When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I haven't been a c5 owner long enough to know if I have a parasitic draw or not. Before getting too deep in to it I've been measuring my daily voltage drop on my battery. I loose about .05 volts per day when the car is not in use. According to charts, with a 100% charged battery 12.65v I'm at about 60% 12.37v battery after a week. Is this normal or should start looking for a problem?
I'm not sure but all I know is that if my Vette is going to be down for a week, I put the Battery Tender on it. My battery is new and it acts like it's as old as I am.
During extended storage I use a tender or disconnect the battery. Living in Florida heat is an enemy to battery longevity. Local parts suppliers will be happy to load test your battery (and sell you a new one) That being said I replace my Walmart battery every three years, no regrets.
One week on a good battery down to 12.37 V indicates a bad battery and/ or too much draw. Get the battery load tested. If good, get a test for current draw.
That said, my C5 has been on a maintainer 24/7 except for driving it since 2010.
2025 C8 Z06/7/E-Ray of the Year Finalist - Unmodified
2023 C3 of the Year Finalist - Unmodified
2021 C8 of the Year Finalist Unmodified
2020 Corvette of the Year Finalist (performance mods)
2019 C1 of Year Winner (performance mods)
2017 Corvette of the Year Finalist
2016 C2 of Year
2015 C3 of Year Finalist
All modern Corvettes drain batteries when they sit. That's true of C5, C6, C7 and C8's. They are maintaining systems when they are sitting. It just makes good sense to keep them on a battery tender when they sit. I do it routinely on all my cars after every drive.
All modern Corvettes drain batteries when they sit. That's true of C5, C6, C7 and C8's. They are maintaining systems when they are sitting. It just makes good sense to keep them on a battery tender when they sit. I do it routinely on all my cars after every drive.
Most modern cars from the mid 90's to now drain batteries while they sit to support the security systems. Some, like my AMG have a pretty good BMS that does a good job keeping the drain to a minimum and I can even turn off "network" features to make the battery life even longer. Plus, the car will send me a message via my Mercedes app to my phone to let me know my drain needs attention.
I did a similar daily test to my 02 Coupe when I got it a 1.5 years ago and I found after 2 weeks, I was close to low level/no start voltage. That is a normal parasitic drain pattern for a C5 from what I have experienced and read across a crap load of threads on multiple forums. The system will conduct checks periodically to make sure everything is copasetic as part of the security system and that takes juice-I bought a NOCO 2 smart charger and mounted it in the battery compartment and plug the car in when not in use. If you can't do that, then you need to plan a routine where you are using the car and keeping the battery up else, you will be buying a new battery sooner than later!
Also buy a jump pack, it is a good thing to have anyway as you can charge things in addition to jumping the car if needed. Better than jumper cables! Below are the two I use. There are many out there but these get great reviews and I am very happy with them.
My battery never discharges. Do not use a battery tender. Reason? I drive it at least once a week for at least 30 minutes letting the alternator do the charging. It is not a garage queen. It is a fun car. But to each their own.
Normal...
The C5 Battery !!.... It gets replaced often and gets a plug-in maintenance to the Schumacher every evening!... Otherwise after a measly one and half years of service, the battery, any brand, any model, anywhere, should no longer be trusted because the thing inevitably quits working!.. Of course Rain constantly happens here in the Pacific Northwest...so One must be battery conscious, C5 battery conscious!
The Red Top in my C5 will be replaced at seven years, about six months from now. It stays on a maintainer 24/7 except when I drive the car. The car and batteries have been on a maintainer 24/7 since 2010.
Normal battery drain
