Honda Accord Battery Not Charging

HONDA ACCORD
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NICK707
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I got a alternator for a non vtech 94 honda accord but my motor is a 98 honda prelude vtech. My batterey is not charging could this be the problem why? Do I need a alternator for a vtech or could it be something else?[img:ffe349e02a]http://www.2carpros.com/forum/automotive_pictures/55589_Picture_276_1.jpg[/img:ffe349e02a]
[img:ffe349e02a]http://www.2carpros.com/forum/automotive_pictures/55589_Picture_311_1.jpg[/img:ffe349e02a]
[img:ffe349e02a]http://www.2carpros.com/forum/automotive_pictures/55589_Picture_342_1.jpg[/img:ffe349e02a]
Jan 24, 2007 at 4:22 AM
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UCC
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The best way to check this is to go to a parts store and have them do a test, however the other way is to remove the negative cable from the battery while the car is running and it will die if the alternator is bad, or start to die. If the alternator is okay then it will keep running smooth (shouldn't change AT ALL when removed) because it is still outputting enough power to keep the car running or to charge the battery.

Good Luck
Feb 3, 2021 at 8:33 AM
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BRUCE HUNT
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Without doing the run thing mentioned above. Was the wiring the same? That is the big issue. You need to be careful when cross matching parts. The schematic for the alternator is what I would look at and see if they are the same. I could track that down but the simplest by far is to get the correct alt for the wiring of the car.
Feb 3, 2021 at 8:33 AM
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CORLEY45
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do not remove the battery cable, with car running ,this will sent voltage spike to diodes when you disconnect the cable and when you reconnect the cable,you could weaken the diodes,put voltage meter across the battery terminals ,with car running should read 13 to14 volts, not running 12 volts,while car is running if voltage read 12 volts replace altenator
Feb 3, 2021 at 8:33 AM
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RASMATAZ
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What I've seen so far-a lot of aftermarket stuffs on it.

Disconnecting a battery cable is a bad practice-uncontrollable voltages will kill the rectifier as mentioned.

Engine not running measure the open voltage of the battery should read atleast 12.4 or better.

Now fire it up measure it again should read somewhere between 13.5 -14.5 if not the alty went south bound-I know what you're thinking, forget about the voltage regulator-change the alty. its okay if the VR is an external.

HTH Good Luck
Feb 3, 2021 at 8:33 AM

Suggested Repair

Measure battery voltage with a meter: at least about 12.4 volts with the engine off, and about 13.5 to 14.5 volts while running. Do not disconnect a battery cable with the engine running, because the voltage spike can damage the alternator diodes. If running voltage stays near 12 volts, replace the alternator with one that matches the car's wiring rather than only the swapped engine.

Conversation Summary

The owner has a Honda Accord with a 1998 Honda Prelude VTEC engine and a non-VTEC alternator from a 1994 Accord, and the battery is not charging. One reply suggested disconnecting the negative battery cable while running, but later replies warned that this can spike voltage and damage the rectifier. Experts advised checking open-circuit and running voltage and using the alternator that matches the vehicle wiring.

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