the only thing it would hurt is the alternator. Its not gonna kill it but it will eventually wear it out faster. The alternator will try to charge the battery run the starter and run the glowplugs. the glowplugs drain a lot of amps. almost as much as the starter. if your engine is already warm, and dont want the glowplugs to always engage, you have to look up the mod. It will save your glow plugs, alternator, and the batteries. you just have to manually hold a button to turn on the glow plugs. if you dont have any electrical background, i would just wait for the voltage meter to go back to 12v.
