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Dead Battery. Solutions?

26K views 34 replies 22 participants last post by  XPRD  
#1 ·
Hi Everyone.

After being left for 3 weeks the battery on my 12c is dead. I've used the manual door lock but the window is stuck in the seals and is preventing me for getting inside. I know the glass will smash if I try and force it :mad:

My local dealer suggested trying to lubricate the window seals and try to slide the glass out which I've tried and failed to do.

Without getting into the car is there any other possible way to get into the boot? I've read its possible to gain access by removing the drivers side front tire and pulling the trunk cable - has anyone performed this procedure themselves?

The car is in a location where it will be difficult if not impossible to tow.
 
#2 ·
How to release the hood with manual release

Yes, I have.

1. Look at the DRIVERS front wheel well for little plastic flat screw thingy at around 1oclock position on the tire wheel well.

2. Use a flat screw driver or needle pliers to GENTLY tug back on it. It's almost like a dry wall screw, so it should just pull back. If you pull it straight out, dont freak out, you should be able to set it back in when you're done, no problem.

3. Pull back the felt wheel arch liner.

4. Look for the trunk wire release line. With the pliers, GENTLY pull back. It will take a fair amount of force. But you should eventually hear the pop.

5. Reassemble in reverse. If the release line pops out, just slide it back into it's holder. It works like a glorified bicycle wired brake line.

Hope that helps. Let us know how it turns out. Below are some photos that will hopefully give you some pointers.
 

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#9 ·
Yes, I have.

1. Look at the DRIVERS front wheel well for little plastic flat screw thingy at around 1oclock position on the tire wheel well.

2. Use a flat screw driver or needle pliers to GENTLY tug back on it. It's almost like a dry wall screw, so it should just pull back. If you pull it straight out, dont freak out, you should be able to set it back in when you're done, no problem.

3. Pull back the felt wheel arch liner.

4. Look for the trunk wire release line. With the pliers, GENTLY pull back. It will take a fair amount of force. But you should eventually hear the pop.

5. Reassemble in reverse. If the release line pops out, just slide it back into it's holder. It works like a glorified bicycle wired brake line.

Hope that helps. Let us know how it turns out. Below are some photos that will hopefully give you some pointers.
Great post! I will remember that one when I need it!
 
#7 ·
More like genius Matt G. of PhiliMac that helped guide an imbecile like me through it when I locked my key in the trunk in the middle of nowhere Texas.

After dealing with me, that guy could teach monkeys brain surgery, I'm sure of it.

If McLaren had any brains whatsoever, they would just start throwing money at his face until he would drown from it and agree to head customer relations for all of McLaren. Total ROCKSTAR.
 
#8 · (Edited)
Until McLaren sort out the manual key/smashed window problem a relatively simple solution would be to run a wire from the battery to a weather-proof connector in the wheel-well so in an emergency you could power up the door/boot latches.
 
#10 ·
P14 update should drop the left window to door opening position on battery getting low. That doesn't help a lot though if the car is in he garage with about 10cm to the wall (UK car, the emergency release is on the passenger side for us). Luckily, the AA guy (they provide McL roadside assistance) knew the trick described by ZP.
Florian
 
#17 · (Edited)
In my case, something killed the battery, after just a couple weeks of the car sitting. The battery was below its cut off and the McLaren battery charger would not even recognize it. After getting the boot open like ZP posted, I ended up pulling the liner out to get access directly to the battery instead of just the aux lighter plug and was able to hook another charger directly to the battery. Once it was brought back a little, the supplied McLaren charger was left on the car and all was good a day later.

Caution, these are lithium batteries and will not work with any charger. There is a cut off circuit in this battery that acts as a cut off switch so the battery is not really flat or zero like a traditional acid battery. I am not sure of the voltage, but its probably around 9.5 volts or so.

I have never had a problem since with same battery.

-----

As something further to add, the indicators on the battery charger do not give a reading of the level of battery. They indicate what process the charger is in. Start, Bulk, Analysis, Maintenance modes.
 

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#13 ·
wow, is that also an easy way to steal a McLaren?
in regard to battery I have a question. I noticed after being away for 8 days my battery was at 77% so I decided to drive it a bit and bring it up as opposed to charging the battery. while driving I notice the charge went from 82% to 97% where as prior it progressed one percent at a time. So question is:
Is it possible I have a dead cell in my battery and that is why it jumped to the next level so quickly or does it all of a sudden just quick charge, or WHAT? And, if a dead cell how does one test for this since I want it covered under warranty if bad, these batteries cost a fortune...
My auto is in for its service right now and I made mention of it to McLaren service department and they said I do not have a dead cell and it is normal to jump all the way up, yet, in my mind, it should not be normal to jump all the way down so quickly either because that is how a battery goes dead quickly?
Feedback appreciated since I know nothing about how these sophisticated batteries operate but I do admit seeing this scares me.
 
#14 ·
Hi

I keep my battery on trickle charge with the Mclaren charger when ever it's not being used.
If I use the car it's full, when I return it's down to 3/4 so it maybe just how they are.
Not sure if it good leaving it on charge 24hrs a day, but seems easier then trying to get in the car from a flat battery!!!
 
#18 ·
I use a lithium battery to provide electricity for when the local electric grid goes out so my heater still works in winter and my food does not spoil and I can still do anything I normally do for a minimum of three hours until the grid comes back on line or the sun comes out. The lithium battery, I was told is good for "so many" charges then it goes bad. The latest design has improved over the original to allow for more charges and more applications. Lithium technology has come a long ways and it is ever impressive over lead acid but you also pay for it big time, there is no free ride.
Still, I wonder if anyone knows how to recognize a dead portion within the battery and what can be done about it...
 
#20 ·
I use the rule of thumb that if the car will be setting longer than a month, I will put on the charger. This is usually just for the winter months. Same for the charger on the P1.

Whats best? I don't think anyone really knows. Its like, eggs are good for your, eggs are bad for you, eggs are good for you...

Have had batteries fail from lack or use, fail from being on tenders just the same. Now using maintainers from saveabattery.com these seem to be working pretty well so far for all my non mclaren cars.
 
#33 ·
Just to be sure, my battery went completely flat after being parked about two weeks. The trickle charger now shows as being in the maintenance mode (level 4) but the dash indicator shows dead and the car still won’t start. Does anyone have any thoughts?
 
#34 ·
If battery dont take charge (lithium battery)
Take battery out from car, connect a working normal car battery direct to lithium battery + to + and - to -
Connect a lithium battery charger to your lithium battery for 3-4hours.
Then disconnect the normal battery and keep on charging your lithium battery to full.


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