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Went to get a car wash both doors were left open for 10 minutes to vacuum ( not sure if that’s relevant ) car says battery life critical low. The top right of the dash reads 0 days left parking and my windows won’t roll 100% up when driving. The car starts but I can’t roll up the windows (probably a fail safe). I plugged the charger in and it read that the battery is 90% fully charged but the dash shows me it’s almost dead.
This cars awesome and very fun but wtf is going on with all this little bull crap. I have 400 miles on the car and already electrical issues?
Does anybody know what I should do? It’s raining tomorrow and I can’t drive in the rain with windows not fully closed. Helpppppppp
 

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How much did you drive it before you went to the car wash and how much afterwards before you plugged it in?

The odd time; the sensor will think that the battery is low when it isn't (this hasn't happened to me on 600 LT but happened a long time ago in 720s (sensor was replaced (this was a common issue at the beginning of 720's when everyone thought that people were leaving the key too close to the car when it was in people's garages, etc.).

If you drove it for at least 15 to 20 minutes then the issue should go away. If it happens a couple of more times then it is the sensor and this will happen the odd time.

If the sensor thinks there is no battery life then it will go into management mode and anything that relies on the battery will go into a sort of shut down mode (windows, power seats).

fwiw; I was with a 720s friend recently. He had left his 720s on a charger for many weeks. When he drove it; it had the same warning. He drove it for a bit and the warning went away and hasn't come back.
 

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Based on your previous posting on another thread.... it wasn't a wise idea to modify the car. It could or maybe not be related but still...
 

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spoke to a couple of my buddies who had the same issues or heard of them. They think I might have gotten the sensor wet at the car wash. They believe the battery sensor will reset overnight and the problem should go away. Worse case I’ll have mclaren change the sensor and keep the spray at a minimum when washing.
 

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How much did you drive it before you went to the car wash and how much afterwards before you plugged it in?

The odd time; the sensor will think that the battery is low when it isn't (this hasn't happened to me on 600 LT but happened a long time ago in 720s (sensor was replaced (this was a common issue at the beginning of 720's when everyone thought that people were leaving the key too close to the car when it was in people's garages, etc.).

If you drove it for at least 15 to 20 minutes then the issue should go away. If it happens a couple of more times then it is the sensor and this will happen the odd time.

If the sensor thinks there is no battery life then it will go into management mode and anything that relies on the battery will go into a sort of shut down mode (windows, power seats).

fwiw; I was with a 720s friend recently. He had left his 720s on a charger for many weeks. When he drove it; it had the same warning. He drove it for a bit and the warning went away and hasn't come back.
I drove the car a lot today. Probably put on 100 miles throughout the day so I’m Almost positive it had something to do with the wash. There’s no way the battery drained from 10 minutes of having the doors up.
 

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McLaren 720S spider, 2020. Spark.
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Please describe this car wash. I do not know where you live and such but I doubt many of us take a car to a car wash, our best rides are only hand washed. Trying to figure how water would get to this sensor.
 

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Please describe this car wash. I do not know where you live and such but I doubt many of us take a car to a car wash, our best rides are only hand washed. Trying to figure how water would get to this sensor.
I live in New York - I took the car to a hand wash spot. I noticed they used a TON of foam though and a couple of buddies of mine believe I wet the sensor and it’s going haywire.
I spoke to the shop foreman at one of the mclaren service centers and he believes the issue should go away tomorrow. (Car needs to go to sleep and reset). I’m very hopeful he’s correct. He also mentioned this is a very common issue and advised me not to be alarmed. Well see.
 

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There is a sensor plug connected to the battery. If you drain your battery quite low and the battery meter on the dash doesn’t change despite putting the battery on the tender, remove this sensor connection to the battery. Recharge the battery to full using the tender then start the car without the sensor connected. It will reset the dash meter then you can reconnect the sensor on the battery and it should read normally moving forward.

If your car has low battery charge from the beginning and you leave the doors open from sometime, it can drain the battery quite fast. I think the system has a failsafe mode that it won’t let you drain the Li-Ion battery completely so that it won’t be difficult to recharge, otherwise, a fully dead Li-Ion is difficult to wake up.
 

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Just wanted to update the thread - Took the car to get wrapped the day after this happened and got the car back last night. The problem disappeared .... Took the car to Mclaren this morning and they say nothing is wrong with the sensor, everything is dry and have no clue why the batter said it was dead when it clearly was full. Ohh Mclaren...
 

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Sounds about right. Glad it worked out.
 

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Sounds about right. Glad it worked out.
yeap.
had a low engine oil pressure alarm accompanied with the customary "stop vehicle at once" thingy. never had this issue before but i had just washed the car the day before. kept driving and next day ,all was clear!
 
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