BMS TUNING RESULT SCREENSHOT
This screenshot is an Onyx 41AH battery around 60 volts after being tuned with an extra 5AH remaining. The extra 5AH translates to an additional range between 4 miles and 10 miles depending on how you throttle. The extra 5AH also increases the top-end charge for an extra 4 miles of full-throttle racing.
FIRST RULE OF BMS TUNING
Before tuning the settings of the BMS for performance and range gains, understand that the voltage level at which the battery rests overnight or for longer periods is super important.
- Rest the battery overnight between 65 volts and 79 volts.
- Avoid resting the battery above 82 volts and below 62 volts.
CHARGING AMPERAGE EFFECTS
Charging at a lower amperage of 1-3 amps is healthier for a battery which also has a side effect of adding a few miles of range but with slightly lower peak output. Charging at higher amperages of 7-10 amps is less beneficial for the battery but has the side effect of increasing the peak output levels.
BYPASSING THE BMS
Advanced riders with a technical understanding of batteries can bypass the BMS for higher discharge levels but run the risk of a lack of cell group cut-off and short circuit protection which can destroy the battery. Sicko mode with BMS tuning almost makes it unbeneficial to do a BMS bypass. It is not worth losing out on all the discharge safety and protection mechanisms.
CHARGE CYCLES AND RANGE ANXIETY
Every 0.10 volts below 4.20 volts doubles the charge cycles. This means that charging an Onyx 23ah battery to 82 volts instead of 84 volts doubles its charge cycle life. Charge cycles can be defined as the number of times a battery can be charged before it degrades to about 80% of its full capacity and outputs less peak power. The difference in range on an Onyx 23ah battery between 84 volts and 82 volts is about 2 miles. It’s worth giving up two miles of range by charging only to 82 volts on an Onyx 23ah battery to double the charge cycle life from 800 to 1600 charge cycles. It’s never too late to change charging habits and benefit from increasing charge cycles.
I keep my batteries fully charged to 79 volts 90% of the time, which gives me more range than I need. While benefiting from a 5x charge cycle increase and performing at stronger higher peaks. When accounting for the 10% of the time that I charge to 84 volts, I will roughly be benefiting from a 4x charge cycle increase.
CHARGE LEVEL CYCLE INCREASE
- 83 Volts (97.5%) is 1.5X Charge Cycles from 800 to 1200.
- 82 Volts (92.5%) is 2X Charge Cycles from 800 to 1600.
- 81 Volts (87.5%) is 3X Charge Cycles from 800 to 2400.
- 80 volts (85%) is 4X Charge Cycles from 800 to 3200.
Keeping track of how many actual miles are often ridden will reveal that charging the battery to full is not always necessary. By experimenting with charging the battery to only 82 volts, most will discover that it’s more than enough charge level while benefiting from doubling charge cycles.
CHARGE CYCLE TIPS
- Don’t range anxiety full charge, instead charge to 80% or 90%.
- Know your actual range and voltage instead of experiencing range anxiety.
- Have an extra dedicated home charger that can be programmed to cut off at 80% and 90% charge.
TUNED ONYX 41AH BMS CONFIGURATION
BMS CAPACITY CONFIGURATION
Use the Xiaoxiang BMS app to tune the Onyx 41ah battery (Xiaoxiang BMS app link below). In the Xiaoxiang BMS configuration screens, the “Total Battery Capacity” field is set to the total amp hours (AH) of the battery’s capacity, while the “Total Cycle Capacity” field is set to 80% of the battery’s total capacity. This applies to all batteries. As an example, in the Onyx 41ah battery, the “Total Battery Capacity” field would be set to 41000 and the “Total Cycle Capacity” field is set to 32800.
- Total Battery Capacity 100%
- Total Cycle Capacity 80%
CAPACITY CONFIGURATION
- Number of Cell - 20
- Total Battery Capacity - 41000
- Total Cycle Capacity - 32800
- Cell Full Voltage - 4150
- Cell Minumum Voltage - 2700
- Cell Self Discharge - 0.2
- Cell 80% Cap. Voltage - 3950
- Cell 60% Cap. Voltage - 3700
- Cell 40% Cap. Voltage - 3400
- Cell 20% Cap. Voltage - 3100
BALANCER CONFIGURATION
- Start Voltage - 3800
- Delta to Balance - 10
- Balancer Enabled - On (Green)
- Bal. Only When Charging - On (Green)
FUNCTION CONFIGURATION
- Switch - Off
PROTECTIONS
T: = Trigger Value / R: = Release Value
- Cell Over Voltage - T: 4200 / R: 4100
- Cell Under Voltage - T: 2600 / R: 2800
- Batt Over Volt. - T: 85000 / R: 83000
- Batt Under Volt. - T: 53000 / R: 59000
- Charge Over Curr. - T: 70000 / R: 32
- (80 Amp BMS) Discharge Over Curr. - T: 90000 / R: 32
- (100 Amp BMS) Discharge Over Curr. - T: 110000 / R: 32
- Charge Over Temp - T: 65 / R: 55
- Charge Under Temp - T: -5 / R: 0
- Discharge Over Temp - T: 70 / R: 60
- Discharge Under Temp - T: -10 / R: 0
