C4 Normal Volt Gauge Reading

[Cruzen]

I have checked out the technical area but can't seem to find an answer to this question.

Under normal conditions, where does the voltage gauge read on the C4. The gauge is marked 8 volts at the low end and 18 volts at the high end. Where should the needle be during normal conditions with no power robbing items such as heater or lights on? I know the manual says it should be 13.5 -16 volts but what does your gauge normally show.

Does your gauge change as the rpm changes?

For the most part the gauge in my C4 sits on the high side near the last mark. It does not go into the shaded area. It does not move much or at all then I am accelerating. It does drop down a bit for a while when I turn the air or lights on but comes back to that high mark.

I was just wondering.

Thanks

 

[gmjunkie]

Most run 13.9-14.9!!

 

[Cruzen]

Most run 13.9-14.9!!

Yep, but I am wondering how that is that is presented on the gauge? Near or at the highest mark or closer to the center mark or????

 

[92BlackVette]

Yep, but I am wondering how that is that is presented on the gauge? Near or at the highest mark or closer to the center mark or????

The analog gauges are not linear devices (remember the OEM sticker?), but that aside, mine normally reads high. You also have to take into effect the parallax too.

 

[Cruzen]

OK Guys I have an ending to this story.

The Volt gauge in my 94 C4 has been reading on the high side. The digital read out was indicating 14.3 volts but the battery was not holding a charge. Recently I started to get the "SYS" flashing on the panel which is an indication of an electrical problem. The battery wasn't that old.

This was bothering me so I just drove the car over to the store that sold me the battery and we tested it. Found out it was shorting out and not holding a charge. I had my receipt and showed them the buy date but they pointed out that the battery in the car was not the same one they had sold me.

When I bought my C5 last year I had placed the C4 with a consignment shop Bromm Auto Outlet here in Scottsdale. After five months they were not able to get the car sold because it was not displayed on their lot. Now I find that while they had the car, amongst the other damage they did to it (if you want info on that contact me) they switched batteries and gave me an old defective battery. Anyway I now installed a new battery correct for the C4 and the problems have gone away. I now have to add this to the list of damage they did to the car while it was in their possession.

 

[92BlackVette]

I bought my 92 from Bromm Auto about 4 years ago, they are awesome.

 

[Red Vette]

My 1994 convertible voltage gauge read on the high side, usually above 14; it bothered me as this was the only vehicle that I had that read that high. I had the battery and the charging system checked out and they were fine. When I eventually installed a new Optima battery, the voltage reading was the same, above 14. My conclusion is that my C4 read in the upper range; yours probably does too. My advice, don't worry about it as long as your battery has 9.5 volts and a CCA greater than 665 amps (I believe those are the correct numbers; Jesse would know).
Barrett

 

[aboatguy]

My 1994 convertible voltage gauge read on the high side, usually above 14; it bothered me as this was the only vehicle that I had that read that high. I had the battery and the charging system checked out and they were fine. When I eventually installed a new Optima battery, the voltage reading was the same, above 14. My conclusion is that my C4 read in the upper range; yours probably does too. My advice, don't worry about it as long as your battery has 9.5 volts and a CCA greater than 665 amps (I believe those are the correct numbers; Jesse would know).
Barrett

If your C4 battery has 9.5 volts its dead............

 

[Red Vette]

If your C4 battery has 9.5 volts its dead............

That's why I replaced it with the Optima. I believe it takes 9.5 volts for the car to start. I probably said it wrong in my reply. Thanks for clearing it up.

 

[OptimaJim]

Hi guys, I saw some confusion regarding batteries and alternators and I’d like to offer some suggestions that might help mitigate future issues. I don’t know how many of your drive your cars daily, but if your car only sees occasional or weekend use, you should consider purchasing a battery tender or at least consider disconnecting your fully-charged battery when parking your vehicle. An Optima RedTop is fully-charged at approximately 12.6-12.8 volts and YellowTops are fully-charged at approximately 13.0-13.2 volts. If you leave your battery disconnected when storing your vehicle, you should check it periodically, to make sure it doesn’t drop below 12.4 volts.

It’s also a good idea to check the voltage of your battery when you bring your vehicle out of storage. If it isn’t fully-charged, it’s better to charge it before driving, than roll the dice and hope your alternator will fully charge it. Sometimes batteries that have been allowed to discharge for long periods of time will have enough of a charge to start a vehicle once, allowing the owner to drive it for a few miles and park it, only to find that the vehicle won’t re-start a short time later.

Likewise, if you find that your battery needs a jump, you should fully recharge the battery with a battery charger as soon as possible. I realize this isn’t always practical, but relying on an alternator to fully recharge a jumped battery could lead to a dead battery/jump/dead battery/jump cycle that will continue until either the battery or alternator fails.

