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Voltage Fluctuation at idle and 1000 rpm

456 Views 4 Replies 2 Participants Last post by  BrettsG6GtConv
ok so today I had to use jump box on my 3.5 g6 2 times. Drove home from work (bout 20 min city driving) and shut off car. Then immediately tried to start and dead battery. I already have the issue with trunk where I have to unplug neg. bt. cable for a sec to pop trunk. I fixed wires in trunk that broke but still same issue. I have aftermarket stereo but on install the only car wires I am using in the harness adapter are the power and ground. Jump wire to turn radio on and cut/spliced speaker wires straight to stereo. Had the ground wire issue behind starter and fixed with new one. Im getting 9.8 volts at idle and 12.4 at 1,000 rpm. Question is could remote wire drain bat that much or am I loosing connect with batt or some other grond? Cable connects are clean no corrosion. Thanks ahead for any possible help.
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The voltages you mention look a bit low. A good battery should supply close to 12v or a little under. When the car is running you should get to 13-14v. I would try measuring the voltage at the alternator when the engine is running to see what the generator output looks like. You may have poor power or ground wires. It may also be worth disconnecting the battery and measuring it directly, without any load. Getting the battery load tested at an auto parts store is probably a good idea - most will do it for free. Personally if I have any battery like issues and it is over 4 years old I will often replace it as that is the most life I usually get from them. After that you might want to look up videos on parasitic draw testing on google to see if something is draining power.
Update- bad ground by radiator in front of the battery where there is 2 grounds. cleaned and tighten ed everthung now reading 13.4 at idle fluctuating between13.1. Starts right up.
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