diff --git a/control/control.go b/control/control.go
index a72a55a..817973f 100644
--- a/control/control.go
+++ b/control/control.go
@@ -138,7 +138,7 @@ func (c *Control) Start() {
 				metrics.SetMetricValue("control", "action", map[string]string{"action": "charge_batteries"}, 1)
 
 				// charge batteries with 20% less than over production
-				batteryChargeWatts := uint(math.Floor(float64(overProductionWatts) * 0.80))
+				batteryChargeWatts := uint(math.Floor(float64(overProductionWatts) * 0.90)) / uint(len(batteries))
 
 				for _, battery := range batteries {
 					if battery.capacity < 100 {