Longer term Ohmmu experiences?

[DeepBlue3]

Yikes....

https://www.reddit.com/r/teslamotors/comments/xtone9

Yeah its pretty sketch..

The sub-par solder connection (bottom) could come off and short to the positive terminal. Technically that voids the Tesla warranty.
The BMS is just chillin' on top to wiggle around and weaken the solder connections. Was the heatsink mounted to the lid? There's glue.
There's nothing on top of the BMS to stop it from hitting the terminals.
The main cables aren't secured to the BMS or chassis, aside from their electrical connection, so they're free to work themselves loose and short out.
The BMS wires are routed around a post near the connector creating unnecessary stress.
Positive and neg. cables cross and there's nothing to prevent rubbing.

Sure it will work fine, but there's little attention to short circuit and fire protection.

Back to the sales guys to keep us "on topic."

 

[Dysan911]

I'd really hope that the open Ohmmu battery was just a test / Dev model and doesn't represent the final consumer product. Hopefully, Sean can pop in and explain that one.

 

[dfwatt]

I'd really hope that the open Ohmmu battery was just a test / Dev model and doesn't represent the final consumer product. Hopefully, Sean can pop in and explain that one.

Unfortunately even if he does this thread has been trolled to death. Mostly by folks who really have no background in electrical engineering.

 

[gearchruncher]

Unfortunately even if he does this thread has been trolled to death. Mostly by folks who really have no background in electrical engineering.

Oh, the irony. I'm a EE but dfwatt has me ignored because he thinks I don't understand the difference between AC and DC.

Anyway, that Ohmmu is not a prototype. I've had a lot of LFP and other lithium batteries apart and that's very common construction for batteries of this type. It's not actually a custom designed battery by Ohmmu and assembled by them. There are companies all over Asia that will build you a battery to your spec and will use cells, cases, and BMS's they already have designed. They all look like this inside.

For all that, it's not that bad, and will probably survive just fine mechanically. For sure it wouldn't pass a real OEM test, but few low volume products would. You are paying a premium against other similar size and construction batteries on the market which you would assume is because it for sure will work in your car and will be supported, but that seems to have faded.

 

[israndy]

Exactly

 

[mstatkus]

Hello guys, it seems the charging profiles have been changed since 2022.24.6

Anyone got the vcfront error with this update?

Yeah I just got that and I checked the battery via the ohmmu app and it said it was at 1%. I am charging it up now but slapped the lead acid back in.

 

[Perscitus]

Will be interesting and telling to see how many succesfull and error free updates to 2022.36.2 take with Ohmmu v4+ installed and at what SoCs.

@mstatkus how long has it been in there to only register 2 charge/discharge cycles? Couldnt have been long and/or the charging logic somehow prevented it from charging up, explaining the low SoC.

 

[mstatkus]

Will be interesting and telling to see how many succesfull and error free updates to 2022.36.2 take with Ohmmu v4+ installed and at what SoCs.

@mstatkus how long has it been in there to only register 2 charge/discharge cycles? Couldnt have been long and/or the charging logic somehow prevented it from charging up, explaining the low SoC.

I put it in about 2 weeks ago. I ended up getting the flu so my first drive was about 35 miles Did a charge to the car when I got home. 2 days later I went out to the car to setup scheduled departure at 8am and I got the low voltage error.
I attempted to reset the car to clear the error. Then went to bed. Battery was at 97% and showing charging. Tezlab said the car went to deep sleep 2.5hrs later.
When I came down at 6am I saw the green tesla logo on the charge port. I went out to check the car and had the vc front error with a message like not having enough power to run accessories.
I checked the battery status and it was 1%. So car must of just ram it down and the HV feed wasn’t charging.
Currently on 2022.28.2

I sent a status to ohmmu. I wasn’t sure if disable discharge in the app would cut power to the car. But when I pushed it the button kept going back to “on”.

 

[Flybyglass]

I put it in about 2 weeks ago. I ended up getting the flu so my first drive was about 35 miles Did a charge to the car when I got home. 2 days later I went out to the car to setup scheduled departure at 8am and I got the low voltage error.
I attempted to reset the car to clear the error. Then went to bed. Battery was at 97% and showing charging. Tezlab said the car went to deep sleep 2.5hrs later.
When I came down at 6am I saw the green tesla logo on the charge port. I went out to check the car and had the vc front error with a message like not having enough power to run accessories.
I checked the battery status and it was 1%. So car must of just ram it down and the HV feed wasn’t charging.
Currently on 2022.28.2

I sent a status to ohmmu. I wasn’t sure if disable discharge in the app would cut power to the car. But when I pushed it the button kept going back to “on”.

