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Linsight Designer
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Discussion Starter · #721 ·
Glad to hear that worked, Michael. Good call on using a syringe instead. Please let me know if you have any other questions/issues. In the future I'll make sure to tape off the screw heads before applying the conformal coating.

-John
 

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Lmfao @mudder I had the same issue with my screws. My brother and I were cringing as I wrenched down on them with extreme force to get them to cooperate. They were making all sorts of angry cracking noises, now I know what it was. Also my other LiBCM board is like that. Looks like I'll whip out the acetone.
 

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Discussion Starter · #723 ·
Lmfao @mudder I had the same issue with my screws. My brother and I were cringing as I wrenched down on them with extreme force to get them to cooperate. They were making all sorts of angry cracking noises, now I know what it was. Also my other LiBCM board is like that. Looks like I'll whip out the acetone.
I didn't even realize this was an issue... nobody had reported it prior to now and I never saw it myself.
I'll make sure the unsold LiBCM units I have in stock don't have this issue. I thought I was being careful enough, but in the future I'll tape the screw terminal prior to applying the conformal coating.
 

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-actual cell voltages: I believe you've already done so, but as a sanity check make sure the pack voltage isn't actually 0.0000 volts. This almost certainly isn't the issue, but it's worth checking.
This: The autoranging meter was either deranged or I didn't read in car correctly. It wasn't 150V, it was 15V. I put my good shop meter on it with it on the bench and that meter has it just over 10V, the other meter is in the trash for pickup. (edit) 10V on HV side
 

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Discussion Starter · #725 · (Edited)
I did try flashing back to ef4a31a8b658a04126ca485ebd5e6df7b454146f from 0.7.5a which I had been running
Are you absolutely certain your LiBCM was running 0.7.5a when you left the car sitting for several weeks?

Background:
In firmware v0.7.2 and previous, LiBCM doesn't turn off when the SoC is low, so the SoC consumption behavior is:
-The SoC will drop about 1% per day.

In firmware v0.7.3 (released 2022MAR27) and later, LiBCM turns 'off' when the battery SoC drops below 10% SoC, so the SoC consumption behavior is:
-When LiBCM is 'on' (i.e. SoC above 10%), the SoC will drop about 1% per day.
-When LiBCM is 'off' (i.e. SoC below 10%), the SoC will drop about 1% per month.
Given the above, right now LiBCM's keyOFF standby time is at least 10 months.

FYI: The function that turns LiBCM off is
SoC_turnOffLiBCM_ifPackEmpty(). This code has not changed since it was added (in v0.7.3). I verified it worked when I wrote it, and I just mentally re-verified the logic works correctly.
FYI: Future firmware upgrades will increase the keyOFF standby time to at least 1 month per initial keyOFF SoC percent (e.g. 50% starting SoC will yield 50 months keyOFF standby time).
FYI: For long term storage, you should either plug in the grid charger or turn the IMA switch off. When the IMA switch is off, LiBCM pulls zero current.


I put my good shop meter on it with it on the bench and that meter has it just over 10V on HV side.
The BMS circuitry does not power up if the stack is less than 50 volts, which explains why you're reading 0.000 volts for all cells.

Your 10 volt stack measurement agrees with my testing: LiBCM's HVDCDC power supply can source power from the IMA battery until the stack voltage drops below ~10 volts. Below this voltage, LiBCM's input current drops to zero. This isn't a design oversight, but rather is a technical limitation caused by LiBCM powering itself from the IMA battery (rather than the keyed 12 volt battery).

So if you are absolutely certain you were running 0.7.5a when LiBCM pulled your IMA pack down to 10 volts in around 15 days, that is a huge issue and I will drop everything to figure out why that happened...
...but if there's any chance you were running v0.7.2 or previous, then the resulting pack voltage after leaving a nearly empty pack for a few weeks makes sense (see 'background', above).

LiBCM's firmware expires every 40 days, but there's nothing preventing you from loading the exact same version right back on... for example, if you downloaded v0.7.2 back in March and then just continued loading that same version every 40 days, then I would expect the behavior you observed.

...

