So my C7Z has been sitting in the garage, probably 4-5 weeks now, given the COVID thing, crappy weather, me not feeling well, etc., etc.

Anyhow, yesterday I went out to fire it up - lights came on, but only solenoid clicking and wouldn't start. Easy I thought, so I put a charger on it overnight, and went to fire it up this morning and now its completely dead - no lights, nothing. Doors won't open. Its DEAD. No signs of life. Is there a reset function or something that would cause this? I had lights, radio, etc. before the charger, so I'd think that even if the charger was busted I'd at least still be there. Only thing I can think is that there was a light on with the rear tail hatch open or something that didn't shut off maybe? I dunno. Have you encountered this before? Its a mostly new C7Z, about 4000 miles on it, and it got a new battery just before I bought it due to sitting on the lot for a while...

 

Even dormant, the car will draw 0.02A so over the course of a couple weeks will draw down the battery to what you see.

This is why a good trickle charger or battery tender is a must for Vettes.

Something like this is what I have: https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1

CTEK makes good stuff.

 

Yep, I ordered a CTEK to keep it topped off, but until then I'm wondering what I've done - did I ruin the battery? Did I get to a voltage level that requires some sort of reset? Because its completely lifeless

 

If you went to dead on the battery, you may have damaged or weakened it for any more usage. When my battery goes to 0, I buy a new battery.

Elmer

 

You can bring the battery to Autozone and have them do a load check on it for free.

 

That's the thing though, it went from having some charge, enough to do everything but start, then to absolutely dead overnight WITH a charger on it. That's what I'm not getting...

 

So I put it on a 10A charge for a while with absolutely no change. So wondering if the charger I have is hosed up. So I jumped the car and got it fired up and ya, all the settings were gone, but its running and I took it out for a 30 min drive, so hopefully that's enough to top off the battery til I can get the trickle charger and maybe bring it back to health and see where the battery is - maybe its toast or maybe it'll recover, who knows. But for now I'll just make sure I drive it once every few days to keep it topped up...

 

What does/did the onboard battery/alternator read when the car was running?

and do you have a multimeter to check the battery charger?

 

Batteries in my VOM are dead too

Dash reads 13.1V when the car is running.

 

that's pretty damn low. 12.5 is minimum to start the V8

 

With the engine OFF you can press the START button for 10 seconds without pressing the brake or clutch. This will put the car into SERVICE mode and you can read the battery voltage. You'll need to press the START button again to exit the SERVICE mode.

By the way, I plugged in my battery maintainer into a tripped circuit and pulled down the car battery. Don't always assume your receptacle has power - mine was off due to a failed GFCI receptacle. Lights on the maintainer came on, apparently powered from the 12 volt side...

Service Mode
This power mode is available for
service and diagnostics, and to
verify the proper operation of the
malfunction indicator lamp as may
be required for emission inspection
purposes. With the vehicle off, and
the brake pedal not applied,
pressing and holding ENGINE
START/STOP for more than
five seconds will place the vehicle in
Service Mode. The instruments and
audio systems will operate as they
do in ON/RUN, but the vehicle will
not be able to be driven. The engine
will not start in Service Mode. Press
ENGINE START/STOP again to turn
the vehicle off.


GL and stay safe!

Ron

 

Thanks Guys!

 

Get a CTEK 7002 battery tender. It's their only model that can revive a dead battery. It's about $105. Also get a cigarette lighter adaptor for this unit for $15 more. Amazon has these.

 

Thats the model I linked earlier in the thread.

 

Very possible, car batteries do not take kindly to a deep discharge especially to zero.

As already suggested, have it load tested to check its condition.

While I keep my batteries much longer than many here (seven or more years is common for me with good care) I likely would just replace the battery at this point.

 

Interesting post, have been concerned about my 2016 Corvette battery, bought car last year and assume it has the original battery in it. Ran the service mode test as posted earlier, when car was sitting there was showing around 12 volts or barely over, not close to 13 volts but as soon as I cranked the car, reading went well above 13, probably at least high 13's or into low 14's, I would assume that this means that my battery is ok, is that correct? Thanks

 

Are you sure the battery charger was making a good connection to the battery. Been there. Thought it was charging when it wasn’t.

 

No it means your alternator is probably working. Probably because if the battery is half shot it will not draw much charging current from the alternator. A battery that is charged should read at least 12.6 with minimal current draw as when in service mode.

You might want to check your battery voltage after charging, when not running, with an external volt meter. If that reads 12. nothing you may want to purchase a new battery as your current one is not capable of holding a decent charge level. It's just sitting there waiting to fail on a rainy night in some out of the way parking lot.

 

I struggle to find a single grain of truth to what you just posted. I question if you understand how the charging system works. Did you not read what his post said? He put the car in diagnostic mode which meant he did not start the vehicle. When you are in diagnostic mode you are just reading the voltage of the battery. He indicated it read 12 volts. Perfect! When you start the vehicle and view the voltage reading in the DIC you are looking at the voltage that is coming from the charging system to the battery. When you start the vehicle it will jump to around 14 something volts because of the battery drain to crank the starter motor. Eventually the DIC volt reading will settle out. The DIC reading will vary depending upon what other electrical systems are being used on the vehicle. All vehicle systems will draw down the battery. If you turn your headlights on, turn on the navigation system, turn on the AC, and then turn in the windshield wipers you will have a greater electrical draw on the battery then if these systems are not running. Under this condition, the DIC could be as high 13 to low 14 volts as the battery is asking for the charging system for more charge from the voltage regulator. There is nothing wrong for a Corvette DIC to operate between 12.5 to 14.5 volts. This is normal. Occasionally test you battery by putting your vehicle in diagnostic mode and check the voltage of the battery on the DIC. Should be right around 12 volts. While the car is not running now turn on a few electrical systems on your car like the radio, lights, etc and watch the voltage drain from the battery. Don't do this very long as you still want to have enough voltage to start the vehicle. I would not worry about your car battery unless the DIC readings ever show up outside the 12.5 to 14.5 volt range.

 

You have no idea about batteries or the charging system for that matter. A charged battery does not read 12v it is about 12.6 under no load. If you don't understand that I'd suggest reading a primer on basic electricity.