Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

12 volt battery options

This site may earn commission on affiliate links.
Why would you go from an agm back to the ohmmu if the agm is performing fine?
Lifespan. I already have a V3 Ohmmu on the shelf waiting for a working replacement. The Ohmmu once figured out should have a life of 8-10 years. I want a 12 volt that once installed I don't have to think about. The V4 Ohmmu could be ready in a month or a year. It's unknown for now until testing is done and manufacturing and distribution started.
 
The original question was looking for alternatives. While Ohmmu works out there issues, their are alternatives.

First, all the manual says as a specification is 33Ah or greater. Most 51R batteries exceed that. The factory AtlasBX is 45Ah. I went with a 51R O'Reilly AGM that happens to be 46Ah. But Advance auto through Diehard also introduce there "EV/Hybrid" replacement 12 volt (it also happens to be AGM) and they have a direct replacement for the 85B24LS.


I've had no issues so far with the 51R O"Reilly. I have a battery monitor and the charge profile has been similar to the regular flooded lead acid. Look at it this way, if Advance Auto is selling a Diehard with a 3 year warranty and they are selling it as a direct replacement for the AtlasBX, then it's covered if it fails early. Others in this forum have run AGM's for 2-3 years and replaced only due to age not failure. I put it to Tesla manual services directly, "If a conventional flooded lead acid is the only suitable battery, it should be clearly stated in the owners manual and service manual." Such as stating "not recommended" etc. There are plenty of cautions and notes in the tire section. The manual and service manual are the controlling documents not endless opinions on this forum.
 
Last edited:
  • Like
Reactions: Rocky_H
The original question was looking for alternatives. While Ohmmu works out there issues, their are alternatives.

First, all the manual says as a specification is 33Ah or greater. Most 51R batteries exceed that. The factory AtlasBX is 45Ah. I went with a 51R O'Reilly AGM that happens to be 46Ah. But Advance auto through Diehard also introduce there "EV/Hybrid" replacement 12 volt (it also happens to be AGM) and they have a direct replacement for the 85B24LS.


I've had no issues so far with the 51R O"Reilly. I have a battery monitor and the charge profile has been similar to the regular flooded lead acid. Look at it this way, if Advance Auto is selling a Diehard with a 3 year warranty and they are selling it as a direct replacement for the AtlasBX, then it's covered if it fails early. Others in this forum have run AGM's for 2-3 years and replaced only due to age not failure. I put it to Tesla manual services directly, "If a conventional flooded lead acid is the only suitable battery, it should be clearly stated in the owners manual and service manual." Such as stating "not recommended" etc. There are plenty of cautions and notes in the tire section. The manual and service manual are the controlling documents not endless opinions on this forum.
That is great that you have success with the O'Reilly Group 51R AGM battery. The Tesla OE 12V (not the new 15V lithium starting battery) is not an AGM battery, it is a maintenance free (MF) flooded lead-acid battery.

The MF and AGM designs are not the same. Both MF and AGM batteries never need to have the electrolyte level checked or distilled/de-ionized water added to the battery's cells. AGM batteries have different charging requirements from flooded lead acid batteries and can become easily damaged if overcharged.

If the battery case of a MF battery ruptures in an accident the highly corrosive electrolyte will splash all over. In a similar crash an AGM battery will leak only a very small amount of electrolyte as the electrolyte, what little there is, is held in the fiberglass mat. An AGM battery can be installed in places inside an automobile where a flooded lead-acid battery cannot such as inside the passenger cabin space, i.e. under the rear seat or below the floor of the trunk or hatch. An AGM battery can be installed on its side or even upside down if that is the only way it will fit the space.

AGM batteries cost more, as much as 2X as much as a flooded battery. AGM batteries excel at resistance to damage from vibration (as much as 20X more resistant to damage from vibration than a flooded battery.) AGM batteries are also more resistant to heat and are less likely to freeze in extreme low temperatures. AGM batteries are well suited to use in hybrid and electric vehicles. Toyota and GM use 12V AGM starting batteries in a number of hybrid, plug-in hybrid and electric vehicles.

In my experience an AGM battery can last the same or longer than a flooded battery. Depending on the vehicle 3 or 4 years; sometimes much longer.

