12V Battery Replacement Megathread

[kallisti5]

Hell. Maybe old Rivians should put a deep cycle battery on primary and a high rate battery on secondary

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[kallisti5]

Whelp, I replaced the batteries.. it was "fun" on the dual battery Rivian.

Now trying to get it back up and running.


Recommendations:

* Put into service mode before hand (hopefully keep it from doing "random stuff"
* Pull the HV disconnect (I didn't pull mine, and enjoyed an angry buzzing from the DC/DC converter while the DC/DC converter was disconnected from the PDU.. as soon as I pulled the disconnect the buzzing stopped.)
* Reverse terminal batteries can be used, but they're extra awkward to put in with "rotated" adapters.
* After replacement, I reconnected the HV disconnect, and was greeted with "all the codes" on the dash and a refusal to be ready to drive.
* Just performed a hard reset. Vehicle now ready to drive with 12v battery warning as before.
* So far, the "12v battery service" button in RiDE hasn't done anything.

 

[Zoidz]

You're right.. but with your logic, the OEM battery is also not "deep cycle".

They say it, but delivering 150A per the specs isn't deep cycle

I feel like based on specs, the linked battery fills all the needs and is a similar use case (ups systems. Moderate draw, as long as possible).

To add a bit more here.. let's look at specs

* OEM 150A max per spec sheet. "Deep cycle"
* OEM changed secondary battery to a capacitor which is definitely not deep cycle.
* Standard group deep cycle battery 5.8A max
* Standard group battery motorcycle 250CCA

Essentially rivian is using a battery in-between deep cycle and high rate.

High rate seems a lot closer to OEM specs.

My logic? What? lol. The OEM battery is clearly labeled "Deep Cycle". You're saying that because it has a certain amp rating it can't be Deep Cycle?

The use case of the linked Duracell battery (i.e. UPS) isn't similar, it's the complete opposite of an EV 12 volt battery. A UPS battery goes weeks or months at full charge with little to no drain, perhaps with a few short sag events where it is drained a few %. Then a power outage hits and it may get drained down to 30%, 20% or even 5%. But then it is slowly charged back up to full power - that's ONE Deep Cycle. A typical UPS may experience half a dozen deep cycles, or less, a year.

An EV 12 volt (LVB for short) experiences "Deep Cycles" (50% - 80% discharge) weekly and even daily depending on use, weather, etc. An AGM Deep Cycle can be recharged at a faster rate than a flooded battery because the plates are thicker and the AGM improves the electrolyte distribution. A flooded battery will sulfate starting at about 50% discharge and has a slow recharge rate compared to Deep Cycle AGM.

How deeply an EV LVB gets discharged is completely up to the software engineers. Rivian has been tweaking this since day one to balance phantom drain on the HV battery vs. discharge depth on the LVB. Their algorithm is design for Deep Cycle charging, which in general means they are going to let the battery discharge 30% to 50% or more, and then rapidly recharge it. Flooded batteries and basic AGM can't handle that long term. My 2004 BMW K1200RS specs an AGM battery for some of these reasons, due to the heavy use of electronics in that bike. And guess what? Owners have found that not using an AGM as spec'd by BMW results in - SHORTER BATTERY LIFE.

CCA means less than nothing in this application. For reference, it is a STANDARD defined as:
" The number of amps that are produced by a charged battery during a 30-second period while maintaining at least 7.2 volts at a temperature of 0°F"
How does that apply to an EV use case?

Your comment about Rivian changing one battery to a capacitor and a capacitor not being deep cycle is factual, but it shows how much you don't understand about this or WHY Rivian made that change.

You can choose to read up and understand the engineering and technical differences between the SLA, AGM and Deep Cycle battery types and their use cases as it applies to Rivian EVs, or you can soar down your "Rivian engineers do not know what they are doing, I know better, a $50 battery is just as good" path.

Good luck and may the odds be ever in your favor.

 

[kallisti5]

How deeply an EV LVB gets discharged is completely up to the software engineers. Rivian has been tweaking this since day one to balance phantom drain on the HV battery vs. discharge depth on the LVB. Their algorithm is design for Deep Cycle charging, which in general means they are going to let the battery discharge 30% to 50% or more, and then rapidly recharge it.

Here's my issue. Just like i'm making assumptions, you are too. None of this is documented (which is a huge DIY problem by Rivian honestly)

My logic? What? lol. The OEM battery is clearly labeled "Deep Cycle". You're saying that because it has a certain amp rating it can't be Deep Cycle?

Everything is a trade-off. Thinner plates, more burst current. Thicker plates tolerate a deeper discharge at less current. Here's the spec for the OEM battery. 180A peak current.

