New alternator not putting out correct voltage?

[240pimp]

Hey,

Just swapped the alternator for a remanufactured one in my 93 s13 hatch and its only putting out 12V. It started at 12.4V when I first measured it after install, but now it has fallen to 12 even.

my old one was putting out 10.45

Thinking it's a bad unit, and probably need to replace AGAIN, but wanted to get some feedback on this. Remanned in China, this may have something to do with it, but its a champion unit, so i was expecting some quality. (it looks nice, lol)

I was expecting readings of 13.5 or higher, since the battery is not fully charged from the old alt not working.

PS- much easier to take it out the bottom, didn't have to disconnect any hoses, etc. to do this. Top removal was definitely a no go.

[jesse_s13]

The output should be way higher than 12.4v. Make sure you connected everything properly, it is not uncommon for reman alts to not work properly. Go back and get one from napa.

Good luck.

[240pimp]

ordered a replacement. Sucks to have to do this twice.

[korito727]

Can they test it off the car before you take this one home? Lol

[codyace]

We've seen a recent 'run' of remanned alternators and starters being poor out of the box, so it's totally plausible. Hope the new unit works out!

[Butcher240sx]

Check your grounds at the engine and body also.

[240pimp]

^ will do, it has the standard positive connection that goes straight to the battery and negative ground wire bolted to the alt case. Its also bolted to the block so i think this shouldn't be an issue.

The new one I just installed is totally not working. Battery voltage just kept steadily falling...11, 10, 9...... Pisses me off since its a little bit of a biatch to get out. There arent many remanned units around, but should have my replacement tomorrow.

Thinking of testing it before hooking up the pos and neg leads. Does any one know if I were to start the car with the unit installed, and no leads connected, and then use an ammeter to test from the pos terminal of the alt to the battery, if this would do any damage to the unit? I just want to confirm that its not the car, and its the unit that's the problem. I will hookup the battery and use an ammeter to confirm that both the positive and ground leads that bolt to the alt are working correctly.

I imagine they would test at the factory in the same fashion (if they did, it is remanned in china after all, replacement parts used in the rebuild are probably not the best quality either)

[fliprayzin240sx]

K, first off, is the belt on tight? If the belt is slipping, its not turning the pulley fast enough. The moment my belt slips, my voltage drops down to as low as 12v (running off battery). Check the ground and make sure its on correctly in the back. Get it the alternator and your battery tested just to make sure. Depending on the machine, get a print out and see what the alternator is actually pumping out. Should see atleast 13v but closer to 14v is ideal.

[future]

Is your battery light on?

[240pimp]

^ nope. No light. Belt is on and the proper tension. Battery is brand spankin new. Using an ammeter to check voltage to the battery. pos and negative leads hooked up correctly at both the alt and battery.

What is the purpose of the light anyways? Circuit fault, or low voltage?

[fliprayzin240sx]

Is your battery light on?

It should be if it drops down to less than 12.4.

[240pimp]

^ hmmmmmm, wonder why it isn't working then. Did a manual swap, and used the manual harness. Car runs fine, but only the 3 of the 4 connectors at the fuse box are able to be plugged in to the matching connectors. The fourth connector is a mismatch to the remaining plugin. Haven't gotten around to hooking up the reverse light, and speedo still doesn't work since I havent gotten around to tracing the leads and hooking them up. Might have something to do with the speedo not being hooked up yet.

Shouldn't affect the alt charging the battery though, since its a really simple circuit. I did test directly from the positive lead off the alt direct to the battery terminal , and I got the same reading as pos to neg test on the battery, which means the alt is not putting out more volts than the battery is receiving.

[future]

It might just be your wiring or a dead bulb. The alternator light means low voltage

Just to make sure while the car is running diconect the battery. If it died your alternator is trash

If it stays on go buy a new volt reader and re-test

[240pimp]

^gonna spend some time on that today. Might as well tear the harness apart and do the reverse light and speedo while waiting for my replacement alt to arrive.

Will post what i find, if anything.

[ka4life87]

Have you checked and make sure u have battery voltage at alt? You sometimes have a fusible link or fuse in line and if its blown, means no connection to battery so will never charge

[fliprayzin240sx]

^^^Or could be dead cells in the battery too.

[240pimp]

Its swapped in, and it wasn't putting out the correct voltage either (12.8), until I noticed that one end of the ground wire wasnt secured properly. The wire basically fell out of the end when I messed with it.Once I fixed that, it works perfectly, putting out 14.8 when i re-tested it.!

what a pain in the ass that was to figure out.