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Longer term Ohmmu experiences?
- Thread starter Durzel
- Start date
Agreed. While reading and signing the petition I had the same takeaway. Disappointing in the least. I also came to wonder if Sean and Ohmmu put this petition and it’s information together before the V3 or even maybe at the same time “hoping beyond hope” that the V3 would work and not throw VC or other codes but that may in fact appear to be happening. It appears at least on face value that possibly the new BMS and inner workings of the V3 are not holding muster. Therefore even more weight and reason behind the petition.
Ski
It really comes across like you do, though. Im not saying that as a mod, but I will also admit that In mod capacity I have wondered the same. The amount of knowledge you have on Ohmmu's processes etc, and as much as you stump for them in various threads, it really comes across that way.
@Flybyglass,
Please keep us updated on what you hear from Ohmmu in response to this issue. Next steps and such. Or anything informational. I have the V3 upgrade but have yet to install due to these apparent issues. You throwing the Atlas back in is not helping my decision! Lol. Trying to decide if I should install it and see as more Data Points and information or just wait for others responses/experiences and /or any information from Ohmmu.
Ski
CCA's are completely irrelevant in a Tesla. In fact, lower CCA's might be better (to a point). The CCA of the Ohmmu would be way less than 500 if measured.
I'm not so sure about that. It may mean that they do not want to be dealing with constantly moving goal posts in terms of how Tesla is managing the 12-volt subsystem. In the first rewrite of that which came in sometime Late 2021 and which precipitated a bunch of errors on lfp batteries but also failure of a lot of OEM lead acid batteries, they drove the charging voltage on the subsystem really high. They appear to have backed off a bit, but it does seem as though Ohmu may be feeling jerked around by Tesla's moving target on the 12 volt sub system. PS I've had no errors since going to version 3 with the add-on module.
Dysan911
Member
Hopefully not but from what I gathered it might prevent software updates from Tesla if it continues. As you can understand Tesla would not want a vehicle with a compromised 12v system to start applying an update halfway through and hiccup and brick something.
Well the main problem is that error prevents the high-voltage system from charging the 12-volt subsystem. If you don't trickle charge the system at night or make up for that in some way, eventually the 12-volt battery dies and you are stranded. That's a bigger problem than not being able to update operating system. With trickle-charging however I was able to limp along for a month or more until ohmmu sent me the replacement version 3 battery which knock on wood has thrown no codes.
Dysan911
Member
Is there a way to see what the 12v SOC currently is? I didn't realize it was preventing the HV system from charging and have just been going on my merry way. Yikes!
What I undersood @dfwatt to mean is that once that error comes up the HV battery stops trying to maintain the 12v battery, so it actually will drain regardless of whether the error message is accurate or not. I guess that's because a LV battery that has been deemed defective should not be charged in case it fails catastrophically.
Dysan911
Member
So I might be running on voltage fumes on my Ohmmu 12v now.
I've had VFront errors found in the Notifications list and yesterday Got one that popped up on my display "Electrical System power reduced". I never assumed it wasn't charging the 12v though. I wonder if I should contact Sean at Ohmmu and request V3 or just replace it with the lead battery that I still have.
I've had VFront errors found in the Notifications list and yesterday Got one that popped up on my display "Electrical System power reduced". I never assumed it wasn't charging the 12v though. I wonder if I should contact Sean at Ohmmu and request V3 or just replace it with the lead battery that I still have.
It isn't simple when it comes to "not charging" the battery. In this mode, it also doesn't let the car sleep, and uses the HV to run the DC/DC 24/7. This causes large vampire drain (well, no larger than having sentry on, which is the same thing). Once the car knows the 12V battery is bad, it runs the car off HV, so it kinda doesn't matter if the 12V dies, but the 12V also won't die because there is no load on it.
You can check if this is happening pretty easily. Turn off sentry. Don't access the car in any way for a few hours (no doors, no app). You can hear the DC/DC running. If the car is making noise after a few hours, it isn't sleeping. You'll also notice the app can access it immediately, and the screen turns on the instant you open the door. You may need to re-try this a few times, as it does wake up to charge a healthy 12V battery now and then, and you could catch it then.
You can check if this is happening pretty easily. Turn off sentry. Don't access the car in any way for a few hours (no doors, no app). You can hear the DC/DC running. If the car is making noise after a few hours, it isn't sleeping. You'll also notice the app can access it immediately, and the screen turns on the instant you open the door. You may need to re-try this a few times, as it does wake up to charge a healthy 12V battery now and then, and you could catch it then.