Here are "valid" replacements I found locally:

https://www.batteriesplus.com/productdetails/slahr12=20c_fr "High Rate"
vs
https://www.batteriesplus.com/productdetails/slaa12=18c_fr "General Purpose"
vs
https://www.batteriesplus.com/productdetails/sladc12=20c "Deep Cycle"


Lets take a step back. Find me a small 18-20Ah deep cycle battery that can do a documented minimum 40-50A (2.0C+) . (I just swapped the battery, the battery cables were around 6 gauge. (that's sized for ~75A DC)

Since the DC/DC inverter runs "through" the terminal block on the battery, it could only expect to draw 10A from the batteries, it could burst to 20A or more. I'm guessing, you're guessing.

I'm ok killing a pair of High rate SLA batteries in a year or two if it means we can build confidence in what batteries are acceptable. What I don't want to do is put a Deep Cycle battery rated for a maximum of 6A (0.3C) into a position where the vehicle is going to draw 20A+ (1.0C)

I'm doing all of this because the knowns are limited. The OEM battery is rated "180A peak" (9C), but is also "Deep Cycle". That's all we have to go on. 9C is pretty high for something Deep Cycle.

 

[kallisti5]

Confirming that a hard/full reset cleared the codes making the vehicle "not ready".

12v battery warning still on. I tried the RiDE "12v reset after replacement" button, so far nothing has happened.

 

[Zoul]

I think where op is having confusion, and admittedly I am as well is that deep cycle batteries are rated in amp hours. For practical purposes I would say cca and peak amperage have a similar meaning. So if I go to my local farm store and grab an ATV/lawnmower battery, they have a cca rating around 200 and an ah rating between 18 and 30 depending on what I pay. If rivian batteries spec at 180a peak and 18 ah, what is the difference? Are you arguing that there is a difference in duty cycle that is unspecified?

I don't think anyone is trying to argue here,there is just some confusion. I come from working on semis, busses, and heavy equipment. They mostly used the same batteries for house and cranking. Generally a(or several) group 31 batteries rated at 950cca and 100ah. Generally a cranking battery could sub in for a deep cycle on the house side as long as amp hours were the same. Most of the time they were the same exact battery with a different sticker.

Ops argument is that even if rivian batteries aren't the same, they still only tend to last a little over a year. If an aftermarket option will work good enough and make it a year it's an option. Since rivian will not readily sell the batteries for diy, and they likely won't keep supporting gen 1s forever, this might be were we have to start.

 

[kallisti5]

Ops argument is that even if rivian batteries aren't the same, they still only tend to last a little over a year. If an aftermarket option will work good enough and make it a year it's an option. Since rivian will not readily sell the batteries for diy, and they likely won't keep supporting gen 1s forever, this might be were we have to start.

Accurate. I'll be the first to admit that I may have made a poor choice in choosing that specific battery. The other one I listed may have been the better choice. Rivian isn't being clear, and the battery manufactures aren't either

* Shallow Cycle: 10-30% DOD (I feel like SLAHR12-20C could be here. "High Rate")
* Medium Cycle: 40-70% DOD (I feel like the OEM battery is here, being sold as "Deep Cycle")
* Deep Cycle: 80-90% DOD (I feel like SLADC12-20C is here. "Deep Cycle")


Take a look at the graphs in the OEM battery spec:
https://assets.ctfassets.net/3inf9w...d0444850f1fad3/EVP_DCS_DataSheet_08312022.pdf

Reliability drops off at 40% DOD.
"Long cyclic life performance (up to 5000x at 30-percent depth of discharge (DoD)"

We know they aren't doing 30% DOD given how quick they're dying

 

[kallisti5]

One more fun data point to end the day on.

* Primary battery testing OK.
* Secondary battery testing Faulty.

 

[HaveBlue]

What about just buying an OEM DCS-18UNC R1T version from one or their dealers? They make 33, 40 and 45ah versions but not sure how to fit the bigger ones.
https://emergencypowercorp.com/products/vrla/Deep_Cycle_Series.html#gsc.tab=0
https://www.cdtechno.com/contact-us/locations

 

[kallisti5]

What about just buying an OEM DCS-18UNC R1T version from one or their dealers? They make 33, 40 and 45ah versions but not sure how to fit the bigger ones.

That's a good call-out. I'll reach out to one now to see if they'll quote me how much for 2. (Last I heard, Rivian won't sell them direct)

 

[zymolysis]

What about just buying an OEM DCS-18UNC R1T version from one or their dealers? They make 33, 40 and 45ah versions but not sure how to fit the bigger ones.
https://emergencypowercorp.com/products/vrla/Deep_Cycle_Series.html#gsc.tab=0
https://www.cdtechno.com/contact-us/locations

The exact C&D DCS battery is not available in the US. I already tried that. I ordered two, and then they got back to me, saying that they were listed as available by mistake, and that there just hadn't been the demand in the US to have those batteries available here.

