Having a 12V Backup Plan-- need input....

[Dark-Fx]

Glad to see it is being monitored-- I did not know that was in the app. I wish the status was shown in the car image on the vehicle dash screen as well.

Got the same notification on the car, I don't think I took a picture of it though. The single red battery icon would persist on the driver's display.

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[dradam]

I was thinking about something like this https://www.rivianforums.com/forum/...-process-update-from-rivian.17701/post-375368
I want to be able to flip a switch or turn a key to quickly get going again.

Yes, I like that plan would be easy enough just to keep a backup 12V in the frunk.

 

[dradam]

Got the same notification on the car, I don't think I took a picture of it though. The single red battery icon would persist on the driver's display.

Glad to know that. Thank you

 

[raylepper]

I like the OP's plan. For charging I've been thinking to use a 4S 10000mAh 25C lipo. Keep it at storage charge (say 3.8-3.85 volts). That will provide 15.5-ish volts to charge the truck battery. Being a 25C pack, it will be happy to deliver 30 amps for several hours. Of course you need some experience with Lipo packs and an appropriate charger. And because it's not unreasonable to be a little concerned about long term storage of the pack inside your vehicle, you could put it inside one of these bumper protectors. If the 12v in the truck is flat, pop the end off the bumper protector, pull out the lipo pack and plug in.

Tell me why this is a bad idea (many of mine are).

 

[UnsungZero_OldTimeAdMan]

Do you know if the leads in the trailer hitch simply go to the positive and negative terminals of the 12V battery? If so I was thinking of making a dumb jump pack with one Ohmmu. That should not only open the car but allow it to run as normal until the 12V can be replaced. TIA

DCE did not know there are jump leads back there already, as shown in Tow Operator Guide. They made a harness and successfully revived their R1S via trailer hook up, so it must. But why when jump leads exist?

 

[dradam]

I like the OP's plan. For charging I've been thinking to use a 4S 10000mAh 25C lipo. Keep it at storage charge (say 3.8-3.85 volts). That will provide 15.5-ish volts to charge the truck battery. Being a 25C pack, it will be happy to deliver 30 amps for several hours. Of course you need some experience with Lipo packs and an appropriate charger. And because it's not unreasonable to be a little concerned about long term storage of the pack inside your vehicle, you could put it inside one of these bumper protectors. If the 12v in the truck is flat, pop the end off the bumper protector, pull out the lipo pack and plug in.

Tell me why this is a bad idea (many of mine are).

Would an Ohmmu in the frunk be safer than what you describe ?

 

[dradam]

DCE did not know there are jump leads back there already, as shown in Tow Operator Guide. They made a harness and successfully revived their R1S via trailer hook up, so it must. But why when jump leads exist?

Sorry, who Is DCE and is there a link to what they did? Thx

 

[UnsungZero_OldTimeAdMan]

Sorry, who Is DCE and is there a link to what they did? Thx

DCE/Weistec.
Long winded Out-of-spec video where DCE talked about jumping through trailer hookup.

DCE also talked about this replacement battery they were working with Optima on. Neither party has talked about it since.

 

[logan]

<snip>
Keep a torx 20 and 25 driver in the trailer hitch compartment --- it should fit . I can access that compartment with a coin.
<snip>

FWIW, if you remove the cap above where the wires are you'll find a decently sized space. If you put a small tool in some kind of padded bag so it doesn't rattle you can hid it away there too. That way if you tow you can still have it handy- just in case.

 

[NY_Rob]

For charging I've been thinking to use a 4S 10000mAh 25C lipo. Keep it at storage charge (say 3.8-3.85 volts). That will provide 15.5-ish volts to charge the truck battery. Being a 25C pack, it will be happy to deliver 30 amps for several hours.

Tell me why this is a bad idea (many of mine are).

A 10,000mAh battery pack is only 10Ah.. might not be enough to jump a flat SLA 12V Rivian battery because the second you connect your full battery to the drained Rivian 12V battery your jumper battery will start discharging.

I would be very leery about permanently storing any Lithium based battery pack anywhere inside my vehicle knowing how hot the interior (and Frunk) get in the summer and how cold the same areas get in the winter.

Vehicle manufacturers are using LiFePO4 cells for their batteries vs Lithium Polymer cells if they decide to ditch the lead-acid 12V battery.

Something like this would work and the cell below is 74Ah, a 200amp BMS should handle the load.

 

[raylepper]

I take you point about temperature.

 

[HaveBlue]

I feel the 12V might be secondary. After you jump the 12V from the rear, the DC-DC should boot up and charge the 12V and keep the systems running to drive. If the HV is flat then a spare 12V doesn't help you much.

 

[dradam]

I feel the 12V might be secondary. After you jump the 12V from the rear, the DC-DC should boot up and charge the 12V and keep the systems running to drive. If the HV is flat then a spare 12V doesn't help you much.

I agree, this is only a consideration if the 12v is dead

 

[dradam]

A 10,000mAh battery pack is only 10Ah.. might not be enough to jump a flat SLA 12V Rivian battery because the second you connect your full battery to the drained Rivian 12V battery your jumper battery will start discharging.

I would be very leery about permanently storing any Lithium based battery pack anywhere inside my vehicle knowing how hot the interior (and Frunk) get in the summer and how cold the same areas get in the winter.

Vehicle manufacturers are using LiFePO4 cells for their batteries vs Lithium Polymer cells if they decide to ditch the lead-acid 12V battery.

Something like this would work and the cell below is 74Ah, a 200amp BMS should handle the load.

So you would need 4 in series?

 

[NY_Rob]

So you would need 4 in series?

Yes, with a properly sized BMS of course.. those cells can safely deliver 180amps, so a 200amp BMS would do.

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