Corvette C6 Battery Concerns

The C6 Corvette is a true World Class performance car with excellent “daily driver” attributes. Everywhere you look on the C6, an electronic device is operating, something we had to either manually perform or think about previously. All of these electronic gadgets require stable voltage for long life. The days of removing the battery cable to see if the charging system is working are long gone. The C6 Corvette battery has to maintain all of the electronic requirements while effortlessly starting the car. In light of this, we typically have very little thought about servicing or checking the battery. They sit there without attention until we have difficulty starting our car.

This is a sign of acid leakage from the side post. We see this very often and have to replace many electrical components due to this leakage. Using an Optima Battery minimizes this concern dramatically.

Lead-acid batteries have been the mainstay for decades, going through just a few changes. The original tar-topped hard rubber case was replaced in 1968 with a plastic composite case. This helped stop the rubber case model’s inherent acid leaks. On many GM models, side post batteries replaced top posts. The side posts worked well until they leaked acid. One had to be easy with the wrench when tightening the side terminals, or he could loosen the post in the battery case.

Fast forward to the nineties, when AGM and electrolytic gel batteries alleviated the problems with caustic acid leakage. AGM batteries use an absorbent glass mat with electrolyte paste tightly wound around lead plates. Optima batteries are AGM battery technology at their finest. The tight-fitting plates encased in individual cells limit vibration that ultimately kills the best of the early battery designs. The spiral cell AGM Optima battery has the best of both worlds covered, as leakage concerns and vibration damage possibilities are minimized.

Electrolytic gel batteries typically use the same design as their predecessors: lead plates stuffed into a case with electrolytic gel surrounding them. Gel’s benefit is less leakage concern. Three things that put any battery to the test are extreme cold, heat, and vibration. The optimum temperature for lead-acid batteries is 77 degrees Fahrenheit. As temperatures rise, battery lifespan is shortened. Likewise, lower temperatures slow the chemical process, straining the battery under high cranking loads.

Why should you care about what battery you have in your C6? The answer lies in the placement of the battery: directly over the Powertrain Control Module (PCM), and several wiring harnesses. Battery acid leakage and voltage spikes may damage these electric components.

We have witnessed wiring harness damage that required many hours of repair with high labor costs. In one particular case, battery acid damaged the a/c system’s vacuum supply tubing. We had to strip the main wiring harness back to the firewall in order to replace the tubing routed with the wiring. This could have been avoided with an Optima or gel-cell battery. Owners spend plenty of time figuring out what upgrades make sense on their Corvettes without considering the battery, yet they sometimes neglect to consider that replacing the OEM battery makes sense as an upgrade and a safety precaution.

If you have a gel cell or OEM-style lead-acid battery that sits for prolonged periods of time, you may be damaging the battery. Electrolytes (sulphuric acid) will eventually sulfate the battery and limit its capacity. Discharging and charging keep all types of batteries active and prolong life. Damage occurs every time your battery is discharged below the 75%-80% mark. Battery drain is inevitable from lack of activity. The C6 Corvette’s multiple memory systems also contribute to voltage loss. An excellent option is to install an Optima Yellow Top Deep Cycle (PN 171132), whether you store your C6 or drive it infrequently. You can also prolong your battery’s life with a Battery Tender Plus (PN 171251). This maintains a specific charge level above 12.6 volts while compensating for temperature variations. If you store your C6 in a heated garage, you consider the Battery Tender Junior (PN 171217). It will constantly monitor the battery’s charge state, charging if necessary. This cyclic activity keeps the battery at full charge and in top condition.

Dead Batteries Are Inevitable

No matter how careful you are, there will be times when a dead battery catches you off guard. How you handle the situation can save you plenty of grief and potential bodily harm. To begin with, Corvette owners who do not carry their key should consider an Emergency Entry Access System (PN 176062) to easily connect a power source to open the door. This system will get your doors to unlock so you can pop the hood and connect jumper cables.