At this point I do not recommend continuing to use these specific EHW5 cells, which are almost certainly damaged. The primary concern is dendrite growth, which massively increases at low cell voltages. Dendrites can eventually pierce the dielectric membrane, causing internal short circuits that could lead to thermal decomposition (i.e. a fire). Other issues caused by over-discharge include: increased gas pressure inside the battery, electrolyte dissolution, lithium plating, increased internal resistance, and decreased ampacity. While you might be able to initially salvage them, they are no longer safe to recharge and use. For this reason, LiBCM will not allow grid charging or regen if any cell drops below CELL_VMIN_GRIDCHARGER (which is 3.0000 volts, i.e. 0% SoC). Even if you change this value (e.g. to 0.0000 volts, but not recommended), the grid charger hardware will not work if the IMA battery is less than 71 volts.

I know that's a huge bummer, but it's impossible to sugarcoat. You're going to need new EHW5 cells.

...

If you are absolutely certain you were running v0.7.3 or later, then I would like to look at your initial LiBCM PCB. It's possible something on it is broken, such that LiBCM wasn't able to turn itself off once the SoC dropped below 10%. My automated tester specifically verifies this circuitry is working properly, but maybe it broke?
 

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Are you absolutely certain your LiBCM was running 0.7.5a when you left the car sitting for several weeks?
Wish it weren't so. I save the code in individual folders by release. Dates on the folder match when I last updated car.
#define FW_VERSION "0.7.5dALPHA"
#define BUILD_DATE "2022APR16"

'something' else went wrong in my pack, because it was parked less than a month. Shouldn't have gone down that far?

At this point I do not recommend continuing to use these specific EHW5 cells, which are almost certainly damaged. The primary concern is dendrite growth, which massively increases at low cell voltages. Dendrites can eventually pierce the dielectric membrane, causing internal short circuits that could lead to thermal decomposition (i.e. a fire). Other issues caused by over-discharge include: increased gas pressure inside the battery, electrolyte dissolution, lithium plating, increased internal resistance, and decreased ampacity. While you might be able to initially salvage them, they are no longer safe to recharge and use. For this reason, LiBCM will not allow grid charging or regen if any cell drops below CELL_VMIN_GRIDCHARGER (which is 3.0000 volts, i.e. 0% SoC). Even if you change this value (e.g. to 0.0000 volts, but not recommended), the grid charger hardware will not work if the IMA battery is less than 71 volts.

I know that's a huge bummer, but it's impossible to sugarcoat. You're going to need new EHW5 cells.
Not a big deal, in this for the fun factor. Agreed, I've read quite a bit on the dendrite issue. I have another 18S+ and 18S-, no 12S, which I think are unobtanium now? Any safe way to slow charge the 12S back up without forming dendrites? Failing that, any known source for 12S?
If you are absolutely certain you were running v0.7.3 or later, then I would like to look at your initial LiBCM PCB. It's possible something on it is broken, such that LiBCM wasn't able to turn itself off once the SoC dropped below 10%. My automated tester specifically verifies this circuitry is working properly, but maybe it broke?
Only wild possibility is the extreme lightning activity during that period. The sequence of events doesn't quite fit a LIBCM failure on storage scenario.
1. Car parked a few weeks.
2. 12v dead, charged, started and moved next to garage. (no issues noted, I think it was IMA start), placed on grid charge (no beeps/flashing 4x20)
3. Another 8 - 10 days, went to move into garage, 12v dead, charged. No IMA start, IMA and CEL on startup, placed on grid in garage and beeps/flashing 4x20.
Are you absolutely certain your LiBCM was running 0.7.5a when you left the car sitting for several weeks?
Yes
(EDIT). I'm printing out a tripod mount for my phone so I can video voltage testing and connections. I've already removed fan housing and screws from LIBCM to make it faster.
 

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Discussion Starter · #728 · (Edited)
Wish it weren't so. I save the code in individual folders by release. Dates on the folder match when I last updated car.
#define FW_VERSION "0.7.5dALPHA"
#define BUILD_DATE "2022APR16"
Alright, then please send me your original LiBCM unit so I can verify it's still functioning correctly. I believe I already sent you a return shipping label.

'something' else went wrong in my pack, because it was parked less than a month. Shouldn't have gone down that far?
I agree: If v0.7.3 or later was installed, then the pack SoC shouldn't have dropped below 8% worst case.

