After 3 months of winter storage, my battery went flat yesterday, so I replaced it last nite.
Here is the question:
I have been using Porsche dual mode charger all the time, will it switch to maintain mode automatically after fully charged? Or I have to press the mode select button?
I always see it is in charge mode, but never turns to maintain mode automatically.
Is my charger bad as well？

 

Should switch to maintain mode automatically as I recall.

Did you check water level in the 6 cells of the battery? Likely they were dry and charger/maintainer over cooked them sealing your battery's fate. They look sealed but are not (at least as OEM Moll is not).

 

Thanks for your info!
Honestly I have never checked water level, how often should I do that?
I already put durlast battery inside.

 

Not sure about the Duralast but some batteries are truly maintenance free and you can't add water. Even though the Porsche battery (Moll) looked like is was "sealed" you could peal back the labels, open the cell caps and add water.

 

I have been using a floating charger (it won't recharge a dead battery) from Black Decker for the last 4 years with great success. It may not be as fancy as the Porsche charger, but it only cost me $20 at Home Depot and it does a fabulous job.

Yves

 

Just FYI I returned from 1 month abroad went to open the Porsche and nothing, thought the battery was dead, until I opened the drivers door with the key which unlocked the car and turned everything back on, must have some auto shut off if not driven for a few weeks, and turning the key in the drivers door switches it back off. Nice feature.

 

Working as designed - from the owner's manual:

The remote-control standby function
switches off after 7 days
If the vehicle is not started or unlocked with the remote
control within 7 days, the remote control
standby function is switched off (to prevent discharging
of the vehicle battery).
1. In this case, unlock the driver’s door with the
key at the door lock.
Leave the door closed in order to prevent the
alarm system from being triggered.
2. Press button 1 on the remote control.
The remote control is now activated again.

 

If it stays in charge mode or takes a long time ( several hours or a few days rather than a couple hours) it likely means your battery is on its way out. This was the case with my battery.