Jwong77

13.07 V at the battery, 11.56 at the alternator. So my newly rebuilt alternator is garbage.... What should I do here? I can return this to the rebuild shop but still need an operational alternator. I see plenty of salvaged S2000 alternators on eBay, should I take a gamble on that?

Does Denso still make this? If so, does anybody know how to get one?

B serious

Well your voltage values agree with your initial post. The alternator was charging at one point.

It does point to a bad alternator.

​​​​​​See if Rockauto has a Denso offering.

Otherwise, try a used OEM one.

Jwong77

Looks like they have it. RockAuto Alternator

Hope this lasts longer than the other two. On the positive side, I've gotten pretty good at removing my stock air box with this much practice.

aaronyuri

You should be seeing about 14V on the battery with the alternator functioning correctly. But to get 13V, you definitely had a working alternator at some point. It could be that your current replacement burnt out quickly.

The OEM alternator is made by Denso so you may get the original OEM unit from Rock Auto.

Blueprint are also a manufacturer that I used with success previously, and it's about 50% the price of an OEM unit new. As the guys have said though, nothing competes with the OEM unit in terms of reliability and longevity.

​​​​​

_valtsu_

Forget what i said. It seems like there is no alternator grounding cable. Alternator is grounded thru engine ground.

_valtsu_

Hang on! Alternator positive and battery positive should allways read the same voltage, because they are connected together.
If there is a voltage difference between, then there has to be a bad contact between them.

Check the wire connections:

Jwong77

I think I said it poorly. What I meant was with the car off the voltage across the battery terminals was 13.07V. With the car running, the alternator showed 11.56V. I did a continuity check between the alternator and the battery positive terminal, and it looked okay.

Jwong77

I bought the rebuilt Denso from RockAuto as well as a used alternator from eBay. The donor car had 47k miles on it, so I think it should be okay between these two alternators. And given my experience, I'll keep one in the garage as a backup.

eBay Alternator I bought

windhund116

Good luck with the alternator. You really shouldn't need a spare alternator, unless there is something else going on. You are using a new OEM serpentine belt, right?

Jwong77

Yes, sort of, I replaced it last year. But it was direct from the Honda dealer.

After two failing Alternators within a span of a month, I'm just going to keep a spare around just in case.