Not a big deal, in this for the fun factor. Agreed, I've read quite a bit on the dendrite issue. I have another 18S+ and 18S-, no 12S, which I think are unobtanium now?
12S modules are hard to find. One potential replacement source is to grab QTY12 EHW5 cells from a donor 18S module. However, I have a better idea:
I'll trade you a brand new 12S module for your 'trashed' modules. I will use these trashed modules for reference on future designs (e.g. when I eventually design brackets for Ford CMAX EHW5 cells). I will also use the BMS connectors (attached to the modules) in my automated tester (once the ones I'm using now wear out).

To ship these modules legally, you'll need to send them as QTY4 properly labelled packages. 12S modules are legal to ship, whereas 18S modules are not. I propose the following:
1a: You ship me the dead 12S module as-is, in a properly labelled box (UN-3481 label).

1b: At the same time, I'll send you:
-QTY1 complete, new 12S module. Let me know what cell voltage your 18S packs are at... I'll charge the 12S module to that voltage so it doesn't take forever to balance.
-QTY1 12S mechanicals (from another 12S module I have).
-QTY2 sets of 18s-to-12s conversion mechanicals.

2: When you receive the package, you'll convert both of your dead 18S modules to pseudo-12S, so that they are legal to ship. FYI: You won't need to install the new wire harness (I won't actually even send it), or even reinstall the bus bars (but I do want all these parts). The cells just need to be all mechanically secured together, with the terminals covered so they can't short out.

3: You'll have QTY6 leftover cells from each 18S module. Assemble these into a fourth 12S pack (using the 12S mechanicals I sent you).

4: Ship me QTY3 boxes, each containing a 12S module, plus all the various leftover bits (harness, bus bars, nuts, etc).


I'll provide all shipping labels, but we'll split the shipping cost (around $90 total, so $45 each).
It's complicated, but legal.

Any safe way to slow charge the 12S back up without forming dendrites?
No. The copper dendrite growth actually occurs while the cell voltage is low.

Only wild possibility is the extreme lightning activity during that period. The sequence of events doesn't quite fit a LIBCM failure on storage scenario.
1. Car parked a few weeks.
2. 12v dead, charged, started and moved next to garage. (no issues noted, I think it was IMA start), placed on grid charge (no beeps/flashing 4x20)
LiBCM has a watchdog timer that will reset LiBCM if the code doesn't execute properly. So even if lightning were to cause LiBCM to glitch, the watchdog would force reset LiBCM. I don't think lightning would cause issues.

I've mentioned it previously, but LiBCM doesn't connect to the 12 volt battery. There is no way LiBCM could drain the 12 volt battery, particularly when LiBCM has turned itself 'off'.

One thought is that your ignition isn't actually turning off, which is leaving the IMA system energized... this would cause both the IMA and 12V batteries to drain. If you weren't previously having 12 volt battery issues, then you need to figure that issue out separately from the LiBCM one.

FYI: If LiBCM had turned itself off (because SoC was less than 10%), then plugging in the grid charger wouldn't have actually caused grid charging, because LiBCM must be 'on' to enable grid charging. However, LiBCM won't turn itself off for ten minutes after each keyOFF event, so that the grid charger will work if:
-the SoC is between 0:9%, and;
-the grid charger is plugged in within ten minutes of turning the key off.
Reminder: The grid charger will not charge if SoC drops below 0% (as explained previously).

3. Another 8 - 10 days, went to move into garage, 12v dead, charged. No IMA start, IMA and CEL on startup, placed on grid in garage and beeps/flashing 4x20.
This makes it sound like the IMA battery discharged in "8 - 10 days".

(EDIT). I'm printing out a tripod mount for my phone so I can video voltage testing and connections. I've already removed fan housing and screws from LIBCM to make it faster.
Greetings fellow 3DP enthusiast!
I will watch this video to see if there's an issue with your setup. Don't worry about making it 'too long'... I am a master at scrubbing through boring videos, so you can just upload the entire teardown process if you want.
 

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'something' else went wrong in my pack, because it was parked less than a month. Shouldn't have gone down that far?
Btw my CVT car just sat for like... 3 weeks and SoC only dropped from 55ish to 35.
 

