Besides running the battery down. Thought I recall years ago reading how that could cause undesirable effects such as arcing across the points and damage them. Any such issue on modern cars?
Does leaving the ignition on without the engine running damage anything?
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Generally, no harm will come on most modern vehicles but on some you can overheat electrical components due to lack of cooling airflow. Rare but still possible.
That said, it's still a stupid idea, just less stupid than it used to be. Unless you absolutely have to have the ignition on, you should be able to use the accessory position and do most anything you need to.
That said, it's still a stupid idea, just less stupid than it used to be. Unless you absolutely have to have the ignition on, you should be able to use the accessory position and do most anything you need to.
Flushing the hydraulic fluid from the convertible top so I have to cycle it a few times. Have a programming charger on the battery so that's not an issue.
That can make the coil hotter than normal with conventional points&condenser ignition system---which was last used in new cars in the US circa 1980.
I can recall when I was a kid my uncle yelling at my cousin that he didn't turn the key off on their boat which had an old 351 Windsor. He said "you'll burn the points".
Nowadays I'm the only person still daily driving GM's from the mid 80s (one with a 76 engine), but I've never owned a vehicle with points. As far as I know leaving the key on with hei will just kill the battery.
My work truck I can leave headlights or interior lights on and it will cut the power before the battery dies. I'm not sure if it will do that with the ignition on or not (2005 Chevy Silverado).
Nowadays I'm the only person still daily driving GM's from the mid 80s (one with a 76 engine), but I've never owned a vehicle with points. As far as I know leaving the key on with hei will just kill the battery.
My work truck I can leave headlights or interior lights on and it will cut the power before the battery dies. I'm not sure if it will do that with the ignition on or not (2005 Chevy Silverado).
Some forklifts used ignition points well into the 90's. VW was still using points on cars in the early 1980's, models that had fuel injection and points!
Do not do this on a diesel engine with glow plugs or a grid heater! The heater will continually cycle on and off and on and off. Not only wearing out the battery, but wearing out the heaters. Grid heater failure on a Cummins Ram, they have been known to fail, melt to bits in the intake manifold and grenade the whole engine.
I still have a vehicle with points and make sure not to leave the ignition on for fear of overheating the coils. If the points happen to be closed the average current that flows is higher than if the engine was running because it's continuous which means the heating effect on the coils is bigger than when the engine is running. Once low resistance coils came along with electronic ignition they had to build in a feature that would shut off the current after a fixed number of seconds. On motorcycles with kick start they had to extend the time a little to ensure the rider had enough time to get it started. Modern coils would last no time at all with continuous current but it's all taken care of in the electronics.
How modern is modern?
You should be OK on anything mainstream from the past 25 (or more) years or so. Do not do it on cars with points and certain electronic ignition retrofits, some Pertronix for example, will be damaged if the key is left on. Same with some very early factory electronic ignitions IIRC.
You should be OK on anything mainstream from the past 25 (or more) years or so. Do not do it on cars with points and certain electronic ignition retrofits, some Pertronix for example, will be damaged if the key is left on. Same with some very early factory electronic ignitions IIRC.
'95 Mercedes. Worked fine although there is a buzzing sound under the hood somewhere while this was going on.
Originally Posted by barryh
... If the points happen to be closed the average current that flows is higher than if the engine was running because it's continuous which means the heating effect on the coils is bigger than when the engine is running. ...
Exactly. On another hand, if the points happen to be open, current through the coil will be zero. Either way, I can't see claims that points will be burned.
... If the points happen to be closed the average current that flows is higher than if the engine was running because it's continuous which means the heating effect on the coils is bigger than when the engine is running. ...
Exactly. On another hand, if the points happen to be open, current through the coil will be zero. Either way, I can't see claims that points will be burned.
I was brought up and told not to leave the ignition key on as well. I never had a problem but made sure I used the accessory position when running the radio etc.
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