In my case with a V3 battery, I had the VCFRONT_a180 message in notifications but not as a popup notice. I removed the Ohmmu and checked and it was at 95% (It was parked and plugged in overnight). Here is what it looks like is happening: 6 months ago, Tesla added a high voltage charge check of the lead acid battery. The Ohmmu has a built in Battery management Computer (BMC) to both balance the cells and protect from over voltage. It an over voltage is detected, the Ohmmu's BMC disconnect for about 5 minutes (as it should). The Tesla sees that as a failure and throws messages. After 5 minutes the Ohmmu is back online. Hence when I checked my Ohmmu is was at 95%. On Version 2 when this happened it would discharge (in that case when I removed it was at 87%.I think it disconnected and stayed offline - Ohmmu could tell you for sure) I believe I saw post that after something like several over voltage test failure it will then throw a popup message on the left screen. If you could push a setting and not allow the over voltage test to occur all of these issues go away. The reason this started, Tesla hired a new engineer who specialized in the Lead acid batteries and started this. Ohmmu even knows the name of the engineer. So a meeting with the engineering team is sought by Ohmmu to prevent this from happened. Clearly Tesla was forward looking and now goes with Lion in all cars. The petition (linked from page 1 of the Ohmmu site) is to show Tesla how many want this meetup to occur. If they can introduce the issue with an software update they can remove it the same way and by adding a setting button it opens the door for more battery options as a day will come where the AtlasBX is no longer around and the Ohmmu is a good alternative. BTW I don't work for Ohmmu (I'm retired) but believe in the product and like how hard they work at service to solve these issues no matter the cost. They work hard to stand behind the product. BTW, any after market LIOn battery should have a built in BMC and would probably suffer the same fate without a software change.
Dysan911
Member
I noticed the Ohmmu website is showing the Lith 12v battery for both Model 3 and Y out of stock so either that's just coincidence or they've halted sales on it which would include the V3 battery since that already replaced V2 which is what I have.
Also, my car sleeps a lot so I assume my 12v must be ok then. At work, I don't run Sentry and I can see how often it sleeps with Teslafi.
Also, my car sleeps a lot so I assume my 12v must be ok then. At work, I don't run Sentry and I can see how often it sleeps with Teslafi.
No sense speculating. Why don't you just email them and ask them if they are out of stock or if they have suspended shipping pending redesign? I've heard nothing from them and in that sense if they felt additional redesign was necessary you would think they would have reached out to everybody with version 3.I noticed the Ohmmu website is showing the Lith 12v battery for both Model 3 and Y out of stock so either that's just coincidence or they've halted sales on it which would include the V3 battery since that already replaced V2 which is what I have.
Also, my car sleeps a lot so I assume my 12v must be ok then. At work, I don't run Sentry and I can see how often it sleeps with Teslafi.
Dysan911
Member
Please relay what you hear. Sean has been very prompt in his Communications at least with me.
This is not accurate. My car has thrown errors with a LFP battery even with no BMS. Tesla can detect a LFP even without the BMS taking it offline. Also, in my testing, Tesla never charges over 14.6V, which is exactly the max voltage of a 4S LFP battery. LFP can be safely taken to 16.8V (4.2 per cell), so if this was the only issue, Ohmmu could just tweak their overvoltage limit. Tesla is more likely checking the float voltage of the battery after a "high voltage" charge.
This is FUD. There are 1 million Model 3/Y cars with lead acid batteries. If they need a replacement every 4 years, this is a solid market of 250,000 batteries a year. The correct answer for 1M Teslas is not a $450 LFP battery. There will be no issue finding a LA well into the future. In fact, why does the supposedly custom Atlas battery have a CCA rating if it's used only in vehicles that do not crank?
If all it takes is a SW change, why can't Ohmmu do that?
I say all of this as someone that wants to run a LFP battery, but I get why Tesla is doing all of this. There is a lot of FUD around the lead acid 12V batteries, and they are trying to catch failing ones as early as possible to minimize the news stories around them. They have zero reason to support an aftermarket LFP battery that can only cause them service hassles, such as not charging in freezing temperatures. Imagine buying a used Tesla and finding out that the battery is some weird aftermarket one that caused issues with the car. In fact, the very detection of these LFP batteries means their system is working well, catching unexpected batteries.
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