-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Longer term Ohmmu experiences?
- Thread starter Durzel
- Start date
Can you wake the car? I find when awake sudden amp draw followed by charging. Or get into service mode LV battery and try reconnect battery. Also check the advanced page for any red warnings.
mstatkus
Member
Car was still functional. Pretty high amp draw than I’ve seen before. I powered it down and swapped back to lead. Thought I’d follow you down the road but I didn’t make it out the gate 
Attachments
mstatkus
Member
Said it right there. Li-ion not supported by PCS.
Other than it claimed it dropped to 12.2V which my monitor did not show that.
Other than it claimed it dropped to 12.2V which my monitor did not show that.
Waiting to see if same happens here. When was you battery made? Ohmmu adjusted the firmware in early December. The latest Tesla software is the same for the Lead Acid cars with 12 volt of the later 15.5 volt cars with Lion. I have a Y and 3. Y with Lion both same version software. I'm curious if any warnings on the advance page or MOS lock or something.
Last edited:
mstatkus
Member
Send a note to Ohmmu to see if firmware can be updated. Later app build will allow update via the app but see if then can update it. Screen shot the advance page.
Last edited:
mstatkus
Member
Yeah I didn’t see any current BCM version or way to update it yet. I’ll keep an eye out.
So it looks like it needs 12.9V+ to be ok with a reset. Nothing the monitor picked up shows a 12.2V dip.
Last edited:
mstatkus
Member
Sent an update with the extra data.
Dysan911
Member
FWIW, I've been checking the App store pretty regularly to see if the Ohmmu app would ever show an update that might include a firmware flashing capability but so far it's been the same version I originally installed. Hopefully, that capability is already present and they're still interested in providing an update for this product.
mstatkus
Member
I looked over the alerts closer and seems like they are set messages for Lead Acid or Li-ion.
Other behaviors I saw after pulling Ohmmu out at 88%.:
- my lithium charger said FUL when connecting it
- ohmmu app said 88%
I flipped it to Lead Acid and it kicked off the DFS. It charged at 5A and took it up to 100% and Ohmmu switched to balancing. Charger seemed to think it was at 40% or at least it was animating 40-100%. It seemed to figure out it was full after balancing.
Still shows 3 cycles after a few discharged to 80% and back to 100%.
Other behaviors I saw after pulling Ohmmu out at 88%.:
- my lithium charger said FUL when connecting it
- ohmmu app said 88%
I flipped it to Lead Acid and it kicked off the DFS. It charged at 5A and took it up to 100% and Ohmmu switched to balancing. Charger seemed to think it was at 40% or at least it was animating 40-100%. It seemed to figure out it was full after balancing.
Still shows 3 cycles after a few discharged to 80% and back to 100%.
Last edited:
mstatkus
Member
Stumbled upon this 3mo old video that appears to chat with Ohmmu about what they did to make this less a problem.
So now 5 days in use with the V4+. No issues. Resting the battery will show about 13.4 volts. Upon car wakeup, the V4+ will discharger at about 7-9 amps briefly until car fully awake. Then the battery charges at 7-9 amps. Again looking at the PCS, output matches battery voltages with the bulk of the PCS amps going to the car with about .1 amps going to charge the Ohmmu. The charge will be at 14.7 volts approx. Once charged the Ohmmu settles back to 13.3-13.4 volts mirroring a 12 volt lead acid on a maintenance charge or an AGM (I've run both - the AGM is about .3-.4 volts above the Lead Acid with a top voltage about 13.4. Both the Lead and AGM never had any issues and so far it looks like the Ohmmu is doing a good job of mirroring. It is also helpful the latest Tesla software allows service mode visual on what the 12 volt battery is doing. That plus the Ohmmu app quite helpful. My confidence is climbing each day.
mstatkus
Member
I gave it another shot this AM. I did not get the message in my app that the low voltage had an issue 6hrs later, but could see the car was still on 7hrs later. I attempted the disable of discharge/charge but that had no effect. I tried service mode and reconnecting the LV Battery. No effect.
I tried clearing VC_Front. No effect. With all that I decided it’s not worth cracking the frunk open to disconnect the HV feed each time this happens. Lead acid back in.
I tried clearing VC_Front. No effect. With all that I decided it’s not worth cracking the frunk open to disconnect the HV feed each time this happens. Lead acid back in.
Attachments
A week now since installation. Consistently each day battery will be 13.3-13.4 volts overnight at 99%. Upon car wakeup, a negative draw of 7-9 amps with a momentary draw of -25 amps. Minimum voltage observed 12 volts (only 1 second) before charging begins and then positive amps of 7-9. Once battery reaches 14.68-14.75 volts charging stops and stabilized for a minutes and showing 100%. Then after a few minutes a draw down at 7-9 amps occurs until battery stabilzes at 13.38-13.4 then back to 0.0 amps 99%. No warnings or messages generated. Have not tested multi-day sleep cycle with Sentry but so far Ohmmu working well. Temperature for battery running between 45-50F with outside temps as low as 25F.
Dysan911
Member
3 weeks this coming Saturday since the reinstall and so far so good. The car is sleeping as it should. Battery showing 99%, 0.0amps in/Out while sleeping. The voltage at 13.29. 21 cycles now and temp at 68.4f
mstatkus
Member
I was wondering how this would work in colder temps too with li-ion not liking a charge and I assume the BMS would manage it but not sure what it does about warming up.
You guys are giving me hope but I think you're right I probably need a firmware update. Back to back failures after 6 hours otherwise.
You guys are giving me hope but I think you're right I probably need a firmware update. Back to back failures after 6 hours otherwise.
![(@r8[]np4nd4](/tmc/data/avatars/l/153/153664.jpg?1711743159){kind=avatar}
(@r8[]np4nd4
Member
I have to make a reset every 2-3 days with the Rev 4 and it's very frustrating, so I switched back to lead acid.
Also the reset procedure for the rev4 on their website doesn't work for me, i always have to disconnect the HV connector. I did that for so many times now that I have to worry that the HV connector broke one day.
I wonder why other people doesn't have issues with the ohmmu battery.
Also the reset procedure for the rev4 on their website doesn't work for me, i always have to disconnect the HV connector. I did that for so many times now that I have to worry that the HV connector broke one day.
I wonder why other people doesn't have issues with the ohmmu battery.
My battery build was early December. Sean said he made a few "tweaks" in the firmware but none specific. Cold WX. There is no 12 volt battery heater other than heat from the compartment since cabin heat os from the front motor. OAT's in low 30's garage temps mid to upper 40's no issues (even though it says to "store" the Ohmmu at 65-80f). I feel better about charging the Ohmmu at 14.7v vs. a Lead acid or AGM that high.
Similar threads
