12 volt battery, replace now or wait for warning?

[iwannam3]

Had some time so I installed the new battery. Screen was black on restart and I had to plug it into the charger to get things back to normal. Battery I took out tested OK at one place and at another they said he pulled 1,000 amps? for 30 seconds and it was fine. Maybe 100 amps seems more reasonable.

 

[Wennfred]

rate install difficulty 1-10

The difficulty Rate of install 1 - 10 is a 1. Simple to replace. Make sure to shutdown the car via the screen. Also look for this small air hose that’s attached to the upper right side of the battery. Gently pull that out first before lifting the battery.

If you have actually made it so far to 19 - 24 months, replace it and save yourself the hassle. Keep it as a spare.

Fred

 

[PhysicsGuy]

Personally, I'd replace it right now.

If the battery degrades naturally over time (as it's supposed to), then yes, you'll get the warning in plenty of time to replace it.

The problem is that if you check out all of the various Tesla related forums/subreddits, you'll find a discouraging amount of people posting about how their 12v battery failed without any prior warning at all.

IMO (gathered from way too much time spent reading Tesla related content), the OEM battery supplier for the Model 3 has put out at least one bad batch of batteries. Rather than gradually degrading over time as a good lead/acid automotive battery should (and failing in this manner is detectable by the Tesla's software), they just outright fail. No prior warnings, nada... just a completely dead battery.

When I finally get around to replacing mine, I won't be replacing it with the exact make/model that Tesla used from the factory, as I don't want to run the chance of getting yet another bad battery from a manufacturer that, up to this point, hasn't owned up to the fact that they have a large amount of bad from the factory batteries.

FWIW, the battery in the Model 3 is a bit different from standard ICE batteries; the Tesla uses a "Deep Cycle" type battery. Might be worth spending the additional time/research needed to make sure the battery you get is an exact match.

Perhaps a bit tangential, but with what I have read about the low current charging of the 12 volt battery, I don't see how it ever gets pushed through a real absorption cycle. Always slow charging will tend to encourage sulfation and will reduce battery capacity and limit lifetime imo. Proper charging protocols with bulk, absorption and float stages, as well as some deslulfation at 14.4 volts now and then, will really enhance the longevity of a "Deep Cycle" type LA battery.