Jumper Cables

With this in mind, remember that every time jumper cables are used to start your C6, there is a potential for a major voltage spike when the cables are disconnected. The alternator sees a major current loss as the cable is removed and spikes voltage momentarily. In some cases, everything seems fine, but then, out of the blue, an electronic component has a failure soon afterward. The best policy with a dead battery is to charge it before starting the car. We all know that this will not be possible to do at times. If you find yourself in this predicament, leave the jumper cables on for five minutes before attempting to start the engine. After the engine starts, leave the cables on for another five minutes to allow the charging system to stabilize. Always connect the negative cable last and disconnect the negative cable first. Jumper cable instructions warn you to connect the negative cable at an engine location rather than the battery’s negative terminal. This is to prevent the explosion of the inherent gasses that all batteries have venting in the area of the terminals. In the side post battery’s case, the vents are on the top and still close to the dangerous gasses. Using the alternator to bring the battery back to full charge adds significant load and heat to the alternator. Alternator life will be significantly shortened if it has to work at full capacity from a weak battery constantly. Likewise, if your battery is consistently dying because of a draw, operating the alternator at full capacity will shorten its life.

Consider investing in a quality set of jumper cables. Cheap jumper cables have very little copper wire and melt unless you’re trying to jump-start your riding lawnmower. We see many jumper cables with impressive insulation, yet only 10-gauge wire coursing through it (remember that as the wire gauge increases in size, its gauge sizing decreases). A minimum 4-gauge cable should be used for jump-starting. You can expect to pay a minimum of $60.00 for good jumper cables.

Battery Charging Techniques

In the event that your battery dies, there are specific charging requirements for each type of battery construction. A good battery can be destroyed forever if improper charging techniques are used. Excessive heat during charging can warp the plates, causing permanent damage. Let’s start with the battery’s condition. There are two likely dead battery scenarios: either the battery has drained from sitting for an extended period of time, or interior or exterior lights were left on. If the battery is completely discharged from an extended period of dormancy, there is a chance that the battery may not come back to life.

Safe battery chargers have voltmeters to monitor the charge voltage level. Charge voltages should not exceed 15.5 volts and 10-12 Amps.

OEM Type Lead-Acid and Gel Cell

To see if the lead-acid or Gel Cell battery will take a charge, start with the battery charger set on high for a half hour. This warms up the electrolyte and begins to release the sulfation paste that surrounds the lead plates. The battery charge indicator gauge will likely show no movement (the battery is not accepting a charge) within the first half hour. If the battery is salvageable, the charge indicator needle will move up to the 14-15 volt range, usually within half an hour. At that point, the charger should be switched to the medium or low position. The charger should be left on for a minimum of 12 hours. In most cases, a completely discharged battery can take 18-24 hours to be fully charged. If the charger volt gauge is working properly, you can tell that a battery is fully charged when the charge indicator needle moves to the 13.0-volt position. Keep in mind that many battery chargers have a rough life, causing gauges to malfunction. A Hydrometer is the best test for battery condition and charge.

With the battery charger set on the high position, monitor the charger’s volt gauge. If the gauge needle does not move off the 13.0-volt area within one hour of charging, your battery should be replaced. Commercial battery chargers have four settings: low, medium, high, and cranking. When you connect the charger, start at the low setting to see if the charger voltmeter moves. As you go up to the high position, the voltmeter should rise an additional volt. This is a good indicator that the battery will accept a charge and has life left. Be very careful with the charger set on high, as overheating can occur after an hour.

Voltmeter Reading

When you start your C6, the voltmeter should be in the 13.4 area. As you drive, the voltmeter reading should rise to the 14.0-14-6 area. This indicates that the battery has topped off and is fully charged. The rule of thumb is that an alternator’s voltage output is lower when it is charging higher amps. When the battery nears full charge, the alternator’s amp output drops, and the voltage rises. Keep in mind that not every gauge is perfectly calibrated; the numbers quoted are typical and can vary. What’s important is the change in voltage output. If the voltage is always low, the battery is dying. Another possibility is there is a major battery draw somewhere. In this case, it would take a long run for the voltage gauge to rise.

Optima AGM

Optima Red Top Charging Information

The following charging methods are recommended to ensure long battery life. Always use a voltage-regulated charger with voltage limits set as described below.

