Trying to Jumpstart the Rivian 12V System Using Schumacher Portable Jumper

Vincent · 2025-01-10T19:33:15+00:00

A friend needed to support his son who would be running a 'very cold' marathon on Sunday while rucking a 30 pound pack. The outside temps will be around 15F-20F the whole time. The location of the race is nowhere close to any L2 chargers, but he's not worried about driving distance to or from the race - it is 50 miles away from his house. He says he will be sitting in his ruck with his laptop and watching his live track+Garmin inReach data for the duration of the race (about 4 hours). He thought about taking his Honda EB2800i gasoline powered generator, if he can use the level 1 EVSE attached to the generator and keep the truck running with full heat + power - without really consuming much of the truck's main battery? He feels it's super dorky to have a gas generator running while attached to a Rivian in the woods, just so he can stay warm, but don't know if it would work ok this way and 'preserve' the main battery so he doesn't need to worry about driving range when we wants to head home. He talked to me about it and I told him the simple answer is NO. I tested this theory the other night when I was plugged into a 5.9kW charger. To maintain the interior amenities (interior and exterior lights, radio, heater, seat heaters), it took almost all of the charge. I charged for 15 minutes, it delivered 1.6kW, and the truck consumed 1.4kW, delivering only 0.2kW to the truck battery. Told him he would be using a laptop at another 200ish watts. The little trickle charger charges at 1.4kW on a good day, 1.2kW is normal for me. You can slow the bleed, but you cant stop it. My advise to him was for him to charge it up to 100% at home, and roll the dice is what I would do.

Rivian Mom

Active Wheeler

Jan 4, 2025

I just posted an article about wanting to replace my 12V battery proactively so as to avoid issues like this. A friend was trying to jumpstart his 12V system on his R1T. There was no issues hooking up to the primary battery but after a few hours and no luck he wanted to try the secondary. After opening the frunk compartment he saw the following.

With no clearly marked negative side indicator. He also saw another thread with a video where a similar looking unit was claimed to be a capacitor (not a battery).

He used a Schumacher portable jumper and it’s was on the 30A setting. After a bit of fluctuations between 3-5v, tends to resolve on 12v as shown in the image. So, is seemed to indicate that it was charged but I don't think he knows cause he recently just bought the Schumacher system.

One tip I've learned so far was, If the left unit's passenger-side terminal is black (negative), then it is an earlier build with dual 12V batteries. If it instead has a red (positive) connection there, then it is a newer build with a single 12V battery (capacitor on the left, 12V battery on the right / driver's side).

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