diff -aur a/acpi.c b/acpi.c
--- a/acpi.c	2012-01-13 03:48:28.000000000 -0800
+++ b/acpi.c	2020-04-27 18:42:55.125614227 -0700
@@ -247,12 +247,18 @@
     return n;
 }
 
-void print_battery_information(struct list *batteries, int show_empty_slots, int show_capacity)
+void print_battery_information(struct list *batteries, int show_empty_slots, int show_capacity, int merge)
 {
     struct list *battery = batteries;
     struct list *fields;
     struct field *value;
     int battery_num = 1;
+	int total_capacity_full = 0;
+	int total_capacity_now = 0;
+	int total_present_rate = 0; // Positive = charging, mA
+	int hours, minutes, seconds;
+	int percentage;
+	char *state = NULL, *poststr;
 
     while (battery) {
 	int remaining_capacity = -1;
@@ -263,9 +269,6 @@
 	int design_capacity_unit = -1;
 	int last_capacity = -1;
 	int last_capacity_unit = -1;
-	int hours, minutes, seconds;
-	int percentage;
-	char *state = NULL, *poststr;
 	int type_battery = TRUE;
 	char capacity_unit[4] = "mAh";
 
@@ -321,7 +324,7 @@
 	if (type_battery) {	/* or else this is the ac_adapter */
 	    if (!state) {
 		if (show_empty_slots) 
-		    printf("%s %d: slot empty\n", BATTERY_DESC, battery_num - 1);
+		    if (!merge) printf("%s %d: slot empty\n", BATTERY_DESC, battery_num - 1);
 	    } else {
 		/* convert energy values (in mWh) to charge values (in mAh) if needed and possible */
 		if (last_capacity_unit != -1 && last_capacity == -1) {
@@ -356,7 +359,7 @@
 		if (percentage > 100)
 		    percentage = 100;
 
-		printf("%s %d: %s, %d%%", BATTERY_DESC, battery_num - 1, state, percentage);
+		if (!merge) printf("%s %d: %s, %d%%", BATTERY_DESC, battery_num - 1, state, percentage);
 
 		if (present_rate == -1) {
 		    poststr = "rate information unavailable";
@@ -387,12 +390,12 @@
 		    seconds -= 3600 * hours;
 		    minutes = seconds / 60;
 		    seconds -= 60 * minutes;
-		    printf(", %02d:%02d:%02d%s", hours, minutes, seconds, poststr);
+		    if (!merge) printf(", %02d:%02d:%02d%s", hours, minutes, seconds, poststr);
 		} else if (poststr != NULL) {
-		    printf(", %s", poststr);
+		    if (!merge) printf(", %s", poststr);
 		}
 
-		printf("\n");
+		if (!merge) printf("\n");
 
 		if (show_capacity && design_capacity > 0) {
 		    if (last_capacity <= 100) {
@@ -405,14 +408,54 @@
 		    if (percentage > 100)
 			percentage = 100;
 
-		    printf ("%s %d: design capacity %d %s, last full capacity %d %s = %d%%\n",
-			 BATTERY_DESC, battery_num - 1, design_capacity, capacity_unit, last_capacity, capacity_unit, percentage);
+			if (!merge) {
+				printf ("%s %d: design capacity %d %s, last full capacity %d %s = %d%%\n",
+				 BATTERY_DESC, battery_num - 1, design_capacity, capacity_unit, last_capacity, capacity_unit, percentage);
+			}
 		}
+
+		/* Accumulate merged stats for all batteries. */
+		total_capacity_full += last_capacity;
+		total_capacity_now += remaining_capacity;
 	    }
 	    battery_num++;
 	}
 	battery = list_next(battery);
     }
+
+	if (merge) {
+		if (total_capacity_now < 100 || total_capacity_full < 100) {
+			/* total_capacity_now is mAh, so < 100 is realistically invalid. */
+			percentage = 0;
+		} else {
+			percentage = total_capacity_now * 100 / total_capacity_full;
+		}
+
+		if (percentage > 100) percentage = 100;
+
+		printf("%d%%", percentage);
+
+		if (total_present_rate > 0) { /* charging */
+			seconds = 3600 * (total_capacity_full - total_capacity_now) / total_present_rate;
+			poststr = " until charged";
+		} else if (total_present_rate < 0) { /* discharing */
+			seconds = 3600 * total_capacity_now / -total_present_rate;
+			poststr = " remaining";
+		} else { /* idle / unknown */
+			seconds = -1;
+		}
+
+		if (seconds > 0) {
+			hours = seconds / 3600;
+			seconds -= 3600 * hours;
+			minutes = seconds / 60;
+			seconds -= 60 * minutes;
+			printf(", %02d:%02d:%02d%s", hours, minutes, seconds, poststr);
+		}
+		/* else not charing or discharging, no extra text needed. */
+
+		printf("\n");
+	}
 }
 