Red Top Type: 34 & 34R – 34/78 – 78 – 25 & 35 – 75/25

These batteries are designed for engine starting applications. They are NOT recommended or warranted for use in deep cycle applications.

Recommended charging information:

Alternator:

  • 13.3 to 15.0 volts, no amperage limit.

Battery Charger:

  • 13.8 to 15.0 volts, 10 amps maximum, 6-12 hours approximate.

Rapid Recharge:

  • Maximum voltage 15.6 volts (regulated), no current limit as long as battery temperature remains below 125°F (51.7°C). Charge until current drops below 1 amp.

Float Charge:

  • 13.2 to 13.8 volts, 1 amp maximum current, time indefinite (at lower voltage).

All limits must be strictly adhered to.

Safety Information:

  • Always wear safety glasses when working with batteries.
  • Always use a voltage-regulated battery charger with limits set to the above ratings. Overcharging can cause the safety valves to open and battery gasses to escape, resulting in premature failure. These gasses are flammable! You cannot replace the water in sealed batteries that have been overcharged. Any battery that becomes very hot or makes a hissing sound while recharging should be disconnected immediately.

Failure to fully charge a battery can result in poor performance and a reduction in capacity.

Courtesy of Optima Battery

Warranty Concerns

Purchasing a new battery is a major expense, as we all know. If you are required to buy a new battery, make sure to keep your receipt. Place the receipt in the glove box or console with your warranty and owner’s manual. Today we see suppliers come and go. Getting a good deal is sometimes costly. Make sure you buy from a reputable supplier, and if the inevitable happens, you move, or the company goes out of business. Your receipt will get you another battery in case of failure. In the case of Optima batteries, call the company directly and explain your situation. Let them know that your supplier is too far away, for instance, and see what they can do for you.

Story and photos courtesy Chris Petris

9 thoughts to “Corvette C6 Battery Concerns”

  1. Hi, I have bought a Corvette C6, from 2006, here in Spain and it run out of battery and I do not have the key, only remote. Does anyone know how I can open the car or charge the battery with no key to open it?

    Thanks in advance for your help.

    1. Your remote has a shiny end. Pull on the shiny end and the remote comes apart – the key is inside the remote. Then use this key to open your hatch; there is a key lock location if you bend over and look just above the rear license plate. Once the hatch is open, there is a cable located on the driver side rear wheel well you pull and the drivers door will open.

    2. Hello Olga,
      I have a Corvette C6, from 2006 here in Spain and I have experienced many problems with the car battery due to battery drains.
      My experience is to let the engine bonnet come down but no to latch it , if battery goes off you con have access to rrload it

  2. 06 vette battery problem…I purchased 6 batteries this year all new place them in the car drive it about `100 miles let the car sit three or four weeks starts right up….then the fifith week battery is dead. All functions are off in the vehicle…what can drain the battery so quick.

    1. Like Chris, author of the article says, “The C6 Corvette battery has to maintain all of the electronic requirements while effortlessly starting the car.” Your security system is always “on” for one. My ’06 Vette Vert battery would not start the car after one week in my garage where it’s 140 degrees during the day, almost half the year (Florida). I don’t ever let that happen. I keep an automatic charger with a built-in an ammeter connected to the battery whenever the car will NOT be used within a few days. Purchase a battery charger and you will only need to purchase a battery every 3-5 years, depending on where you live…problem solved.

    2. there are 13 on board computers to maintain plus the task of staerting the car 4 vweeks is actually a long time to drain a new battery as a battery tender plus and a duracel 47(H5) AGM and you will never have to change one out for 7 or so years. Hope this helps.

    3. I had the same problems and learned the C6 with the standard transmission have to be in reverse when you shut it off or the computer will not shut off. A good way to know if you have it turned off correctly is the chirp you get about 15 seconds after you exit the car. If you don’t get that chirp the car is still on. The battery will draw down pretty fast and there won’t be enough to crank it over if this happens. I have a battery tender installed so I can keep the battery topped off when I’m not driving it. If that battery is even slightly less than fully charged on my Z06 there is not enough to crank it.

  3. I have heard that if you park the car, leave it in reverse and set the hand brake this will virtually eliminate parasitic draw on the battery. Is this correct?

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