), the life span of the battery is significantly reduced. The sweet spot is to keep a battery charged between 80 and 100% capacity; not over- or under-charged.