Okay so today, and yesterday, my battery light kept popping on and going off at misc. times while driving.

Today I got it narrowed down to when my headlights and heater were on full blast. It only would happen when Id be at a stop light or not reving the motor. Under 1k rpms.

Now this is a little disturbing cause both battery and alt are new. Now I got my multimeter out and tested the battery and the alt at idle.

Both read 14k volts.

Then I turned on all the electrical equipment and tested it again.

Both read around 12k volts.

I would rev up the engine and it would go up to 14k again.

I defenatly dont want to get effed one day at a red light. I went to Autozone to have them test it and well they cant test in the rain, pretty crappy.

It could be a bad connection, but that wouldnt explain the why its fine w/o the electrical on and bad when its got the electrical

 

Probably a bad alternator, autozone's rotating electrical parts suck. The brushes inside the alternator probably aren't making good contact, so at low rpm's the alt. isn't putting out enough power.

 

Well Im still going to head back tommorrow after work. What a piece of junk. The only other thing I can think of is that the belt may not be tight enough.

 

Had to change my Alternator twice, first the original, then the Autozone one went out a week later.

 

48 amps on the alt.

Battery is good.

Im replacing the battery termianls and checking.

 

Check the continuity from the alternator wire to the battery terminals, and check for resistance.<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Acidcrakker &raquo;</TD></TR><TR><TD CLASS="quote">

Both read 14k volts.

Then I turned on all the electrical equipment and tested it again.
Both read around 12k volts.
I would rev up the engine and it would go up to 14k again.
</TD></TR></TABLE>
I hope it's not at 12-14k volts. It should be 12-14 volts not thousand. Anyways, check for loose grounds too, the battery and alt. could have a hard time keeping up with more load if you have a loose ground. Check to make sure the alternator and battery cables/terminals are tight, and if everything checks out, likely a faulty alternator.

 

Yeah my battery is turbo charged thats why its reading 12k

Anywho, I replaced the ground terminal last night, Ill finish with the positive terminal later today and go back and get it rechecked again.

Also with a multi-meter how can I check amps off the altenator, or is that even posible?

 

Im not sure if your multi-meter can handle the amperage of the alternator especially if you have those typical one that can only handle 10amps (maximum).
I have fluke and i blew the 10amp fuse and those fuse aren't that cheap.

I dont know how much amp does alternator have on a prelude but I would guess it's more than 10A.

 

Yeah mine has a 10 amp, but I was hoping that there was another way to set it.

OEM ALTENATORS have 90 amps

Auto Zone have 80 aps.

 

Okay well I started to work on this issue again. The Battery light hasnt come on today, but the lights are dimming pretty noticable at 0.9k idle.

I went to autozone pretty fed up, thinking its the alt. I pulled the alt, and nothing. They tested it and its good. Okay so now Im like this sucks.

So I said ground wire. So I pulled the ground wire that runs from the battery to the tranny or motor(whatever it is, theres only two negs on the battery I pulled the bigger one.)

It was pretty coroded at the end of it where its on the motor. So I cleaned it with battery cleaner and a wire brush. Wrapped it in electrical tape, extra support.

Okay now heres where I make a discovery.

Thinking OMG I finally found it. Yes easy fix. I cut the wires and fix them. No they arent solidered right now, but the connection is good enough for the time being.

Okay everything put back together again. Good to go, Right?


Wrong!!!!!!

I put the car on and let it sit at idle. Everything looks good. Then I turn all the electrical equipment on lights, highbeams, heater, windshield wipers. And bam, the lights are dimming again under 1k idle.

Pissed off, now. Cause the car works fine it drives and blah blah blah. But its so insignificant, and its driving me damn near mad here.

Ive just about run out of Ideas. Ive alreay gone over all connections. Cleaned all grounds, and what not.

Im sure Ill see more battery light pop on in the future. And it seems to really do it alot in the rain, when its wet outside, even when all the electrical stuff isnt on.


So anyone who reads this, if you have had an eletrical issue where it was something like this, tell me what you did to fix it

Thanks

 

just wrapping the wires together likely isnt allowing enough power to pass through the connection aka resistance.

what wire set is that?

 

Its the wires that run off the Alt.

Looks like they were being rubbed by a moving belt which is why they got jacked.

Ive been to have the amps tested while the alt was in the car, it was at 60amps. The Alt is rated at 80amps, which is the 10 amps less than OEM.

 

Do you have underdrive pulleys? If so, it will slow down the alternator speed and can cause low charging voltage during idle and output to the rest of the electrical system.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JT &raquo;</TD></TR><TR><TD CLASS="quote">Do you have underdrive pulleys? If so, it will slow down the alternator speed and can cause low charging voltage during idle and output to the rest of the electrical system.</TD></TR></TABLE>

Yeah I do. UR Pulley.

