How to adjust the Luna charger
They all have 3 potentiometers in them, we will call them P1, P2 & P3
This is a simulated charge cycle of the Shark 13.5ah GA 52V on a 3amp charger set to 100% charge.
. On the left the latest Luna mini charger with the 2 rotary knobs (either 48V or 52V)
On the right the first generation 300W advanced 52V with the red toggle switch (80/90/100%) and the recessed amp switch (3-5amps).
NOTE: the 300W advanced with the 2 rotary knobs is the same as the first generation charger.



To adjust P1, you will need a multimeter set in the right VDC range plugged in the output of the charger (AC plugged in). No battery connected.
Be careful not to touch anything else but the potentiometer!
If you are patient you could tune it better with a battery connected when the charger is actually in the CV part of the charging phase when the current is close to the cutoff. But you will require a amperage meter hooked in between the batt and charger (batt-man, watt-meter, cycle analyst) to do a good job. I find that just setting the voltage unloaded and test and adjust later is better and easier.
NOTE: Do not raise the voltage if the charger is outputting the correct voltage (unplugged from the battery) but cutting short like a few volts off.. that can be the BMS cutting the charger due to a detected problem. Only tune it if you tested the BMS and know the pack is balancedd and the charger is slightly off track!
They all have 3 potentiometers in them, we will call them P1, P2 & P3
- P1 is CV (Constant voltage) adjustment. turning this pot will change the final voltage.
- P2 is CC (Constant current) adjustment. turning this pot will raise or lower the max current in the constant current phase.
- P3 is the current cutoff at the end of the charge cycle. Basically what will terminate the charge. turning this pot will change at what amperage the charger will stop. Normally is will cutoff at around 5% of the max amperage. So a 300W set at 5amp will cut the charge to .25amp (regardless of the amperage switch position).
This is a simulated charge cycle of the Shark 13.5ah GA 52V on a 3amp charger set to 100% charge.
. On the left the latest Luna mini charger with the 2 rotary knobs (either 48V or 52V)
On the right the first generation 300W advanced 52V with the red toggle switch (80/90/100%) and the recessed amp switch (3-5amps).
NOTE: the 300W advanced with the 2 rotary knobs is the same as the first generation charger.
To adjust P1, you will need a multimeter set in the right VDC range plugged in the output of the charger (AC plugged in). No battery connected.
Be careful not to touch anything else but the potentiometer!
- On the mini turn clockwise to raise the voltage and counter-clockwise to lower the voltage.
- On the 300W advanced, it's the opposite, CW to lower and CCW to raise.
If you are patient you could tune it better with a battery connected when the charger is actually in the CV part of the charging phase when the current is close to the cutoff. But you will require a amperage meter hooked in between the batt and charger (batt-man, watt-meter, cycle analyst) to do a good job. I find that just setting the voltage unloaded and test and adjust later is better and easier.
NOTE: Do not raise the voltage if the charger is outputting the correct voltage (unplugged from the battery) but cutting short like a few volts off.. that can be the BMS cutting the charger due to a detected problem. Only tune it if you tested the BMS and know the pack is balancedd and the charger is slightly off track!
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