I can't seem to find a list of OEM Honda alternator outputs. I know the OBD0 alternators are 60-65amps and I've heard some of the OBD1's are 70 amps, then OBD2 ones are 80-90amps. I have a OBD2 alternator lying around and seem like a good upgrade while I'm at it. I know the plugs are different, but I can swap them out easy. Know of the output differences?

How well do B-series OBD2 alternators bolt up vs D-series OBD2 alternators to a OBD0 D-series engine? As in, can I use different brackets and have it bolt up or do I gotta go custom?

Also, if you have a 60amp alternator vs 90amp alternator would they put out the same amperage at idle under light load? Or do they just have a higher max output? My OBD0 alternator now is 30amps under full load at idle and goes up to 50-60amps as I rev it up.

 

You can go to rockauto and look up the alternator of any car you want and it should show the alternator output rating.

 

 

When doing the output test make sure the engine is at full operating temp, and make sure the cooling fan isnt running when doing the test. Rev the engine to 2000 rpm and check the output. According to the chart on Mitchell, 30amps at idle, your well within spec.

 

I think he's talking about a list of different alternators output ratings.

 

Last sentence in the OP states the reason he is asking. He has reason to believe his alternator isnt producing the correct amount of amperage.

However according to everything I have read, he is well within specifications.

Just trying to save the guy some time in telling him maybe his alternator isnt as bad as he thinks.

 

Yeah, I believe I'm in spec, but the trouble is that at 30 amps voltage drops way too much. Will headlights, heater and cooling fan on voltage drops to 13 volts and keeps falling (will go down below 12 volts if I don't rev the engine). All the stock hondas I've worked on all drop to 13.5V or so under heavy load and stay steady (even with all accessories and cooling fan on). Everything in the system is working fine, but with larger cooling fans and aftermarket fog lights the draw seems to be more than the output of the alternator. That is why I'm considering a larger alternator. I noticed that if I rev it slightly past idle speed (even 1200-1500rpm) amperage goes up to 40-55amps and holds voltage steady at 13.5V, so I know it just needs a little more power.

I've seen a lot of graphs like the one posted, but they usually don't say what they are from. I have a OBD2 B16 alternator from a Del Sol lying around, the aftermarket ones I see say 80amps but aftermarket ones seem to be rated slightly higher than OEM ones. If the idle output isn't any higher than the one I have now, then it wouldn't help anyway.

I was thinking about getting a slightly smaller alternator pulley (this would run the alternator faster). I can get one slightly smaller, so the alternator speed is the same as 1200-1500rpm so output is higher. If it's slightly smaller then I don't think it would hurt it at higher rpms (over work it) as much as a really small pulley, because people rev the stock engines much higher than stock and alternators seems to handle it.

 

If the voltage drop off is the real concern here, use a voltage regulator. However, everything in the car should be fine down to just below 12 VDC...

The battery is there to make up for any shortcomings of the alternator while idling. You only need more power from the alternator if you're managing to drain the battery while driving the car normally.

 

The graph above is from a 90 Civic Si.

Rule of thumb, if amperage isnt within spec or falls below spec, replace the alternator.

If voltage is not within specification, replace defective voltage regualtor.

Would you like me to pull up a graph from said obd2 b16 Del Sol?

 

The car has a new alternator (it's an OEM Honda) and I've also tried other used/new autozone/napa alternators. I read the Honda alternator/charging system testing from front to back and everything is working as it should. Voltage regulator was tested and worked perfectly. All wiring is new, everything is new (still did it when everything was old). Everything should be fine, based off the Honda FSM and all my electrical training.

The thing is that the amperage draw is the same/higher than output, for example my two cooling fans are 10-15amps each = 20-30amps plus fog lights which are probably at least 6 amps (30-50 watts each/12 volts = 6-8 amps), so the aftermarket parts I have have more draw than the 30 amps it can put out. This is not even including the headlights/heater/radio amperage. Everything can run on 12 volts, but that is not normal and puts a strain on everything. I want constant voltage, I don't like seeing voltage drop below 12V whenever I come to a stoplight and seeing my headlights start to dim if everything is on. If everything was stock, then everything would be fine. If the headlights/radio are on, voltage stays steady at 13.5 volts and about 20amp output, but as soon as the cooling fans/fog lights go on voltage drops.

Oversteer_ms: I think the graph you posted is for an OBD1/OBD2 alternator, because the stock 88-91 Civic/CRX alternators are 60 amps (have a 60 amp fuse in fuse box, so according to that graph the fuse would blow all the time revving it over 4K).

 

The graph I posted was from 90 Civic Si. Thats what I had looked up on Mitchell On Demand 5, as well as Snap On Shop Key.

Theres always the option of buying an aftermarket high amperage alternator. But I dont know about brands and what not. I havent had any issues with OEM alternators. Even with stereo systems, fogs, ac, etc etc.

 

I've know some people with HO alternators and they don't seem to last very long, but is another option. Did you check voltage when you had a stereo/fogs? maybe it did the same thing but you didn't notice.

 

I didnt ever check voltage at the time. I didnt however notice any out of the ordinary draws unless the bass hit hard.

But I dont doubt that I was pushing it pretty hard.

 

I don't think I would really notice, but I have a voltage gauge on my dash so I can see it all the time.

I found a company that sells slightly smaller diameter alternator pulleys for $30, so I might just try that and see if that helps enough. If it doesn't then I will try the other one I have.