Gen 1 Vampire Drain (Possibly) Solved (or Hacked)

[chops]

Great question, don't know the actual answer BUT I'm guessing it would not.

I'm just guessing it wouldn't based on the amount of power needed to jump the battery from the pigtails is greater than from the battery directly. There must be some type of circuitry that avoids a free flow of current to the 12V all the time.

this was the first thing i tried. it did not work

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[DaisyRivian]

Here are some photos of my trickle charger install from yesterday.

- I removed the frunk tub (6 bolts and two cable connectors) so I could climb in and work on routing the 120V feed from the front tow hook under and across to the drain port at the bottom of the frunk tub.
- The 120V AC feed to the trickle charger runs through the horn opening that's right above the driver side tow hook in the front grill.
- When not plugged in, I just tuck the male 120V plug end in to the tow hook pocket and the tow hook rubber gasket holds it snugly in place, nice and neat.

314159

Thank you very much. So much new to learn and consider. DH

 

[Herb]

Anyone try charging through 7 pin or other 12v "cigarette lighter"?

Not sure if there ever was an answer. I have successfully connected through the cigarette plug in the gear tunnel. This will require to adjust the delay timer for the outlets (this is buried in the settings and the max. delay is 72hrs). I have a 1 battery T and I have no idea to which battery the plug connects to in a 2 battery models. Through the connection I track been able to monitor and track SOC of the 12V battery and can confirm that when the 12V battery drops to a certain level the DC/DC system and the HV battery recharge. I've done this a while ago and forget the numbers but it was between 12.xx and 13.xx. I think that the condition of the 12V battery is directly related to the level of VD.

 

[Riviot]

Alright y'all, having sold my motorcycle and still owning the trickle charger, my first winter project will be rigging it up to ?.

For @CO-rayman....
If you pop the lid off the red fuse/connection terminal covers in the top photo, you'll see each battery has one unused 300 amp fuse terminal stud inside. That's where I connected the positive leads for the primary and secondary batt charger, it takes an M8 size metric nut. I used the negative lead post on each battery for the negative charger leads. If you hold the negative leads down tight on to the post when you remove the nut to install the charger ring terminal the vehicle won't throw any codes because the 12V batts stay connected during the procedure. Mine didn't throw any codes when I started it after the install.

Did you connect one split line to both batteries? So both 12v batteries are now directly connected? Without opening mine and looking, I'm not sure if they are.

Since I think the OBD2 port only connects to 1 battery, you should only need to connect to one battery (the "primary" closer to the driver side) to the trickle charger. I might test it out, but can't do it this weekend.

Did you test? @CO-rayman seems to have less loss charging both, but single is still an improvement.

After a couple of weeks monitoring the supplemental 12v charging I'm seeing a consistent 0.44 Kwh/day consumption use by the 12v charger. If I let the vehicle sit, after 3-5 days the Rivian display will show 1 Kwh of consumption, but I'm not sure how to interpret that since I see no drop in range or power use by my 220v charger. So depending on if I count that 1 Kwh or not vampire drain is using between 0.44 and 0.67 kwh/day. Prior to adding the 12v charger I was consistently losing 2.33 kwh/day, so I'm very happy with the improvement.

The only thing I have turned off is gear guard. No other special settings. This is a March 2024 single battery version Vin ends in the 36,000's

For ease of charging I'm connecting the 12v charger via a ChargeSafe - Magnetic Trickle Charger which I attached via included double sided tape to the left lower front windshield. The cable hangs down from the ceiling about 3 feet off the floor (as does by 220v charger cable) such that they are just in front of the left corner of vehicle where I park in the garage. This makes plugging and unplugging very ease. My 12v charger is rated to 4 amps, but I'm not sure if that matters.

I don't drive much, so the vampire drain was nearly half of my overall Rivian consumption and driving me crazy. I'm not worried about VD when on trips, since it's such a small portion of the time my Rivian spends inactive. I'm very happy with the results of this setup having cut loss down to about a 5th of baseline

.

Is your real name Dexter? That's a lot of primeval murder potential.

Starting to wonder if this is the longest thread at 28 pages

In any case, thanks to all your input on this subject (and for @shrink who started this thread), I decided to install SAE connectors direct to my two 12V batteries. This approach allows me to directly trickle charge those batteries as well as test the batteries for health before bricking (using a device like this https://www.amazon.com/gp/product/B0017R5EQK/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)

I tend to drive my R1T regularly and at most may let it sit for 4 days. In summary, with both 12V connected to 2 separate trickle chargers (4 Amp ones), I lose 0 miles and 0% SOC over the extended 4-day non-use.

I first tried using the OBDII port (per @JerseyGreens) since it would be easy, followed by just trickle charging the primary battery direct, and finally settled on trickle charging both batteries (per@NY_Rob).

Here is my log for losses over 4 days:

OBDII charging lost 2%, 7 miles
charging primary 12V lost 1%, 3 miles
charging both 12V lost 0%, 0 miles

My data is just for 4 days at a time since that is my maximum period for non-use. Also, I didn't track how much power the trickle chargers use, but they definitely don't stay on long and I am sure they won't make up for the huge percent losses from the high voltage battery.

