My baby is all fixed up but seriously McLaren could not make a dead battery any worse - McLaren Life
  • 9 Post By sean1397
  • 4 Post By BigHead
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post #1 of 10 Old 04-22-2019, 11:47 PM Thread Starter
Join Date: Apr 2019
Posts: 2
My baby is all fixed up but seriously McLaren could not make a dead battery any worse

So I love the car. My MP4 is the best car Ive ever driven - only thing close has been a Porsche 918 I can't afford.

And thanks to these forums and 4 days I have it back fully up and running after letting the battery die.

But seriously, McLaren must make it so difficult to fix a dead battery so that 90% of us like me who have never opened a hood just take it in and pay $2000-3000. The stupidity of how hard it is to fix a dead battery is incredible.

Three very simple questions:

Why is the battery connector inside the boot for which you need battery power to open the car (to open the windows, to unlock, to open the boot, etc). If you are smart enough to build a car this wonderful and include a battery charger why wouldn't you put the port on the outside of the car? (Is it a patent issue - Bentley does it. Is is an aerodynamic issue?)

Number two why do you need both a regular screw driver and allen/hex head to get to the battery? The only possible explanation I can come up with is to make it harder and justify a trip to the dealer. Everyone has a screwdriver. Not everyone has a hex head.

Number three. Why is there not a computer reset button inside the car or on the keys. Why is the only two ways to reset the computer to either take it in for repair or disconnect the battery that is near impossible to get to.

If anyone from McLaren is reading this a few simple fixes:

1. Battery charging port outside the car!!
2. Computer reset button in the car or on the key.
3. One set of boot screws (Philips)
4. But even better - let me introduce my new and invented item, called the Boot Battery door!!! Ding ding. Just a little door that opens so you can easily get to the battery!

Now for anyone else who is as mechanically dumb as I am and leaves their car for 3-4 months unplugged here is what you do in dumb like me terms. I never would have figured this out without about 6-8 posts on this forum.

1. Make sure you have your trickle charger and extension cords or go to eBay and buy cords and CTEK McLaren charger like I did.

2. Pop end off key.

3. On the US drivers door towards the back like between the door and the rear tire there is a panel you can pop off (reminder to self I should put mine back). You can stick a finger in up behind it and pull hard. Don't worry. You won't hurt the car and the car won't drive anyways so yank. After a few hours of frustration you will yank hard enough.

4. Insert metal key that you popped the end off. Before you do this make sure your car cracked the window. It is supposed to when the battery gets to 10%. If your window is not cracked tow to dealer. You will break it if you open the door.

5. If your window is cracked, turn key. If yours is like mine, it will not budge. I had to grip it with a pair of pliers to get the door to open. Yay. You're in.

6. Find the boot opener. On the US drivers door right below the hinge is a little round black thing. You can grab it. Yay. Boot opens.

7. Hook your charger (one you had or a new CTEK lithium one to the port in the front of the boot.

8. Now this is key. If your battery is very dead, McLaren somehow disconnects it to protect the battery. To override this on the CTEK (I don't know if stock McLaren charger works the same way but probably has a similar feature since CTEK makes it) push and hold the reset button and the #7 lights up. Let go. The #1 will then light up for at least 30 seconds. It may move to #2. If it moves to #2 go to bed. Come back tomorrow.

9. Assuming instead of moving to #2 it lights up the red error button. Try holding reset for 10-15 seconds again and wait till the 7 lights up. Mine kept failing. The directions say try this 5 times then go to dealer. I noticed whenever I held the reset for 10 seconds my battery was clearly getting charged cause I could unlock the doors, the windows rolled down on their own, and lights on the middle console would flicker. After about and hour of holding reset down for 10-15 seconds, letting it start over, etc maybe 50 times, and twice unplugging the charger and replugging it in it went from #1 to #2 instead of error. #1 means the charger is seeing if it can charge. #2 is when it is charging. Yay!. I have no idea if unplugging is key but it went to 2 after the second unplug so maybe. Clearly the charger will think it can't charge if the battery is very dead and holding reset for 10-15 seconds repeatedly will get you some charge. I could tell because the more I did this the more lights and sounds that went on. Thus I just kept doing this. It eventually locked into charge mode.

10. Next morning start the car. Drive it. IT will read a ton of faults and one that says something like go home call dealer. It won't let you go faster than like 65mph and you have minimal power, no wiper, radio, etc. The car minimizes what it will do to protect itself.

11. Many forum posts said turn it off and on and drive and try again and again. This did not work for me and hasn't seemed to work for anyone.

12. Take out the boot. Fairly easy to do but you need a Philips and hex thingie. Take out like 30 screws and lift out boot.

