Product Request: Capacitor retrofit

[tmbm50]

Funny, I just added a second battery to my single battery R1T

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[Giddy89]

Figured I would post this after seeing the NACS retrofit request here


It would be nice (tm) if Rivian offered a retrofit capacitor for early dual-battery R1 vehicles.

It's been confirmed via testing the 12v low voltage service button in the vehicle won't clear DTC's due to a low secondary 12v battery. The only option to clear the 12v DTC for the secondary battery is to go to a service center after DIY replacing them for the Rivian service tools to clear the warning.

Community members have witnessed the secondary battery getting fully drained and charged 22x compared to the primary battery getting charged and discharged 9x in the same time period. Two 12v batteries every two years is a high maintenance (and time) expense.

I'd much rather shell out $500 for a retrofit kit from Rivian vs spending an extra $400 every two years.

I’m about to DYI 12v replacement in the coming days. Just to confirm your vehicle was still operable after your 12v replacement just had errors you couldn’t clear from RIDE?

 

[tmbm50]

I’m about to DYI 12v replacement in the coming days. Just to confirm your vehicle was still operable after your 12v replacement just had errors you couldn’t clear from RIDE?

When I was messing with mine, I used an old honking 12v thats been kicking around for years to keep juice applied using some alligator clips to the wires coming off the positive terminal. You don't need 100amps to keep it powered on....the OEM battery is pretty low CCA anyways.

It is a bit cumbersome tho.

 

[kallisti5]

I’m about to DYI 12v replacement in the coming days. Just to confirm your vehicle was still operable after your 12v replacement just had errors you couldn’t clear from RIDE?

Vehicle can still be operated. Annoying 12v warning in Rivian mobile app, on dash, and I can no longer upgrade.

Keep in mind, this only impacts early dual-battery R1 vehicles. Single battery vehicles can use the built-in RiDE system to clear the warning.

 

[Epzey]

Funny, I just added a second battery to my single battery R1T

Did you use an isolator kit or do you have them in parallel?

 

[tmbm50]

Did you use an isolator kit or do you have them in parallel?

Just parallel. No real need for an isolator. They are mostly useful when you have a high draw starter battery and a smaller aux battery which could cause an inrush between the batteries. The oem battery is so tiny, I just added an identical 20ah so the odds of a big imbalance are minimal. I did install a 150a fuse just in case.

I don't know why EV vendors don't just use a normal size car battery thats in every honda civic since 1995....it would be 5x the capacity and last so much longer.

 

[UnsungZero_OldTimeAdMan]

Funny, I just added a second battery to my single battery R1T

For a sub amp? And what’s your vampire drain now?

 

[UnsungZero_OldTimeAdMan]

Just parallel. No real need for an isolator. They are mostly useful when you have a high draw starter battery and a smaller aux battery which could cause an inrush between the batteries. The oem battery is so tiny, I just added an identical 20ah so the odds of a big imbalance are minimal. I did install a 150a fuse just in case.

I don't know why EV vendors don't just use a normal size car battery thats in every honda civic since 1995....it would be 5x the capacity and last so much longer.

5x capacity but also potentially higher draw from HV pack. Wanna do a forum search for complaints on vampire drain? More isn’t necessarily better.

 

[tmbm50]

5x capacity but also potentially higher draw from HV pack. Wanna do a forum search for complaints on vampire drain? More isn’t necessarily better.

How does the capacity of the 12v battery affect draw? Draw is a function of the load. I've had an earlier Model X, well aware of vampire drain. And searching on prior 12v issues is exactly why I added one and why I did the same on my X to stop that from eating batteries.

 

[UnsungZero_OldTimeAdMan]

How does the capacity of the 12v battery affect draw? Draw is a function of the load. I've had an earlier Model X, well aware of vampire drain. And searching on prior 12v issues is exactly why I added one and why I did the same on my X to stop that from eating batteries.

Then you're saying the load doesn't call for a 12V with 5x capacity. So why migrate to such a large battery if you don't need it? At issue is not size of the 12V, but ability of BMS to manage what size 12V it has and recharge it reliably so the vehicle isn't bricked.

 

[tmbm50]

Then you're saying the load doesn't call for a 12V with 5x capacity. So why migrate to such a large battery if you don't need it? At issue is not size of the 12V, but ability of BMS to manage what size 12V it has and recharge it reliably so the vehicle isn't bricked.

The capacity of the 12v directly affects the depth and number of charge cycles. Charge/Depth cycles directly affect battery life. Its the number one metric for AGM/Leadacid battery life.

If the idle vampire drain is similar to Tesla at 40w, then the OEM 20ah battery will need a charge cycle every 2.5hrs. Doubling the 12v capacity to 40ah of course doubles your time between charge cycles which at a minimum doubles the life the batteries.

In reality its actually more than double life because BMS function on soc percentages, so 70% (typical recharge depth for a tesla) of small battery is much more stressful to the small battery because any transient load causes a quicker voltage dip (since there is less reserve) and all modern electronics increase amps when voltage dips which stress that small battery more.

This isn't special to Rivian, anyone thats worked with 12v battery banks/inverters works to get the most AH per dollar they can afford. I have 20 years in megawatt datacenter design, which uses lead acid banks for UPS. Its all the same, just a difference in scale. The off-grid solar folks do the same.

They use small batteries cause its cheap.

 

[tmbm50]

As an aside, I'll log/graph the vampire drain this weekend over say a 24hr period and post it. Curious actually what the real load is. I don't use the gear guard at home but maybe I'll try it on and off to show the difference.

 

[HaveBlue]

What causes the Vamprire drain is not so much the little 18ah battery but the fact that starting the car up every few hours to charge it is very inefficient. Having a larger battery that can survive sleep cycles while parked for several days means the 12V battery would only be charged while driving when all the systems are up anyway.

Several of us have looked and there are dealers for the DCS battery and so far I haven't heard anyone that has them in stock.
https://www.cdtechno.com/products/deep-cycle-series-dcs-agm-battery

Also for an ordinary 18ah battery:
https://soonishev.com/products/battery-post-relocator
with this
https://www.jegs.com/i/Full-Throttl...VXNSBkFT37Vzb9yNkIa40wJi4Y9ZUtS4aAkb_EALw_wcB

 

[tmbm50]

What causes the Vamprire drain is not so much the little 18ah battery but the fact that starting the car up every few hours to charge it is very inefficient. Having a larger battery that can survive sleep cycles while parked for several days means the 12V battery would only be charged while driving when all the systems are up anyway.

Several of us have looked and there are dealers for the DCS battery and so far I haven't heard anyone that has them in stock.
https://www.cdtechno.com/products/deep-cycle-series-dcs-agm-battery

Also for an ordinary $40 18ah battery:
https://soonishev.com/products/battery-post-relocator

Exactly. And because I added a battery to get more AH, I used an XS XP750 since I don't need the post in the same spot.

 

[Dark-Fx]

False. You can DIY (see Ohmmu's YouTube video) and until a recent OTA, it could have been done without triggering errors. To that Wassym has said will be addressed in future update—i.e. 12V swap option added to service mention in vehicle settings.

Until that happens, it's a SC appointment to have the errors cleared.

Ohmmu's batteries have a different charge curve. Current software can get confused about it.

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