class d current draw

I have a 2003 Nissan Altima with a stock 110A alternator. Do you think running a class-D amp at 4 ohms will put a strain on the charging system? The amp i'm looking at is a Power Acoustik OV1-3000D--rated 900Wx1 RMS at 4 ohms (although this is probably an inflated figure--under completely ideal conditions) The amp has 3 30A fuses, but I assume that the full 90A is only really used if someone wanted to run their system at 1 ohm, b/c the amp is 1 ohm stable. I have 2-4 ohm DVCs, 400 watt RMS apiece, and I could run them at 1 ohm. But i'm pretty sure that would be extremely taxing on a stock charging system.

I've also considered just bridging a 2-channel amp, since I can probably get it cheaper than a class-d monoblock...but I would really like the benefit of the higher efficiency and less overheating. All the literature i've read about class-d amps is that they supposedly produce more power while drawing less current. Is this necessarily true with a stock charging system, or would it be as equally taxing as a class a/b 2-channel amp?

Any input is greatly appreciated.

ANY additional accessory will put some amount of strain on the alternator. Class A/B, Class D, it won't matter:

900w out /.8 (80% efficiency) =1125 watts IN
1125W / 14.4 = 78.25A

You are starting with 110A, about 80% of that is already alotted to the car and the OEM accessories, by Nissan.

110 * .8 = 88A

This will only leave you 22A to run an accessory that wants (at least) 78A.

You have to upgrade your alternator.

The same math above applies with a Class A/B amplifier, just the efficiency number I use is 50%, rather than 80%.

900watts out / .5 (50% efficiency) = 1800 watts in
1800 watts / 14.4v = 125A

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