One question: What was the voltage while charging was working? When I tested a V4 (not V4+) the full battery voltage was at or lost to the charing output voltage so effectively not much charging taking place. After about 6 hours (when first installing 12 volt the system going into 12 volt charging for 4-6 hours) VCFront errors started and by the 3rd the car isolated the battery and stopped charing it with an "active" VCFront error. My thesis, once car stopped charging battery it still saw 14.2 volts, concluded something else was charging the battery and isolated it. When I got my 3rd VCFront with isolation, 12 volt battery dropped quickly (couple hours). I was at 80% when I removed it. Had I not been monitoring charge voltages I never would have noticed an issue until the VCFront error went active and amber. I was hoping on the most recent software updates the 12 volt charge voltages might have been raised enough to prevent more VCFront errors. (from 14.2 charging to 14.5 - something higher than resting battery voltage at 100%). Just a thesis.

 

[mstatkus]

One question: What was the voltage while charging was working? When I tested a V4 (not V4+) the full battery voltage was at or lost to the charing output voltage so effectively not much charging taking place. After about 6 hours (when first installing 12 volt the system going into 12 volt charging for 4-6 hours) VCFront errors started and by the 3rd the car isolated the battery and stopped charing it with an "active" VCFront error. My thesis, once car stopped charging battery it still saw 14.2 volts, concluded something else was charging the battery and isolated it. When I got my 3rd VCFront with isolation, 12 volt battery dropped quickly (couple hours). I was at 80% when I removed it. Had I not been monitoring charge voltages I never would have noticed an issue until the VCFront error went active and amber. I was hoping on the most recent software updates the 12 volt charge voltages might have been raised enough to prevent more VCFront errors. (from 14.2 charging to 14.5 - something higher than resting battery voltage at 100%). Just a thesis.

Every time I looked at it prior I was around 13.3-13.7V charging in the car ~ 97+%. I only ever saw 97% at it’s lowest installed; when it threw the low voltage schedule service message.
I bench charged it back to 100%. That was more like 14.4V around 8 amp. The BCM Tool (app) reports different voltage. Just more pondering there as at the time I installed the ohmmu app hadn’t hit the App Store. ( photo upon delivery )

I will mention with the lead acid the week prior the car was waking up every hour. I kicked out everyone from the tesla app, and trouble shot the SSD but I couldn’t figure out why the car kept waking up burning 8mi of energy a night. After I put the ohmmu in it stopped.

 

[Flybyglass]

Every time I looked at it prior I was around 13.3-13.7V charging in the car ~ 97+%. I only ever saw 97% at it’s lowest installed; when it threw the low voltage schedule service message.
I bench charged it back to 100%. That was more like 14.4V around 8 amp. The BCM Tool (app) reports different voltage. Just more pondering there as at the time I installed the ohmmu app hadn’t hit the App Store. ( photo upon delivery )
View attachment 863387
I will mention with the lead acid the week prior the car was waking up every hour. I kicked out everyone from the tesla app, and trouble shot the SSD but I couldn’t figure out why the car kept waking up burning 8mi of energy a night. After I put the ohmmu in it stopped.
View attachment 863389

Good data. There has been an update to the Tesla app to version 4.13.3 which corrected frequent (several times an hour) wake ups. If it threw a VCFront message at 13.3 volts then that thesis goes out the window. Now I am running a DiehardEV battery which is an AGM at charged voltage settles at about 12.9v. The AtlasBX was I recall about 12.6-12.7.

 

[mstatkus]

Good data. There has been an update to the Tesla app to version 4.13.3 which corrected frequent (several times an hour) wake ups. If it threw a VCFront message at 13.3 volts then that thesis goes out the window. Now I am running a DiehardEV battery which is an AGM at charged voltage settles at about 12.9v. The AtlasBX was I recall about 12.6-12.7.

my vc_front message was on the car when I got to it at 7AM or so. So something happened in the middle of the night so I unfortunately don’t have an idea about the battery voltage, but even at 1% it was claiming 12.87V so yeah its perplexing. I’m more surprised it let it just deplete without charging.

