blizz20oma

iTrader: (1)

Any car audio gurus know a rule of thumb for the maximum your system should draw for a given alternator output?

Trying to make sure I'm within safe ranges. My amp draws a max of 40A I believe, and the stock alt in our SEs is 110A...with the alpine hu powering my eclipse coaxs, and other accessories, am I still in a safe range?

Hehe...you should have seen me try to run this amp/sub in my old integra. I never figured out for sure, but the stock alts put out either 60A or 80A. It seemed like the amp could never draw enough current to hold good control of the sub - on loud low frequency hits it'd bounce all over the place. Hopefully the problem won't crop up in the max - I'm not sure that was the issue, as I may need a bigger enclosure, etc.

jmax

The stock alt in the max is good for at least 150 - 200 amps of max current draw. At least in a daily driver. As the only times you will see anywhere close to max current draw is during musical peaks. And those peaks are enough to cause significant headache and long term eharing loss. Not to mention that a good capacitor will keep the voltage at 14.4 through the peaks. In the past two years I have thrown the conventional wisdom out the window as the conventional wisdom indicates that we should all have a generator in the trunk to power the stereo. But, the real thruth is that capacitors, a good quality fairly small battery, and high quality wiring can get your daily driver to pound.

Sorry, high quality amps are also generally better regulated/powered than the cheaper varieties.

dwapenyi

iTrader: (3)

I just noticed in my FSM about the ALT. the 110 amp one Maxima SEs have is rated at 110 amps, at 1300 rpms it puts out >36 amps, at 2500 rpm its pushing >85 amps. Only at 5000 rpms is it putting out >110 amps.

Food for thought.

DW

jmax

For my '99 SE the numbers are > 36 @ 1300 RPM's
> 85 @ 2500 RPM's
> 110 @ 9000 RPM's

But, those are alternator RPM's - not engine RPM's. Measure the size of the alternator pulley and underdrive pulley for the ratio of engine rpm's to alternator rpm's. Those 110 amps at the alt are good for twice that number of amperage draw at the amps max current rating. Because, as I said above. Max current draw in a daily driver is only attained for fractions of a second in music. And the time between those fractions of a second is enough for the 110 amp alt to recharge a capacitor.

blizz20oma

iTrader: (1)

Thanks for the info. Helps me understand a little more how the alternator operates. I haven't read up in my haynes about the alt yet.

I haven't entertained the thought of a cap yet, more or less for monitary reasons, and I'm still not sure what I'm going to decide as far as amp mounting, so I don't know if I'll have a little makeshift rack to mount a cap onto, etc. I'd like to do some more research on capacitors in general before I add one to my system, mainly to read into the differences between brand-name car audio caps, and rat shack caps.

jmax

If you want to read up on caps get a general physics book or a basic electronics book. A cap is only needed when the amplifier has a poorly regulated power supply, or the curent demands greatly exceed what the alt is capable. I have heard of maxima's with 500 watts or more that had no electrical problems without a cap.

nismo240sx

esr is the biggest thing to look out for. the lower the better.

eric