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My 2016 C7 is connected to a Deltran Battery Tender year round except when being used. I started doing this back in 1987 with my first C4 Corvette and then my 1989 C4 and have that Batteries last 10 years. My tractor is also connected to a Deltran tender and the battery is 12 years old !
A malfunctioning diode in the alternator can create a parasitical drain on a car's battery. Diodes should allow current to pass in only one direction, but a bad diode will keep the charging circuit open even when the engine is not running, allowing the battery to go dead. This often happens overnight.
Parasitic draw- A certain amount of draw is normal- in the region of 25mA (milliamps)-but if you have 100mA or more being lost, something is up. It could be anything from a dome light staying on, or a glove box compartment switch stuck on.
What is a alternator ripple test?
Alternator AC ripple- without ECM control. The purpose of the test is to check the rectification of the alternator output voltage, where the alternator output is not regulated by the engine control module (ECM).
Notes1: Ripple (specifically ripple voltage) in electronics is the residual periodic variation of the DC voltage within a power supply which has been derived from an alternating current (AC) source. The ripple is due to incomplete suppression of the alternating waveform after rectification.
Notes2: Rectification=The conversion of an alternating current to a direct current.
Does the ripple in fact drain the battery causing it to go dead? Is this something I should address at the dealership?
As Submerge indicated it usually happens due to some sort of alternator problem. The alternator generates a DC voltage by first generating an AC voltage that is converted to 12VDC by using diodes to rectify the waveform, there are usually some filter caps to filter out any ripple seen due to the rectification process but they can fail or a diode can fail thus causing an excessive ripple. The regulator circuit that controls current flow in the alternator could also be out of spec and that can cause a ripple. To get ripple riding on the DC voltage means there has to be a source for the ripple, which would be the alternator. I don't know of any other device on the car that will generate a ripple as everything else runs on DC power. How did the AAA person measure the voltage? Was it when the engine was running?
You state you were told the ripple voltage was .45V. That is 450 millivolts or 0.5V (rounded) which is a fairly high ripple voltage. You should hear that in the sound system. It would be a frequency that varied with engine speed and would sound like somebody whistling at various frequencies.
Bill
Last edited by Bill Dearborn; Nov 16, 2021 at 04:06 PM.
hmm I had the same issue with a good battery going bad overnight full charge down to 3 volts. I pulled the battery advanced auto charged it . It is back in the car on a trickle charger and the car goes into the dealer tomorrow. I did note that the convertible top had not gone through the full range when the car restarted, I am not sure if that caused the drain with the car off. any way I will have them check the whole electric system while they have it in the shop
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.
