Tesla Won't Install Ohmmu [aftermarket 12v battery]

[israndy]

Its on the third party battery manufacturer to make their product work, not the manufacturer.

But they were working perfectly. If a manufacturer expects customers to be happy with their products they can't be playing cat and mouse games with 3P products that people put in their cars. If you are going to make a change to the software that will break a lithium battery in an attempt to upgrade the battery life of lead acid you simply put in a setting "I have a 12v Lithium battery". If the want people to buy Tesla products and people wanna buy Lithium 12v batts they should retrofit the battery new cars come with.

This is NOT the first time Tesla made an unpopular decision about servicing vehicles. Eliminating Supercharging in salvage cars that had no electrical damage comes to mind.

 

[jjrandorin]

But they were working perfectly. If a manufacturer expects customers to be happy with their products they can't be playing cat and mouse games with 3P products that people put in their cars. If you are going to make a change to the software that will break a lithium battery in an attempt to upgrade the battery life of lead acid you simply put in a setting "I have a 12v Lithium battery". If the want people to buy Tesla products and people wanna buy Lithium 12v batts they should retrofit the battery new cars come with.

This is NOT the first time Tesla made an unpopular decision about servicing vehicles. Eliminating Supercharging in salvage cars that had no electrical damage comes to mind.

Tesla has an obligation to make their OEM battery work properly. On model 3s, In many cases, it was not properly notifying people when it was dying, leaving them stranded. They have an obligation to fix that. They dont have any obligation at all to ensure that any fix they make also needs to work with every third party solution.

Tesla would have no idea if any change they made in support of trying to meet their obligation to correct the issues with their own 12v battery would impact third party solutions, nor do they have any obligation to test that.

Tinkering with your own car and putting in aftermarket parts has always been a "at your own risk / your mileage may vary" situation, and this is no different.

 

[israndy]

Uh huh

 

[M3noob]

Ohmmu installation is outlined on the Ohmmu site. A 10mm socket is needed. Following the instructions takes about 10 minutes to do the installation. They have instructions in text form and video. I retain the AtlasBX on the shelf as a backup.

Don't forget to trickle charge it while on the shelf

 

[israndy]

I think it said to give it a biannual charge while on the shelf, not a trickle like LeadAcid needs. I actually hooked a battery monitor to mine that texts me if the power goes low:

Battery Tender® Wireless Battery Monitor

Must be connected to WiFi to read your battery's voltage.MONITOR YOUR BATTERY: Connect the device to your home WiFi and monitor your battery's health from anywherePEACE OF MIND: Know if a vehicle light was left on and is draining the battery, if the average voltage is low over a period of time...

www.batterytender.com

 

[nitrous]

Thats absolutely not what happened here in any of these threads, though.

Changing algorithms so that your battery works better / differently is not the same thing as "shutting down all non oem" batteries. someone can still go buy a non oem lead acid battery.

Its on the third party battery manufacturer to make their product work, not the manufacturer.

I think you might find that if the manufacturer alters the algorithm simply to deactivate non-OEM parts, it will be deemed illegal/unfair practice. You're mixing apples and oranges. The "coincidence" of a non-oem product no longer working after the manufacturer does an 'update' doesn't need to be proved as a targeted act... it comes down to what a 'reasonable man' would interpret the findings to mean. Apple has struggled with these court decisions since many jurisdictions have enacted 'right to repair' laws.

 

[israndy]

And third party accessories. I still remember when we came out with an update that destroyed the firmware on LaCie external HDDs making all the data unretrievable for customers who did the update day one. That was a fiasco!

 

[dfwatt]

Tesla has an obligation to make their OEM battery work properly. On model 3s, In many cases, it was not properly notifying people when it was dying, leaving them stranded. They have an obligation to fix that. They dont have any obligation at all to ensure that any fix they make also needs to work with every third party solution.

Tesla would have no idea if any change they made in support of trying to meet their obligation to correct the issues with their own 12v battery would impact third party solutions, nor do they have any obligation to test that.

Tinkering with your own car and putting in aftermarket parts has always been a "at your own risk / your mileage may vary" situation, and this is no different.

The problem with this is it assumes a neat separation between changes in code that might crash aftermarket lithium iron phosphate batteries and changes in code that are in fact burning up lead acid batteries. The evidence is that those are the sometimes the same changes, namely changes that took place around the end of 2021 where the charging voltage was driven up to the point where it caused BMS in aftermarket batteries to disconnect the battery to protect it from overcharging. This caused error codes on my aftermarket battery but also fried my wife's battery which was OEM lead acid. I don't think Tesla fully knows what they're doing with that subsystem and they keep moving the goal posts and shifting things around, which is not the signature of a well-established understanding/implementation of a technology but rather some version of a cut and paste empiricism.

