[LowCarbon]

I just built my LiBCM pack. It's sitting on the bench grid charging. When I first plugged it in, about an hour ago, the highest cell was 3.831 and the lowest was 3.563. Now the highest is at 3.858 but the lowest hasn't moved. It's still at 3.563. Is this cause for alarm? Or am I just being impatient?

Never mind. That low voltage is the lowest since power up. Naturally it's not going to change. Hopefully, everything's working as designed. I'll let it charge overnight and put it back in the car and see how it works.

 

[LowCarbon]

I don't need any support. I'm just posting here to show off my LiBCM build.

My friend, Lance, is working on the junction board, and I'm working on the wire harness. My brother-in-law, Jack, was the host and took the photos. He collects antique cars and has a very well equipped garage.

Getting the batteries ready. (I should have plugged these in outside in case of bent pins. Oops.)

Connecting the 12S pack to the junction board. Mudder's excellent videos guiding every step of the way.

Hooking up power to LiBCM.

First power up. No sparks, no smoke! LiBCM is beeping and asking for software. I'm starting to feel confident.

It works! I let it balance overnight and Jack and I installed it in the car the next day. It worked perfectly. A good time was had by all.

 

[LowCarbon]

Thanks for posting build pictures!
If you have any feedback on the build process (or otherwise), I'm all ears.

Let me just say that both of my cohorts remarked on how good your step-by-step instructions were. Those videos really made the job doable for a first timer.

I don't have much to complain about except maybe that 20x4 display. It seems to fritz out fairly often. (Although I haven't driven the car that much and I don't have a good average.) The display is supposed to warn me if something is going wrong, but so far, the only thing that has failed is the display itself.

One small suggestion: I had trouble getting the wires into the connector on the top of LiBCM. I should have tinned them, I think, to prevent stray wires from missing the hole. The wires from the charger had ferrules on them. Maybe the kit should include a couple of ferrules for the power leads. One little strand could cause a nasty short.

But, overall, this was a great project and a great mod to my car. I was starting to get cold feet as I filled out your safety quiz, but I'm glad I persevered.

 

[LowCarbon]

There are QTY8 separate wires that go into the screw terminals on top of LiBCM:
-QTY2 wires go to HVDC+ & HVDC-. These should have a ferrule crimped onto them, hence no wire fraying.
-QTY2 wires go to grid+ & grid-. These should already be tinned... if not, I forgot to do that on yours. Note that I cannot crimp a ferrule on these wires because that makes them too thick to insert into the screw terminals.
-QTY2 wires go to pwm+ & pwm-. These should have a ferrule crimped onto them, hence no wire fraying.
-QTY2 wires are from your OEM wire harness... I never had them, hence I neither ferruled nor soldered them.

So was it those last two wires (from your OEM wire harness), or did I forget to perform one of the above steps?

I was talking about the wires from the MCM. They had to be cut to length. You warned in the video to be careful not to leave any stray wires, and I didn't. But I would tin the wires or use a ferrule if I was doing it again.

My complaints were nits, believe me. This thing is a huge improvement over NiMH and went together very smoothly.

 

[LowCarbon]

I'm charging my LiBCM pack and I'm getting some odd behavior. When I plugged in, it was at about 65% charge. The charge started to slowly climb, then peaked slightly below CELL_VMAX_GRIDCHARGER (I changed it from 39000 to 39100.) Now, even though it's still plugged into the charger, the charge is not going up. In fact, it's falling slightly. I looked at the code in cellBalance.cpp and I don't see how this can be happening. Logs attached.

[Edit]
Okay, just to make me look bad, right after I posted this, the charge started climbing. Now it's at 75% and slightly over 3.900 volts. This is good, but now I'm flummoxed. I don't like being flummoxed.

 

[LowCarbon]

There's a small hysteresis to prevent the grid charger from rapidly turning on and off when the batteries are full. I believe it's something like "stop at 75%, start again at 70%".

Hmm... I'll have to look at that code. The SoC was < 75% while this SoC was bouncing around.

The hysteresis code I was looking at is in cellBalance.cpp. Maybe I was barking up the wrong tree. Or not. If the lowest cell voltage was so low that all the other 47 cells needed to be balanced, would that take all the juice from the charger? IOW, would that lowest cell not move, and the overall pack voltage would go down while those high cells were bled? (I'm just thinking out loud.)

Bottom line, the SoC does not increase monotonically as long as it plugged in until it hits 75%. It bounces around a little. Now that I know this, I'm not going to worry about it anymore. It charges eventually, and it doesn't overcharge. That's all I care about. (But you've piqued my curiosity about the code the shuts off charging.)