13. Disconnect the negative lead from the battery. I am no battery expert so used a leather glove and rubber handle pliers. You will need a pliers or socket wrench to loosen battery lead. Once I had the lead lose I got it off by hitting it a few times with the pliers - may or may not be the normal way this is done.

14. I pulled the red tab on the battery sensor cord. I Could not get the cord off the battery and I am not sure if pulling the tab out reset the sensors. This step may or may not be needed.

15. Wait 15 minutes. Marvel at the fact you have gotten this far and nothing has caught fire, exploded, or shocked you to death.Swear you hate McLaren

16. Push the red tab on the battery sensor unit back in.

17. Reconnect the battery negative lead. I tried. It sparked. I cried. Called mom. Swore I wasn't gonna die. Called a friend who had worked on cars before. He came over and reconnected the negative lead. It sparked. He hates his wife so said he didn't care if he died. I watched. Basically you put the thing back on and have balls to do it. Not sure how to avoid this issue. Gloves, rubber tools, etc are all recommended on line but calling a friend worked for me.

18. Put the boot back in. Screw for 30 minutes.

19. Turn car on. Only fault will not be low tire pressure.

20. Go to tire place. Ask to fill back to 32 and front to 29. Tip the guy.

21. Reset clock and calendar.

22. Go to car wash.

23. Go pick a hot chick up. That's why you own this thing to begin with and now you have a get laid Im a mechanic story.

Good luck
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post #2 of 10 Old 04-23-2019, 12:22 AM
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Location: Wild West LA, California
Posts: 634
Good job! But the battery inside and no easy access if the battery's dead isn't a McLaren-only conundrum. My Lotus had the same status. Perhaps it's a Brit thing, perhaps Ferraris do the same, I don't know. I keep the battery tender that came with mine on any time it's not in use, just as the manual advises.
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post #3 of 10 Old 04-23-2019, 04:00 AM
Join Date: Apr 2017
Location: Boston, MA
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This is an EPIC story (out of a rather mundane but probably all-too-common situation). Well written, and quite entertaining! Thanks for sharing your pain.


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post #4 of 10 Old 04-23-2019, 08:27 AM
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Join Date: May 2014
Location: Windsor, UK
Posts: 107
For the next time, especially if the car doesn't roll down the window on dead battery and/or you don't want the rigmarole with the emergency key: Unscrew the inner fender top/front on the left hand side of the car (the emergency release is on the same side left- or righthand steer), plug you hand into the resulting gap and yank on the emergency release line which will conveniently pop the trunk. This is how the dealer does it without shattering the window.
Good luck with the "i am a mechanic" story, keep us posted :-)....

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post #5 of 10 Old 04-23-2019, 05:11 PM
Join Date: Nov 2017
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Originally Posted by Scalpel View Post
Good job! But the battery inside and no easy access if the battery's dead isn't a McLaren-only conundrum. My Lotus had the same status. Perhaps it's a Brit thing, perhaps Ferraris do the same, I don't know. I keep the battery tender that came with mine on any time it's not in use, just as the manual advises.
Porsche have the same issue... My Boxster has gone dead several times (due to sitting for long periods), and the only way to get in the trunk is to open the door with the physical key, then apply power to the fuse box (i.e. find a specific fuse and literally put a 12V power source on it), then use the key to unlock the doors, which releases the trunk control so you can open the front compartment. The other way is put you hand inside the wheel liner, find the mechanical cable release, and pull hard on it!

Not sure if they solved it on the 997/987/991/etc, but my 986 and the 996 has that issue for sure.


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post #6 of 10 Old 04-23-2019, 05:22 PM
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Location: Arizona
Posts: 273
Can we get step by step of photography next? Or did you forget the glasses and used manual focus?
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post #7 of 10 Old 04-23-2019, 08:06 PM
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Join Date: Mar 2018
Posts: 132
Sorry you had to go through this headache. Thanks for documenting it. I always leave my car plugged in because my dealer is 3 hours away.
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post #8 of 10 Old 04-24-2019, 02:02 AM
Join Date: Feb 2015
Posts: 208
Best write-up ever.
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post #9 of 10 Old 04-25-2019, 03:23 PM
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Join Date: Dec 2015
Location: Wiesbaden/Cape Town
Posts: 67
I feel your pain. I was project manager for service readiness once and an issue like this fell into my lap and I would present this to the vehicle development team.

The reply would be: How many times per unit sold do we anticipate this to occur?

My number would be some measure as a combination of milage, time, units sold - multiplied by frustration. And the answer would always be: Your number does not justify the expense during production to make this easier for the client (or dealer).

Does the owners manual give any hint how to find the release cable?

Nothing is as it seems!
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post #10 of 10 Old 04-26-2019, 01:56 AM
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IKEA's looking for a man like you.
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