After reading the posts regarding battery troubles people are having, should I not plug my Chevy battery tender into my 2025 Stingray. I have not done it yet. I just unhooked my battery over winter storage. Hooked my battery back up in March of this year and it started up no troubles. I purchased the car Feb. 2025 here in Michigan and brought it home at the end of March 2025.

 

I use the tender on mine, but only because in winter it might be a week, maybe two, between drives. Don't get much snow here, but when it's really cold just don't feel like taking her out.

 

I rarely use a battery maintainer on my C8, and I have several battery maintainers. For me it isn't worth the hassle and it really doesn't help a daily driver. I only connect one if I know the car is going to be sitting for a long time. GM recommends using one if the car regularly sits more than a week without driving. My car has sat for several weeks without a maintainer and it always started right up.

I use my maintainers on cars that go a long time without being used, my generator, boat, ATV, etc.

One thing about cheap maintainers, many of them will overcharge a battery over time. Always check your battery after a few weeks being on a maintainer with a voltmeter. The voltage should be between 13.2-13.6 volts for a flooded lead acid battery. Overcharging is worse than undercharging, I prefer closer to the 13.2v end. Some maintainers will cycle instead of maintaining a constant float voltage and will go under and over this range but should still be between 13.2-13.6v on average.

Most battery maintainer manufacturers say to regularly check your electrolyte level when using a maintainer on a flooded lead acid battery. That is nearly impossible on today's sealed batteries and, at least, impactable. Continuously charging will eventually lower the electrolyte level.

 

I plug mine in when I’m not driving it for at least 2 weeks. Never an issue in about 4 years on the C8. Did the same with my 17Z.

 

I have a 2021. I keep it on the Corvette branded CTEK charger at all times while it is parked in my garage. I replaced the battery at 5 years, as a matter of routine. It did not show any signs of being weak. I have a few collector cars and a few vintage tractors - all of them stay on a battery maintainer (Deltran) all the time. And are kept inside. I have FLA batteries that last 10 years or more.

If you drive the car regularly a few times a week, the maintainer is not necessary, but it is what I do. If you go more than a week, GM recommends the use of the maintainer. A battery that is disconnected but not on a maintainer will still lose charge over time. Your car charging system does not charge a battery to 100% usually. It typically will charge the battery to 80% (this is not made up - it is described in the Service Manual). So, if you have not been using a maintainer (a maintainer brings it up to 100%), and you simply remove the battery from the car for storage, then your battery starts out at 80% and looses charger from there. I personally would not do that. The battery could decay to lower, and still be able to start your car - but that does not mean it was good for the battery. I personally would still put it on maintainer even if disconnected for storage.

 

I use battery tenders (and have for more years than I care to recall) on my six non-regular drivers. It has never been an issue. Just sayin'... but, do whatever works for you.

 

No particular reason not to.

 

Have had two C7s for 7 years since my 1st a 2014 and now two C8s for 6 years since my 2020 C8. Have been on vacation for 3 weeks many years. Never used my CTEK made and for my E-Ray GM logo make by CTEK Li-Ion/Lead Acid charger. Have chargers just in case.

Looking at Pic below with info from my 2014 C7 4 volume Service Manual. Also considering @Andybump measurement of a very low parasitic current draw in his C8 of 10 milliamps NO need for even a 3 week car sit! With the C7 recall someone had his car at the airport for longer than planned, 5 weeks, and it started fine!

So if battery is 3/4 years or newer should be zero issue starting after a 3 week sit. Frankly with my E-Ray Li-Ion battery 6+ weeks. Since I drive my cars at least 2 to 3 days each week and most drives are ~60 miles round trip to town they are Fully charged. In fact my frequent observation of battery dash voltage (really alternator) in ~30 miles with Lead Acid battery after sitting for ~5 days it's fully changed. On my E-Ray less than 10 miles fully charges any loss in 5 days.

Your Car Your Choice. Always plugging it into a charger will increase lead acid battery life somewhat. If the effort and time to do that does not bother you, may be worth it for some BUT not needed.


Looking @Andybump measurement of ONLY 10 mA parasitic current draw in his C8 should be able to go 4+ weeks with C8 Lead Acid battery. Your car your choice. It's not like my 1st Vette, a 1988, with no current reducing circuits when parked!

 

Since mine is essentially a DD I only use the tender if I'm going to be gone for a month or more.
8 Vettes, 1,000,000 miles - 36 years

 

My car is still brand new. But I was gone for the month of April and I plugged it in. Hopefully, I didn't damage my new battery. I also have a CTEK tender that I bought for my Porsche. I have a Z51 and live in GA on the north side of Atlanta so there will be times in late Dec-Mar that it's below 40F and I won't be driving due to the summer tires. I'll probably plug it in.

 

I have used the factory battery tender on my C7 for 3-4 months solid in the 7 winters since I bought it (didn't with my previous C3 and C5).