 

[dfwatt]

One question: What was the voltage while charging was working? When I tested a V4 (not V4+) the full battery voltage was at or lost to the charing output voltage so effectively not much charging taking place. After about 6 hours (when first installing 12 volt the system going into 12 volt charging for 4-6 hours) VCFront errors started and by the 3rd the car isolated the battery and stopped charing it with an "active" VCFront error. My thesis, once car stopped charging battery it still saw 14.2 volts, concluded something else was charging the battery and isolated it. When I got my 3rd VCFront with isolation, 12 volt battery dropped quickly (couple hours). I was at 80% when I removed it. Had I not been monitoring charge voltages I never would have noticed an issue until the VCFront error went active and amber. I was hoping on the most recent software updates the 12 volt charge voltages might have been raised enough to prevent more VCFront errors. (from 14.2 charging to 14.5 - something higher than resting battery voltage at 100%). Just a thesis.

I share your mystification and wish I had an answer other than just speculation. I had the same experience with a V2 battery where the system simply stopped charging it and then days later actually gave me the VC front error. When I pulled the thing out and replaced it with the V4 plus version (which still seems to be working without a hiccup), the battery was basically dead and must not have been getting any meaningful charging from the dc/dc circuit for days). There's something about Tesla's operating system that it mistakenly identifies these batteries as defective don't know if this is because overcharging causes the BMS to disconnect or whether the float voltage is something different from what it expects to see (this is hard to believe because the float voltage on these is within a tenth of a volt of the float voltage of lead acid contrary to all the self-styled experts claiming otherwise.) So bottom line is I just don't get it hi there but something explains these disconnects happening consistently. It would be one thing if Tesla's monkeying around with the 12-volt subsystem actually improved the longevity of the OEM batteries but from my understanding and from what other people have described with older model 3s they're failing actually more often rather than less often.

 

[mstatkus]

Ok, doing a fresh round of tests. I’ll keep an eye on it closer.

 

[Flybyglass]

Ok, doing a fresh round of tests. I’ll keep an eye on it closer. View attachment 863918

14.41v is about the highest charge voltage I get with an AGM. You should start seeing any issues after 4-6 hours

 

[mstatkus]

14.41v is about the highest charge voltage I get with an AGM. You should start seeing any issues after 4-6 hours

It’s sitting at 14.5V after 5hrs. Still 100%. And T logo green. Car hasn’t gone to sleep, but Tezlab said the deep sleep assistant was starting a hour ago.

Car went to sleep a hour later.

 

[dfwatt]

14.41v is about the highest charge voltage I get with an AGM. You should start seeing any issues after 4-6 hours

Yes and from my recollection when I tested the new version 4+ battery and charged it up with an outboard charger before installing it, the battery tries to disconnect at a float voltage above 14 volts. It does not like that much voltage.

And related to that I believe there's a possibility that Tesla introduced a desulfating charge cycle in their continuing modification of the 12 volt routines. This is where you take a fully charged battery and overdrive it for a brief period of time with something like 15 - 16 V. This will improve reversible sulfation but it will trip BMS protection circuits in most aftermarket lithium iron phosphate batteries. For folks interested in a real expert instead of some of the people who've been trolling this thread with pseudo expertise, take a look at this interesting tutorial: How To Charge Lithium Iron Phosphate (LiFePO4) Batteries - Power Sonic. These folks make it pretty clear that you can't have a desulfating routine in your12V charge system routine because that is a No-No for lithium iron phosphate batteries

 

[Flybyglass]

It’s sitting at 14.5V after 5hrs. Still 100%. And T logo green. Car hasn’t gone to sleep, but Tezlab said the deep sleep assistant was starting a hour ago.

Every battery I've installed goes into a constant charge for that 4-6 hours then starts winding down the charge. That's when I've had the Lithium errors. Fingers crossed.

 

[mstatkus]

Every battery I've installed goes into a constant charge for that 4-6 hours then starts winding down the charge. That's when I've had the Lithium errors. Fingers crossed.

@dfwatt @Flybyglass - Ok this makes a bit of sense. I saw it doing like a charge pulse of 0.42A on and off over the 6 hrs.
Car did go to sleep. Glad you guys have done the hard work already.

 

[dfwatt]

Every battery I've installed goes into a constant charge for that 4-6 hours then starts winding down the charge. That's when I've had the Lithium errors. Fingers crossed.

When you say lithium errors do you mean errors coming out of the Bluetooth battery monitoring system or errors coming from Tesla's VC front error codes? If you are charging a lithium iron phosphate battery to 14.6 volts and then putting it in the car that battery is a bit overcharged and it's going to start misbehaving potentially. That's very possibly a higher voltage than the battery really needs or wants.