In the Tesla vehicle the 12V battery is located in front of the firewall, not in the passenger cabin space. A replacement flooded lead-acid battery would work as a replacement for the Tesla OE 12V battery and would cost less than an AGM battery.
 
That is great that you have success with the O'Reilly Group 51R AGM battery. The Tesla OE 12V (not the new 15V lithium starting battery) is not an AGM battery, it is a maintenance free (MF) flooded lead-acid battery.

The MF and AGM designs are not the same. Both MF and AGM batteries never need to have the electrolyte level checked or distilled/de-ionized water added to the battery's cells. AGM batteries have different charging requirements from flooded lead acid batteries and can become easily damaged if overcharged.

If the battery case of a MF battery ruptures in an accident the highly corrosive electrolyte will splash all over. In a similar crash an AGM battery will leak only a very small amount of electrolyte as the electrolyte, what little there is, is held in the fiberglass mat. An AGM battery can be installed in places inside an automobile where a flooded lead-acid battery cannot such as inside the passenger cabin space, i.e. under the rear seat or below the floor of the trunk or hatch. An AGM battery can be installed on its side or even upside down if that is the only way it will fit the space.

AGM batteries cost more, as much as 2X as much as a flooded battery. AGM batteries excel at resistance to damage from vibration (as much as 20X more resistant to damage from vibration than a flooded battery.) AGM batteries are also more resistant to heat and are less likely to freeze in extreme low temperatures. AGM batteries are well suited to use in hybrid and electric vehicles. Toyota and GM use 12V AGM starting batteries in a number of hybrid, plug-in hybrid and electric vehicles.

In my experience an AGM battery can last the same or longer than a flooded battery. Depending on the vehicle 3 or 4 years; sometimes much longer.

In the Tesla vehicle the 12V battery is located in front of the firewall, not in the passenger cabin space. A replacement flooded lead-acid battery would work as a replacement for the Tesla OE 12V battery and would cost less than an AGM battery.
I agree with all said. I would add in my case overcharging hasn't been an issue. Battery specs charging voltage range is 13.8 to 14.6v. Since installation the highest charging I've seen is 14.2v. Also, the battery basic voltage prior to installation was about 12.9v. Once the charge cycles end (I have a battery monitor attached to see what it's doing), the voltage drops back to 12.9 until a short term demand is made then charging jumps back to 14.1-14.2. I have not observed any float charging with the AGM. The AtlasBX would occasionally float to 13.1. I also notice a much more stable charge pattern with the AGM vs. basic lead acid.

Here are two images of AGM charging:

IMG_1518.PNG


IMG_1519.PNG



In contrast, here are two images of AtalsBX lead acid charging:

IMG_1520.PNG


IMG_1521.PNG
 
can you please also share when the car was awake/sleeping on those days
Sleeping normally in my garage. Sleeping nights until scheduled charging and during day until I awake it to precondition. Behavior is normal as if my lead battery was installed. Those graphs above are when lead battery or AGM installed. I now have an Ohmmu and working normally for 3 weeks. In the above graphs sleeping is the long lines until a wake up commanded then the spike.
 
Last edited:
Got up early today to get the best rate at the Supercharger ! Opened the door, got in.... and Nothing, not even a light. I thought that was strange, until I tried the door open button. Won't open, not even lit... Pulled the latch the door opened as I took a breath. No warning, nothing. Seems that something would tell the charger that just maybe that battery is not quit right.... no, nothing. Set up a service call for the next day! Elon runs a company that wants to but man on mars... Maybe he should spend a little more time on his earth bound products. Replacing these batteries under warranty cost Tesla money. I would think they would allow software to figure out what kind and condition of battery is in the car, weather a lead acid (1859 tech) or the latest lithium type. Wouldn't it be just great if you had to pick what kind of battery you replaced the stock battery with? Someone with very basic software skills could set this up in about and hour, maybe less. Now for a question... Has anyone replaced the stock battery with anything that doesn't have acid, .... and it worked?
March 2021 MYP 25k miles.
:)
 