 

[LowCarbon]

I installed the current hack board set at 20% today. I logged LiBCM on my test drive. I got this:

Key:ON
Charger: OFF
METSCI buffer sync..
-1,0,A, 178,147,V, 3.724,3.721,V, 3000,mAh, -0.2,kW, 23,C
-1,0,A, 178,147,V, 3.724,3.721,V, 3000,mAh, -0.2,kW, 23,C
-1,0,A, 178,147,V, 3.724,3.721,V, 3000,mAh, -0.2,kW, 23,C
-1,0,A, 178,147,V, 3.724,3.721,V, 3000,mAh, -0.2,kW, 23,C

which repeated continuously. Is this normal, or did I mess something up? The car drove fine and seem zippier. No IMA or CEL lights.

I also installed the monster ferrite on the HV cables while I had the cover off. Is this supposed to improve the reliability of the 20x4 display? It's been behaving itself since the ferrite installation.

 

[LowCarbon]

What I have noticed is that if I slow down with the car in neutral, autostart kicks in at about 10 mph. Then if I put it in 2nd rather than 1st, it doesn't start up. If I move the stick towards 1st, even if I don't actually shift into 1st, it starts up. At least that's the way I remember it. There's some kind of weirdness with autostop when shifting to 2nd rather than 1st. None of this is new with LiBCM. Sharpmj, could this be what is happening to you?

 

[LowCarbon]

Here's mudder's discussion of the safeguards to prevent overcharging from the grid. It sounds very thorough. G1 Honda Insight Lithium BMS Discussion

As an LiBCM user, I can tell you that it has never let the battery go over its configured max voltage while I was driving it. In fact, the battery always seems to be between 45% and 75%. (I don't live in a hilly area.)

@mudder recommends that you install a calpod switch to be able to prevent regen manually, but I think that would only be necessary in case of some extraordinary failure.

I'm sure one of the experts will chime in with a more detailed answer.

 

[LowCarbon]

I'm seeing a big jump in standby power consumption since I've moved from 0.7.4 to 0.7.8. The charger is connected to a smart plug, so I can monitor the power used and also control the charger via a timer. Typically, my car goes for days without being driven. So my routine is this: after a drive, I charge the pack until full (74-75%.) After that the timer tops it off every morning. With the old version, it discharged from 74% to 72% over 24 hours and took only 14 watts and 13 minutes to top off again. This was very consistent. Now, with the new version, the pack drops 10% in 24 hours. It takes an hour (104 watts) of charging to get back to full.

Is anybody else seeing this? Are there some config.h parameters I should change?

 

[LowCarbon]

I may have been seeing this when I first switched to 0.7.8, months ago now. It went away when I changed the parameter to only allow cell balance above 70% SOC. Also changed the config for balance within counts. Consider this anecdotal, as it has been a while. I think I posted some screenshots and it was discussed in this thread.

Sounds promising. I'll give it try.

 

[LowCarbon]

Thanks for reporting this... Can you see if the behavior persists in prerelease v0.7.9? v0.7.9 has a new fan controller core, which allows multiple subsystems to independently request fan speeds.

Yeah, I can do this.

Just to be clear, the timer essentially "unplugs" the grid charger overnight, and then "plugs it back in" every morning?

Yes, that's exactly what it does. In fact, it's unplugged most of the time. It was only scheduled to run from 9:00 to 9:15 every morning. That's all it took to keep it topped off. If I drove the car, I turned it on manually until it was full, then let it go back to the timer.

Just to be clear, do you mean "and took only 14 Wh [to recharge]"? I just want to verify I'm interpreting this information correctly.

Yes. The smart switch keeps track of power usage and I can read it from my web browser. Here's what it looks like right now.

You can see that it used 104 watt hours yesterday. It used to take 14. (I changed the schedule to 9:00 to 10:15)

Does where you're parking your car get above 30 degC, or is it parked in the sun?

v0.7.8 allows the fan to cool the pack when the key is OFF. You can disable this behavior by commenting out the following line in config.h:
#define WHEN_GRID_CHARGING_COOL_PACK_ABOVE_TEMP 30

The car is parked in a garage. It may occasionally reach 30C, but that's unusual. I have noticed that the fan seems to be running more often than it used to. Is that enough to explain the power drain? (I'm guessing no.) I could comment out that line, or maybe just up the number to 35. That should be enough to stop the fan.

What would you like me to try first: Changing the "Cool the pack" define, or go straight to 0.7.9?