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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

 

Here is a video showing the parts you don't need:

You need everything else in the IMA bay

 

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?

 

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).

 

Do you recommend the Mod to keep 12 volt battery charged, with LiBCM? Mod to keep 12 volt battery charged

Since it is preventing the ECM from controlling the DCDC converter by cutting the WHT/GRN wire; it seems that LiBCM is compatible and it would benefit the 12V battery as mentioned.

Thanks.

 

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.

 

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:

Mod to keep 12 volt battery charged

Howdy folks, here's a video showing a quick, simple modification that prevents the ECM from controlling whether the DCDC is charging the 12 volt battery. This means the DCDC will always keep the 12 volt rail at 14.x volts when the car is running (or in autostop), unless the IMA battery is...

www.insightcentral.net

Peter's comment:

Mod to keep 12 volt battery charged

Howdy folks, here's a video showing a quick, simple modification that prevents the ECM from controlling whether the DCDC is charging the 12 volt battery. This means the DCDC will always keep the 12 volt rail at 14.x volts when the car is running (or in autostop), unless the IMA battery is...

www.insightcentral.net

 

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.

 

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

 

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.

 

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.

 

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?

 

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).

 

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!

 

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.

 

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.

 

I've received a couple PMs regarding cell balancing.

Q: Is cell balancing safe right now?
A: Yes, LiBCM's existing balancing algorithm is very safe, but not terribly efficient. The OG Beta Alpha crew and I have been using it for several months without issue. It's well tested.

Q: The cells in two different modules (that I'm going to use for LiBCM) are at vastly different voltages. How long will it take LiBCM to initially balance the cells?
A: The existing balancing algorithm is very slow, and requires that the grid charger be plugged in (i.e. balancing does not occur when the car is off).
A: The next version of the algorithm will balance around twice as fast, and will do so whenever the key is off (whether or not the grid charger is plugged in).

Q: When will the new balancing algorithm be released?
A: This is my next firmware task.
A: My goal is to write this firmware tomorrow, but then it will take a day to run through the safety process (before I push the code up to y'all).
A: Obviously if any major issues are reported by the Beta crew, the balancing algorithm will be put on hold until I fix said issues.

Q: Can I drive my car with an unbalanced pack?
A: Yes, but the SoC range will be restricted. For example, if one 18S module is at 30% SoC, and another is at 70% SoC, then LiBCM is only going to use 35% of the SoC range (to prevent cell over/under voltage).
A: If your pack is unbalanced, you will want to download the above-mentioned firmware update (once I write and release it). Otherwise, if you use the latest code as of today, you will need to leave the grid charger plugged in - whenever you aren't driving - until the cells are balanced (which could take days).

 

Pro tip for assembling the pack: there is such a thing as too tight!

Don't be an idiot like me and break your main IMA switch by overtightening the screw terminal...

And here I thought I was going to finish the install tonight 😂

 

Wow I didn't know it was possible to over tighten the #3 Phillips on the IMA switch. Were you using power tools?

 

Agreed it's a real swine to undo as very tight ,but over tighten..

 

Pro tip for while waiting for goodies from Mudder: there is definitely such thing as NOT tight enough)))
Don’t be an idiot like me and almost set you gloves on the fire cus you didn’t tighten the high voltage cables to the battery good enough. Actually don’t even put anything on top of the hybrid system if you have the cover removed while waiting for the new goodies. Actually, make them tight and just put the cover back on )))

 

I have now built the first three packs for the UK Guinea pigs and they are charging on the bench.

Making the process easy especially when building multiple packs is all about preparation!
Watch John's videos, study all the forum threads and get everything ready.

I prepped five cases, three switchboards, upgraded fuses to 200A, modded MCM's with IMAC&C P&P, current hacks etc, fitted five sets of temp sensors and MCM E connectors etc etc etc.

I installed the 4 main power cables onto the HV switchboard not the batteries. (Hence my minor case webbing mod)

By attaching those cables to the switchboard and attaching it to the case once you have inserted the 12S module everything is safer IMO for the final connections. HV switch off of course and the red anderson connector (unconnected until everything is in.) One you have the 12S module installed and connected the two 18S modules are a cinch.

I cut out a small piece of webbing at each end of the 12S slot as shown so you can slide the pack back and forth and access the battery terminal with the switchboard attached and HV cables routed through the pack.

These videos explain about the webbing and show the three packs charging on the bench.

