Running an aftermarket stereo system in a BJ60. Is the alternator strong enough?

[KingSpence]

I'm currently running an aftermarket JVC deck and four door speakers. I've been wanting to run a subwoofer for some time now, just to give the music a much nicer note. My only concern is the capability of the alternator to keep a charge while the amplifier and subs are drawing. The alternator on the BJ60 is only a 55amp, which is fairly low. I understand the low rating seeing that the truck never needs much of a charge anyways being a mechanical diesel with next to no accessories other than lights, radio, and blower fan.

Will my alternator keep a charge running two 10 inch subwoofers, about 600w in total?


Thanks

 

[TobyB]

Yup.

If you measure the current draw of a '600w' amp, it's probably less than 5 amps average.

The rear window defroster draws a lot more than that.

t

 

[KingSpence]

Yup.

If you measure the current draw of a '600w' amp, it's probably less than 5 amps average.

The rear window defroster draws a lot more than that.

t

I'm not going to say I don't believe you, but if an amp draws less than 5 amps on average, why would it want a 4ga wire running directly to the battery with a 40amp fuse?

 

[Kynot62]

Simple formula Watts = Amps x Volts Or Watts/Volts = Amps That amp at full power should be capable of putting out 50 amps but it's not going to put that out that all the time. Whats the install manual for the amp suggest? More important is what is the draw of the amp not the output. Your electrical system is more concerned with the draw than the output.

Tony

 

[KingSpence]

I haven't actually bought anything yet, I just know I'll want to run close to the same system as I did before. Two JL 10w1's and a Clarion XR2110 420w amp (the XR2110 used to be the APX1301). I can't find much info on Clarion's website as for amplifier draws, just outputs. I don't know much about car audio, I usually leave it up to the individual I buy it from, who gets paid to know car audio.

Here is a link to the amplifier. Really, any 420w monoblock should run close to the same amount of current from the battery I assume.

Clarion Canada | XR2110

 

[Kynot62]

By the math that amp could draw 35 amps. But that doesn't mean it will do that all the time. That would explain a 40amp fuse. It also doesn't mean it won't work, my winch can draw up to 360 amps and the rig doesn't die. The power comes from the batteries, alternator just keeps the batteries charged.

Time to talk to the stereo store, all I run in my rig is an aftermarket stereo, no amp

Tony

 

[torfab]

It should be fine, however this may cause your alternator to prematurely fail. It will be working pretty hard to kep up with the amp. This is actually a pretty low power system design, so I wouldn't worry too much.

 

[klinetime574]

I have no idea what my 2F alternator puts out.

I have been running a head unit, four speakers, an amp, and two twelve inch subwoofers for a while now. No issues.

Even with the radio off my voltmeter goes up and down with the blinkers

Gotta love old electronics

 

[TobyB]

' why would it want a 4ga wire running directly to the battery with a 40amp fuse?'

Easy- PEAK current draw. That 600w amp (if really CAN draw 600w) will draw 600w/14v = 43 amps
when you have it at full toot- but only on each kick drum hit. So if the wire's too small, it acts as a
current limiter, giving you floppy kick sounds. The battery can support that level of draw,
so if you use a nice big wire, you effectively gain headroom at high levels.
(and won't need those goofy 'super caps')

But the kick's only 10% of the signal (or so), so most of the time, you're not drawing 43 amps.
Even death metal's 85% silence, 15% noise... (ish) In the old
days, if you were trying to get loud, you got really hot, but now with
class D switchers sounding OK, heat's not such
a big deal. And the amps are a lot more efficient, and draw very little idle current.

But I work in an industry where a 600w amp DOES put out 600w (into 4 ohms at 100hz with .05% TH distortion) and having taken apart (and tested) a few car amps, if they say 600w they aren't going to be able to do 600w. At least, not listenably.
Even if they did, if you use reasonably efficient speakers, you'll never need that much.
Even in a LoudCruiser.

Upshot- really- your alternator will be fine.

Buncha big lights- now THAT might be a problem...

t

 

[KingSpence]

Buncha big lights- now THAT might be a problem...

t

So then running all my spot lights will draw more than a stereo system will. Oh yea, I also have a Warn 8274, and an on board compressor. I guess I should be fine with subs, I just won't be cranking my music as loud as possible, with all my spot lights on, trying to winch out an f350, while airing up my tires.

 

[TobyB]

I guess I should be fine with subs, I just won't be cranking my music as loud as possible, with all my spot lights on, trying to winch out an f350, while airing up my tires.

see, now that's just common sense...

t

 

[T-bones 60]

Your alternator should be fine. I would recomend a capacitor though. Your voltage regulator won't like the sudden peak draws of an amplifier, and a capacitor helps even that out, thus extending your alternators life. It will also lessen the 'dancing headlights' at night.