diff --git a/health/2.1/README.md b/health/2.1/README.md
index bfcf13b..1ab306f 100644
--- a/health/2.1/README.md
+++ b/health/2.1/README.md
@@ -24,6 +24,9 @@
         ```mk
         # Install default passthrough implementation to vendor.
         PRODUCT_PACKAGES += android.hardware.health@2.1-impl
+
+        # For non-A/B devices, install default passthrough implementation to recovery.
+        PRODUCT_PACKAGES += android.hardware.health@2.1-impl.recovery
         ```
 
         You are done. Otherwise, go to the next step.
@@ -42,6 +45,8 @@
               implementation, See
               [Upgrading from Health HAL 2.0](#update-from-2-0).
 
+        1. [Install the implementation](#install).
+
         1. [Update necessary SELinux permissions](#selinux).
 
         1. [Fix `/charger` symlink](#charger-symlink).
@@ -95,6 +100,18 @@
   `HealthImpl::getHealthInfo` or `HealthImpl::getHealthInfo_2_1` because they call
   `getDiskStats` and `getStorageInfo` to retrieve storage information.
 
+# Install the implementation {#install}
+
+In `device.mk`:
+
+```mk
+# Install the passthrough implementation to vendor.
+PRODUCT_PACKAGES += android.hardware.health@2.1-impl-<device>
+
+# For non-A/B devices, also install the passthrough implementation to recovery.
+PRODUCT_PACKAGES += android.hardware.health@2.1-impl-<device>.recovery
+```
+
 # Update necessary SELinux permissions {#selinux}
 
 For example (replace `<device>` with the device name):
diff --git a/health/2.1/default/android.hardware.health@2.1-service.rc b/health/2.1/default/android.hardware.health@2.1-service.rc
index 917f1c2..b6d9e3b 100644
--- a/health/2.1/default/android.hardware.health@2.1-service.rc
+++ b/health/2.1/default/android.hardware.health@2.1-service.rc
@@ -1,5 +1,5 @@
 service health-hal-2-1 /vendor/bin/hw/android.hardware.health@2.1-service
-    class hal
+    class hal charger
     user system
     group system
     capabilities WAKE_ALARM