Discharge Curve
The ONYX RCR 41Ah battery does not discharge at a constant rate. Instead, the discharge follows a curve, with voltage depleting faster near the top of the charge (above 82 volts) and towards the bottom (below 66 volts). While the full 84 volts are available, the discharge rate varies depending on the charge level.
Battery and Cell Voltage Chart
| Battery Volts | Cell Volts | Description |
|---|---|---|
| 86v | 4.30v | Damage Will Occur |
| 85v | 4.25v | Do Not Use |
| 84v | 4.20v | 100% Actual |
| 83v | 4.15v | 100% Stock & BMS Tuning |
| 82v | 4.10v | |
| 81v | 4.05v | |
| 80v | 4.00v | 80% BMS Stock |
| 79v | 3.95v | 80% BMS Tuning |
| 78v | 3.90v | 75% Actual |
| 77v | 3.85v | |
| 76v | 3.80v | 60% BMS Stock |
| 75v | 3.75v | |
| 74v | 3.70v | 60% BMS Tuning |
| 73v | 3.65v | |
| 72.5v | 3.625v | 50% Actual |
| 72v | 3.60v | 40% BMS Stock |
| 71v | 3.55v | |
| 70v | 3.50v | |
| 69v | 3.45v | |
| 68v | 3.40v | 40% BMS Tuning |
| 67v | 3.35v | |
| 66v | 3.30v | 25% Actual (20% BMS Stock) |
| 65v | 3.25v | |
| 64v | 3.20v | |
| 63v | 3.15v | |
| 62v | 3.10v | 20% BMS Tuning |
| 61v | 3.05v | |
| 60v | 3.00v | 0% BMS Stock |
| 59v | 2.95v | |
| 58v | 2.90v | |
| 57v | 2.85v | |
| 56v | 2.80v | |
| 55v | 2.75v | |
| 54v | 2.70v | 0% BMS Tuning |
| 53v | 2.65v | Minimum |
| 52v | 2.60v | Do Not Use |
| 51v | 2.55v | Do Not Use |
| 50v | 2.50v | Damage Will Occur |
Sag Discharge Curve
This screenshot illustrates the voltage curve variation between cells during discharge. While no two batteries discharge exactly the same, understanding a battery’s unique characteristics is crucial. Factors such as charging amperage, resting charge levels, ambient and operating temperatures, charge cycles, and age all influence a battery’s discharge curve.
The example shown features an ONYX RCR 41Ah battery with an 80-amp BMS in full Sicko mode, starting at 83.6 volts. From a cold start with a dead pull, the battery drops 15.4 volts, nearly reaching its output capacity of 18,000 watts. The latest revision of the ONYX RCR 41Ah battery is equipped with a 100-amp BMS, capable of handling a 20,000-watt pull for even greater performance.
Low Voltage Discharge Curve
- 8% Charge: 62 volts
- 4% Charge: 61 volts
- 0% Charge: 60 volts
C- and E-Rates Explained
In battery terminology, the discharge rate is often expressed as a C-rate to standardize comparisons across batteries with different capacities. The C-rate represents how quickly a battery is discharged relative to its maximum capacity.
-
1C rate: The current needed to discharge the entire battery in 1 hour. For example, a 100Ah battery discharged at 1C would require 100 amps.
-
5C rate: The current needed to discharge the battery in 1/5th of an hour (12 minutes), which equals 500 amps for the same 100Ah battery.
-
C/2 rate: The current required to discharge the battery in 2 hours, which is 50 amps for a 100Ah battery.
Similarly, an E-rate is used to describe discharge power.
- 1E rate: The power required to fully discharge the battery in 1 hour.