 

[Flybyglass]

The problem with this is it assumes a neat separation between changes in code that might crash aftermarket lithium iron phosphate batteries and changes in code that are in fact burning up lead acid batteries. The evidence is that those are the sometimes the same changes, namely changes that took place around the end of 2021 where the charging voltage was driven up to the point where it caused BMS in aftermarket batteries to disconnect the battery to protect it from overcharging. This caused error codes on my aftermarket battery but also fried my wife's battery which was OEM lead acid. I don't think Tesla fully knows what they're doing with that subsystem and they keep moving the goal posts and shifting things around, which is not the signature of a well-established understanding/implementation of a technology but rather some version of a cut and paste empiricism.

They may have tinkered with the charging profile again. With the latest FSDBeta, the charging profile changed. Before FSD update:

After :

 

[dfwatt]

They may have tinkered with the charging profile again. With the latest FSDBeta, the charging profile changed. Before FSD update:

View attachment 855844

Float voltage on lithium ferric phosphate is supposed to be like 0.2 volts higher than lead acid which shouldn't really make much of a difference. What's strange is that they're able to get battery Management Systems to intervene most of those allow 14.6 to 14.8 volts before disconnecting. Curious what some of the battery gurus think about all this.

 

[ApexProxy]

No (not the one you are talking about, anyway). I dont know if the brand new Lithium battery that comes in brand new 2022s does, but the $85 dollar one does not have a bms because its a dumb battery and doesnt need one.

Every single lithium ion based battery system with more than one cell will have a BMS short of maybe a flashlight. It is literally essential to their function as it keeps cell voltage balanced and prevents over charge and over discharge. Even if the BMS cannot be seen it is there or the lifespan would be horrendous and the risk of catastrophic failure would be very high.

 

[STS-134]

Even if the BMS in the Ohmmu could be designed to exactly emulate the charging profile of the OEM lead acid battery, why would anyone install one of those? I doubt they put anything in it that makes it act like a de facto voltage regulator/buffer the way a lead acid battery does (and remember that the entire charging system and low voltage power supply, including the stuff that powers your accessories, was designed for the OEM lead acid battery). So in addition to getting stranded because the car's BMS doesn't like something about the Ohmmu battery, you could also damage your accessories on the 12V outlet and anything else attached to the low voltage power supply if the aftermarket battery isn't regulating voltage like the DC-DC converter and charging system expects it to.

If you really want a Li-ion low voltage battery, then have Tesla do the retrofit and replace the DC-DC converter, low voltage battery charging system, and washer fluid pump (which apparently had to be redesigned to deal with the higher voltage of around 15V). I'm sure that they also put an additional voltage regulator into that system if it's required. You shouldn't just change battery chemistries without changing the charging system as that's asking for trouble.

This reminds me of people who would try to "upgrade" their headlights from halogen to HIDs by just putting a HID bulb where the halogen bulb was supposed to go. No, this is NOT the proper way to do things! The entire optics of the headlight had been designed for a halogen bulb with a halogen filament, and a HID bulb outputs light from a different source, in different wavelengths, at different intensities, and emits light from a different shape (arc vs. a halogen filament). You cannot just add ballasts and swap bulbs because the beam pattern will be wrong (one advantage of HID headlights is that they are able to put more light out to the sides), and you'll blind other drivers because the light going straight ahead will be too strong (HID bulbs are more intense) and the wrong parts of the headlight housing will be reflecting light as it's coming from an arc instead of a filament. To change the type of bulb you're using, you have to replace the entire optics of the headlight in addition to the bulb, and to change battery chemistries, you have to replace the entire charging system.

 

[israndy]

Where are you getting this mis-information? People put LiFePO4 batteries (like the Ohmmu) in all sorts of situations that originally had Lead Acid. That's why they are all over the marketplace. You keep mentioning that the Lead Acid OEM battery accomplishes voltage regulation. But you don't support your statement, instead you say we are doing the same thing are headlight upgraders, w/o supplying any correlation.

LiFePO4 batts have almost exactly the same charging curve as a lead acid, so they are drop in replacements, but you can get thousands of charge cycles out of them. This means not thinking about your battery for a decade or more. Perhaps the life of the car. That's one more thing you don't have to worry about as long as Tesla can keep from putting bugs in their updates.

