Sean.
Active Member
Nearly 5 years old. Should I be worried? Maybe I’ll look up the service manual and run an inductance/CCA test on the existing battery.
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There was a 3rd party 12v lithium battery but I can't find it online anymore. Anyone have a link?
Attach your small 12v (or 9) to the cowing hole coverCarrying an MN23 to break into the car sounds pretty sensible, but where? I also have a print of the manual pages of how to use the mini leads to pop the frunk in a dead battery situation, but they, like the battery, would be in the rear centre console.
If the 12v goes you can't get into the car, can you? So my instructions for how to, and the battery to do it with are in the locked car? Should I strap both to the inside of the tow bar cover so they can be accessed?
Overall tho, I think I'd go for just replacing the main 12v battery rather than carrying a spare? My car is coming up to 3 years, so may add that to the pre-first MOT list along with brakefluid etc.
As others have said, if you think the battery is only good for 2 years (personally I'd say you should expect 3 years, and early failures were due to poor charging that Tesla has now fixed in software) then why not just replace the original rather than carrying around the spare?As I spend a fair number of thousand kilometers in foreign parts and rue the limitations of Tesla's roadside empty promises, I bought a 12 V battery from Europarts. Good price as they are having a mid-year sale of sorts. I got a four year warranty which seems to be a lot better performance than the one that Tesla fits that seems to die after two years. Having passed my 3's second birthday, I thought it wise to gird myself.
I think the idea is that you can pop the bonnet using your small battery and then get access to the 12v battery in the car ... attach ye olde jump leads to any other 12v vehicle battery and hope that starts the car and lets you in. (Of course few people carry jump leads these days so it's probably going to need a call to AA or other rescue service anyway! Having said that I do carry my home made mini fob which contains the necessary 12v battery to start that process.)If the 12v goes you can't get into the car, can you? So my instructions for how to, and the battery to do it with are in the locked car? Should I strap both to the inside of the tow bar cover so they can be accessed?
This is my DIY mini fob that nowadays contains a plastic wrapped 23A 12v battery as well as my old keycard electronics (it was breaking after sitting on it once too often!)I think the idea is that you can pop the bonnet using your small battery and then get access to the 12v battery in the car ... attach ye olde jump leads to any other 12v vehicle battery and hope that starts the car and lets you in. (Of course few people carry jump leads these days so it's probably going to need a call to AA or other rescue service anyway! Having said that I do carry my home made mini fob which contains the necessary 12v battery to start that process.)
And in case someone is wondering if this means your frunk could be opened by a bad person… this battery trick only works to open the bonnet if your main 12v battery has actually failed.You can fit the MN23 with the leads behind the tow cover in the front bumper. Put one in a good plastic bag, then insulation tape it to the leads so its there when you need it. Just press on the cover around the 2 o'clock position and pull it out, then feed the wires back in once you've put the battery in place. Then you've a 12v right where you need it should the situation ever arise.
As others have said, if you think the battery is only good for 2 years (personally I'd say you should expect 3 years, and early failures were due to poor charging that Tesla has now fixed in software) then why not just replace the original rather than carrying around the spare?
12v batteries are bolted down for good reason - in an accident that is a heavy object that could do a lot of damage and get acid leaks on top of any physical damage it could do.
Lead acid batteries need to be kept charged so unless you regularly charge that battery it will end up in a worse state than your original.
If I felt the need to carry a 12v battery then I would have just gone with a small 12v motorbike battery and leads to use as a temporary replacement to get me out of a tight spot - carrying around a full size replacement seems overkill.
All good, but I am sure, like 100%, that you can purchase a simple 12v battery at any petrol station in france. Why you want to carry it, really? You definitelly were not carrying spare batteries or alternators with you in your old ICE car, were you?All that is on board. I stow the rescue 12V in the lower boot so no spillage/crash disasters anticipated. I have a 12V lithium jumper battery (with a handy torch/beacon that signals SOS if required) stowed in the frunk and an MN23 secreted about the tow eye port. I charge the rescue battery weekly with a trickle charge when I am not gadding about.
ISTR the M3 battery is an uncommon size. I'm unwilling to surrender to chance and the rape of a motorway service station/recovery assistant's assessment of the depth of my crisis. When I drove a 64 Lotus Elan back in the States, a spare battery option was a consideration ;-) Smith Electrics - still revenging the revolutionary war of 1776.All good, but I am sure, like 100%, that you can purchase a simple 12v battery at any petrol station in france. Why you want to carry it, really? You definitelly were not carrying spare batteries or alternators with you in your old ICE car, were you?
But it's like failing ICE - in some cases it happens unexpectedly.Sadly I know what an inconvenience 12v failure is, although to be fair, it actually turned out to be a safety issue with the main battery that caused the car to shutdown.
Nevertheless I now have an MN 23 taped to the 12v wires behind the towing eye so that I can quickly and easily get into the frunk where I keep a more powerful jumper battery and most importantly a USB mobile phone charging cable (attached to a juice pack).
A major point I took away from my experience earlier this year was how long I spent on the phone organising the recovery (or not!).
I also carry a RoadHero spare on any long journeys and a puncture repair kit too.
The trouble with the dreaded 12v failure is that it's quite possible that you will have no idea it's coming.
It's just reminded me to fit one of those bluetooth battery monitors - I shall do it on Sunday.
Nearly 5 years old. Should I be worried? Maybe I’ll look up the service manual and run an inductance/CCA test on the existing battery.
Sadly I know what an inconvenience 12v failure is, although to be fair, it actually turned out to be a safety issue with the main battery that caused the car to shutdown.
Gruber.comThere was a 3rd party 12v lithium battery but I can't find it online anymore. Anyone have a link?
Also how long is the 12v supposed to last?