How big of an alternator do I need?

How do you figure out the proper amp alternator and circuit breaker I should run? I have a 90amp now.

My system consist of
-JL 1000/1 sub amp
-JL 500/1 sub amp
-JL 450/4 boat amp
-JL 300/4 tower amp

-2 blue top starting batterys
-4 6 volt trojan stereo batterys

Thanks for the help.

i think a balmar 160 amp will do the trick. try and ask g bling. he knows a lot about batteries and charging systems.

If you upgrade, let me know if you want to sell your stock alt.

Here is a excel spreadsheet I use to calculate battery and alternator needs. Download it and plug in your system values, it should give you some answers.

Upload Alternator calcs.xls (17.4 k)

Impossible to tell with the given information.

The maximum output of the amps is not a good metric to base alternator size on. It is quite likely that unless all the speakers are perfectlly matched to the amp (both impedance and power handling) you won't get full power from the amps. The amps would only attempt to provide their maximum output when you have the volume turned all the way up and the musis was playing a steady tone.

The best thing to do would be to take some measurements at various "typical" operating conditions. Use a clamp on amp meter and measure alternator out and net charge/discharge into the battery and current draw for the amps for several conditions. Obvious conditions would be stereo playing at typical cruise volume. Another test with all the major electrical on: blower, heater, ballast pumps, etc.

If you already have a 90 amp alternator then you may be okay. To go higher than 100 amps puts quite a strain on a single belt, so to maintain reliability you would need to add a second belt which can be quite a project.

Rod

Thanks for the info guys. I will see how things go with my 90 amp for now.