Taza858

my battery died on my 09 s550. I tried using the manual key and it still wont unlock the car. I tried every method including turning the key and pulling the handle at the same time and it doesn't work. I can still open the trunk with the manual key

DaveW68

DaveW68

After turning the key counter-clockwise, you have to leave it in that position and pull the handle very quickly. If you pull the handle too slowly, it will not unlock.

You'll find out if there is any charge left in your accessory battery if the alarm goes off when you unlock it manually.

You will likely be able to start your car after you get in. The starter battery is separate from the accessory battery. You may want to get the accessory battery in your trunk load tested to see if you killed it...or if it's just discharged and needs a good charge. If it's still the original battery, it probably needs to be replaced. You can pick up an AGM H8 battery from Walmart for around $150 or less.

Taza858

Thanks for your help I got the door open but it seems like the battery is completely dead nothing works. I put my battery charger on the battery under the hood, where is the battery in the trunk located?

bha

If you open the trunk and look forward, the carpeted "wall" you see can be removed and the battery (and LOTS of electronics) are behind that wall.

But to charge it, you can certainly use the power point under the hood. Way way easier than removing all the trim in the trunk.

Put a trickle charger on the terminal under the hood. I avoid using my 10A one and use a 2A one, just to be sure I don't cook either battery (probably OK, but why risk it?)

Leave the trickle charger on overnight and you can start the engine. Drive the car at least 30 mins before you shut it down. Not everything will work (ie COMAND, heated seats, etc.) until the trunk battery charges up quite a bit.

Other option is if you don't need the car, leave the trickle charger on for a few days until everything is fully charged, then drive it. That way you know it's fully charged.

I'd charge enough to start it then go for a drive..

Taza858

I left it on trickle charge and it looks like it won't even get a charge nothing in works still

Taza858

bha

I'm a little confused.. your battery died so you couldn't get into the car.. now you're in and the battery won't take a charge?

If your battery died, did you replace it? or are you trying to charge the existing battery? Maybe the battery is toast.

Which battery did you replace.. front or rear?

When you say it isn't taking a charge, which battery?

First thing to do is ensure you have a good starter battery (front). Replace if necessary. Trickle charge till full then start the car.

Once past that step, you can work on the rear battery. You can actually drive the car with an almost dead rear battery, it's just that you may get locked out and some electronics don't work.

First figure out your front battery and get it in good shape. Then move on to the rear.

If you don't know how old your front battery is, just replace it and start from there.

Taza858

The car sat for about 3 months and they have the original battery I belevie at least the front is original. I got in the car with the manual key I got it to work. I let the car charge over night and this morning still nothing works. No electronics work when I put the key in the ignition nothing happens nothing turns on or anything.

DaveW68

Both batteries are likely originals and need to be replaced.

bha

DaveW68 is correct. You likely need 2 new batteries.

Go and get a front starter battery and connect it up. Then you can at least drive the car. You can then see if the trunk battery charges up or not. Even if it does, I'd plan on getting a new one of those too. But at least you can drive the car in the meantime.