Best power supply for car audio, no car?

Thread Starter


Joined Dec 23, 2012
I was given a car audio system consisting of 2x12'' subs, 2x400W max amps and 2 6x9'' speakers. It is too loud for my ute so I've set it up as an e-kit amp (drums) in my garage.
It's currently operating on a 12v, 20A switchmode, but the switchmode is crerating crackle in the speakers.

I'm about to buy a new battery for the ute so I was thinking- should I hook up the system to my old car battery, and leave it trickle charging?
My concern is: will the trickle charger be damaged by overcurrent when starting the amp every day? It has a 1 farad cap connected across the supply also. And the amps have 40A fuses. I'd like to leave it on charge while playing as I dont think the battery will last more than an hour or so (it's 5 yrs old).

Is this a good idea? I figured I'd need a transformer nearly as bulky as the battery anyway, plus the old battery is free.


Joined Sep 9, 2010
Do the math. 23 hours of trickle, let's say 1A to be generous (100mA is more likely), would give no more than 1 hour at 23A, and probably only half that. In other words, I don't think your trickle will keep up on average.

Depending on your trickle charger, it may have over-current protection. It's common for people to hook them up to a weak battery, and it seems like they wouldn't last long if they couldn't protect themselves from that.


Joined Nov 23, 2012
Are you sure it is the SMPS that is causing the crackle? Have you heard it operate in a car without the crackle?

Most people don't just give away their 800 watt stereos to a friend for no reason.

Also, you have 2 x 400 Watts! That is 800 watts and at 12 volts, you will need nearly 70 amps (or 2 x 35 amp supplies).

Also, older SMPS run at a much lower frequency than current supplies run. You shouldn't hear anything with a new one of good quality (like a new ATX supply).

Thread Starter


Joined Dec 23, 2012
How about an old atx psu, 12v @ 20amp easy.
thanks dave you've given me good advice in the past ill look into that.

Gopher, I went to trade school with this guy, we got into a fight together at a pub recently, it was his fault and he was going to get beaten up, he's off the rails atm, next weekend, wrote off his car and lost his license, gave me stereo. Exceptional circumstances.
It's 2x400w max, not rms. Was running fine on a 20A smps.

Thanks externet.