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Longer term Ohmmu experiences?
- Thread starter Durzel
- Start date
android04
Active Member
The info is under their Battery Info section under Battery Performance (Better Performance | ohmmu). However, it's been there since their 1st gen battery and I don't believe their 2nd and 3rd gen batteries kept the same capacity because they reduced the weight from the 1st gen. I hoped that Will Prowse would get an Ohmmu battery to dissect and test the capacity on in his YouTube channel, but as far as I know he never did.
+1 for me. I bought one for my MS, but faced similar problems like on 3/Y and they are not responding.
ElectricLove
Member
Wondering if you could tell me the email you used when submitting the case at support.ohmmu.com; I can get it bumped in priority. don't see anything "cbdream..." related when searching.
The challenge of balancing a whole bunch of things at once has overwhelmed us:
1. Sudden sales drop off cliff (pulled 3/Y sales altogether)
2. Sudden massive influx of customer support issues (3/Y related software updates)
3. Sudden massive financial strain related to redeveloping 3/Y battery (R&D costs, new production costs, dead inventory, etc)
So at the same time we need to be able to hire more help to support customers better we also experienced both a drain of our finances in trying to fix the problem with our earliest attempts and then a drain on our revenue with the loss of 3/Y sales. All at once it is the perfect storm to obliterate our ability to keep up with customer support in a responsible/timely manner and also support the business needs otherwise.
I'm not saying that to say we are giving up or "giving the finger" as someone else stated earlier. I get all the customers being upset and certainly Tesla isn't gonna give a rats-anus that their software updates caused this so the anger gets squarely put on us. I understand the upset, truly, and we have been working on this for 9 months now trying to solve it, at a tremendous cost, so we are able to do the right thing (in our mind) and provide the community a real solution!
You ARE important to us and we want to support your needs!
ElectricLove
Member
We did provide Will a battery, I don't think he considers this to be an important matter with his videos. We have also tried to get his attention/time on reviewing other batteries for us, we stopped hearing back from him. I assume his massive following amounts to his being a bit unobtainable without a big name/bank/company behind you. But I say that not knowing for sure at all.
In terms of Ah capacity on the Ohmmu battery, this is a moving target and has changed half a dozen times. Being one of the few variables that has an externally accessible impact on the behavior of the 12V battery in the car it is something we have been adjusting over and over to try to minimize alerts. It is easy to assume that the car is happier if you increase Ah and I wish it were that simple, our first revision after the alerts was to produce a batch with 20% higher and also a batch with 20% lower Ah, the higher ones produced alerts very quickly in every vehicle they went into, the lower ones were less so (though still not 100% no alerts). We scaled that way up and sent hundreds of those units out with the lower Ah, it went "better" but not good enough (still a 20% or so alert rate, that we know of, assume there are also customers who just give up and don't tell us, so the real number is higher). We decreased Ah again and got less alerts, in around 40-50 vehicles we have a rate under 10%. I don't like how high that alert rate is still but we feel that if we deploy another feature we have been working on for a year along with this 90% version of the battery we will account for 95-99% of customer complaints/issues. This is the V4+ coming soon, it is our V4 battery but with the added feature of Bluetooth BMS connectivity. Our app for this has been in the works for weeks and is almost ready as well.
ElectricLove
Member
A "warranty claim" is not going to lead to a refund, I don't think that is how it works with any company, that I'm aware of, refund/return policy and warranty policy are very different things.
DeepBlue3
Member
@ElectricLove
What is the source of the alerts? Is the car not happy with the discharge curve? Is it the calculated capacity? Is the BMS falling asleep, or voltage surges causing BMS faults? Maybe the chemistry is causing unusual float voltages etc.?
What capacity are you targeting? AntiGravity and MPP claim to have zero issues but they have different capacities, so that throws a wrench in the spokes of that theory.
I'm experimenting with a 9 ah lead acid battery in parallel with a 4s LiPO (not LiFePo4) and even with the lead acid disconnected I can get about 4 days without alerts. I also tried a smaller LiPo with same result.
My swollen 5 year old OEM battery works fine though with 110k miles.
What is the source of the alerts? Is the car not happy with the discharge curve? Is it the calculated capacity? Is the BMS falling asleep, or voltage surges causing BMS faults? Maybe the chemistry is causing unusual float voltages etc.?
What capacity are you targeting? AntiGravity and MPP claim to have zero issues but they have different capacities, so that throws a wrench in the spokes of that theory.
I'm experimenting with a 9 ah lead acid battery in parallel with a 4s LiPO (not LiFePo4) and even with the lead acid disconnected I can get about 4 days without alerts. I also tried a smaller LiPo with same result.
My swollen 5 year old OEM battery works fine though with 110k miles.
MPP is an EarthX. Here's someone having issues with the EarthX:
That sounds super weird. Tesla will never charge above about 14.6V as they assume a Lead Acid. 14.6V on a 4S LiPo chemistry is about 10% SoC on the LiPos, so they are basically empty, and always at such a low SoC that they are eating themselves. Once not charging, Tesla will allow discharge below 12V, which will destroy the LiPo given any real time.
