[gde061]

I went out and bought a small 2A battery tender with the cigarette lighter type hookup due to all the cold weather. Tried to get it to work today and all it says is that the A/C power is there.... it doesn't seem to register that there is a battery connection at all, let alone go into charge mode.

Is there some kind of special circuit isolation of the cigarette lighter on the 335xi? I tried both with the car off and in "acc" mode (push start button w/out foot on pedal). I really hate to go hooking up to the batter terminals for something like this.

[gde061]

Figured it out... not only does the car have to be in ACC mode with key in, but this particular charger has to plug in a certain order. Makes no sense, but putting in the plug and then turning on ACC didn't register, but doing the ACC first, then testing that there was V to the cigarette lighter, and then connecting the charger... it worked.

When car is OFF, there is not voltage to the cigarette lighter but the charger must detect something like a fault condition.

[gde061]

Originally Posted by gde061

Figured it out... not only does the car have to be in ACC mode with key in, but this particular charger has to plug in a certain order.

No, turns out that wasn't it either. Cause I did exact same procedure again after turning off car to mess around under hood, and this time it didn't go into charge mode. So I'm hooking up to the terminals under the hood to avoid whatever circuit protection is on the car that is isolating the cigarette plug sometimes in ACC but not others.

[Meeni]

Just don't do it. Charge from the charging posts under the hood.