My battery on my 2001 Montero Sport won't hold a charge I have had the battery and the alternator hooked up to testers and they are both good. also I have had the wires to and from the alternator checked and they are all good and tight. what else could be the problem???
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Re: good battery not holding charge
There could be a draw in the electrical system. with key out of ignition and all doors closed. disconnect neg battery cable and put test lite in between cable and battery terminal, if it lites up strong, then there is a draw down. to trace the draw, leaving test lite hooked up, remove interior lite fuse. then remove one fuse at a time(returning previous fuse to proper place) until test lite goes out. that is the circuit that is drawing down. you pull the interior lite fuse first cause door will most likely be open to ck rest of fuses. hope this helps
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sometimes "new" alternators and batterys are bad from the factory, or sent out with a defect. Check your battery connections from battery to alt/starter, check connection of battery ground. Check ground from engine to frame or body.
I assume that your battery is not charging or holding a charge. You should be able to bring the car to an Auto Parts store and most of the time they can bring out a multi-tester that tests batteries and charging systems. It hooks up to the battery and tells you total cranking amps, volts AND charging system output, which is what you want.
I'm not sure if you have all of the info you need to go forward with this. The battery may be rated for 800 amps but could have less than 12 volts if the alternator is not charging it. It could have a dead cell which would keep it from holding a charge. You would need to check the charge of the battery with a volt meter, then see if the alternator is charging at 14 volts when the engine is running. The battery should be at least 12 volts with the engine off. The problem could be in the wiring from the key switch or dash gauges back to the alternator.
I doubt it is the belt because if the belt is slipping you should hear it. The alternator could be about to crash and not charging at lower speeds. You would check alternator output to find out. The battery and brake warning lights are on the same circuit.
Instructions1 Clean the positive and negative battery terminals to ensure a good connection with the tester's clamps. 2 Connect the positive and negative clamps to the appropriate battery terminals. The clamps must make firm contact with the battery terminals or the test results will be inaccurate or the tester may not work at all. 3 Turn the tester on and choose the option for "full charging system test." This will test your battery, starter and alternator and provide the most accurate picture of the problem. 4 Follow the directions on the tester's screen. These instructions will include cranking the vehicle after the battery test is performed, holding the engine at a certain RPM range and turning on certain accessories. 5 Read the results displayed on the tester's screen. The tester should scroll through the results, starting with the battery, then the starter and finally the alternator. An alternator test result showing diode ripple problems indicates a bad alternator. Thanks
CHECK ALTERNATOR DRIVE BELT COULD BE LOOSE NEED ADJUSTING OR GLAZED NEED REPLACING. IF ALL IS GOOD, CHECK ALTERNATOR VOLTAGE OUT PUT AT BATTERY SHOULD BE 13.5 - 14.5 VOLTS. IF NOT ALTERNATOR FAULTY BUT CHECK ALTERNATOR BATTERY FEED AND VOLTAGE REGULATOR WIRES FOR LOOSE CONNECTION OR DAMAGED FRAYED WIRES. CHECK ALTERNATOR FUSE.CHECK THOSE THINGS BEFORE BUYING NEW ALTERNATOR.FIRST TURN OFF RADIO BEFORE DISCONNECTING BATTERY CABLE TO KEEP FROM LOCKING OUT RADIO.
well running the voltage from alternator should be at least 14 volts or a bit higher, engine off it should read at least 13 volts at battery. if alternater is less then 14 volts, it is the alternator at fault. or a loose alt, belt.
Get a volt meter and check alternator voltage at battery while engine running, should have no less then 13.5 volts, if you have good voltage at battery, disconnect battery terminal neg. hook test light at cable (neg) and at battery, make sure every thing is off and door's are close if test light lights up you have a battery draw you'll need to fine short.