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Back up option to wake up the 12V battery in MX

Rice&Curry

Member
May 9, 2018
475
236
San Jose
My 2019 MX has not been driven much ( under 1 K miles) since Jan 2020 due to pandemic and WFH. I am planning to go on a 2 week road trip to AZ and UT to visit the National Parks in Oct. Not sure if the 12V battery will create issues during the trip. Since i will be miles away from any Tesla support, I need a back up plan in case 12V battery dies w/o a warning as has been reported by few members. I can open the frunk pulling the emergency cords in the front bumper and based on the videos , get access to the 12V battery leads. My question is if i have to jump start the battery from an external power source as an emergency measure, will a portable battery charger work? Are there any WH or Amp requirements. I found 2 types available-
1) https://www.amazon.com/jfegwo-Porta...p/B074FS69F9/ref=psdc_318336011_t4_B00RZXVQSU
2) TACKLIFE T8 Car Jump Starter Orange, Midnight Green, Light Yellow and Red
The 1st one also doubles as a air compressor,- Any suggestions/recommendations from the Yoda's in the community.
I
 
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DCGOO

Active Member
Nov 24, 2015
1,718
1,009
Indianapolis, IN
My 2019 MX has not been driven much ( under 1 K miles) since Jan 2020 due to pandemic and WFH. I am planning to go on a 2 week road trip to AZ and UT to visit the National Parks in Oct. Not sure if the 12V battery will create issues during the trip. Since i will be miles away from any Tesla support, I need a back up plan in case 12V battery dies w/o a warning as has been reported by few members. I can open the frunk pulling the emergency cords in the front bumper and based on the videos , get access to the 12V battery leads. My question is if i have to jump start the battery from an external power source as an emergency measure, will a portable battery charger work? Are there any WH or Amp requirements. I found 2 types available-
1) https://www.amazon.com/jfegwo-Porta...p/B074FS69F9/ref=psdc_318336011_t4_B00RZXVQSU
2) TACKLIFE T8 Car Jump Starter Orange, Midnight Green, Light Yellow and Red
The 1st one also doubles as a air compressor,- Any suggestions/recommendations from the Yoda's in the community.
I
Would you worry about a failed 12v battery if you were in an ICE vehicle? If no, I wouldn’t worry about it in your Tesla either. Besides in the Tesla, it is automatically charged from the traction battery whenever it is deemed necessary, even when the car is off. The bigger thing to worry about is how you are going to charge when in the NPs. Some are pretty remote.
 
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Rice&Curry

Member
May 9, 2018
475
236
San Jose
Would you worry about a failed 12v battery if you were in an ICE vehicle? If no, I wouldn’t worry about it in your Tesla either. Besides in the Tesla, it is automatically charged from the traction battery whenever it is deemed necessary, even when the car is off. The bigger thing to worry about is how you are going to charge when in the NPs. Some are pretty remote.
Have booked in hotels near NPs which have destination chargers and have back up options with nearby RV parks with 14-50 or 30 Amps connections where i can charge for a fee Plus a long cable for 5-15 overnight charge in places where we may spend 2 nights or more and where destination chargers are not available. I have also ordered a Modern Spare tire just in case and have spare button cells for the fob in my car , so right now the 12V battery is the one thing i can think of that is still open. I guess I can request help from an ICE car to jump start it worst case. But Murphy's law rules over all contingency planning.. lets see...
 
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mxnym

Active Member
Mar 9, 2018
1,157
541
Bloomington, IN
Have booked in hotels near NPs which have destination chargers and have back up options with nearby RV parks with 14-50 or 30 Amps connections where i can charge for a fee Plus a long cable for 5-15 overnight charge in places where we may spend 2 nights or more and where destination chargers are not available. I have also ordered a Modern Spare tire just in case and have spare button cells for the fob in my car , so right now the 12V battery is the one thing i can think of that is still open. I guess I can request help from an ICE car to jump start it worst case. But Murphy's law rules over all contingency planning.. lets see...
Every time I have a fob battery die, the fob seems to die with it. I got 2 or 3 new fobs during the factory warranty and never got to use a spare battery. TBH, I have the same concern as you re: 12V just because in my experience, batteries fail in ways that computers don't detect more often than not, so the odds of a bad battery warning seem slim to me. I guess there's not really any reason jumper cables from an ICE vehicle wouldn't the trick, but if I was carrying jumper cables, I'd just as soon be carrying a jumper pack so that I could help someone out since the X battery obviously isn't going to jump most ICE vehicles.
 