That Tesla went to lithium batts in the newer vehicles PROVES it's a good idea. They did use a different chemistry (Li-Ion, same as the traction battery), different voltage so they needed to use different parts, like the washer pump you site.

 

[israndy]

Every single lithium ion based battery system with more than one cell will have a BMS short of maybe a flashlight. It is literally essential to their function as it keeps cell voltage balanced and prevents over charge and over discharge. Even if the BMS cannot be seen it is there or the lifespan would be horrendous and the risk of catastrophic failure would be very high.

I think the $85 dumb battery he was referring to was the OEM Lead Acid, it is a dumb battery w/o BMS

 

[STS-134]

Where are you getting this mis-information? People put LiFePO4 batteries (like the Ohmmu) in all sorts of situations that originally had Lead Acid. That's why they are all over the marketplace. You keep mentioning that the Lead Acid OEM battery accomplishes voltage regulation. But you don't support your statement, instead you say we are doing the same thing are headlight upgraders, w/o supplying any correlation.

Lead acid batteries are well known to be able to supply a lot of surge current, like for starting an engine, and can even be used for welding. If a device starts drawing a lot of current on the low voltage bus, and exceeds the alternator's (or DC-DC converter's) ability to generate power, the battery kicks in and can act as a huge capacitor that dumps current into the system and keeps the voltage (relatively) steady. Li-ion batteries do not have the same discharge curve. They can't provide the same amount of current and hold the voltage relatively steady because their internal resistance is way too high. I'm not 100% sure about absorbing voltage spikes but I think lead acid is better at that too, again because of the high surface area of the plates inside and low internal resistance.

LiFePO4 batts have almost exactly the same charging curve as a lead acid, so they are drop in replacements, but you can get thousands of charge cycles out of them. This means not thinking about your battery for a decade or more. Perhaps the life of the car. That's one more thing you don't have to worry about as long as Tesla can keep from putting bugs in their updates.

That Tesla went to lithium batts in the newer vehicles PROVES it's a good idea. They did use a different chemistry (Li-Ion, same as the traction battery), different voltage so they needed to use different parts, like the washer pump you site.

Yeah, absolutely, the cells are different voltages because of the different chemistry. Hence, they are NOT drop-in replacements. If they were drop-in replacements, you'd be able to change out the battery without changing the charging system, and Tesla wouldn't have had to redesign the washer pump either.

 

[israndy]

Perhaps we need to drop this, you have yet to provide anything but a fanciful dream of what could go wrong. You know why you don't need the power of a Lead Acid battery in a Tesla, because there is no starter motor attached to it.

And again you seem to confuse LiFePO4 (Lithium IRON) batteries with Lithium ION, just missing the 'R' so it's understandable.

But get this: Lithium IRON 12 volt batteries can be drop in replacements for Lead Acid. The whole RV industry is doing it. Just buy the battery, and replace your old Lead Acid batt. All the chargers for Lead Acid work perfectly for Lithium IRON. Only you don't have to keep it charged up, you can use it down to 20% or even less w/o any issues, where as this will kill a Lead Acid.
Thus it's perfect to drop in a Tesla as long as Tesla's software guys realize that the Lithium BMS cutting out isn't a Lead Acid battery failing catastrophically.

 

[dfwatt]

Even if the BMS in the Ohmmu could be designed to exactly emulate the charging profile of the OEM lead acid battery, why would anyone install one of those? I doubt they put anything in it that makes it act like a de facto voltage regulator/buffer the way a lead acid battery does (and remember that the entire charging system and low voltage power supply, including the stuff that powers your accessories, was designed for the OEM lead acid battery). So in addition to getting stranded because the car's BMS doesn't like something about the Ohmmu battery, you could also damage your accessories on the 12V outlet and anything else attached to the low voltage power supply if the aftermarket battery isn't regulating voltage like the DC-DC converter and charging system expects it to.

If you really want a Li-ion low voltage battery, then have Tesla do the retrofit and replace the DC-DC converter, low voltage battery charging system, and washer fluid pump (which apparently had to be redesigned to deal with the higher voltage of around 15V). I'm sure that they also put an additional voltage regulator into that system if it's required. You shouldn't just change battery chemistries without changing the charging system as that's asking for trouble.

