12V Questions

[Visket]

Greetings -

What runs off of the 12V batteries?

What are the technical specs of the DC-to-DC charging system (charging voltage / amperage / low-voltage kick-in / high-voltage stop)?

Are the placement of the 12V batteries more susceptible to outside temperature, or inside temperature? (might Pet Mode keep the batteries from freezing?)

Asking for a friend...

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[shap]

Hello, there are plenty of posts about 12V batteries - I suggest you search the forum. There are also a few youtube videos on how to replace them, that show how they are installed and what each of them is used for. Basically, as with any EV, internal car systems are powered by 12V batteries, for Rivian one battery powers left side, the other right side of the car electronics.

 

[rivian_germany]

Greetings -

What runs off of the 12V batteries?

What are the technical specs of the DC-to-DC charging system (charging voltage / amperage / low-voltage kick-in / high-voltage stop)?

Are the placement of the 12V batteries more susceptible to outside temperature, or inside temperature? (might Pet Mode keep the batteries from freezing?)

Asking for a friend...

I can tell you it kicks in at 12.09V. Then it charges for about 1h40m, if it is a full recharge. What are you.. I mean your friend.. trying to do?

 

[EVLander]

Hello, there are plenty of posts about 12V batteries - I suggest you search the forum. There are also a few youtube videos on how to replace them, that show how they are installed and what each of them is used for. Basically, as with any EV, internal car systems are powered by 12V batteries, for Rivian one battery powers left side, the other right side of the car electronics.

If your R1 has two batteries, one is the main battery, vbatt1, and the other is a back up, vbatt2. All of the ECU are powered by vbatt1, and some specific ECU are connected to vbatt2 and will switch if the voltage drops on vbatt1.

 

[godfodder0901]

If your R1 has two batteries, one is the main battery, vbatt1, and the other is a back up, vbatt2. All of the ECU are powered by vbatt1, and some specific ECU are connected to vbatt2 and will switch if the voltage drops on vbatt1.

I don't think that's what happens here. We've seen plenty of evidence that each of the batteries powers half of the car. Recalling one specific example from this forum, a single battery failed and the passenger side of the vehicle went down, including lights on that half of the vehicle.

 

[Visket]

OK. Relavent answers so far:

What runs 12V: ECU, 12V sockets

Tech Specs of charger: Kicks in at 12.09V; runs 100 minutes.

I shouldn't explain my reasoning any further, for fear that the thread will turn into the usual "I don't know", "you should...", "over-thinking", "why this-or-that...?", "existing thread...", "Yes it is... / No it isn't", "Yo Mama...", blah, blah, blah. But here goes.

I am, er... my buddy is, contemplating two specific issues regarding (here we go - seatbelts on!) replacing the 12 volt lead-acid batteries with LiFePo4 batteries. From previous experience doing such on other projects, I know better than it being a "drop in" affair. Let's stick with the 12.09 volt kick-in, and 100 minute charge time, shall we?

If the charger kicks in at 12.09 volts:

The L-A battery starts getting recharged at 40% DoD. The LFP @ 93% DoD (and dying rapidly). Right?

I said: Right?

So, depending on the charging voltage / amperage, 100 minutes may, or may not charge the LFP battery to 100% (remember, 80%-100% charges much slower than 0%-80%).

So the obvious next question: What are the charging voltage and amperage of the 12 volt charging system?

Rivian_Germany - might you have some technical papers you can share with me? Thanks for furthering this thread.

 

[CommodoreAmiga]

If your R1 has two batteries, one is the main battery, vbatt1, and the other is a back up, vbatt2. All of the ECU are powered by vbatt1, and some specific ECU are connected to vbatt2 and will switch if the voltage drops on vbatt1.

Confidently incorrect.

 

[Visket]

I don't think that's what happens here. We've seen plenty of evidence that each of the batteries powers half of the car. Recalling one specific example from this forum, a single battery failed and the passenger side of the vehicle went down, including lights on that half of the vehicle.

I have a hard time believing that there would be 2 separate 12 volt circuits (left / right), but let's assume that is accurate:

Exactly *what* on the left and right sides of the vehicle are powered by 12 volts?

Thanks -

 

[godfodder0901]

I have a hard time believing that there would be 2 separate 12 volt circuits (left / right), but let's assume that is accurate:

Exactly *what* on the left and right sides of the vehicle are powered by 12 volts?

Thanks -

Search the forum. There are drawings of the left and right fuse boxes. And if you are looking for a replacement battery chemistry, that exists as well. Ohmmu: Rivian R1S / R1T - 12V Battery Installation (Ohmmu) - YouTube

 

[Donald Stanfield]

Someone posted a really great video last week that does a great job explaining why you should NOT change to lithium batteries for the 12v system but YMMV.

 

[Visket]

Someone posted a really great video last week that does a great job explaining why you should NOT change to lithium batteries for the 12v system but YMMV.

I'm trying to categorize which of my questions you are answering... Nope. No help.

But thank you for your participation!

 

[Visket]

Search the forum. There are drawings of the left and right fuse boxes. And if you are looking for a replacement battery chemistry, that exists as well. Ohmmu: Rivian R1S / R1T - 12V Battery Installation (Ohmmu) - YouTube

I searched for "Drawing fuse box" and didn't come up with any threads - except this one. The drawings might (or not) answer my specific questions, so if you can provide a link to said topic, I would much appreciate it.

However, still looking for my other answers!

Thanks -

 

[godfodder0901]

I searched for "Drawing fuse box" and didn't come up with any threads - except this one. The drawings might (or not) answer my specific questions, so if you can provide a link to said topic, I would much appreciate it.

However, still looking for my other answers!

Thanks -

https://www.rivianforums.com/forum/...king-fuse-location-and-type.15029/post-328933
https://www.rivianforums.com/forum/...king-fuse-location-and-type.15029/post-328937

 

[Visket]

https://www.rivianforums.com/forum/...king-fuse-location-and-type.15029/post-328933
https://www.rivianforums.com/forum/...king-fuse-location-and-type.15029/post-328937

I call that a "WIN". Everything I... er.... my buddy wanted know about what sucks down the 12 volt batteries... Thank you.

NEXT:

Charging system voltage / amperage: Waiting for Rivian_Germany to wake up tomorrow morning.

Is battery protected from freezing temps by it's placement?

 

[EVLander]

Confidently incorrect.

You can check my credentials if you like. I was an electronics engineer for Rivian for over three years. My role was to specific test and validate all of the ECUs on both the R1T and the R1S. I have intimate and comprehensive understanding of the ECU functions and circuitry, including power requirements, mechanical restraints and system design. My work there contributed to many design changes that resolved pre-production issues that are reflected in the vehicle today. You are more than welcome to call me out on anything, but you better have proof and data to support your claim.

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