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Discussion Starter · #1 ·
I am posing this question to my guide, but thought it would be worthwhile to share here as well.

"I was looking in the Rivian tow guide, and on Page 38, it shows procedures for disconnecting the HV and 12V batteries, but nothing about reconnecting them. If I disconnect them for an extended period (30-60 days) will the HV battery continue to discharge, or is it considered an open circuit? When I reconnect the batteries (in reverse order I assume), will a simple software or vehicle restart bring it back to life (in theory)? (from restart procedures in the Tow guide)"

Purpose: shipping the vehicle, I am trying to avoid a dead battery on arrival, in case the ship sits outside some random port (like Charlotte) for 6-8 weeks... which happened with my Tesla M3LR (thankfully it did not have much vampire drain)
 

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Those are great questions. I know from experience that "flooded cell" and AGM batteries will self-drain (to the tune of about 10% per month) when they are completely disconnected and stored. For some reason, they tend to drain faster when sitting on a concrete floor or steel shelf than they do when stored on a wood shelf or a wooden block on a dirt floor. I don't think that's merely anecdotal or an "urban myth".

EDIT: I looked this up. It appears that it "used to be true" but isn't anymore (now that the battery shells are made of polypropylene. The rubber (and before that--wooden) battery cases would permit a circuit to be completed when the acid "sweated" through the case or moisture penetrated the wood from outside. This can still happen if the terminals and battery case are "filthy" (like in a lawn mower or tractor)...the circuit is completed between positive and negative poles of the battery and causes it to drain faster.
 

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If I disconnect them for an extended period (30-60 days) will the HV battery continue to discharge, or is it considered an open circuit?
Well it will be an open circuit, but Lithium batteries do have some amount of self-discharge (charge goes down over time even when disconnected from any circuit). I don't know how much that is with the Rivian batteries/BMS, but I'm sure it's a lot less than the "vampire drain" of leaving the 12V and HV connected. Sounds like a good option for you, but I would confirm with Rivian!


When I reconnect the batteries (in reverse order I assume), will a simple software or vehicle restart bring it back to life (in theory)?
As long as the batteries retain a sufficient charge, I would expect all you have to do is reconnect them. The 12V might be the one that gives you the problem if the vehicle sits around too long - I would make sure those are fully topped up before trying to reconnect them. Again, I advise checking with Rivian - preferably one of the service center guys, as they are likely to have more practical knowledge of this than the CS representative on the phone.
 

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If you MUST have to disconnect the batteries than the correct way to do this is:

Locate the frunk manual release cable and make sure it will be accessible, otherwise you won't be able to open the frunk when the vehicle is dead. (driver side near the steering rack).
Locate and disconnect the fireman's loop connector ( driver's side under the cowl cover)
disconnect both primary and secondary 12V battery ground cables (careful not to drop the nuts)

!!!!!! THIS PROCEDURE WILL COMPLETELTY DISEABLE THE VEHICLE IN WHATEVER STATE IT IS!!!! MEANIG LOWERED, OR RISED, LOCKED, UNLOCKED, CLOSED TAILGATE AND FRUNK WINDOWS UP, ETC..... AND YOU WILL NOT BE ABLE TO CHANGE ANYTHING UNTILL YOU ENABLE POWER AGAIN !!!!!

To bring the vehicle back to life.
First reconnect the fireman's loop
Reconnect both 12V ground cables.( !!!THIS PART IS IMPORTANT!!! ) "timing this procedure as close as possible" ( if there is more than a few seconds delay between primary and secondary batteries powering up you will have multiple DTC's (trouble codes)
You might need some help to get the nuts started while you hold the cables in place. or you can wait until the vehicle completely powers up, after the DCDC have take over (around 3 minutes) you can let go of one of the ground cables and reconnect the 12V battery nuts one at the time.
Perform a 12V soft reset

Hope this works. good luck!
 

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THANK YOU for your experience. :) What do you mean by 12V soft reset? Also, may I ask how you learned this? Just trying to mine any valuable lessons learned here. Thank you so much!
to do a 12V reset press and hold the left outer button on the steering wheel and the hazard button at the same time for about 20 seconds until you see a notification on the screen that the vhicle is going to do a 12V reset. you can let go of the buttons and let it do its thing (takes about 5 minutes)

I took this picture 2 years ago in Baudette Minnesota during cold wehater testing ;);)
Wheel Tire Automotive parking light Car Sky
 

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Discussion Starter · #8 ·
To bring the vehicle back to life.
First reconnect the fireman's loop
Reconnect both 12V ground cables.( !!!THIS PART IS IMPORTANT!!! ) "timing this procedure as close as possible" ( if there is more than a few seconds delay between primary and secondary batteries powering up you will have multiple DTC's (trouble codes)
You might need some help to get the nuts started while you hold the cables in place. or you can wait until the vehicle completely powers up, after the DCDC have take over (around 3 minutes) you can let go of one of the ground cables and reconnect the 12V battery nuts one at the time.
Perform a 12V soft reset
I would still like to know how you know this! The truck is loaded in the container and the fireman's loop and ground cables are disconnected, and the frunk is propped open with a foam noodle:
Automotive parking light Vehicle Grille Hood Car


I should have it in about 30 days...but at least now I am not worried about vampire drain. Only worried that it might be a brick when I try to resuscitate it...
 
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