The factory gauges installed in most vehicles are not always accurate and rarely specific enough to let you know exactly what is going on under the hood. If you manually check the voltage of your battery while your vehicle is running, that will indicate the output of your alternator and as was mentioned earlier, it should be somewhere in the range of 13.7-14.7 volts. If you have any other questions, I’ll do my best to answer them. I appreciate your interest in Optima batteries!

Jim McIlvaine
eCare Manager, Optima Batteries

 

[LastOfTheV8's]

The battery in my 93 C4 has only 550 CCAs but starts fine on the first turn of the key, my own issue is that the reading in my digital display has begun to vary considerably, from 12 as high as 15 sometimes, driving at idle (for example parking in reverse) she can go as low as 11, with the headlights dimming momentarily as a result. I was told this is a sign of a dying battery? ?
When I was searching previously for a new battery I was advised that if the voltage when the engine is switched off drops below 12 at all then the battery needs replacing. Just my two cents worth.

 

[OptimaJim]

LastOfTheV8’s, I can’t speak for other batteries, but I can tell you that the low internal resistance of Optima batteries allows them to provide power at much lower voltages. This can lead to situations where Optima batteries become deeply-discharged, well below 10 volts. When typical flooded lead-acid batteries are discharged to this extent, their ability to recover and provide meaningful use again is very limited. However, the spiral cell, AGM-design of Optima batteries allows them to recover from multiple deep discharges and still provide excellent power. In fact, many of the “bad” batteries returned to us by auto parts stores are merely deeply-discharged and provide excellent power, when properly recharged.

Once properly-charged, if a battery does not hold a charge over time, then it is cause for concern. This can be checked by fully-charging a battery and letting it sit (disconnected from a vehicle) for 12-24 hours. If you measure the voltage after that period of time or even a week or month later and the voltage is not close to the maximum, then there is good cause for concern.

If the battery holds a charge when not connected to your vehicle, but loses significant voltage while connected, there is probably a high parasitic draw (key-off load), possibly an alarm system or other electrical device that is causing the battery to lose power.

You can measure the output of your alternator by directly checking the voltage of the battery while the engine is running. Although this typically varies from 13.7-14.7 volts, that is not an exact range for every vehicle and every situation. If your lights are dimming, that could indicate an alternator is not producing enough power and your lights are running off your battery. It’s also a good idea to check all the wiring on your battery and alternator. It’s almost impossible to have grounds that are “too good.” One-wire alternators are especially sensitive to good, quality grounds.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.

 

[keremarsan]

Hi !

The middle of the gauge is 13 V , and between every little line , there is 2,5 V

Even the gauge is not linear for analogue gauge, the optimum reading must be logically
between the middle line and the first little line after the middle ( 13 V ) line.

At startup , you can read 15 V but generally it goes down to 13,6 - 13,9 V for normal engine operating condition....

( sorry for my English )

 

[roger longman]

Hi !

The middle of the gauge is 13 V , and between every little line , there is 2,5 V

Even the gauge is not linear for analogue gauge, the optimum reading must be logically
between the middle line and the first little line after the middle ( 13 V ) line.

At startup , you can read 15 V but generally it goes down to 13,6 - 13,9 V for normal engine operating condition....

( sorry for my English )

Hi keremarsan, Apology not needed, your English is better than our Turkish. Roger.

 

[WhalePirot]

I can tell you that the low internal resistance of Optima batteries allows them to provide power at much lower voltages.

Sounds nice, but: too bad I had three bad Optima Red Tops and NO SUPPORT from Optima. Some local stores stopped selling them for that reason.

Never again will I buy one. My car's problems went away when the Optimas left.

 

[OptimaJim]

WhalePirot, I’m sorry to hear about your past experiences with our RedTops. I took a look at some of your previous posts and it looks like the problems you had coincided with your engine swap- http://www.corvetteactioncenter.com/forums/c4-technical-performance/46488-no-hot-start-new-starter.html

I noticed some testing was done on your last Optima. Many auto parts stores use conductance testers that will not provide correct readings and not accurately determine the condition of an AGM battery. They may also try testing a battery which has not been charged properly, which will give an invalid test result. Battery specialists like Interstate Batteries and other independent battery distributors are experts, who can help determine if your battery is recoverable or not.

I also noticed in several of your other threads that you were trying to chase down a variety of issues and I hope you have resolved them all. I did notice something in this thread about your audio system that does concern me- http://www.corvetteactioncenter.com/forums/audio-electronics/68974-largest-door-spkr-84-vette-2.html

In that thread, you mentioned moving your battery inside your passenger compartment and that “vapors may be a concern.” I don’t know if you have venting provisions for that battery, but any battery located inside an enclosed space (passenger compartment or trunk) should be vented to the outside. This includes batteries like Optimas, which will not normally vent. Good luck with your car.

Jim McIlvaine
eCare Manager, OPTIMA Batteries, Inc.
www.facebook.com/optimabatteries