Heater Draining battery
Hello, my son has a Chevy Silverado pickup with crew cab and full bed. I don't know the year. When he forgets to turn off his heater the battery goes dead. Battery was checked and it is ok and starts ok if you remember to shut off heater when getting out. Battery charges good while running and running heater doesn't affect battery when truck is running. I know, I know, remember to shut the heater off, easier said than remembered. Thanks for any help.