akuma4u Posted July 4, 2020 Report Share Posted July 4, 2020 Hey just want to know if a resting or idle voltage of 14.0v to 14.2v without any load is fine? Or should it be higher? Car has a 120amp stock alt and 2 agm batts. 1 starting and 1 in trunk. Both medium to large size and fully charged. Link to comment Share on other sites More sharing options...
1point21gigawatts Posted July 4, 2020 Report Share Posted July 4, 2020 Were these reading of done while the engine was hot or cold? Even though it’s one circuit, were these readings done on the front battery or rear battery? “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.” Link to comment Share on other sites More sharing options...
akuma4u Posted July 4, 2020 Author Report Share Posted July 4, 2020 Both batts are connected and this was done today i guess while engine is cold I was told since both batts are connected parallel that the car sees it as 1 bank. So the voltage im seeing is for the 2 batts together as 1 not one or the other. Link to comment Share on other sites More sharing options...
1point21gigawatts Posted July 4, 2020 Report Share Posted July 4, 2020 Did you connect the dmm to the battery under the hood or the battery in the rear? First read the alternator directly on the positive post of the alternator and the negative ground bolt of the alternator and compare that voltage to the voltage of the under the hood battery beside it and if that battery is reading lower then that battery has a weak positive connection or bad ground and then test the rear battery the same and if it reads lower then it has a bad ground or a weak positive connection. Make sure on the positive connections that the fuses are snug and tight and well connected and make sure the grounds on the battery are short, 18” or smaller, and grounded hard. Too long of a ground will result in lower voltage, no matter how hard and good it’s grounded. If your alternator is reading 14.2 then the batteries and connections are fine and that’s just that alternators voltage. Factory alternators voltages range from 13.8 to 14.6. So don’t worry. Just grab a dmm and start checking things out. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.” Link to comment Share on other sites More sharing options...
akuma4u Posted July 4, 2020 Author Report Share Posted July 4, 2020 I didnt do any of that. I have a voltmeter in the car and i just follow that. That reads 14.2 at cold start up and idle. Upon driving it can range 14 to 14.3 I use to be higher like 14.3 to 14.6 cold start idle and driving for the first few mins then it would settle to 14.0 to 14.3 I guess its ok where im at..i just psychologically feel more at ease with 14.3 and above Link to comment Share on other sites More sharing options...
1point21gigawatts Posted July 4, 2020 Report Share Posted July 4, 2020 Solder a 1N4004 diode to the alternators sense wire. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.” Link to comment Share on other sites More sharing options...
1point21gigawatts Posted July 4, 2020 Report Share Posted July 4, 2020 The sense wire is the wire that reads battery voltage even when the vehicle is off. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.” Link to comment Share on other sites More sharing options...
akuma4u Posted July 4, 2020 Author Report Share Posted July 4, 2020 K something is def wrong. No system playing with mild ac on. Voltage is jumping from 13.8 to 14.2 driving at 3k rpm and up for an hour. It never did this before. Voltage always rose when rpms went up and it would stay steady not jump around. I think i got a loose or corroded wire or terminal or perhaps alt is starting to die. I was pushing 2500rms on stock alt. Maybe that fucked it up. I gotta dig deeper and figure this out Link to comment Share on other sites More sharing options...
1point21gigawatts Posted July 4, 2020 Report Share Posted July 4, 2020 You have a bad connection somewhere like I stated in the first post. After you fix that issue and get back to normal voltage, add a diode to increase voltage anyways. It’s better so why not. “How can we help you?” “And don’t forget to tell them that the customer isn’t always right.” Link to comment Share on other sites More sharing options...
Ampped up Posted July 10, 2020 Report Share Posted July 10, 2020 depending on the veiclce year it sounds like the battery management system giving you a work out to me. I have learned this the hard way. Link to comment Share on other sites More sharing options...
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