There is an experimental diff that sets vsys to desired voltage if you wish to change it. I have not tested it though.
diff --git a/common/charge_state.c b/common/charge_state.c
index 500ad22b73..50b825cc00 100644
--- a/common/charge_state.c
+++ b/common/charge_state.c
@@ -487,8 +487,10 @@ int charge_request(bool use_curr, bool is_full)
* otherwise the BGATE FET body diode would conduct and
* discharge the battery.
*/
voltage = charger_closest_voltage(
- curr.batt.voltage + charger_get_info()->voltage_step);
+ curr.batt.desired_voltage);
/* If the battery is full, request the max voltage. */
if (is_full)
voltage = battery_get_info()->voltage_max;