POLOG91

I use the Battery Minder on my C4 & C5 & have for years. I have a cigarette lighter attachment & plug them in the center console & feed the wire out the window I leave slightly open. The only on 'power always on' accessory plug in new C7 convertible I got 8-20 is in the trunk. I now have 133 miles on it. I have the dashboard display in Touring because I like the extra info always displayed. When I get in & just press start to put auxiliary power on, I can see the voltage readout which is 2.9. When I start the car, the volts go into the high 13's & low 14's.

My issue it the resting/cold volts. I believe I should be seeing a minimum of 11.8 volts.

I am not closing the trunk on the cord since I'm sure overtime there will be a depression in the trunk weather strip. I bring the trunk to it's lowest, non-closing position. The trunk light times out after 10 minutes so I didn't see that as a problem. The Battery Minder does go into float mode but compared to my other cars it takes much longer. If I unplug it & plug it back in 5 minutes later, it may take 45 minutes to start blinking again.

Am I doing something wrong with this hook-up or did I get a bad battery off the production line.

Any thoughts are appreciated.

NSC5

If it was truly down to 2.9 volts none of the electronics would work and the car wouldn't start. This sounds like a display electronics glitch instead of an accurate reading.

With only 133 miles on the car I would let it go awhile, hopefully with a few somewhat longer trips, to fully charge the battery before growing too concerned about the float charge behavior.

You could also measure the voltage at the battery terminals with a voltmeter after it has been sitting for awhile to see how far the battery charge level is actually dropping.

Shortimer

I get the same 2.9 volt reading when I shut the engine off. I had two friends check their C7's and they got the same low voltage readings when the engine shuts down. It seems to be the norm.
As stated above, if the battery voltage was really that low the car would not start. That said, my battery failed after five months. My dealer checked the battery with a "GR8" tool and found a bad cell. It would not hold a charge. They replaced the battery with another AC Delco but it had more cold cranking amps, 615. The factory battery was just 550 CCA.
I use a CTek 3300 to keep the battery charged via the port in the trunk area.

Modshack

The only way to get an accurate resting voltage is to use a digital meter AT THE TERMINALS with the car off.. Any time you key on, lots of loads are started. This should be done 12 hours after a full charge or drive. The resultant voltage will indicate battery health...the batteries ability to hold a charge. Shown in % on the gauge below. Once resting voltage gets to 12.2 or so you should start planning on a new battery..

Also to the OP,Yes, the only socket that remains hot (for charging) is the one in the back.
I thinkk your 2.9 is a false reading as mentioned above. I would not worry a minute about it..

eboggs_jkvl

Correct on the socket status. There is one other place to charge the battery and that is in the engine compartment at the rear of the fuse block. It is a hot lead to the battery for a charger. I have my CTEK hooked up to that connector and a ground elsewhere in the engine bay. I use the magnetic connector ( http://www.ls2.com/forums/showthread...ery-topped-off ) sold by a forum sponsor ( https://www.corvetteforum.com/forums...ry-tender.html )

It is for the C6, but I modified it and used it for the C7.

Elmer

JoesC5

I agree that the engine compartment is the best place to connect a float charger. I leave my hood resting on the springs(raised about 2 inches as it gives me a visual reminder that I have the float charger connected). I don't like the idea of leaving the rear hatch lid partially open(so as not to possibly crease the weather stripping) over the winter, as those furry little creatures can enter the cabin with only a 1/4" wide opening. Doesn't matter leaving the hood up slightly as the creatures can enter the engine compartment even with the hood closed, yet the little creatures can't access the cabin from under the hood.