diff --git a/log.capnp b/log.capnp
index 64a577b..1e75c6f 100644
--- a/log.capnp
+++ b/log.capnp
@@ -286,6 +286,7 @@ struct ThermalData {
   networkType @22 :NetworkType;
   offroadPowerUsage @23 :UInt32;  # Power usage since going offroad in uWh
   networkStrength @24 :NetworkStrength;
+  carBatteryCapacity @25 :UInt32;  # Estimated remaining car battery capacity in uWh
 
   fanSpeed @10 :UInt16;
   started @11 :Bool;