This reminds me of people who would try to "upgrade" their headlights from halogen to HIDs by just putting a HID bulb where the halogen bulb was supposed to go. No, this is NOT the proper way to do things! The entire optics of the headlight had been designed for a halogen bulb with a halogen filament, and a HID bulb outputs light from a different source, in different wavelengths, at different intensities, and emits light from a different shape (arc vs. a halogen filament). You cannot just add ballasts and swap bulbs because the beam pattern will be wrong (one advantage of HID headlights is that they are able to put more light out to the sides), and you'll blind other drivers because the light going straight ahead will be too strong (HID bulbs are more intense) and the wrong parts of the headlight housing will be reflecting light as it's coming from an arc instead of a filament. To change the type of bulb you're using, you have to replace the entire optics of the headlight in addition to the bulb, and to change battery chemistries, you have to replace the entire charging system.

Pure FUD and the latest illustration that a little knowledge is a dangerous thing. Reminds me of all the self-styled exports on the Forum who predicted that the aftermarket lithium ferric phosphate 12 batteries were all going to catch fire. The real problem is the Tesla does not know how to manage the 12 volt subsystem. They've changed 12 volt subsystem code more times than anybody can count, and they have a remarkable track record of inducing failure in lead acid batteries well before they tend to fail in ice vehicles. This includes a brief flirtation with nearly 15 volts charging voltage which induced a whole lot of failures including in my wife's OEM lead acid battery right about the same time (late 2021) that people reported issues with a number of lithium ferric phosphate batteries that had been working just fine. Get your facts straight before posting a categorical statement so you don't embarrass yourself.

 

[ApexProxy]

I think the $85 dumb battery he was referring to was the OEM Lead Acid, it is a dumb battery w/o BMS

Ah, guess I read it wrong.

 

[STS-134]

Perhaps we need to drop this, you have yet to provide anything but a fanciful dream of what could go wrong. You know why you don't need the power of a Lead Acid battery in a Tesla, because there is no starter motor attached to it.

And again you seem to confuse LiFePO4 (Lithium IRON) batteries with Lithium ION, just missing the 'R' so it's understandable.

You know that LFP batteries are a type of li-ion battery, right?

But get this: Lithium IRON 12 volt batteries can be drop in replacements for Lead Acid. The whole RV industry is doing it. Just buy the battery, and replace your old Lead Acid batt. All the chargers for Lead Acid work perfectly for Lithium IRON. Only you don't have to keep it charged up, you can use it down to 20% or even less w/o any issues, where as this will kill a Lead Acid.
Thus it's perfect to drop in a Tesla as long as Tesla's software guys realize that the Lithium BMS cutting out isn't a Lead Acid battery failing catastrophically.

They're not. The voltage curves are different:

And even if you could match the curves exactly, the problem is that lead acid needs to be stored at close to 100% SoC for maximum life, whereas LFP likes to be stored at something far less than close to 100% SoC. So you need to tell the charging system to not top off the battery all the time. If this chemistry were so great and it could just be used as a direct drop-in replacement and have OEM reliability, Tesla would have just used it as the OEM battery and wouldn't have redesigned anything else.

 

[ApexProxy]

Lead acid batteries are well known to be able to supply a lot of surge current, like for starting an engine, and can even be used for welding. If a device starts drawing a lot of current on the low voltage bus, and exceeds the alternator's (or DC-DC converter's) ability to generate power, the battery kicks in and can act as a huge capacitor that dumps current into the system and keeps the voltage (relatively) steady. Li-ion batteries do not have the same discharge curve. They can't provide the same amount of current and hold the voltage relatively steady because their internal resistance is way too high. I'm not 100% sure about absorbing voltage spikes but I think lead acid is better at that too, again because of the high surface area of the plates inside and low internal resistance.

Yeah, absolutely, the cells are different voltages because of the different chemistry. Hence, they are NOT drop-in replacements. If they were drop-in replacements, you'd be able to change out the battery without changing the charging system, and Tesla wouldn't have had to redesign the washer pump either.

Unfortunately you seem to have a few misinformation issues here.

LiFePO4 cells can sustain greater discharge currents than lead acid in the same form factor and voltage configurations with higher volumetric and weight energy density. LiFePO4 cells are known for their amazing discharge curve being unusually flat and that higher discharge currents have significantly less effect on available capacity than lead acid.

Internal resistance of a lead acid is lower and in general LiFePO4 is capable of less burst current when using an equal capacity battery. However when the much higher energy density is accounted for LiFePO4 is able to withstand engine starting currents.

Differences in operating voltages is fairly nominal and usually just means the LiFePO4 cells charge up to less than 100% SOC. BMS systems can help with this.