ADias

After washing my car I raise the engine lid spoiler to dry that area and rubber bellows. To do that one needs to turn on the ignition to position 1 and push the spoiler button at the bottom of the center console. I did that this morning but failed to turn the ignition key off, leaving it in position 1 (ON) for over an hour... and ended up with a sufficiently discharged battery that would not start the car.

When the ignition switch is ON (position 1) there is a large battery current drain for the DME (high current) and other loads. In my case I left the key ON for over 1 hour and my reduced capacity (50Ah Optima Red) battery dropped quickly. This is particularly important with Optima batteries which must have be always charged at least at 80% capacity.

Quickly recharging the battery - 2h on CTek 4.3A was enough to start the car. PSM error and loss of PASM (Sport) were reset after driving 200ft.

I hope this is helpful. Clearly my mistake to leave the key in the ignition.

Wayne Smith

It goes back over 25 years ago when I incorporated an Optima battery into a roll around auto adjusting industrial lift device. Forgive me if my memory is wrong. This was a very quick design. I've done many projects since then. I recall problems with the red batteries for the exact reason that you mention. I also recall going to the deep cycle Optima battery (that I believe was yellow) to solve this. I don't recall if there was a weight difference. Deep cycle is not something you usually worry about in a car.

As you know, once the red battery (any non deep cycle type) goes below 80% it may not be reliable. Time to replace it.

Good advice to all of us to not leave the key in the ignition.

mikes70

there's a special sequence to recharging the reds. I forget how it goes. now have yellow and blue in my 70 camaro and performance boat. no problems with either, but when low/no start, a trickle is only way.

ADias

My red is fine. The Ctek recharge cycle completed to floating just fine. And yes, Optimas (AGMs) do need 80% charging, but an ignition key left on ON can drain just about any battery, especially a marginal/old one, AGM or not.

Petza914

I have Optima reds in all of my vehicles, except the boat, which has 2 optima blues (marine deep cycle) and the Cayenne (Optima doesn't make one large enough) and they've been extremely reliable for at least 5 years each. The Pcar ones are always on a Battery Tender in the garage though since one may not be driven for a few days or couple weeks, depending on many variables. I use the Optima branded battery charger if recharging a good ery low one, otherwise the Ctek or Battery Tender brand to float maintain them.

Porsches will kill a battery in short order with the ignition key turned on to the accessory position. In the 30 minutes it took the tint shop to tint my Cayenne cycling the key to put the windows up and down, open and close the rear hatch, etc, the car needed a jump at the end.

mikes70

I've done it twice in the 1.5 year of P-car ownership. At least i know my car better now, the "emergency frunk release".

rherring

I also have an Optima red in my 997.2. I have found that it is extremely easy to drain it down so that it will not start the car. I will probably pick up a lithium battery booster for those rare occasions when I get into a bind where the engine will not start.