FAQ - Lithium

Other Batteries

Q: Will LiBCM work with other lithium modules (besides 5AhG3 and 47Ah FoMoCo)?

A: Yes, but it will require custom mechanical fitment (e.g. HVDC current and BMS ribbon cables).

A: Linsight will create custom-length ribbon cables to any length.

A: You must determine how to correctly connect these cables to each cell/module.

A: At present, LiBCM only supports 48S & 60S configurations.

A: Without firmware modifications, LiBCM supports batteries from 0.5 Ah to 65.5 Ah.

A: Linsight only officially supports 5AhG3 and 47Ah FoMoCo lithium modules.

Q: Which lithium chemistries does LiBCM work with?

A: LiBCM's hardware supports all known lithium cell chemistries.  Specifically, LiBCM supports any cell that charges with a CC/CV profile.

A: At present, LTO & LiFePO4 modules are NOT supported in firmware.

A: The firmware defaults attempt to keep each cell between 3.47 volts (10% SoC) and 4.01 volts (85% SoC), with absolute max values between 3.01 volts (0% SoC) and 4.2 volts (100% SoC).  

A: These values can be changed in firmware (at your own risk) to any value between 1.1 & 5.0 volts.

Q: How many cells in series does LiBCM support?

A: The hardware supports from 4S to 60S.

A: At present, the firmware only supports 48S and 60S.

Q: Can LiBCM work with packs larger than 60S?

A: Not easily.  You would need to connect an additional BMS PCB to LiBCM's SPI bus, and then rewrite the firmware to talk to it.  It's possible, but you're on your own.

Q: Can LiBCM work with packs less than 36S?

A: Probably not, as the pack voltage becomes too low for the OEM MCM, which severely limits assist below 120 volts.

A: If the voltage drops too low, the MCM will enable force background charging, which could overcharge packs less than 36S.

Q: Can I use LiBCM with the original NiMH cells?

A: Yes, but you'd need to change the firmware.  I will not help you do that.

A: I can't think of a reason why you'd want to do this.

Q: Can I use LiBCM without any battery at all (e.g. as a defeat device to pass emissions)?

A: Per 42 USC 7522: defeating an emissions component is felony in the United States.  LiBCM's firmware will not work unless a lithium battery is connected.

Q: Why would placing the fuse/switch between modules 2 & 3 damage LiBCM?

A: Six cells in each of these two modules share a single voltage monitoring IC, which is only rated to measure up to 8 volts per cell.  If the fuse and/or switch are installed between modules 2 & 3 - and the fuse blows and/or the switch is turned off - then the entire pack voltage would develop across one measurement circuit.  This would (safely) destroy the LiBCM PCB.

A: The ideal solution is to use a different IC (e.g. LTC6813, which was unavailable during to the Great Chip Shortage, when LiBCM was designed).

Q: Considering the abundance of 18S modules, and that a 54S (18S*3) setup fits inside the OEM enclosure, why doesn't LiBCM support 54S?

A: While QTY3 18S modules mechanically fit inside the OEM enclosure, placing an 18S module in bay 1 (closest to the junction board) prevents the high current cables from cleanly routing to the junction board.  

A: Numerous firmware changes are required to support 54S.

Q: When will the LiBCM firmware support 54S?

A: No idea, but not anytime soon.  If you want to use LiBCM anytime soon, you should use either a 48S or 60S battery.

A: If 54S ever ships, it will require a few cable changes and a new BMS adapter.  The LiBCM PCB itself won't require any changes.  

Q: What other firmware changes are required to use a non-supported lithium pack?

A: You'll need to characterize your particular cell's discharge voltage over SoC, and then create a new entry in SoC.cpp parameterizing those results into a lookup table.  See the existing LUTs for the 5AhG3 and 47Ah FoMoCo cells.  LiBCM uses this LUT to calculate the Voc->SoC value when the key is off.

A: Depending on your particular cell's discharge/charge behavior, you might need to create your own voltage spoofing parameters (see config.h).

A: You'll need to change "STACK_mAh_NOM" to your cell's nominal capacity (e.g. 47000 mAh for 47Ah FoMoCo).