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12V battery troubles

Milermore

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is the 12v battery problem a "suddenly it doesn't work" problem or are there hints that can be observed as it begins to lose charge?
Such as in an ICE you'd see trouble cranking when starting the motor before you get all the way dead battery.
Maybe dimmed or flickering lights? Multiple attempts needed to unlock doors? etc... just pulling guesses from the air here.
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PappaBolt

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Yep, you could in theory run until the NOCO dies. I don't have my Rivian yet, but for this and a few other reasons, I just ordered a NOCO from Amazon. They have some great CyberMonday discounts running right now.
Where would one store the NOCO so it’s accessible in the event of a locked cabin and flat 12v’s?
 

Zoidz

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Where would one store the NOCO so it’s accessible in the event of a locked cabin and flat 12v’s?
In the frunk. There is a mechanical way to get into the frunk in an emergency. Certainly not convenient, but doable.

Also, some of these dead battery issues have been reported to happen overnight at home, so it does not necessarily need to be on-board.
 

CharonPDX

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Post-Mortem Update on Bricked 12v Battery caused (Per Rivian) by file corruption issues caused by its own recent update to the vehicle"
Oh, crap. I got a "Service 12V battery system immediately" warning while driving yesterday. I rebooted the car, and it went away; I assumed it was a one time fluke. If I get it again, I'm immediately opening a service ticket.
 

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BrianNakata

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I use the Lithium version of this on one of my cars that has a lightweight LiFePo battery as it's a dry weather only vehicle so stays on a float charger all the time: Bluetooth Battery Tracker.

You simply connect it to a battery and it monitors it continuously. You connect to it via a free phone app via Bluetooth and you can connect up to five of these to the phone. Seems like you could get two and connect them to the primary and secondary 12V batteries and monitor them whenever you want by firing up the app on your phone. There's then no need to dismantle the cowling to put a DMM on them to measure their voltage.

The company did tell me that if you use more than one for multiple batteries, those batteries cannot be connected in serial or parallel.

Does anyone know if the two 12V batteries are connected together in some way? I would think that they are using an isolator so that both charge but only one is used at a time.

Brian
 

ironpig

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(2) New dashboard digital guage that will show the current status of 12V battery (primary and secnodary) given how critical their state of charge is for people who drive this vehicle. Keep in mind it is not a redunant set up but hemispherical. The left side of the truck relies on the primary and the right half the secondary. That is bad and especially problematic when I am blind about their charge status.

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Definitely should be able to monitor the health of those batteries on screen. We should push for that.

These smaller batteries are always an issue. My wife has had a series of Prius and they use the small 12v batteries in the trunk. I just replaced another one because it died after the car sat for a month. In my anecdotal experience, these batteries never revive after a full draining the way better standard size 12V batteries seem to be able to do.
 

mini2nut

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I wish Rivian would ditch the dual batteries and go with a single lithium 12v battery like Tesla has done.

The voltage of a 12v battery is a good way to determine the state of charge. Here's a handy table with the breakdown:

State of Charge Voltage

100% 12.7 - 13.2

75% 12.4

50% 12.2

25% 12.0

Discharged 0 - 11.9

If your battery is:

Reading 0 volts, chances are the battery experienced a short circuit

Cannot reach higher than 10.5 volts when being charged, then the battery has a dead cell

Fully charged (according to the battery charger) but the voltage is 12.4 or less, the battery is sulfated
 
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Supraman16

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Just had my 12V batteries replaced due to random errors popping up. First if was motor fault error, then power steering, then finally the 12V Batteries. All these errors were only intermittent, resulted in no noticeable issues driving the truck. I thought it was a software issue but it turned out that one of the 12V batteries was starting to go bad. The Service Center replaced both batteries. Here's hoping that was the fix.
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