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· Linsight Designer
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Discussion Starter · #1 · (Edited)
This thread is for any and all questions related to LiBCM during the Open Beta.
After browsing www.linsight.org, if you still have questions, please post them here.

I will answer questions posted in this thread by updating the FAQ/Instructions/Documenation/etc at www.linsight.org.
I will probably respond to questions posted in this thread by replying with a hyperlink to the answer (which I may have just written).
 

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<Placeholder>

This thread is for any and all questions related to LiBCM during the Open Beta.
After browsing www.linsight.org, if you still have questions, please post them here.

I will answer questions posted in this thread by updating the FAQ/Instructions/Documenation/etc at www.linsight.org.
I will probably respond to questions posted in this thread by replying with a hyperlink to the answer (which I may have just written).

I just looked at your kit and it looks impressive. Thanks for all of your effort with this endeavor.

My main battery has been completely gutted from the rear. Nothing left including all brackets. Lots of room!

I completely disassembled the battery pack and used all of the parts needed to maintain the 14vdc for the 12v battery. I didn't go the MeanWell path. Why when all of the required parts are in the battery case. This also let me put everything under the Tom mix bar. I have all of the unused pieces of the main battery.

What parts of the battery pack are needed to complete your system?

Will I need a complete battery pack without the batteries to make your system work? My thought was to mount the new batteries behind the seats.

Thanks again!

Vic
 

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I purchased battery modules from @JAG35 when they were available earlier this year. That means that I have only 18S modules. I have emailed BumbleBee to see if they will sell 12S modules separately. If they do not, I understand that I will need to convert an 18S. That will leave 6 individual cells left over. I'd like to hold on to those cells for future use ( for example, replacing a potential bad cell that LiBCM pinpoints as you mentioned in the videos). I believe and want to confirm that for those cells to remain useable, I need to devise a way to keep the cells compressed in storage. Is this correct?
 
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· Linsight Designer
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Discussion Starter · #5 ·
Bumblebee does not offer the 12S+ module separately.

Related: I won't speak for Eli, but I understand BB will eventually start selling the 18S- cells individually.

Uncompressed cells are overwhelmingly damaged during charge/discharge cycles and heat fluctuation. If you leave the cells uncompressed in a climate controlled room, they will only age just slightly faster than compressed cells would. So maybe 9.8 years instead of 10.0 years for SoC(actual) to drop to 80% of SoC(nom). Here's a paper related to your question.

You would certainly want to compress the cells prior to charging them, no matter how low the current is. Before you take the module apart, you'll want to discharge up/down to 50% SoC (3.72 volts resting).
 

· Linsight Designer
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Discussion Starter · #7 ·
Good question. I've added it to the FAQ.

Yes, I always recommend cutting the WHT/GRN wire heading to the DCDC converter. This forces the DCDC to output 14.x volts (like a normal car's alternator would). Cutting the WHT/GRN wire still allows the MCM to disable the DCDC entirely (which is controlled by GRN/BLK).

FYI: I haven't discussed this previously, but LiBCM supports the ability to control the GRN/BLK wire (instead of the MCM). That allows LiBCM to more intelligently control when the DCDC is active. Once I've announced how to do this, the primary reason to do so will be to allow the DCDC to charge the 12 volt system whenever the key is in the 'ON' position... even if the car isn't started.
 

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Yes, I always recommend cutting the WHT/GRN wire heading to the DCDC converter. This forces the DCDC to output 14.x volts (like a normal car's alternator would). Cutting the WHT/GRN wire still allows the MCM to disable the DCDC entirely (which is controlled by GRN/BLK).
I'm open to this. Can you clarify whether you are recommending this for the benefit of LiBCM? Or, is cutting this wire just your preference? The reason I ask is that I recall in your original thread about this mod @retepsnikrep mentioning that cutting this wire caused a hit to fuel economy.

Original thread:

Peter's comment:
 

· Linsight Designer
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Discussion Starter · #9 ·
Cutting WHT/GRN is for the benefit of your 12 volt battery. The "hit to fuel economy" issue - if it exists - is a false economy: killing the 12 volt battery every few years by chronically undercharging it is more environmentally detrimental. I don't hypermile, so I have no data on any supposed fuel economy penalty.

LiBCM and cutting the WHT/GRN wire are mutually exclusive things. You can cut the WHT/GRN wire with or without LiBCM.
 

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Mudder, I'm thinking of rerouting the LiBCM charger power cord, similarly to how things were run for Mike Dabrowski's grid charger. I already have a hole on the metal IMA box wall and then another that goes up to the top. This has allowed me, over the years, to very easily plug in my grid charger. If you never had one of this chargers, here is a link to his installation video (I've got the link set to jump right to the part of the video that shows the cable routing that I'm talking about).


My thoughts are to:

1. enlarge the two holes as necessary
2. Install a rubber grommet in the hole in the IMA box wall. Something like this, perhaps.
3. Install a power inlet port with extension cord in the top of the "shelf". Something like this.
4. Route the LiBCM charger cord underneath the fan shroud and out through the protected hole in the IMA box wall and plug it into the power inlet port extension.

