Vampire Drain Fix: How to solve in under a minute (indoor or outdoor)

[BobinIndy]

I have a question for those with dual battery versions. It seems likely that supplying 12v via the OBD2 port will only maintain one of the batteries. Since the truck will no longer wake up and run a periodic 12v charge cycle the second battery will eventually lose enough charge that the truck will not boot up fully. This might leave you in the situation where the only choice is to access and charge the second battery via the frunk. Is my understanding correct.

I was wondering the same.

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[KMWNAZ]

I know this is mostly about how to offset VD while camping, but I'm not sure why I would need to plug in the OBD if I am at home. Why not plug the trickle charger into a regular household outlet? Is there a benefit to plugging it into the OBD?

 

[Highmeadows]

Using the OBD port is more convenient than connecting directly to the battery(ies). There are several threads where owners have addressed the VD problem by installing 120v powered battery chargers for when parked at home. In my case the truck lives outside the garage so the solar panel option is the best one.

 

[MacO512]

I know this is mostly about how to offset VD while camping, but I'm not sure why I would need to plug in the OBD if I am at home. Why not plug the trickle charger into a regular household outlet? Is there a benefit to plugging it into the OBD?

You do both at home - you plug the input of the trickle charger into a household outlet. You plug the trickle charger output to OBD to keep the 12v battery topped off. Many users report KWh savings plus it might prolong the health of the 12v AGM.

Instead of pugging output to OBD you could wire directly to the 12v battery. OBD connection is just a convenance.

 

[KMWNAZ]

You do both at home - you plug the input of the trickle charger into a household outlet. You plug the trickle charger output to OBD to keep the 12v battery topped off. Many users report KWh savings plus it might prolong the health of the 12v AGM.

Instead of pugging output to OBD you could wire directly to the 12v battery. OBD connection is just a convenance.

Ahhhh... Didn't realize that part. "plugging output to OBD" that it feeds the 12V. Thanks for clarification.

 

[MacO512]

I have a question for those with dual battery versions. It seems likely that supplying 12v via the OBD2 port will only maintain one of the batteries. Since the truck will no longer wake up and run a periodic 12v charge cycle the second battery will eventually lose enough charge that the truck will not boot up fully. This might leave you in the situation where the only choice is to access and charge the second battery via the frunk. Is my understanding correct.

That's a good question. If I had a dual battery R1 I probably wouldn't use the trickle charger to OBD unless it was for a rare camping trip or extended parking.

Would change my opinion if someone has an explanation of the OBD charging keeping the secondary battery maintained. I guess someone with dual AGM could do a test and see what voltage drop the secondary battery has over 24/48hrs or such. If all of the vampire drain only hits the primary battery when asleep the OBD trickle charger should be fine.

 

[RJK75]

Is it part of the design / spec to allow energy to be back fed into the ODB port? Just seems like a bad idea to feed energy into a system was not design for it. But maybe its part of the design / specs and I've never known.

 

[gultin]

Good question indeed, and I was wondering the same since I have a dual 12V. My reasoning so far has been that given that charging via the OBD route is basically nearly fully arresting the vehicle wake ups, I imagine much of the drain was going out of the primary battery. If the secondary battery were to also be contributing to the drain, I imagine Rivian's systems would've been smart enough to do the necessary wake up to charge the secondary whenever needed. If the two 12V batteries were truly independently wired, it wouldn't make sense to use the primary's charge/voltage level to charge both batteries. Any fallacy with this reasoning (other than trusting Rivian to do the right thing, which they didn't do in the first place w.r.t the whole 12V architecture)?

@MacO512, so far I've not done a long enough trip gather conclusive evidence on this. If the secondary 12V were to be slowly draining, I'd be more worried about it on an extended trip though, since for shorter trips, I imagine both batteries would get charged during the drives as well.

Related question for extra credit:
What sub-systems in the vehicle do each of the primary and secondary 12V batteries support?

 

[gultin]

Is it part of the design / spec to allow energy to be back fed into the ODB port? Just seems like a bad idea to feed energy into a system was not design for it. But maybe its part of the design / specs and I've never known.

ICE vehicle owners have used battery maintainers via OBD for quite a while. I'm simply hoping that architecture isn't all that different for EVs using 12V systems.

 

[MacO512]

Is it part of the design / spec to allow energy to be back fed into the ODB port? Just seems like a bad idea to feed energy into a system was not design for it. But maybe its part of the design / specs and I've never known.

The R1 system was designed to have vampire drain, waste energy, and overload a tiny 12v battery which often leads to failure in a year or less possibly bricking the vehicle.

I'm sure the R1 was not designed to have a trickle charger on the OBD or anywhere. This is a hack to mitigate R1 poor design.

The hack has a tiny current at 3amps, and AGM batteries are fine being maintained at 100% so I don't see any risk. But if you want an official solution from Rivian you'll need to accept their official stance of 5% vampire drain a day being "normal"

 

[MacO512]

Good question indeed, and I was wondering the same since I have a dual 12V. My reasoning so far has been that given that charging via the OBD route is basically nearly fully arresting the vehicle wake ups, I imagine much of the drain was going out of the primary battery. If the secondary battery were to also be contributing to the drain, I imagine Rivian's systems would've been smart enough to do the necessary wake up to charge the secondary whenever needed. If the two 12V batteries were truly independently wired, it wouldn't make sense to use the primary's charge/voltage level to charge both batteries. Any fallacy with this reasoning (other than trusting Rivian to do the right thing, which they didn't do in the first place w.r.t the whole 12V architecture)?

@MacO512, so far I've not done a long enough trip gather conclusive evidence on this. If the secondary 12V were to be slowly draining, I'd be more worried about it on an extended trip though, since for shorter trips, I imagine both batteries would get charged during the drives as well.

Related question for extra credit:
What sub-systems in the vehicle do each of the primary and secondary 12V batteries support?

It was explained to me primary controls locks/infotainment and drivers side while secondary controls passenger side and some others ECU. Someone else might know more exactly.

 

[Gurule92]

Anybody set up a usb battery on this thing yet? My anker 737 can do like 15v at 3A (hoping it would adjust but may need something closer to 12), and charge when the truck's on, but i dont have my truck yet lol

 

[MacO512]

Anybody set up a usb battery on this thing yet? My anker 737 can do like 15v at 3A (hoping it would adjust but may need something closer to 12), and charge when the truck's on, but i dont have my truck yet lol

It wouldn't charge an AGM battery to proper voltages. If in a real pinch - like camping and needed every mile of range, I'd be fine doing it for a few days. For longer solution you can get a 3amp battery tender for as little as $20.

 

[bbonkk]

https://www.amazon.com/SUNER-POWER-...D52WDM/ref=cm_cr_arp_d_bdcrb_top?ie=UTF8&th=1

Looks like the solar charger noted is also a battery tender. So why do you need the OBD connecter and a tender if you plug it into the 12v cig outlet?

 

[SSteveEV]

Looks like the solar charger noted is also a battery tender. So why do you need the OBD connecter and a tender if you plug it into the 12v cig outlet?

The OBD port is always connected to the battery but the 12v outlet is only active when the system is booted up, ie car on. The tender is used instead of the solar when plugged in to shore power.

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