 void print_ac_adapter_information(struct list *ac_adapters, int show_empty_slots)
diff -aur a/acpi.h b/acpi.h
--- a/acpi.h	2009-03-23 08:23:12.000000000 -0700
+++ b/acpi.h	2020-04-27 18:32:14.712265524 -0700
@@ -60,7 +60,7 @@
 
 void free_devices(struct list *devices);
 
-void print_battery_information(struct list *batteries, int show_empty_slots, int show_capacity);
+void print_battery_information(struct list *batteries, int show_empty_slots, int show_capacity, int merge);
 
 void print_ac_adapter_information(struct list *batteries, int show_empty_slots);
 
diff -aur a/main.c b/main.c
--- a/main.c	2013-10-31 11:59:18.000000000 -0700
+++ b/main.c	2020-04-27 18:45:28.626385255 -0700
@@ -32,12 +32,12 @@
 			{ COOLING_DEV, "fan", "thermal", "cooling_device" }
 			  };
 
-static void do_show_batteries(char *acpi_path, int show_empty_slots, int show_details, int proc_interface)
+static void do_show_batteries(char *acpi_path, int show_empty_slots, int show_details, int proc_interface, int merge)
 {
 	struct list *batteries;
 
 	batteries = find_devices(acpi_path, BATTERY, proc_interface);
-	print_battery_information(batteries, show_empty_slots, show_details);
+	print_battery_information(batteries, show_empty_slots, show_details, merge);
 	free_devices(batteries);
 }
 
@@ -202,11 +202,13 @@
 	}
 
 	/* if nothing was chosen, we show the battery information */
-	if (!show_batteries && !show_ac_adapter && !show_thermal && !show_cooling)
-		show_batteries = TRUE;
+	if (!show_batteries && !show_ac_adapter && !show_thermal && !show_cooling) {
+		do_show_batteries(acpi_path, show_empty_slots, show_details, proc_interface, TRUE);
+		return 0;
+	}
 
 	if (show_batteries) {
-		do_show_batteries(acpi_path, show_empty_slots, show_details, proc_interface);
+		do_show_batteries(acpi_path, show_empty_slots, show_details, proc_interface, FALSE);
 	}
 	if (show_ac_adapter) {
 		do_show_ac_adapter(acpi_path, show_empty_slots, proc_interface);
--- a/acpi.c	2020-05-07 17:32:50.579352165 -0700
+++ b.acpi.c	2020-05-07 17:31:43.465878060 -0700
@@ -368,6 +368,7 @@
 		    if (present_rate > MIN_PRESENT_RATE) {
 			seconds = 3600 * (last_capacity - remaining_capacity) / present_rate;
 			poststr = " until charged";
+			total_present_rate += present_rate;
 		    } else {
 			poststr = "charging at zero rate - will never fully charge.";
 			seconds = -1;
@@ -376,6 +377,7 @@
 		    if (present_rate > MIN_PRESENT_RATE) {
 			seconds = 3600 * remaining_capacity / present_rate;
 			poststr = " remaining";
+			total_present_rate -= present_rate;
 		    } else {
 			poststr = "discharging at zero rate - will never fully discharge.";
 			seconds = -1;