 

After watching retepsnikrep's video above I am a little concerned about my unit. I have it on the bench plugged into the grid charger. My voltages are going up, but so is my delta. And the delta is much higher than retepsnikrep has. Is this normal?
Thanks.

 

Peter:
Now that I've seen your notch, I don't have any concerns. Note that if you follow the instructions on linsight.org, then when you install the 12S module - and connect the cables to the junction board - the maximum possible voltage is only 49.2 volts (less than 60 VDC safety limit). So the shock hazard is near zero. However, your way works, too... just unnecessary steps IMO. No harm in doing that, so I have no issues with it.

In regards to your fan issue, you're probably correct that the BMS ribbon cable is pressing into the fan. Use an insulated tip to move it out of the way (as shown in the installation video).

You now have more assembled LiBCM units than I ever have .

...

@Crimpcap
Based on the pictures provided:
-It looks like one of your modules is at a different state of charge than the others.
-Peter's cells are all from the same batch, so they're all at the same SoC.
-It's ok for the delta to increase during the initial bulk charge (i.e. until you get to 3.9 volts for the first time).
-Once you get to 3.9 volts, the balancing circuit will take over, discharging the cell(s) with the highest voltage.
-With the existing balancing firmware, it's going to take around 16 hours to balance your pack. Once I update the balancing algorithm, the balancing algorithm will be more than twice as fast.

My recommendation is to keep grid charging unless the high cell voltage (top left corner on the LCD display) exceeds 4.2 volts... as long as that doesn't happen, there's no safety issue. Note that while grid charging, the high cell voltage shouldn't ever get above 3.900 volts.

Overall, I'm not worried.
However, until you're comfortable the grid charger is working properly, don't leave it plugged in overnight.

...

I'm just finishing up applying comformal coating to QTY15 PCBs... so they can ship tomorrow (the coating takes hours to dry). So now I'll switch over to rewriting that grid charger firmware (to make it faster).

 

@mudder,

Thanks for your response above. You are spot on. I bought the 12S module from a different set than my 18s.
I let the grid charger run for a few hours last night. The voltages were climbing as expected. I unplugged the grid charger and turned on the pack switch to go to bed.

Today after work I wanted to continue grid charging I turned the pack switch on, the #2 LED started flashing, #4 LED on constant and the display turns on then off. I plug in the grid charger and things go unexpected. The display starts flashing and the buzzer starts. I unplugged the grid charger and just the buzzer is going until I switch off the pack.

Do I need to simulate a key on off? Ideas?

 

In the first video, the LEDs are working as expected.
In the second video, the voltages shown on the LCD are not good! Fortunately, they're probably not accurately displaying the cell voltages either, as 5.016 volts would almost certainly have caused a fire by now. My guess is something isn't plugged in correctly. Check the following:
-Is the RED 75 A Anderson connector plugged in? Note that if the grid charger is plugged in while the RED Anderson connector is disconnected, then that will permanently damage a component on the LiBCM PCB.
-Are all three BMS connectors plugged in?
-What are the individual cell voltages? (see below)

Video showing how to see all QTY48 cell voltages:

FYI: The reason the screen is flashing (and the buzzer is beeping) is that LiBCM thinks a cell voltage is too high... so it's trying to get your attention.

 

So I posted this in the other lithium thread but I'll post it here. Mudder, based off what you posted above it answered my question.

So on another note, I think I had LiBCM get angry at me tonight. I was getting off the freeway doing about 70, and I pushed the brakes enough to cause high Regen. After about 5 seconds, the display started to turn off and on, LiBCM was beeping Everytime it turned off, and when I looked at the display I noticed one of the batteries 'high' was 4.061. Is this the behavior when you get near the 4.1V danger zone?

 

The screen will flash (and the buzzer will beep) if any cell voltage exceeds 4.200 volts. In the picture you posted, the highest logged voltage (during this keyON event) is only 4.061 volts... so is that picture representative, or actually just after the event you describe occurred?

In general, as long as the beeping stops when you disable regen (e.g. Calpod), there's no safety risk. FYI: The maximum 'safe' cell voltage the EHW5 module can tolerate is 4.25 volts.

Please make sure you're using the latest firmware (0.6.2), which has much improved SoC limiting over the previous versions.

 

I took that picture about 10 seconds after it happened. I hadn't keyed off yet. I'll check what firmware I have, I uploaded new firmware Tuesday, not sure if it's been updated since then.