jtyson8602

Okay so this is probably an odd question, but has anyone ever thought about running a second supplemental alternator? And Im talking still with a single battery? I cant see a reason why it wouldn't work Im just stressed about overcharging the battery and having it explode. But how do you know how many amps are too many for the battery? Give me some thoughts or if anyone has tried it let me know how it went

Al Hasse

Have you thought about a higher output alternator. Most good auto sound shops should be able to get a line on one or two. I had an alternator/generator/starter shop rewind my stock alternator to put out 140 amps over the original 105.

Before going to that trouble, you should also think about doing what's called the Big 3 by upgrading the wire size from the battery to alternator, battery ground to chassis ground, engine ground to chassis ground.

To figure out if your alternator (not battery) can handle the load, find the RMS power out on your amplifier (in watts), divide that by 14 volts (auto electrical system is typically 13.6 - 14.4 volts), if that's significantly less than your alternator's output, you should be OK.

My system has a Memphis Belle 5-channel amp rated at 1400 watts RMS, I have the front & rear channels at 2 ohm instead of the rated 4 ohm, so that 300 watts is effectively 600 making 1700 watts RMS. 1700/14 = 122 amps.

jtyson8602

I understand what youre saying. Im actually having the issue with a different car of mine. I dont have any stereo equipment at all. My amperage draw is my electric fan and my MSD, and my lights. Other than that I have no electrical equipment. Im actually just trying to add the alternator in place of an AC bypass. I need a functional pulley for tension purposes. I dont necessarily need the extra amps though when Im at the track it would be nice to be able to run my fan while Im running and not just in the return lane. So would there be a way to find RMS watt output for an electrical fan, and a hot fire ignition? Those things aren't typically measured in watts but rather amps. Maybe some sort of reverse equasion similar to yours?

Al Hasse

I suppose I misread the question at the end I read how many amps as in amplifiers and not amperes. I believe you are correct that the electric fan output (draw) is measured in amps, best place to check would probably be the fan's fuse. To answer the question on the reverse equation - amperage X voltage = watts.

jtyson8602

My bad for not specifying amperes instead of amps. I used to be a stereo junky and I would have read the same.

Now I dont have a fuse for the fan but rather a relay so would that be the same?

NINÅ

You want to run another alt just for a fan ?

Not necessary.

Anyway, just for info, it doesn’t matter how many alts you have across your bat.

As long as none of the alts exceed 15 volts.

It has nothing do to with how many amperes the alts are capable of.

Also, unless you are off road racing, you should not be running excessive lights.

Use a ‘dummy pulley’ since you deleted the air-con.

The MSD should draw no more than 1 ampere / 1,000 RPM.