Using tender, can I start it while connected?
Thread Starter
Pro
Joined: Feb 2005
Posts: 725
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From: East Northport NY
Using tender, can I start it while connected?
Sorry guys but I cant find an answer on this, so I need YOU.
I lost my garage privileges so Im outside the garage. Dont ask, it's a long story.
Temps are dropping here over the next few days and my voltage was pegged at 15.2 volts all day today as I drove around. So I decided to put the tender on for a few days.
If I want to start her up to let her run for a while, do I have to disconnect the tender, does it matter?
Thanks
I lost my garage privileges so Im outside the garage. Dont ask, it's a long story.
Temps are dropping here over the next few days and my voltage was pegged at 15.2 volts all day today as I drove around. So I decided to put the tender on for a few days.
If I want to start her up to let her run for a while, do I have to disconnect the tender, does it matter?
Thanks
Popular Reply
Dec 3, 2025, 11:05 PM
Race Director
Joined: Sep 2013
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From: Ft Lauderdale
Tech Contributor
absolutely you can. But why do you want to start it up and run it for a while? If you’re doing it because it’s in winter storage and you just wanna warm it up, don’t do that. Never start a car when you put it to sleep for the winter unless you can drive it 20 minutes or so to fully warm it up under a load. Idlingt it for 10 minutes or so doesn’t do anything good for the engine. In fact it can add more condensation in the crank case. Once you put it to sleep, leave it sleep until you’re ready to drive it in the spring or if it’s a nice day and you can take it out, then do that. But don’t idle it occasionally.
Race Director
Joined: Sep 2013
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From: Ft Lauderdale
Tech Contributor
absolutely you can. But why do you want to start it up and run it for a while? If you’re doing it because it’s in winter storage and you just wanna warm it up, don’t do that. Never start a car when you put it to sleep for the winter unless you can drive it 20 minutes or so to fully warm it up under a load. Idlingt it for 10 minutes or so doesn’t do anything good for the engine. In fact it can add more condensation in the crank case. Once you put it to sleep, leave it sleep until you’re ready to drive it in the spring or if it’s a nice day and you can take it out, then do that. But don’t idle it occasionally.
Race Director
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From: Ft Lauderdale
Tech Contributor
I mean, whatever you do your preparations for not using it during the winter. Taking out the battery, hooking it to a tender whatever you do… Once you complete all that process, don’t start it back up until you can do the things I said in the above post. Either take it out on the road or leave it alone.
Melting Slicks
Joined: Jan 2006
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From: Oregon
I always dis-connect the charger when I start a car. I don't want voltage coming from the charger into the car, or car into the charger.
I have no proof that this is bad, it's just common sense for me to not connect those two voltages together.
I agree with Glen e. A short run just creates more condensation in the crankcase.
It is best to drive long enough (at least 15 minutes) to get the coolant and oil get up to temp, and get the trans warmed up, and the battery charged.
I hope you are not going to leave your car outside for the winter. I would sleep in a tent outside before I would leave my C8 outside,
I have no proof that this is bad, it's just common sense for me to not connect those two voltages together.
I agree with Glen e. A short run just creates more condensation in the crankcase.
It is best to drive long enough (at least 15 minutes) to get the coolant and oil get up to temp, and get the trans warmed up, and the battery charged.
I hope you are not going to leave your car outside for the winter. I would sleep in a tent outside before I would leave my C8 outside,
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You can start the car with the tender still attached but you are not gaining anything by doing that....it takes a good 15-20 minute drive to recover the battery power used when starting the car
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Glen e has it right - leave the car alone unless you can drive it long enough to get things up to temp and burn off all condensation. And I disconnect my battery maintainer when I start the car.
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I’ve owned six vettes and started every one of them in the winter about every 30 days. I let them run for 30-45 minutes. And if the driveway is not deep in snow, I’ll back in in/out a few times. And I rev the motor some as opposed to idle the entire time. If I did any damage to the car, it was not evident.
Last edited by Dale06; Dec 5, 2025 at 01:02 PM.
Safety Car
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From: panama city beach florida USA
St. Jude Donor '09
old school we would try to never start a car while a battery charger was on so not to get a voltage spike .....we are talking GM electronics your car your roll of the dice
Racer
Joined: May 2020
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From: Maryland
It depends on the charger. It's possible the alternator voltage will be high enough to damage the charger. I would ask the charger maker. But: it's so easy to disconnect the charger if it's connected in the frunk, why not do that?
Safety Car
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From: panama city beach florida USA
St. Jude Donor '09
its the cars electronics that can be spiked and damaged ....rare but it happens