Absolutely no issues, and whereas I used to have to replace the C3/C5 batteries every 5 years, the 7 year old factory battery on the C7 is still strong & starts the car well.

 

I have absolutely no clue where these thoughts are coming from. I use a CTEK on my C8 all the time. It's still on the original battery - approaching 6 years old. The only valid concerns I've seen are:

• To unplug the until from the A/C before you disconnect from the car. My CTEK owners manual recommends this and I have seen posts of not following this procedure in rare cases has caused problems.
• Don't bypass the battery charge monitor (if you use the frunk cig plug, this is a non-issue). If you use direct battery connection, connect the black lead to a vehicle ground, NOT to the negative battery terminal.

 

I have never used the tender sits on the shelf in the garage, have had C8's sit over multiple winters in Massachusetts and never had an issue with car not starting right up when the weather gets warm enough for the summer tires.

 

I have Battery Tender brand unit. I move it around all four of the cars I don't drive in the winter.
Although old, both Mercedes need some power to keep their computers happy.
The other two vehicles are ancient without computers, I plug them in to maintain their battery.

I bought the GM unit with my C8 because of TBE different power plug...or I could have bout an attachment for my current unit, but theorem was cheap enough.

No brainer.

 

I never know if mine will sit a day or a month so I plug it in just out of habit. I use a CTEK. Haven't had any issues.

 

I have a '22 that has an in service date of mid Aug '21. Original battery still works fine. It's parked for 4-5 months in an un-heated garage for the winter. The first winter I didn't use any kind of charger. I'd start it once a month or so. It did show a low battery on the dash one day and turned over just enough for it to fire up. Let it run for a while and it's been fine ever since. I bought a C-Tek 5.0 the next fall for winter storage, and now I let it sit until spring without firing it up. Based on my experience, I don't agree with folks that say it needs to be on a charger any time it's parked, or even if it's going to be for a week or 2. A month or more, sure, probably a good idea, can't hurt as long as you're using a smart charger/maintainer, not a constant power trickle charger.

 

Hmm, far better for the engine and oil to use a battery charger and NOT start the engine when stored. Here is why:

Starting the car for ~10 minutes to left the battery charge is not a good idea! The worse thing for engine and oil is cold starts. The cold pistons let the main product of combustion, in addition to heat and pressure, WATER get past the cold piston to cylinder wall gap go into the oil. Also cold combustion chambers don't support a good air/fuel mixture so it's usually running rich for a short while. Now unburned fuel as well as water gets into the oil. If the car does not run enough the oil will not get hot enough long enough to evaporate much of the water. The water will combine with "stuff" in the Oil (and fuel) like Sulfur and forms Sulfuric Acid. It corrodes metal while the car is parked. That is why GM before the OLM (like my 1993 Vette) recommended if most drives where under 4 miles or mostly bumper to bumper driving to change oil every 3 MONTHS or 3000 miles, whichever occurs first.

BTW, is what Jiffy Lub, some dealers etc used to justify a sticker on the inside of your windshield after and oil change that said "Come back for the next oil change in 3 months or they added 3000 miles to the Odometer reading." That is based on SAE tests that showed oil gets contaminated and needs to be replaced. The OLM even under good driving conditions says change oil at minimum every 12 months. Your Owner's Manual also notes under some conditions the OLM will shorted that 12 month period.

Your car you'll do what you want but far far better to use a battery maintainer.
Although I don't use one for my DD Vettes as been retired since 2000 BUT drive several days a week and usually a ~60 mile round trip to town. I have observed over several years that my 2020 C8, if it sat for 5 days will not be fully charged until I'm in town, ~30 miles. That's driving with average rpm well past idle.

FWIW I have a street rod with an 8,2 Liter Big Block. It only goes to a few car shows each year. I keep in on a maintenance charger 24/7. Currently using the one I bought for my 2014 C7 as needed a new one for my E-Ray for the Li-Ion battery. No harm as all CTEK and most maintenance chargers are NOT supplying any current to the battery after it reaches full change. BTW I also will not pull the Street Rod out and back if I need access to a ladder! I have a ~25 mile route I take so the oil gets hot enough long enough to evaporate that cold start water that passes the pistons.

Although I don't use a maintenance charger on my DD Corvettes because not needed my Street RoD is one one 24/7!

YOUR CAR YOUR CHOICE!
PS: To Validate the above this is what Google AI said:
Yes, starting a cold engine and making short drives traps unburned fuel and water of combustion inside the crankcase. If the oil never reaches full operating temperature, the water mixes with the byproducts of fuel combustion to form corrosive acids.

 

At my R8C delivery in 2023, my delivery person said to leave the battery tender plugged in when not driving the car. It had something to do with "Over the air updates" and battery life.

 

I don't have charts or graphics to show you, only actual experience to share and that is this: My 2021 C8 has been on a CTEK battery tender every day that it has not been started. I would guess that 300 days out of the year it is on the CTEK. And once again, my original (factory) battery is on its 5th year and is doing fine. I'm at about 20K miles.

Just my .02....