Question: Battery protection & voltage

[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.

 

[LLC5]

A fully charged battery should show 12.6V. Don't trust the number on your dash display, go right to the battery and measure the voltage with a quality voltmeter.

Yes, you could have a bad battery that is new. It would need to be load tested after being fully charged to be sure.

Are you having any issues with the battery going dead, and do you have to jump start it?

 

[POLOG91]

Thanks for the reply, LLC5. I was pretty sure the volts were off & I do know (but do not have) an actual meter to put on the battery. It seems to crank a little slower than the first 2-3 days I had it. Fortunately, no need to jump it yet ....

Would you agree the trunk light has nothing to do with this since the light times out?

 

[LLC5]

Thanks for the reply, LLC5. I was pretty sure the volts were off & I do know (but do not have) an actual meter to put on the battery. It seems to crank a little slower than the first 2-3 days I had it. Fortunately, no need to jump it yet ....

Would you agree the trunk light has nothing to do with this since the light times out?

Correct, if the light times out then that would not be a source of a battery drain. Try and find a digital voltmeter and connect it to the battery after sitting over night and check the voltage and write it down. Crank the engine over and see what the voltage is during cranking. You state that it cranks slower than it did originally, so in my opinion you might want to take it to your dealer and have them check the system out under warranty before you possibly get stuck somewhere, which would make you an unhappy customer since you just purchased the vehicle.

Good luck with it.