hey there I just got a 220amp HO Alternator for my stereo system in my 2006 F150. everything works fine and my alternator is charging my system well but When there is something like a low bass note that takes the charge to about 12volts and then lets up the Voltage will spike to about 15.8volts. So like say i have a bass note on (40hz) and its pulling the voltage down to 12 volts. When I pause it. The VOltage will spike up to 15.8volts. So it seems to be sending that surge to charging the battery but when i press pause that surge goes to my amps and they go to protect mode.The Battery and Alt are good I had them tested at Advanced auto and auto zone. I was told the Battery Maybe be to small with 700CCA and 850CA Evermaxx.

 

...have the alternator checked by the place that made it. Put your original back in while the new one is out for testing

 

You could always put in an aftermarket voltage regulator, but that's more of a band-aid fix.

 

I'd have to agree with the auto parts stores. That is a rather tiny battery compared to what's on the market and way too small for a system that required a upgraded alternator. I'd get a good Interstate or Diehard Platinum. Stay away from Optima they are now making junk batteries.

 

Are you using a capacitor(s) for the subs? They'll provide steady power for the amp and help to keep the charging system from getting drawn down like you mentioned. They will also help to absorb voltage spikes.

Just a thought.

 

Does the same happen with the engine off? How much power are you drawing?

An overshoot like that can be caused by one or a few of things:
- inductance in the line kicking back as a result of the 'surge'. Weak wiring can be a cause
- slow regulator. Not much you can do about this...
- high impedance battery -- get a Kirkland from Costco or equivalent with 1000CCA's. I just replaced my stock battery with this for $70.

Most importantly, I assume you have a good size wire and ground
connection between your battery and amp? Those multifarad stiffening caps are bandaids...they don't really address the real problem.

 

No this only happens when the RPM is above 1200 and which is when the alternator is pushing 220amps+. my current draw is only around 200amps at most. the most my system can ever draw is 350 amps. and yes i have 0 gauge wire on my grounds and Big 3

 

did you ever figure out what the problem was? I’m having the same issue with my camaro, gm 4 pin 250amp alt all grounds and power leads 1/0 ofc (big 3) Charges 14.5 at idle 15-16v spike at higher rpm when heavy bass drop hits amp goes into protection momentarily

 

There is some lack of electronics knowledge in this thread, leading to why the issue occurrs.
It has to be understood that those bass note draw a huge amplifier current from the system.
It has to come from somewhere.
If there is no 'system reserve', the voltage goes low, the regulator senses it and runs the Alternator field winding for max output until the system load goes down and battery voltage recovers.
Bottom line is there is not enough reserve current capacity at the moment it is needed. >>the regulator cannot know ahead of time when the bass notes will begin<<
The Alternator can be a thousand amp rating, if there is no reserve, the system capacity has been exceeded.
A large value capacitor bank and larger battery capacity should alieviate the issue along with the higher capacity Alternator.
It's not all the fault of the Alternator.
Also the regulator 'may not' respond fast enough as it was not made to follow fast changing high loads such as Audio; only head light, fan motor, A/C clutch etc. that are slow DC load changes, not hit and run changes.
The load does not run off the Alternator but off the battery. To boot, the rest of the vehichle is also taking power from the same source. At night and with A/C the load plus electric cooling fans, it's even higher.
Putting these kinds of loads on a system requires a redesign of the total system engineering to be fully sucessful.
Good luck..

 

did you end up figuring this out... I literally have the same issue