I placed my SAE connectors at the two corners under the hood towards the windshield (per @ascientist).

Do you have one on each side of the windshield, and both connected to both batteries?

 

[NY_Rob]

Did you connect one split line to both batteries? So both 12v batteries are now directly connected? Without opening mine and looking, I'm not sure if they are.

The trickle charger I used was a dual bank charger that has two cables and separate charging circuits, it keeps the batts isolated.

 

[Riviot]

The trickle charger I used was a dual bank charger that has two cables and separate charging circuits, it keeps the batts isolated.

What do you think would happen if they were directly connected? They load balance when on already, right, so this would be a continuous load balance.

 

[NY_Rob]

What do you think would happen if they were directly connected? They load balance when on already, right, so this would be a continuous load balance.

In Theory, I think that would be okay, but I was unwilling to try that on my $90K vehicle.
The 400V DC to 12V DC charging circuits are most likely isolated in the Gen 1 vehicles, but again, testing that was a chance I was unwilling to take due to the high risk/low reward ratio.
It's likely the 12V load circuits in the vehicle would not care if they are being powered by a single or dual batts as they all share a common ground/return path anyway. I'd be more concerned about the discrete 12V charging circuits now being bridged if you combine the 12V batts into one circuit.

Being we are completely operating in a vacuum due to Rivian locking down any info on their electrical circuits, IMO, combining the two 12V batts is a very risky proposition.

 

[Riviot]

In Theory, I think that would be okay, but I was unwilling to try that on my $90K vehicle.
The 400v DC to 12V DC charging circuits are most likely isolated in the Gen 1 vehicles, but again, testing that was a chance I was unwilling to take due to the high risk/low reward ratio.
It's likely the 12V load circuits in the vehicle would not care if they are being powered by a single or dual batts as they all share a common ground/return path anyway. I'd be more concerned about the discrete 12V charging circuits now being bridged if you combine the 12V batts into one circuit.

Thanks! I'll be poking around later today. I'm feeling bold with the low voltage circuits, let's see what happens. Tis the season!

 

[NY_Rob]

Thanks! I'll be poking around later today. I'm feeling bold with the low voltage circuits, let's see what happens. Tis the season!

I've been toying around with making my own 12V battery packs out of cells I get from batteryhookup.com for several years now, and one piece of advice I can offer if you go down this road is to disconnect the common neg lead from the batts, let them settle for a bit and measure their individual voltages very closely. They need to be very close in voltage before you bridge them otherwise bad things (Boom!!) can happen! Big differential, big spark!!

 

[FraserC]

Wow, this is an interesting and informative thread!! So I have a new 2025 R1T with only 1200 miles, with (I would hope) a new, healthy 12V battery. But I am seeing big VD numbers, and having been out of town for 2 weeks the R1T was sitting on my driveway in chilly Cincinnati. From when we left to return (12 days) it lost 55 Kwh or 5Kwh per day. Since a 12V trickle charger is inexpensive, and I already have two power banks (300Wh and 1000Wh), I figured I would trickle charge that 12V battery and compare with the VD I've been seeing so far. I'll report back on my results. P.S. Anyone else with a near new Rivian seeing this kind of VD level?

 

[NY_Rob]

Since a 12V trickle charger is inexpensive, and I already have two power banks (300Wh and 1000Wh), I figured I would trickle charge that 12V battery and compare with the VD I've been seeing so far. I'll report back on my results.

I think you will be happily surprised with drastically reduced VD numbers!

Looking forward to seeing your results, good luck!

 

[an-thu-knee]

I have a setup I can use based on the success of others in this thread - a battery tender trickle charging through the OBDII Port. Either plugged into an outlet or my 750wh power station. One question - is there any risk to running this setup for several days while away, while my car (in my garage) is also plugged into my JuiceBox home charger (40 Amp)? I know there's not really much of a benefit since I'd be saving nothing more than a few cents of energy at best, but more curious as an experiment.

 

[FraserC]

I suspect that if you charge both the 12V and the drive battery you won't see any difference, since while plugged into your Juicebox there will be no VD for the power station to prevent...?

 

[an-thu-knee]

I suspect that if you charge both the 12V and the drive battery you won't see any difference, since while plugged into your Juicebox there will be no VD for the power station to prevent...?

My home charger is on a schedule so it only charges overnight. it usually kicks on every night to recharge the 1-2 miles I've lost that day.

 

[CO-rayman]

Alright y'all, having sold my motorcycle and still owning the trickle charger, my first winter project will be rigging it up to ?.



Did you connect one split line to both batteries? So both 12v batteries are now directly connected? Without opening mine and looking, I'm not sure if they are.



Did you test? @CO-rayman seems to have less loss charging both, but single is still an improvement.



Is your real name Dexter? That's a lot of primeval murder potential.

Do you have one on each side of the windshield, and both connected to both batteries?

I have one on each side of the windshield tucked in at the edge and each is connected to a single battery.

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