I thought about that before, but strangly enough. I dont think thats it. It might be for all I know.

 

Before you rule it out, think about the effect of alternator speed and output. I have underdrive pulleys for my other car and below is the test result of voltage output in relationship to load and alt speed. I turned on one accessory at a time to increase the load and noted the result. As you can see, under certain driving condition which requires more than a few accessories being on at the same time, the alternator output may not be able to keep up. Then again, YMMV.

 

so is the main reason ppl dont do ur mods?

 

It sounds like you've basically got it figured out, but to sum up:

-the lower the RPM's, the less voltage the alternator will produce
-you're also using underdrive pullies that will further reduce the speed at which the alternator pulley is spinning, therefore supplying even less voltage at low RPM's
-you're using an alternator that is rated over 10% lower output than stock (and may not have as good of a power curve as a stock alt)

I think what you've run into is a combination of factors that have piled together to create your problem. If it's really only noticeable at idle, I would simply suggest you raise your idle ~200rpm. Naturally, make sure all your grounds are good as well, but I'm pointing my fingers at the other factors you've got going on.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dre2day &raquo;</TD></TR><TR><TD CLASS="quote">so is the main reason ppl dont do ur mods?</TD></TR></TABLE>
Huh, Please dont waste a post.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gstrudler &raquo;</TD></TR><TR><TD CLASS="quote">It sounds like you've basically got it figured out, but to sum up:

-the lower the RPM's, the less voltage the alternator will produce
-you're also using underdrive pullies that will further reduce the speed at which the alternator pulley is spinning, therefore supplying even less voltage at low RPM's
-you're using an alternator that is rated over 10% lower output than stock (and may not have as good of a power curve as a stock alt)

I think what you've run into is a combination of factors that have piled together to create your problem. If it's really only noticeable at idle, I would simply suggest you raise your idle ~200rpm. Naturally, make sure all your grounds are good as well, but I'm pointing my fingers at the other factors you've got going on.</TD></TR></TABLE>
Yeah thats what Ive pretty much figured out too. JTs chart was great. Really hit me in the head for a second. Ive checked all the volts before hand, and my read outs were the same as on this chart pretty much.

I think in the future, Ill pick up a bigger alt. And Mabey look for a smaller pulley on the alt.

 

It still seems odd. Even with under drive pulleys that alt should be fine. I wonder if the regulator is different than on the OEM Honda unit?

 

hey i can say from experience that with my subs blasting, high beams on, blower motor on and being equipped with an underdrive aem pulley my lights dim at idle and my voltage gauge drops under 12 volts. but my battery light has never came on, but i am using the 90amp OEM alternator not the 80 amp autozone one, thats probably why youre getting the battery light on

 

Well here is an update on this thread.

This morning I went out to start the car and no go. Battery read 10v but it wouldnt start.

Had to call a buddie for a jump and it jumped.

Drove right to autozone and turned car off and and tried to turn on again and didnt work. Which meant its a bad battery and I drove there on the alt. All the gauges died on me too. My heart jumped cause I thought I really effed the elctrical system up, cause I degreased the engine bay last night.

Anywho, Autozone testd the battery and it would hold 10v easy but under load it was dropping to 4v and what not.

Battery came back as a fail. New battery in there.

Im still thinking of replacing the altenator with a high permormance one, because I still think the autozone alt cant hack it.

 

Some years of honda alternators have higher ampherage outputs. Instead of autozone I highly suggest you look for a used alt even from ebay. Stock/Oem parts is the way to go with electrical.

The bad thing about low voltage systems is even with a mild drop of only 1-2 volts, its enough to cause a shiet load of problems. For example my work truck's battery was f'ed. It would hold 10-11 volts after a overnight trickle charge. 10-11 volts was not enough to start the truck. Once it was running it would be okay, but if you shut if off even for 10 minutes, it would not start without a boost.

So hows the new battery holding up?
Have you been able to test the ampherage out put of your alternator with new battery?

Worst case scenario if nothing changes you should put your stock pulley back on and see if it clears up. If it does atleast you know whats doing the dirty work!

 

The new battery is just find. Havent had a chance to actually test it yet.

Im assuming its not related to the pulley and more to do with the crappy altenator out put, which was last time checked was 58 amps.

Very crappy. Ive check connections time and again and have not come up with any breaks or reasons why the altenator is producing the other 22 amps its supposed to.

I think I seen a 140 amp alt on ebay Im gonna pick up when I get some more money up.

Im pretty sure the crappy alt out put is what destroied that battery. Well its under warranty at auto zone and worst case senario is I have to do an exhcange on Battery every 6 months. But by the tme this one gets destroied Ill have a bigger alt on there.