Thoughts? Concerns?
-Bryan
 

· Linsight Designer
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Discussion Starter · #11 ·
As long as you use edge trim or grommets it'll be safe. @Natalya has another cool idea to install a waterproof, external 5-15P plug near the license plate. I leave these modifications to the community at large.
 

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FYI: I haven't discussed this previously, but LiBCM supports the ability to control the GRN/BLK wire (instead of the MCM). That allows LiBCM to more intelligently control when the DCDC is active. Once I've announced how to do this, the primary reason to do so will be to allow the DCDC to charge the 12 volt system whenever the key is in the 'ON' position... even if the car isn't started.
Finally, the built-in jump start that Honda should have put in from the beginning. :)
 

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Finally, the built-in jump start that Honda should have put in from the beginning. :)
I'm trying to figure out how that would work. I've been stuck where I had plenty of IMA voltage and enough voltage + current from the lead-acid battery to power the ECUs but not enough to kick over the main IMA contactor or turn over the 12V starter. I could push-start the car but this doesn't close the contactor and the car soon dies when the 12V battery is exhausted. Doesn't the contactor need to close to complete the HV circuit to power the DC/DC converter so that it can then provide 12V to charge the lead acid battery? (I think I'm missing something important.)
 

· Linsight Designer
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Discussion Starter · #14 · (Edited)
Yes, the contactor needs enough voltage to kick over... otherwise the DCDC isn't activated. However, I often want to turn the radio/headlights/whatever on without first starting the car. But yeah, all bets are off if the contactor won't close.

The more important reason I'm adding this support to LiBCM is so that you can remove the lead acid 12 volt battery entirely, and replace it with the QTY6 leftover lithium cells from an 18S->12S conversion. With a lithium battery in place, LiBCM needs to be able to turn the DCDC converter off entirely as a safety backup, to prevent over-charging the 12 volt lithium battery. Obviously this also turns the dashboard battery and brake lights on, but that shouldn't happen in practice; LiBCM will first pull WHT/GRN low, which sets DCDC to 12.x mode. I haven't spent more than twenty minutes thinking about this feature, but it should work eventually.

Taking a step back, probably the #1 reason I want the DCDC to charge whenever the key is on is so the 12 volt battery doesn't go flat while grid charging (a NiMH pack). But that's no longer an issue, since LiBCM no longer needs 12 volts to run the fans.
 

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This leads me to three related questions:

1. If the 12V battery is replaced with 6 leftover lithium cells, will that work for those times that it is cold enough that the conventional starter has to turn over the engine?

2a. Does LiBCM eliminate the need for extreme cold starts from the conventional starter?

2b. What part of the car instructs the conventional starter to do the engine turning? Will that part of the car still function after moving to LiBCM?
 

· Linsight Designer
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Discussion Starter · #16 ·
1. That's the goal, but haven't done enough research to see if that's actually possible. For sure the stock fuse (from DCDC to engine fuse panel) would need to be larger. All TBD.

2a: We're still working the details out on this. But yes, LiBCM can technically allow the IMA to start the engine at any temperature... I just still need to do more research on the lowest temperature that can safely start the engine without damaging the lithium battery.

2b: Three separate computers control whether the backup starter is used. The BCM (replaced by LiBCM) gives "all systems go" if it thinks the IMA battery is in good enough shape to IMA start. The MCM listens to the BCM's status. If the BCM says 'go', then the MCM does its own checks, too. If all is good in IMA land, then the MCM tells the ECM "all systems go". If the ECM gets a "go" signal from the MCM, then it will wait five seconds for the IMA system to start the engine. if the engine still isn't spinning after five seconds, then the ECM will activate the backup starter.

So what this means is that yes, LiBCM can 'trick' the car into starting at ANY temperature, as long as the IMA system isn't throwing any P-codes (which would make the MCM abort the IMA start).
 

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For the modest current < 40A and <1 second it takes to start the car with the IMA I think the possible damage to the battery (Lithium or Nimh) scenario is effectively nil.

LiPo can operate to -20C albeit with reduced output.
We don't need 150A just 30/40A for half a second.
The big PDU filter caps probably do some of the initial cranking work!
 

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For the modest current < 40A and <1 second it takes to start the car with the IMA I think the possible damage to the battery (Lithium or Nimh) scenario is effectively nil.
I was actually going to ask what the starter current might be under the conditions in question, namely, if the engine has been cold soaked to more than -20F, which was a number at which someone reported (in a different thread) that the car was below when the legacy starter was commanded. I think that such a cold soak might not only make oil thicker, but impact tolerances? So unless tested or calculated otherwise, it is not out of the realm of possibilities that the current could be significantly higher or vary between vehicles.
 

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FYI, my car started on the conventional starter the other afternoon after sitting ouside all day. It was -3 F (-19 C) at the time.
 

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I think that such a cold soak might not only make oil thicker, but impact tolerances? So unless tested or calculated otherwise, it is not out of the realm of possibilities that the current could be significantly higher or vary between vehicles.
I think that going to have negligible impact, and even if the IMA demands 50% higher current say 60A for <1S again I consider that zero battery impact territory..
 
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