User 051420

Now that I have the 150amp alt, I seem to be losing (electrical) power at idle. I'll give it gas and the power antenna works faster, the windows work faster, and the lights are significanly brighter. Does anybody know of an overdrive pully for my alternator?

Bigkahuna808

this is with the HO alernator??? I havent heard of problomes from the alternators. Contact Mr. Alternator and find out why? Because that is in my purchase list, and I want to find out how well it works

User 051420

Yeup..this is with my 150 amp.. When I was shopping a long time ago, I remember ExcessiveAmperage including an overdrive pulley to do with their 200amp alt. I'll ask Mr. Alternator......

midiwall

I have the same issue with my Mr. A alternator. I _think_ this is normal in that I've noticed it happen in all cars/trucks that I've ever been in.

("most"?) Alternators have two stages of output - one for idle or low RPM, and a higher one for higher RPMs. The upper range on mine kicks in about 1000-1100 RPM.

My OEM alternator did this as well...

turboale

Ive got the same problem. For a little while it wasn't charging the battery enough with my city driving and had to get two free red-tops (thanks advanced autoparts!) Have you asked them about it? Should we send a joint email or email them seperately? Its annoying to me... it did NOT do this with my stock unit. It only started when I got the bigger alt. I think they need to put smaller pulleys on...

User 051420

From what I gather, this isn't normal. My output drop *seems* to be significant. Also, I remember an auto electric shop telling me that it's very difficult to make our alternators product 150amps+, and a smaller pulley IS important.

If somebody wants to setup a "group email", I'm down with that. If not, I'll just send out my own..although, communicating with Mr. Alternator is VERY difficult.

midiwall

'k... well, if you/we find out from Mr. A that we shouldn't be seeing this, then I'm in on what it takes to get the output consistent.

As for getting ahold of Tom, yeah, I think we talked about this while you were waiting for yours. He can be slow on emails.

For the record:

User 051420

I shot him an email explaining the problem, and explained that I know of at least two others with the same concern. Hopefully, he'll get back shortly. Whatever his decision is, I think I'll pursue obtaining the smaller pulley. I'll keep you two posted.

midiwall

Thanks Neil!

4Crawler

iTrader: (3)

It is common for higher output alternators to not put out as much current at low RPMs as a lower output alternator, especially if the high output unit is simply a rewound low output unit. Reason being that when they rewind an alternator for more output, you are replacing more turns of a smaller wire with fewer turns of a larger wire in the stator. This does two things for the alternator output. The internal impedance of the alternator is reduced, thus for a given internal voltage, the output current is higher (and alternator can be modeled as an internal variable voltage source with a series resistance). However, since there are fewer windings in the stator, the internal voltage, as a function of RPM, is lower. This is because the rotor spins at the same speed, and thus has the same frequency of magnetic flux changes cutting through the stator windings. The internal voltage induced in the stator is proportional to the frequency of flux changes and the number of windings cut. More windings=more voltage, fewer windings=lower voltage. Putting a smaller alt. pulley on ups the speed of rotation and frequency of the flux changes, so can help boost idle output.

http://www.fastcougar.com/forums/mes...threadid=73334

I find my 160A Premier Power Welder (large case) alternator can't quite keep up for night wheeling where there is a lot of stopping/idling, when I have all my lights on (headlights, foglights, rocklights). The control box for the welder has a switch to provide extra charging current (~25% more), I'll have to try that boost switch next time I find the idle output is low, and see how that helps.

User 051420

Roger saves the day...Thanks!

Yoda

Yeah, what 4crawler said. In addition, a smaller pulley will make the alt spin faster. But it also makes the "contact area" with the belt smaller. This can make the belt slip more (esp at higher output requirements) More power out = more HP needed to turn the alt. You don't want your belt slipping.

Bigkahuna808

so HO alternators from Mr. Aletenator yeah or nah. I kinda need the high output at lower rpms. I run high output sounds, and need more of the power at idel than at high rpms

User 051420

I know that Excessive Amperage uses the smaller pulley, and has a lower cut in speed. BUT, don't turn away from Mr. Alternator if he can offer a solution.

dbikeman

I have the excessive amperage unit and it still only cuts on at around 1000-1200rpm. i wouldnt advise getting a smaller pulley because these units produce more heat than a factory one anyways and I think making it turn even faster wouldnt be good. To remedy my problem I just adjusted my idle to 1000rpm's

4Crawler

iTrader: (3)

Or leave your idel speed normal and rig up a hand throttle or switchable fast idle setup. I have both on my '85. For the fast idle, I used a VSV to operate the idle-up valve on my 22RE. I can dial in a fast idle speed on up by adjusting the fast idle knob on the valve.

Bigkahuna808

hey David, where did you get your alternator from? Price? and how well did it fit in? Im pushing somewhere in the neck of 2000 plus watts to my stereo system. So i need a HO alternator for SPL competiton. But in SPL the class I want to go into, you cant really rev your motor to bring up the charge. So I need the higher output at the low rpm. Any brands you can recmomend? Thanks guys

User 051420

http://excessiveamperage.com $315 shipped for a 200amp alt. $325 with 0 Gauge wire.

superjoe83

another thing that you may want to consider is Alt. RPM, generally the Alt. pulley is about half the size or less of the crank pulley, that would mean at 5,000 RPM engine speed, the Alt is spinning 10,000 RPM, I'm not sure what they build the Alt. to withstand but putting a smaller pulley on might over speed it. Just a thought.......

User 051420

Mine cuts in around 1800-2000 rpm. The only problem I could see with it spinning faster would be the chance for accellerated wear from the higher speed. We have voltage regulators to cover any power issues. My idle will be staying as it is.

Math guys: How much smaller of a pulley would it take to make up for the dip at idle?