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Thanks for the datapoint, which is pretty much spot on: (~-1%/day * 21 days = ~-21% SoC).
No problem mudder! I kinda panicked when I got in the car and then realized 'jeez I haven't touched this car in 3 weeks, that makes sense'. Poor car got parked because of the Citrus xD.
 

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Alright, then please send me your original LiBCM unit so I can verify it's still functioning correctly. I believe I already sent you a return shipping label.
Yep, miscommunication in family unit :). Thought it went out before we went on anniv vaca last week. Going out tomorrow.

I agree: If v0.7.3 or later was installed, then the pack SoC shouldn't have dropped below 8% worst case.

12S modules are hard to find. One potential replacement source is to grab QTY12 EHW5 cells from a donor 18S module. However, I have a better idea:
I'll trade you a brand new 12S module for your 'trashed' modules. I will use these trashed modules for reference on future designs (e.g. when I eventually design brackets for Ford CMAX EHW5 cells). I will also use the BMS connectors (attached to the modules) in my automated tester (once the ones I'm using now wear out).
Thank you! Very nice of you and beyond the call for sure. I'll get my modules out tomorrow out after work and measure my boxed 18S. Existing 12S should go out Wednesday ish.

To ship these modules legally, you'll need to send them as QTY4 properly labelled packages. 12S modules are legal to ship, whereas 18S modules are not. I propose the following:
1a: You ship me the dead 12S module as-is, in a properly labelled box (UN-3481 label).

1b: At the same time, I'll send you:
-QTY1 complete, new 12S module. Let me know what cell voltage your 18S packs are at... I'll charge the 12S module to that voltage so it doesn't take forever to balance.
-QTY1 12S mechanicals (from another 12S module I have).
-QTY2 sets of 18s-to-12s conversion mechanicals.

2: When you receive the package, you'll convert both of your dead 18S modules to pseudo-12S, so that they are legal to ship. FYI: You won't need to install the new wire harness (I won't actually even send it), or even reinstall the bus bars (but I do want all these parts). The cells just need to be all mechanically secured together, with the terminals covered so they can't short out.

3: You'll have QTY6 leftover cells from each 18S module. Assemble these into a fourth 12S pack (using the 12S mechanicals I sent you).

4: Ship me QTY3 boxes, each containing a 12S module, plus all the various leftover bits (harness, bus bars, nuts, etc).


I'll provide all shipping labels, but we'll split the shipping cost (around $90 total, so $45 each).
It's complicated, but legal.
Awesome.

LiBCM has a watchdog timer that will reset LiBCM if the code doesn't execute properly. So even if lightning were to cause LiBCM to glitch, the watchdog would force reset LiBCM. I don't think lightning would cause issues.

I've mentioned it previously, but LiBCM doesn't connect to the 12 volt battery. There is no way LiBCM could drain the 12 volt battery, particularly when LiBCM has turned itself 'off'.
Knew about the 12v not connected to LIBCM, was including for complete scenario.
One thought is that your ignition isn't actually turning off, which is leaving the IMA system energized... this would cause both the IMA and 12V batteries to drain. If you weren't previously having 12 volt battery issues, then you need to figure that issue out separately from the LiBCM one.
Possibility, the column switch is 'difficult', always has been. Haven't noted a 12v on issue after key off/removal, but it's another test point.
This makes it sound like the IMA battery discharged in "8 - 10 days".
Aye, potentially a non-LIBCM related battery fail issue.
Greetings fellow 3DP enthusiast!
Addict....messed around with an Ender 3Dpro for a few months then went Prusa MK3S+
I will watch this video to see if there's an issue with your setup. Don't worry about making it 'too long'... I am a master at scrubbing through boring videos, so you can just upload the entire teardown process if you want.
Boring it will be
 

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@thibble Sorry I might have missed this, have you pulled the packs now and 100% confirmed they are all at very low voltage?

Have you checked your meter by measuring the 12v battery or some other known good voltage source?
 

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Discussion Starter · #734 ·
@thibble is doing that after a 3D printed tripod finishes printing.
Based on our troubleshooting, it's likely the cells are actually empty.

My leading theory is that the ignition didn't actually turn off when the key was placed in the 'OFF' position. I primarily base this on the fact that the 12 volt battery was flat twice in a row, whereas it didn't previously have any problems.

