I have a 3500w system I need to know if I need a high output alternator or can I just replace my stock battery with a 4800 w energie battery

  • Welcome to Motor Vehicle Maintenance & Repair! If you'd please edit your question and add information about what vehicle (year/make/model/engine), we might begin to tell you what you might need. Information about the system components you are trying to install would also be helpful. Commented Sep 22, 2022 at 11:10
  • 3.5kW is a sound system for a rock concert. A vehicle system is more likely to be 3W. Are you sure of your figures?
    – Chenmunka
    Commented Sep 22, 2022 at 13:17

1 Answer 1


There is no shortage of "3500W" automotive audio power amps on the market and most of them will produce something like that momentarily into the right load (usually 1 Ohm) and with a proper power supply. These cannot product anything like 3500 Watts RMS as a professional sound reinforcement amplifier might do.

So do you really need to provide an additional 3500W from your vehicle's alternator to support this? Probably not!

What many installers do is to run heavy gauge wire from the vehicle's battery to the amp and then back that up with an array of capacitors to handle the heavy transient loads.

The question you need to ask yourself is "how much power do I need ON AVERAGE to power this amp. My guess is that it's no more than 100-200W. Then you need to determine if your current alternator has reserve capacity of that much. If so, you're good to go. If not, then you may want to explore a high-output alternator option for your vehicle.

Just replacing the battery with a larger one is not going to solve the problem because batteries just store energy, then don't generate it. So if you are consistently drawing more from the battery than your alternator is producing, the battery is going to go flat on you and then neither the car nor the amp will be working.

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