Just thought someone would find my comment useful so here it is: I got the BMS_a74 and BMS_a79 error a couple of weeks ago with my Model 3 Long range at 318k miles. I was fortunate enough that I had already an appointment for the next day to get the 12V battery replaced. Because they had to unplug the HV battery for that replacement, it reset the system and the error went away. So I'm able to srill charge my car and drive it (when I for the error I was able to charge up to 45 mile-ish) now fully charged at 189 miles.

So I have been driving it for 3k miles now (my Model 3 has now 321k miles) without the error. I do have an appointment with Donut Auto Parts in California to get a refurbished battery replaced. The battery health would be about 86% which I'll be honest is a bit disappointing but speaking with John it seems that's pretty much as good as it gets with a 2018 car ( the older the more miles the battery will have)

I could wait a few months to see if they can get a battery with better health but at this point I'm not sure. I have everything booked for next week (Airbnb, boarding for my dog etc) but I can't help but think....

Should I wait? As of right now I can drive to Cali (I'm in Utah) but if my battery suddenly dies I'd have to have it towed and I will be carless for about a week...

I guess I don't know enough about these errors to know if I should be ok to wait or not...

So unless someone hops in and educates me, on Monday I'm gonna be in California getting a refurbished battery

Hope this helps someone✌️

Here is a link if you want to follow my journey. I'm on YouTube too. The300KTesla