Hey guys so I recently fully charged my battery in my hummer h2 since it sat for 1-2 weeks and the battery was fully dead. I put it in the truck today and then I remembered that my radar detector does a voltage reading so I turned that on and I noticed that my voltage would only be between 13.5 -
13.6v while driving with no Ac/fan and the stereo shut off. I even shut the lights off and same thing, when I got home I let it idle and it was between 13.5-13.6v

is this normal because my battery was just recently fully charged? Or is something wrong? The alternator is about 5 years old and it’s a China one so it could a about to go but just wanna make sure what values I should be seeing. I’m also going to be getting a HID kit very soon so I don’t want anything to go wrong with that especially

 

I think in a perfect world the numbers are 13.8 to 14.2 so I'd say you're close enough.

Tim

 

Check the accuracy of your radar detector, and test at the battery with a meter.

 

yeah i should always trust the direct battery connections aahah,. i used my voltmeter/multimeter and at idle hooked to the battery i saw 14.2V ish which is obviously good. however i noticed inside the vehicle the gauge is always less then 14v, it seems to always sit around 13.5v - 13.7 v at all times, this seems to match the radar reading. is there a reason for this discrepancy?

 

Voltage is the difference in charge between two points. Current is the rate at which charge is flowing. Resistance is a material's tendency to resist the flow of charge. (Georg Ohm's law 1827)

 

The important measurement is directly at the battery terminals and this seems OK from what you said. Voltages will drop futher down the wiring harness, but it's impossible to estimate and depends where it is measured.

Why not compare the voltages of the auxilliary power outlets using the same meter, then you will know.

Your battery my be discharging due to some parasitic drain, this is a well covered topic.

 

Great advice, since there could be a voltage drop due to corrosion in the contacts, common with aux outlets. I just checked all 3 of my auxiliary outlets, all 3 match exact to the voltage at the battery.
Note of caution when testing auxiliary outlets, send positive probe straight into the back of the outlet center contact, hold it straight, then touch the outer ring with the negative probe.

 

oh those things aren't coin holders? where will the kids put all the coins now?