DeepBlue3
Member
I'm estimating 30% SOC remaining at ~14 volts on the LiPO and I haven't seen it going over 14.3. Cut off is 10 volts. The lead acid helps mimic the original battery chemistry ( I hoped) and will still power the car incase of a BMS fault. 500 watt hour estimated capacity (full discharge depth.) Its lighter than even the LiFePO4s everyone is selling and based on customer feedback, it works just as well. I happened to have the batteries laying around. Sure I can build a LiFe battery, or pay 600 for one that still throws codes.
From what I've seen the battery doesn't drop under about 12.5 volts at any time. The model S has been known to surge over 15 volts. How is the LiFe BMS going to like that?
4 X 3.7= 14.8 Nominal.
Do you have any ideas, other than strapping down the 28 lbs of lead that came with the car originally?
From what I've seen the battery doesn't drop under about 12.5 volts at any time. The model S has been known to surge over 15 volts. How is the LiFe BMS going to like that?
4 X 3.7= 14.8 Nominal.
Do you have any ideas, other than strapping down the 28 lbs of lead that came with the car originally?
LFP is fully safe to 4.2V per cell, which is 16.8V for 4S. It doesn't really store anything extra above about 3.6V (14.4) which is why it is a perfect drop in for Lead Acid in dumb charger applications.
Not sure where you get 30% SoC at 3.5V per cell for LiPo. There is a massive knee at 3.7V, and 30% SoC is more like 3.8V.
Lipo Voltage Chart: Show the Relationship of Voltage and Capacity - Ampow Blog
Show you the lipo voltage chart show the base voltage from 1s to 6s and the relationship of voltage and capacity on here.
blog.ampow.com
10V cutoff is 2.5V per cell. This is deep into the damage-a-cell voltage, which is generally considered to be 3V per cell (12V for 4S).
You can't parallel two batteries and have different voltage, so the lead acid doesn't "help mimic" the LA curve. It just means that when the charge cycle shuts off, the LiPo will spend some time float charging the Lead Acid.
As you say, you haven't solved the code issue, so I don't know what the point is. If you don't want codes, put a lead acid in. If you can stand codes, put a 10lb LiFePo4 in.
DeepBlue3
Member
The point is, we're doing R&D work. I build these for fun so I have parts laying around. The lead acid I'm using has an effective capacity of approx. 65 w/hr, so it doesn't take much more from the LiPO to reach the capacity target.
I'm not aware of any LiFePo4 BMS that can take over approx. 3.65 V per cell, but that's interesting to know. LiFe is not my area of interest. The internet says you will see cell degradation charging LiFe to 4.2V however.
Would you agree the remaining SOC at a fixed voltage depends on the particular chemistry of the cell? I'm operating within LG Chem's voltage range (protected cells).
Next test is an actual capacity test rather than calculations. Not confident we will solve this until Tesla offers programing for various chemistries and capacities.
I'm not aware of any LiFePo4 BMS that can take over approx. 3.65 V per cell, but that's interesting to know. LiFe is not my area of interest. The internet says you will see cell degradation charging LiFe to 4.2V however.
Would you agree the remaining SOC at a fixed voltage depends on the particular chemistry of the cell? I'm operating within LG Chem's voltage range (protected cells).
Next test is an actual capacity test rather than calculations. Not confident we will solve this until Tesla offers programing for various chemistries and capacities.
The only error I always got was VCFront a180 vehicle may shutdown unexpectedly... now its been a week and no errors with this new update... This is on a V2 Battery btw
I have a V4 battery on the shelf. Putting a monitor module on it (prior to removal) a fully charged Ohmmu V4 was about 14.0 volts resting. I found the charging would go to 14.1 or so for 6 hours initially (common when first installing a new battery) but when it wanted to drop down to non charge levels the battery of course stayed at 14.0. After 2 VCFronts within an hour the third locked out charging of the 12 volt battery and an amber message stayed. Monitored 12 volt levels started dropping rapidly. I removed at 80%. It's like the car saw 14 volts when it stopped charging (when it would see normally 13 +/- and concluded there must be a second charge source and isolated itself. Removal and reset cleared this. So it's good news that no error yet. I'm wondering it it would work with the V4. I an still on FSDBeta from May so no updates there.
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Dysan911
Member
Man that sure would solve a lot of problems if Tesla did in fact make a change that inadvertently resolved this issue were all having with the Li Battery
DeepBlue3
Member
There's a chance it could be related to the float voltage like mentioned above. Also a chance its the discharge curve. I'm currently running a tiny motorcycle battery to see if the capacity "loss" results in an error message or if the float and discharge characteristics are accepted.
DeepBlue3
Member
The under capacity sealed lead acid threw a few VC Front codes after about a day. I'd guess it went through a few quick discharge/charge cycles and flagged it.
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