1999 Sebring convertible 2.5 battery not charging

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The battery light goes off when the car is started, but goes back on in a few seconds, and remains on. I have replaced the alternator (although the old one tested good), and replaced the battery. The problem persists, and the battery goes dead after driving the car maybe 50 miles. Does anyone have a solution?
 
What is the voltage at the battery when the engine is running? I'm not sure, but that car may have the regulator built into the ECM.
 
With the engine running, battery voltage is about 12. The voltage regulator is internal to the alternator, as far as I know,
 
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The regulator may be within the processor. You need to do some further diagnostic work in that area and the wiring from it to the alternator.
 
Measure the voltage at the alternator itself if it has the correct voltage look at the connections especially at the starter motor if there is one, these sometimes rot.
You can run a direct wire of the correct gauge from the alternator to the battery with ring terminals to at least test the system, then you have an idea where to start looking. Do not connect both wires, disconnect the original first.
 
Measure voltage at battery with engine off and engine running. Should be at least 1V higher with engine running.

Have alternator tested at a place that rebuilds alternator and starter. They should have an oscilloscope to see waveform. Ask for their opinion.
 
Dodges use external voltage regulators. Yours is inside the computer but you can find instructions online on how to use a $10 external one from a 1970's Dart.

You should have a field wire you can ground... do that and it'll make ~18 volts, proving the alternator works and you have a regulator issue.
 
OK, you should have a 2.4L not a 2.5L correct me if I'm wrong please (is not relevant all the cars use the same system). The voltage regulator is in fact inside the ECM (engine control module) they are very reliable so I would check wiring/plugs first, it sounds that when it is cold there is contact and when it heats up there isn't, if the light comes on in less than 5 seconds after starts the problem is there all the time, it takes few seconds for the computer to check all systems and take action or not if it takes more than that then check voltage at the battery as soon as the engine starts with the battery charged and before the indicator light goes on if possible, voltage should be between 13.8v and 14.4 or voltage climbing to this range at this time of the year and keep on watching to see if the voltage drops down as soon as the light goes on all this will tell you if it is the voltage control system (field) or if it is the ground/charging wire (high amps). I have in the past unplugged the computer and plugged it back and many gremlins have disappeared (poor contact). If after checking all wires and contacts the problem persists it should be the internal voltage regulator, me personally would connect an external regulator for any Mopar vehicle between 1968 and 1989 (non computer vehicle) but get a "heavy duty" regulator the normal duty will not be able to handle the field in the nippondenso alternator you have, you can even get an adjustable heavy duty regulator and set the voltage to your liking, also try to fit the regulator besides the battery or as close as you can, it has a temperature sensor inside to help with the proper charging of the battery so the closer the better, after that if the indicator light bothers you a resistor can be fitted to the original plug coming from the computer fooling it into believing that it is connected to the alternator it works 2 out of 3 times. Good luck and keep us posted
 
i agree , Check voltage at the alternator . Is the belt slipping . Id you need to , run an external charging wire from the alternator to the battery , as has been suggested .

Also , check grounds . Run an external wire for ground , too , if necessary .


Report back what you find .
 
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