Got up early today to get the best rate at the Supercharger ! Opened the door, got in.... and Nothing, not even a light. I thought that was strange, until I tried the door open button. Won't open, not even lit... Pulled the latch the door opened as I took a breath. No warning, nothing. Seems that something would tell the charger that just maybe that battery is not quit right.... no, nothing. Set up a service call for the next day! Elon runs a company that wants to but man on mars... Maybe he should spend a little more time on his earth bound products. Replacing these batteries under warranty cost Tesla money. I would think they would allow software to figure out what kind and condition of battery is in the car, weather a lead acid (1859 tech) or the latest lithium type. Wouldn't it be just great if you had to pick what kind of battery you replaced the stock battery with? Someone with very basic software skills could set this up in about and hour, maybe less. Now for a question... Has anyone replaced the stock battery with anything that doesn't have acid, .... and it worked?
March 2021 MYP 25k miles.
:)
You can have the battery replaced under warranty. If not desired, another option is an AGM battery (the factory Atlas is lead acid non-AGM. The DiehardEV would work or any 51R AGM battery. O'Reilly's has an AGM 51R for Tesla. (AGM has lead acid but is somewhat more durable). For Non acid Ohmmu.com has a lithium battery. They are in AZ if you wanted them to install. Tesla had made design changes that gave issues to Lithiums for about a year and a half but I have one in now in my 3 that seems to be doing OK with no warnings or issues and software updates occur OK. You can monitor the condition of the battery via an app. For a non-Ohmmu you can install an external module and monitor via 3rd party software. Amazon has many available for under $30.
 
Last edited:
Flybyglass... Thanks for the response. Did I get it right, you have an Ohmmu battery? Both of the batteries you show are "cranking" batteries, not deep discharge as I think you should have in a Tesla. The lithium battery you have has lots of good and bad press. I have the mobile service comming today to replace the stock battery, I will quiz the tech as to what he sees around the Phoenix area. Some people think they have hot weather,.... WE have hot weather ! ICE cars suffer from very high battery replacement in the area, Tesla cars shouldn't be any different. Thanks again for the response!
 
Last edited:
I have an Atlas, DiehardEV and Ohmmu. Currently running the Ohmmu. The Ohmmu is my preferred. I got the DiehardEV (which is AGM) because for a while the Ohmmu kept getting rejected by the car. History: For the first 1.5 years it worked flawlessly. Then tesla started tinkering with the charging software. So I put an AGM battery in a=having more confidence in that over a regular lead acid (Atlas). The only specification in the manual is the battery should be above 33Ah. Any 51R or the DiehardEV are above. Recently, the Ohmmu, which the software can be updated via a phone app, seems to have figured out how to work with Tesla or Tesla has revised software. Like you I wanted a button to tell it what battery installed but the flip side is someone would install a mismatch selection. Right now, the car appears to figure out what is installed. Living in AZ, I get how heat can ruin a lead battery. Some on here are anti Ohmmu but they have stood behind the product and worked to correct issues. Most recently, they added a heating element for colder climates. I discovered that as the charging profile had changed and in cold the Ohmmu would not charge at very low amps (.01-.04) but the heating should fix that. I am seeing other manufacturers now adding heating to their batteries as well. I would drive to Ohmmu, talk to the owner Sean and have them install (although installation not hard.
 
Last edited:
I have an Atlas, DiehardEV and Ohmmu. Currently running the Ohmmu. The Ohmmu is my preferred. I got the DiehardEV (which is AGM) because for a while the Ohmmu kept getting rejected by the car. History: For the first 1.5 years it worked flawlessly. Then tesla started tinkering with the charging software. So I put an AGM battery in a=having more confidence in that over a regular lead acid (Atlas). The only specification in the manual is the battery should be above 33Ah. Any 51R or the DiehardEV are above. Recently, the Ohmmu, which the software can be updated via a phone app, seems to have figured out how to work with Tesla or Tesla has revised software. Like you I wanted a button to tell it what battery installed but the flip side is someone would install a mismatch selection. Right now, the car appears to figure out what is installed. Living in AZ, I get how heat can ruin a lead battery. Some on here are anti Ohmmu but they have stood behind the product and worked to correct issues. Most recently, they added a heating element for colder climates. I discovered that as the charging profile had changed and in cold the Ohmmu would not charge at very low amps (.01-.04) but the heating should fix that. I am seeing other manufacturers now adding heating to their batteries as well. I would drive to Ohmmu, talk to the owner Sean and have them install (although installation not hard.
Tesla service showed up on time and installed an Atlas battery. Seems to be the fix. I too would like to have tesla support anything that fits in the space! Thanks for your detailed story and I hope your Ohmmu works out in the long run!