diff --git a/app.py b/app.py
index f9f25d0..29c745f 100644
--- a/app.py
+++ b/app.py
@@ -759,7 +759,7 @@ def create_app(config_object="config"):
             flash(f"Device '{name}' added.", "success")
             if parent_device:
                 return redirect(url_for("device_detail", device_id=parent_device.id))
-            return redirect(url_for("device_list"))
+            return redirect(url_for("device_detail", device_id=device.id))
 
         return render_template("device_add.html", device_types=device_types,
                                device_locations=device_locations,
@@ -809,11 +809,18 @@ def create_app(config_object="config"):
                 if changed:
                     db.commit()
         flat_installed = []
+        children_avail = {}
         if device.has_children():
             for child in device.children:
                 for b in child.batteries:
                     if b.status == "installed":
                         flat_installed.append((b, child.name, child.id))
+                avail_q = db.query(Battery).filter_by(status="available")
+                if child.battery_size:
+                    avail_q = avail_q.filter(
+                        (Battery.size == child.battery_size) | (Battery.size == None)
+                    )
+                children_avail[child.id] = avail_q.order_by(Battery.label).all()
         return render_template("device_detail.html", device=device, brands=brands,
                                available_batteries=available_batteries,
                                device_types=device_types,
@@ -823,7 +830,8 @@ def create_app(config_object="config"):
                                ha_enabled=ha_client.enabled,
                                ha_live_pct=ha_live_pct,
                                logbook_entries=device.logbook_entries,
-                               flat_installed=flat_installed)
+                               flat_installed=flat_installed,
+                               children_avail=children_avail)
 
     # ------------------------------------------------------------------ #
     # Devices — edit
diff --git a/templates/device_detail.html b/templates/device_detail.html
index 112491a..57a9969 100644
--- a/templates/device_detail.html
+++ b/templates/device_detail.html
@@ -112,13 +112,79 @@
 <div class="card">
   {% if device.children %}
   <h2>Sub-components</h2>
-  <div style="display:flex;gap:0.75rem;flex-wrap:wrap;margin-bottom:0.75rem;">
+  <div style="display:flex;flex-direction:column;gap:0.5rem;margin-bottom:0.75rem;">
     {% for child in device.children %}
-    <a href="{{ url_for('device_detail', device_id=child.id) }}"
-       style="display:block;padding:0.6rem 0.9rem;border:1px solid var(--border);border-radius:6px;text-decoration:none;min-width:140px;background:var(--bg-card);">
-      <strong>{{ child.name }}</strong><br>
-      <small class="text-muted">{{ child.installed_count() }}/{{ child.battery_slots }} slots &middot; {{ child.battery_size }}{% if child.ha_entity_id %} &middot; HA{% endif %}</small>
-    </a>
+    {% set child_free = child.battery_slots - child.installed_count() %}
+    {% set child_batteries = children_avail.get(child.id, []) %}
+    <details style="border:1px solid var(--border);border-radius:6px;background:var(--bg-card);">
+      <summary style="padding:0.6rem 0.9rem;cursor:pointer;list-style:none;display:flex;align-items:center;justify-content:space-between;">
+        <span>
+          <strong>{{ child.name }}</strong>
+          <small class="text-muted" style="margin-left:0.5rem;">{{ child.installed_count() }}/{{ child.battery_slots }} slots &middot; {{ child.battery_size }}{% if child.ha_entity_id %} &middot; HA{% endif %}</small>
+        </span>
+        <span style="display:flex;gap:0.5rem;align-items:center;">
+          {% if child_free > 0 and child_batteries %}<small class="text-muted">{{ child_batteries|length }} available</small>{% endif %}
+          <a href="{{ url_for('device_detail', device_id=child.id) }}" onclick="event.stopPropagation();" style="font-size:0.8rem;">View</a>
+        </span>
+      </summary>
+      <div style="padding:0.6rem 0.9rem;border-top:1px solid var(--border);">
+        {% if child_free <= 0 %}
+          <p class="text-muted" style="margin:0;">No free slots.</p>
+        {% elif not child_batteries %}
+          <p class="text-muted" style="margin:0;">No compatible batteries available.</p>
+        {% else %}
+          <form method="post" action="{{ url_for('device_install_batch', device_id=child.id) }}">
+            <div style="margin-bottom:0.4rem;">
+              <label style="font-size:0.85rem;cursor:pointer;">
+                <input type="checkbox" id="select-all-child-{{ child.id }}" onchange="toggleAllChild{{ child.id }}(this)"> Select all
+              </label>
+            </div>
+            <div style="max-height:180px;overflow-y:auto;border:1px solid #cbd5e1;border-radius:4px;padding:0.4rem 0.6rem;">
+              {% for b in child_batteries %}
+              <div>
+                <label style="font-size:0.9rem;cursor:pointer;">
+                  <input type="checkbox" class="child-bat-{{ child.id }}" name="battery_ids" value="{{ b.id }}">
+                  {{ b.label }} — {{ b.brand }}{% if b.battery_percentage is not none %} ({{ b.battery_percentage }}%){% endif %}
+                </label>
+              </div>
+              {% endfor %}
+            </div>
+            <button class="btn btn-sm btn-primary" type="submit" style="margin-top:0.5rem;">Install Selected</button>
+          </form>
+          <script>
+          (function() {
+            var FREE_{{ child.id }} = {{ child_free }};
+            var queue_{{ child.id }} = [];
+            document.querySelectorAll('.child-bat-{{ child.id }}').forEach(function(cb) {
+              cb.addEventListener('change', function() {
+                if (cb.checked) {
+                  queue_{{ child.id }}.push(cb);
+                  if (queue_{{ child.id }}.length > FREE_{{ child.id }}) {
+                    queue_{{ child.id }}.shift().checked = false;
+                  }
+                } else {
+                  queue_{{ child.id }} = queue_{{ child.id }}.filter(function(c) { return c !== cb; });
+                }
+                document.getElementById('select-all-child-{{ child.id }}').checked = false;
+              });
+            });
+            window['toggleAllChild{{ child.id }}'] = function(masterCb) {
+              var all = Array.from(document.querySelectorAll('.child-bat-{{ child.id }}'));
+              if (masterCb.checked) {
+                queue_{{ child.id }} = [];
+                all.forEach(function(c) { c.checked = false; });
+                all.slice(0, FREE_{{ child.id }}).forEach(function(c) { c.checked = true; queue_{{ child.id }}.push(c); });
+                if (all.length > FREE_{{ child.id }}) masterCb.checked = false;
+              } else {
+                all.forEach(function(c) { c.checked = false; });
+                queue_{{ child.id }} = [];
+              }
+            };
+          })();
+          </script>
+        {% endif %}
+      </div>
+    </details>
     {% endfor %}
   </div>
   {% else %}