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

[HimuraMOdo]

One more update:

clear pattern. The big question and only Rivian can provide this info - who is consuming the power while sleeping? And Rivian decided to ignore this.

Looking at this chart, it seems the truck's voltage threshold for a float charge cycle is at about 12V.

It looks like there was a surge current that momentarily pull the battery voltage down below 12V (probably due to the age of the battery causing a slightly higher internal impedance) triggering the charging cycle at ~12:20PM and ~2:40PM.
Has your 12V battery been replaced recently? Or it's the original one? How old is it?

Once the charge cycle is done, the battery voltage float down to ~12.6V and being drain consistently. From 12:40PM to 2:40PM, it normally drop by about 0.3V. For an 18Ah battery, that means the average current draw would be about 1.3A (Assuming your battery is healthy and has full capacity)

I can see why Rivian changed the secondary battery to super cap now.

Sponsored

 

[shap]

Looking at this chart, it seems the truck's voltage threshold for a float charge cycle is at about 12V.

It looks like there was a surge current that momentarily pull the battery voltage down below 12V (probably due to the age of the battery causing a slightly higher internal impedance) triggering the charging cycle at ~12:20PM and ~2:40PM.
Has your 12V battery been replaced recently? Or it's the original one? How old is it?

Once the charge cycle is done, the battery voltage float down to ~12.6V and being drain consistently. From 12:40PM to 2:40PM, it normally drop by about 0.3V. For an 18Ah battery, that means the average current draw would be about 1.3A (Assuming your battery is healthy and has full capacity)

I can see why Rivian changed the secondary battery to super cap now.

I have an original battery. March 2023, single battery.

When you say "I can see why Rivian changed the secondary battery to super cap now." - can you explain why you think they replaced the battery with a capacitor? To remediate the dip?

 

[mudito]

I have an original battery. March 2023, single battery.

When you say "I can see why Rivian changed the secondary battery to super cap now." - can you explain why you think they replaced the battery with a capacitor? To remediate the dip?

While he sounded like an expert and I am not one, my best answer is that because of how capacitors behave (Attenuating charge/discharge curves), they can provide with an immediate higher current amount when needed by a component which will avoid the sudden voltage drop on the main battery.

Let's say you have 2x 12V batteries in parallel with each able to supply up to 30amps (WARNING, I'm making up numbers here! ), then those two will able to supply a surge of demand of a bit over 60amps but if that's the case, the voltage WILL drop triggering a DC-to-DC charging event.

If I add a capacitor in that circuit (even better, a super-cap), it can slowly charge to it's capacity and might be able to supply current to a 100 or 200amps demands easily (I've seen supercaps banks that are rated to 1900 amps) and that means that 12V battery won't sweat on that surge and take over for the nominal steady-state current supply keeping the voltage more stable and not needing the immediate DC-to-DC charge after that current surge spike.


I'm not an electronic engineer (used to be an Electromechanical engineer back 25 yrs ago!, but have been working in IT for a while) so take what I said with a grain of salt. I just know enough to know that I might be in the right direction with this concept

 

[shap]

Make sense, thank you!

 

[NY_Rob]

While he sounded like an expert and I am not one, my best answer is that because of how capacitors behave (Attenuating charge/discharge curves), they can provide with an immediate higher current amount when needed by a component which will avoid the sudden voltage drop on the main battery.

Let's say you have 2x 12V batteries in parallel with each able to supply up to 30amps (WARNING, I'm making up numbers here! ), then those two will able to supply a surge of demand of a bit over 60amps but if that's the case, the voltage WILL drop triggering a DC-to-DC charging event.

If I add a capacitor in that circuit (even better, a super-cap), it can slowly charge to it's capacity and might be able to supply current to a 100 or 200amps demands easily (I've seen supercaps banks that are rated to 1900 amps) and that means that 12V battery won't sweat on that surge and take over for the nominal steady-state current supply keeping the voltage more stable and not needing the immediate DC-to-DC charge after that current surge spike.


I'm not an electronic engineer (used to be an Electromechanical engineer back 25 yrs ago!, but have been working in IT for a while) so take what I said with a grain of salt. I just know enough to know that I might be in the right direction with this concept

I think you're pretty spot on in your analysis!

I have a automotive booster/jump starter device that has no internal batteries that need constant charging and are always dead when you need it. This device has an 800amp capacity and has a series of super caps inside which you simply connect it to the "dead" car battery and it can usually pull enough energy from that battery (for a few min time) and burst it back on demand which will usually start the dead vehicle. If the dead vehicle battery is really "dead", like only several volts and doesn't have enough energy to charge the super caps, you simply plug the device in to your vehicle (cig lighter port or directly to your 12V battery) and let it charge up for about 2min and then use it on the dead vehicle. it's an ingenious design that works great and never requires a charged battery inside the booster pack. I used it several times when we had a spare BMW 330i that we didn't run for months at a time.. it's alarm system eventually killed the 12V battery after sitting for 45days+ so it always needed a jump.

 

[mudito]

I think you're pretty spot on in your analysis!

I'll show this to my wife when I tell her "I'm always right"

 

[NY_Rob]

I'll show this to my wife when I tell her "I'm always right"

Yeah, no.. that never ends well (for us guys)

 

[JerseyGreens]

Side question in this lengthy thread.

For those that had dual 12v batteries replaced. Do they replace one with a capacitor or just two new 12v batteries?

 

[mudito]

Side question in this lengthy thread.

For those that had dual 12v batteries replaced. Do they replace one with a capacitor or just two new 12v batteries?

Two new batteries, same dual 12V setup. I've got mine replaced 10 days ago.

I've read a rumor that Rivian might have changed the provider/model of the batteries but I couldn't validate that w/o disassembly the newly installed batteries which I'm not planning to do

 

[HimuraMOdo]

I have an original battery. March 2023, single battery.

When you say "I can see why Rivian changed the secondary battery to super cap now." - can you explain why you think they replaced the battery with a capacitor? To remediate the dip?

Well, I thought you have dual battery system.
But now I'm not sure anymore.
I originally thought Rivian reroute the 12V system to use the primary as the source and have the super cap(because of the low impedance) in parallel with the primary to lower the surge current dip. But it seems it's not the case now since you have the cap but still seeing the dip in the battery voltage.
It could still be the cap is helping but what Rivian put in isn't enough to soften the blow.
If the cause of the dip before the 12V charge cycle is really because of the surge current of the 12V system waking up. I think Rivian could possibly come up with an Apollo 13 turn on sequence to lower the surge.

 

[JerseyGreens]

Here we go. Dual 12v batteries. Keeping this connected overnight. OBD route. I usually dip 5-7 miles every night. Curious what tomorrow shows.

 

[JerseyGreens]

As expected no VD overnight. Sitting at 135 miles which is the same as last night. Awesome way to protect my excess solar production now.

 

[mudito]

As expected no VD overnight. Sitting at 135 miles which is the same as last night. Awesome way to protect my excess solar production now.

Neat!
How many miles you have on your R1S?

I want to gather data on how long until I start seeing evident signs of VD after the 12v batteries are replaced

 

[JerseyGreens]

Neat!
How many miles you have on your R1S?

I want to gather data on how long until I start seeing evident signs of VD after the 12v batteries are replaced

17,739 to be exact!

 

[ascientist]

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

.

Sponsored