DIY Rear Brakes: Why is a battery charger needed? Using Carista for svc. position.

[Captain Tuttle]

I've searched the forum for the exact question to this question...Why is a battery charger needed to replace the rear rotors and pads?

I understand the EPB needs to be placed in the service position and there is a very specific procedure if using VAGCOM.

But, I'm planning on using the latest version of Carista which has an option to retract the EPB. Do I still need to hook up a battery charger? I really need to understand WHY because it's not making sense to me that the EPB will somehow draw down battery voltage during the time it takes to change rotors and pads.

What am I missing?

I'm tempted to just remove the EPB motor and retract the EPM using the TORX 40 bit by hand avoid the whole headache. But, I'd prefer to do it the "right way".

[bayonet14]

If it takes you that long to change rear brake pads to hook up a battery charger - the your battery is about dead anyway.
Just did mine w/Carista - once it retracts the rear pads... thats it - switch the ignition off and swap your rear pads - Once complete - turn ignition on a activate the brakes

[UberBrute]

the epb motors are very voltage sensitive apparently and can be easily damaged. Hooking up a charger prevents any voltage drops that might cause a problem. When I did mine, i watched a ross tech video that explained how the motors are 350 something dollars a piece. In my mind it was better to buy a battery tender jr (30ish dollars) and hook it up while I did the pads than to risk 700 dollars in epb problems. Besides, a battery charger isn't the worst thing to have around the house. Lastly, if you do screw up an EPB motor, now your car is stuck until you get it towed or have someone drive you to a dealer or get the part shipped. The charger is really just cheap insurance.

https://www.amazon.com/Battery-Tende...tery+tender+jr

[tjenne69]

I just did mine with Carista, no charger, and no issues.

[cjw]

I didn't use a charger either. It's maybe a 20-30 minute job. Living on the edge!

[SwankP3RF3ct10n]

No battery charger here either. Turned ignition to On position and retracted the EPB then turned the ignition to Off and left the key in the car. Did fronts and rears at same time since I was also rotating tires. This included pads and rotors, so it took a while. No issues. When done, I turned the ignition back to On and cycled the EPB in VAGCOM again to close them back up to the new pads. Unhooked laptop and then cycled the parking brake a couple of times just to make sure no issues. Then drove to break the new pads in. If you're worried about the voltage, then just simply unhook the plugs on the motors after you retract them. No more worry and there's no way they'd cycle back down since there's no power going to them now.

[Captain Tuttle]

Thanks all. I know how to change pads and rotors.

Normally, I don't have a battery charger connected when my car is just sitting there in the garage and the parking brake is set. So, what is happening during a brake and rotor change that is somehow causing voltage to drop requiring a battery charger? I understand if using VAGCOM the key is in the on position, the EPB motor is running in the beginning and the end which draws power.

But if I'm using Carista, the battery charger seems unnecessary.

[SwankP3RF3ct10n]

Thanks all. I know how to change pads and rotors.

Normally, I don't have a battery charger connected when my car is just sitting there in the garage and the parking brake is set. So, what is happening during a brake and rotor change that is somehow causing voltage to drop requiring a battery charger? I understand if using VAGCOM the key is in the on position, the EPB motor is running in the beginning and the end which draws power.

But if I'm using Carista, the battery charger seems unnecessary.

Did you read my previous post. Even if you were using VAGCOM, you don't need to leave the car On. Retract the damn motors and then turn the car Off. Then unplug the plugs on the rear brakes and do about your process until you're done. Then hook the plugs back on and then turn the car On and lower do the second process to reengage the motors back down on the new pads. Simple. Doesn't matter what you use to do the electronic process for back them out and back in.

[LaCross]

i just jumped it with a battery.... /shrug