diff --git a/Cargo.lock b/Cargo.lock
index 2646de8..5370896 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -239,7 +239,7 @@ checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
 [[package]]
 name = "charge-controller-supervisor"
-version = "1.9.9-pre-23"
+version = "1.9.9-pre-24"
 dependencies = [
  "chrono",
  "clap",
@@ -2203,7 +2203,7 @@ dependencies = [
 
 [[package]]
 name = "tesla-charge-controller"
-version = "1.9.9-pre-23"
+version = "1.9.9-pre-24"
 dependencies = [
  "chrono",
  "clap",
diff --git a/Cargo.toml b/Cargo.toml
index aa7819e..a9db690 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,7 +4,7 @@ default-members = ["charge-controller-supervisor"]
 resolver = "2"
 
 [workspace.package]
-version = "1.9.9-pre-23"
+version = "1.9.9-pre-24"
 
 [workspace.lints.clippy]
 pedantic = "warn"
diff --git a/charge-controller-supervisor/src/controller/tristar.rs b/charge-controller-supervisor/src/controller/tristar.rs
index ef43c46..cbbf234 100644
--- a/charge-controller-supervisor/src/controller/tristar.rs
+++ b/charge-controller-supervisor/src/controller/tristar.rs
@@ -106,7 +106,7 @@ impl ModbusTimeout {
         Ok(r??)
     }
 }
-#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct TristarSettings {
     network: Option<NetworkSettings>,
     charge: ChargeSettings,
@@ -154,7 +154,7 @@ impl NetworkSettings {
     }
 }
 
-#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ChargeSettings {
     absorption_voltage: f64,
     float_voltage: f64,
@@ -191,7 +191,7 @@ pub struct LedThresholds {
     yellowred_to_red: f64,
 }
 
-#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
+#[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ReadOnly {
     hourmeter: u32,
     charge_ah_resetable: f64,
@@ -203,11 +203,18 @@ pub struct ReadOnly {
     va_max: f64,
     days_since_last_equalize: u16,
     battery_service_timer_days: u16,
-    serial: u64,
+    serial: Serial,
     model: Model,
     hardware_version: u16,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(untagged)]
+pub enum Serial {
+    Valid(String),
+    Invalid(u64),
+}
+
 #[derive(Debug, Clone, Copy, Serialize, Deserialize)]
 pub enum Model {
     Tristar45A,
@@ -325,11 +332,20 @@ impl ChargeSettings {
                 let s2 = get(buf, TristarEepromAddress::Eserial2)?;
                 let s3 = get(buf, TristarEepromAddress::Eserial3)?;
 
-                let mut serial = u64::from(s0);
-                serial |= u64::from(s1) << 16;
-                serial |= u64::from(s2) << 32;
-                serial |= u64::from(s3) << 48;
-                serial
+                let mut serial = [0; 8];
+                serial[0..2].copy_from_slice(&s0.to_le_bytes());
+                serial[2..4].copy_from_slice(&s1.to_le_bytes());
+                serial[4..6].copy_from_slice(&s2.to_le_bytes());
+                serial[6..8].copy_from_slice(&s3.to_le_bytes());
+                if let Ok(v) = std::str::from_utf8(&serial) {
+                    Serial::Valid(v.to_string())
+                } else {
+                    let mut serial = u64::from(s0);
+                    serial |= u64::from(s1) << 16;
+                    serial |= u64::from(s2) << 32;
+                    serial |= u64::from(s3) << 48;
+                    Serial::Invalid(serial)
+                }
             };
 
             let model = if get(buf, TristarEepromAddress::Emodel)? == 0 {