 

[kallisti5]

The exact C&D DCS battery is not available in the US. I already tried that. I ordered two, and then they got back to me, saying that they were listed as available by mistake, and that there just hadn't been the demand in the US to have those batteries available here.

Oh Rivian.

"Lets use the most proprietary connectored, reverse terminaled, hand-curated battery we can, only sold by distributors deep in old Europe, and have it air-lifted here by helicopter."

There's why 12v replacements from Rivian are like $900

 

[Bob S]

New to Rivian, just took delivery of a 2023 R1T. There seems to be a lot of threads on dyi battery replacement but not on battery management. I am having a hard time finding any information about Rivian‘s charging profile. It appears it is being tweaked with every software update. I might be wrong. If an AGM is at the high end of its charge it should last many years. In an ICe vehicle the alternator is putting out 14.4+v and the battery will accept only what it needs to stay full. I’m going on year 5 with the original battery in my Ridgeline. How is the 12v being charged in the Rivian? Is it better to keep it plugged in (HVB) even if it’s not needing a charge. Just trying to understand.

 

[Zoidz]

New to Rivian, just took delivery of a 2023 R1T. There seems to be a lot of threads on dyi battery replacement but not on battery management. I am having a hard time finding any information about Rivian‘s charging profile. It appears it is being tweaked with every software update. I might be wrong. If an AGM is at the high end of its charge it should last many years. In an ICe vehicle the alternator is putting out 14.4+v and the battery will accept only what it needs to stay full. I’m going on year 5 with the original battery in my Ridgeline. How is the 12v being charged in the Rivian? Is it better to keep it plugged in (HVB) even if it’s not needing a charge. Just trying to understand.

Yes, an AGM kept at a high level of charge can last many years. But since Rivian uses the 12 volt battery to power all the electronics, just waking up the vehicle drains 1 to 2 amps, and much more if the lights, climate control PreCool or PreHeat is on, etc. Since this is a only an 18 AH battery, one can see that it can discharge quickly several times a day.

Here's a Rivian charging profile from February 25 that somone captured. As a side note, anyone can do this if they desire using Home Assistant. I had Home Assistant running in a Docker container with the Rivian plug in and monitored this data for months... until the Docker container file system corrupted, and no, I didn't have a backup. I haven't rebuilt it yet.

As you can see, it Deep Cycle discharges to around 12.0 volts before the charge cycle kicks in. From the timeline you can see a sleep cycle at 13.45v, followed by a discharge until the voltage drops and the charge cycle kicks in. In this case, the vehicle was doing almost 3 full cycles a day. Based on this pattern, 80 a month, 240 a year. Your results will vary depending on Gear Guard configuration, how often you or Rivian wakes it up, temperature, and many more pseudorandom factors. Deep cycling a traditional Lead Acid battery like this will kill it quickly because it will sulfate. Deep Cycle batteries tolerate it better, but it's still quite a "workout" for a Deep Cycle battery.

Keeping the HVB plugged in does not directly affect how the LVB is charged. Rivian is monitoring the LVB and kicking in the LVB charging algorithm as needed, powering the LVB charger via the HVB. They don't run the LVB charger all the time, since that would create more "Phantom Drain" drain by powering up more subsystems for a longer time and less sleep time. That in and of itself requires more power from the LVB when charging starts. It's presumed that this algorithm/curve below is what Rivian has been tweaking to optimize the life of the 12 volt battery. There is also a thread here that indicates Rivian may have pooched a software update and some vehicles may have had 19 volts applied during charging, damaging the battery and leading to the proactive replacement program.

We clearly don't know many details about the charging algorithm and Rivian's decisions as to why they do what they do, but the graph below shows the final result that we can see.

 

[zymolysis]

New to Rivian, just took delivery of a 2023 R1T. There seems to be a lot of threads on dyi battery replacement but not on battery management. I am having a hard time finding any information about Rivian‘s charging profile. It appears it is being tweaked with every software update. I might be wrong. If an AGM is at the high end of its charge it should last many years. In an ICe vehicle the alternator is putting out 14.4+v and the battery will accept only what it needs to stay full. I’m going on year 5 with the original battery in my Ridgeline. How is the 12v being charged in the Rivian? Is it better to keep it plugged in (HVB) even if it’s not needing a charge. Just trying to understand.

Your Rivian will wake up to charge the 12V battery, when the level drops too low. The sleep/wake-up cycle increases vampire drains. The level to which the 12 battery is allowed to drop, and the number of charge cycles, decreases the life span of the 12V battery. Other users have reported longer sleep cycles after using a trickle charger (even if only using it intermittently), which would indicate an improvement in the health of the 12V battery. This relates to the Gen 1 Rivians; Gen 2 Rivians have direct charging method that does not require waking the vehicle.

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