I have a 2011 4.0 Ranger XLT and have a 750w subwoofer system. Currently, the headlights dim when when the bass hits.

I did a little research and could not find any alternator upgrades (apparently it is a Mitsubishi alternator). I was wondering if there is any possibility of getting a 200 amp alternator that fits in the truck.

I found this thread however no one seemed to reach a conclusion and it has been a few months.

Forgot to mention, I have the stock battery and 4 gauge wire running to the amp. I plan to install 2 gauge for the alternator and battery.

Thank you

 

You need a large capacitor for the subwoofer, higher output alternator won't help for that symptom.

A capacitor is like a quick discharge battery, it stores "volts/amps".

Here is what is happening in your vehicle.

After starting the engine the alternator will re-charge the battery with 14.8volts, after a few minutes voltage will drop to maintenance voltage and the system should be 13.6volts, running system above 14volts will damage battery over time.

This change in voltage is done by the voltage regulator in the alternator, when you turn on the lights the voltage will drop to 13.3volts then quickly come back up to 13.6volts, that is the voltage regulator reacting to more power being needed so it sends more amps/volts.

If you turn the Fan to high, same thing will happen, voltage drops, regulator gives more volts to system.

With a subwoofer the power draw on a heavy bass note is not constant, voltage regulator can not react fast enough, it does react, just not fast enough.

So even a bigger alternator would suffer the same fate, the quick voltage drop and lights dimming.
A capacitor at the subwoofer stores voltage/amps when there is plenty in the system, and when there is a sudden drop it releases some of it's energy so voltage drop is never seen on the vehicles electric system.


If your lights were dim all the time and car wouldn't start any more because of the sound system power draw, then yes a bigger alternator would help.

A 1 farad would be all you need for 750watt, $20-$30, 2 farad is $30-$40

They are very easy to hook up,
Battery-----------(+)capacitor(-)------------sub amp

The closer to the amp the better, but it isn't that important

 

I might give that a try. It would be a lot cheaper than an alternator.

I bought a new battery (Optima YellowTop) (I needed one anyway) and it didn't help (didn't figure it would).

I'll also upgrade the wiring when I get the cap.

 

Yes, it is not a Voltage issue, new battery or new alternator wouldn't help, it is a short term voltage drop issue, which can only be handled by a quick amp release, capacitor does that.