LiBCM can't turn itself off when the switched 12 volt rail is powered (i.e. the condition when the key is in the 'ON' position). This is a hardware chicken-and-egg issue... when LiBCM turns itself off, some external signal needs to turn it back on... that 'something' is resistor R32, which enables LiBCM's EHW5-powered 5 volt rail when the ignition is turned 'ON'.

If I remove R32, then LiBCM can turn itself off when the key is on (to prevent IMA battery over-discharge when the key is ON), but then LiBCM won't turn back on when you cycle the key OFF and then ON. If I leave R32 in place, then LiBCM can't turn itself off when the key is on, hence the SoC consumption remains 1% per day whenever the switched 12 volt rail is powered (versus 1% per month whenever the switched 12 volt rail is unpowered).

Alpha LiBCM testers will remember that they had to plug in LiBCM's USB cable the first time after they turned the IMA switch on... it was for precisely this reason that I added R32 (along with C165+R327 to provide the same behavior when the IMA switch is first turned on).

...

But yes, I agree @thibble should verify his measurements with a known-good meter.

@thibble should also take this time to verify there's minimal current draw from the 12 volt battery when the key is OFF.
 

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Discussion Starter · #735 ·
Any updates, @thibble ?
FYI: I'm not in any rush, but I'm waiting to here back from you before I ship out the replacement 12S module:
-Are the modules in fact at 0.2 volts/cell?
-What voltage should I charge the 12S module's cells to?
-Find anything interesting during the teardown?
 

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Any updates, @thibble ?
FYI: I'm not in any rush, but I'm waiting to here back from you before I ship out the replacement 12S module:
-Are the modules in fact at 0.2 volts/cell?
-What voltage should I charge the 12S module's cells to?
-Find anything interesting during the teardown?
Nah I'm behind as usual, too tired after work to touch it. This getting old thing sucks rocks. The LIBCM board return did get into the mail so one item down. Today is hopefully better at work and I can get into it.
 

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My first LiBCM install is going well.

Just a few notes on the welded EHW5 modules.

When preparing the 18S welded modules:

I found that it wasn't necessary to remove the orange part of the connector in order to remove the orange tape from the end of the battery management connector. The wire guard on the welded modules is orange instead of black.

When installing the temperature sensors:

The EHW5 welded modules have rivets instead of screws where mudder has you put the temperature sensors. I tried forever to drill out the rivets with a cobalt drill bit and I barely got through the top of the rivet. It is much easier to carefully cut the top and the bottom of the rivet off with a Dremel while holding the wires back. Then you just poke at it with a pick and it comes right out. I replaced the rivet with a small screw and nuts.

Automotive tire Motor vehicle Bumper Automotive wheel system Automotive exterior

Motor vehicle Automotive tire Automotive fuel system Auto part Machine


Light Motor vehicle Fluid Tap Auto part

Product Automotive tire Motor vehicle Auto part Gas


Cable management after module installation:

The end of the welded modules is a little different and it doesn't have the point mudder has you connect the zip tie that secures the bay 3 to the bay 2 connection under the LiBCM. Instead I put a zip tie through the middle round hole between the third and second bays. Then I used another zip tie to secure the Bay 3-2 wire.


Motor vehicle Hood Automotive design Vehicle Automotive exterior
 

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Discussion Starter · #738 ·
Thanks for the feedback.
Recommendation: Flip the temperature sensor over to the bottom side, so it accurately measures the heat in the steel surround bracket. See post #700 for @FlyingHood395 's implementation.
 

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Oke done. Video is uploading so I'll have to link later tonight or in the morning. Storm is raising hell on starlink. Removed, the 18Ss were about 5.4v each, the 12S down at 3.6 I think, on video. Def discharged to the bone. Video sucks but maybe you can see something :). I saw nothing suspicious in teardown. My unused 18S+ and - are at 63.76 and 63.86.
 
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Thanks, I'm glad I saw this before I put battery in the car. That was an easy change to make.

The welded EHW5 module should be on its way to you. It's going to be interesting to see if there is any difference in the cell behavior and to hear your opinion on the physical differences of the case. I like the plastic on the bottom the NSX modules.


Thanks for the feedback.
Recommendation: Flip the temperature sensor over to the bottom side, so it accurately measures the heat in the steel surround bracket. See post #700 for @FlyingHood395 's implementation.
 
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