Silicon Desert

Active Member
Oct 1, 2018
3,675
3,789
Sparks, / GF1
OP, I bet you got all 3 Covid vaccines ;) Ok, just a joke. Sounds like you want to be well prepared for possible things to go wrong. That's me when I go on long trips. My question is when was the last time the 12V battery was replaced? I would focus a bit on the probability that the battery can fail. If in the last couple of years, then you are probably over-thinking the battery thing.

As a side note, I am planning to take another very long trip and last month I was thinking it's been over 4 years since my battery was replaced so I was going to proactively replace it before my trip and not wait for the warning. I scheduled service in the app to have it replaced. Strangely, on the morning I was due to have Tesla replace the battery, I got the warning message in the car. Maybe the car was sending signals to my brain in advance :oops:
Both of those portables should work fine. They don't even need to be that strong. Those are meant for ICE vehicles where you need cranking power for the starter.
 
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Silicon Desert

Active Member
Oct 1, 2018
3,675
3,789
Sparks, / GF1
Every time I have a fob battery die, the fob seems to die with it. I got 2 or 3 new fobs during the factory warranty and never got to use a spare battery.
Interesting. I've had my fobs for 5 years now. Replaced batteries in both of them every year when the batteries expire and quit delivering energy. Never had either fob die.
 
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ATPMSD

Member
Mar 12, 2021
450
438
Atlanta, GA
Here is an idea - maybe. Many people have added leads from the battery to the storage compartment in the fronk to be used when the car is in long term storage, at which time they attach a charger to the leads. I suppose you could carry a spare battery and just hook it up if you have a battery problem. Remember the Tesla does not use the typical big ampreage car battery, the one is my car is just 30Ah. I have no idea if this would work, just an idea the popped into my mind.

What do you think battery gurus?

But you should definitely carry an air compressor with you all of the time. One that plugs into a 12V outlet should be fine.
 
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Rice&Curry

Member
May 9, 2018
475
236
San Jose
Here is an idea - maybe. Many people have added leads from the battery to the storage compartment in the fronk to be used when the car is in long term storage, at which time they attach a charger to the leads. I suppose you could carry a spare battery and just hook it up if you have a battery problem. Remember the Tesla does not use the typical big ampreage car battery, the one is my car is just 30Ah. I have no idea if this would work, just an idea the popped into my mind.

What do you think battery gurus?

But you should definitely carry an air compressor with you all of the time. One that plugs into a 12V outlet should be fine.
Thanks for your suggestion - I am not sure how the Tesla BMS will react with external trickle charging w/o completely disconnecting the 12V . During travels jump start looks to be a more viable option till you can drive to a location where help may be available for long term fix. Not sure if the head lamps, brake lights and turn signal will work after I am able to jumpstart the 12V and drive to get the 12v fixed.
 
Thanks for your suggestion - I am not sure how the Tesla BMS will react with external trickle charging w/o completely disconnecting the 12V . During travels jump start looks to be a more viable option till you can drive to a location where help may be available for long term fix. Not sure if the head lamps, brake lights and turn signal will work after I am able to jumpstart the 12V and drive to get the 12v fixed.
I put a trickle charger on the 12V non lithium battery when I left for a few weeks and it works fine. The deep cycle 12v battery has no BMS system, but I imagine the new Teslas with the lithium 12V battery would have a BMS system built in. I also have lithium batteries with built in BMS for a fifth wheel and had to buy a charger designed to charge a lithium battery in order to charge one of the batteries.
 

Rice&Curry

Member
May 9, 2018
475
236
San Jose
I put a trickle charger on the 12V non lithium battery when I left for a few weeks and it works fine. The deep cycle 12v battery has no BMS system, but I imagine the new Teslas with the lithium 12V battery would have a BMS system built in. I also have lithium batteries with built in BMS for a fifth wheel and had to buy a charger designed to charge a lithium battery in order to charge one of the batteries.
Thanks. I do have a portable trickle charger will keep it handy.
 

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