220Vac to 12Vdc 2kW power converter high amperage

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thordruid

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Hello, we are a cycle / recycling company in London (electronic amateurs with some help from students). we are a facing a problem with a sound system, we have previously powered with 12V leisure batteries. now we have got us a generator 2.2kW max power out put and we need to convert the 220V power output to 12V. The challenge is, that we need high Amperage for the 1.8kW soundsystem ( 2 woofers 15" and 12", one horn, 2 amplifiers and we also would like some lights and a laser show in the future. Can somebody please assist us with a recommendation? If we can, we would like to work with recycled materials, to safe money. The generator also has a 12V output, which delivers only 15 amps. not much good to us. We would like to get the sound system up and running in 2 days time and the only alternative we can think about at the moment, is getting a 220V amp, which can power the speakers. However, in this case scenario all our previous amps we have purchased cannot be used anymore and we need to sell with a loss. Thank you in advance for your assistance and reading our cry for help. thanx thor and the druid cycles team in london.:thumbsup:
 

Re: 22V to 12V power converter high amperage

There should be plenty of 12V switchmode supplies on ebay, but 2kW is a lot of amps at 12V, keeping voltage drop under control at 200A peak draw is going to be problematic, there is a HP unit that manages 1.5KW, commonly available for £25 or so if you wanted to go that way..

If I was you I would use the fact that most PA only averages about 1/8th of full power (That is what amplifier designers generally use for themal calcs), so a 500W switcher and some modest batteries to carry the peaks might do it, at which point PC power supplies start to look feasable (Modern ATX supplies have really butch 12V outputs, and are dirt cheap, I would be somewhat surprised if a visit to London Hackspace would not turn up a few).

Regards, Dan.
 


If you can find any commercial 2kW Amplifier that uses conventional 4/8 Ohm speakers that runs off 12V, I'll buy it for you. Otherwise re-think your requirements to something like √(1kW*4Ω)=V² or Vrms=64V, thus Vdc = 100V. Now you owe me a pint.
 

we need high Amperage for the 1.8kW soundsystem
Click to expand...

This means 150 A draw a 12V supply. Did you measure the draw? Is it really that high? This could be important. It's one thing to say it puts out '1800 W music power'. It's another thing to hook up an ammeter to the power supply.

To step down 220 V to 12 V, can be done with transformers. I recommend you don't try to rely on just one power supply. If it goes out, you'll have no sound. Since you want to DIY, it's a good idea to have redundancy in your power supplies.

From your description it sounds as though your batteries are a single 12V supply. Do your amplifiers run on this?
 

@ above commenters, some 12V amps (a lot these days actually) pump up the 12V to +/- 50v so that they can do the power advertised.

@ThorDruid, to get 12VDC 200A reliably from 220Vac requires pretty decent switchmode converters, say 4 x 50A units with the o/p's paralleled, Ebay is your best bet for low $ here.
 

Hi Brad, we have used before 12V deep cycle leisure batteries. Once one of the batteries was down, we switched over to the 2nd battery. This gave us an approx. working time of 2 to 2.5h on a bike ride like the Critical Mass, when the system is almost all the time on full power. We have calculated that we need approximately 2000W from the 220V generated this equals 168Amp, when we use max power. I was looking at the option of using 2 1000W PC power supplies, but we would like to consider all possible ways taking into account also the costs. I have checked ebay and if we go for 2nd hand power supplies, we maybe get away with £100, brand new more in the region of £180. We basically need a lot of ideas. Do you think it is possible to charge a 12V battery constantly from the generator and also draw power from that same battery? or is his dangerous and not possible? please let us know, if you can. We are not specialist electronic technicians, we are more mechanics, but two of us build sound systems in the past. Thank you for your input to all who replied. thor and the druid dream team.
 

This shows the operating specs for a transformer supplying 1.8 kW at 12VDC.

It's a basic power supply. Cheap and easy to make if you only want 36 W output (like my homebrew supply).



The 1k resistors are unnecessary.

The .1 ohm is unnecessary. That is where you will put a fuse and switch.

L1 is a choke. It reduces voltage swings. It helps smooth the output waveform. It also reduces demand on other components. L1 broadens current pulses that would otherwise be spiky and intense.

If you don't install L1, then you will have trouble getting optimum performance from the power supply.

C1 also smoothes the output. However if you don't install L1, then (a) you'll need a much larger C1, and (b) it will have current pulses on the order of 100A going in and out of it.

You can be sure that two 1 kW supplies will be easier for you to make. One advantage will be the efficiency you gain by shorter cable runs to your two amplifiers.
 

@Thordruid, using OHms Law even if the loudspeakers were 1 Ohm you need V^2/R to get power, which is why you cannot generate this kW audio power you expect from 12V.

What Power Amplifier do you have that is unsuitable?
 

Car audio amps sunny, they generally have a switched mode input stage that takes the 10V or so they see under load up to +-50V or so for the audio power stages.
Silly as it sounds, a KW into a few ohms from a 12V supply rail is quite commonplace.

As to big power supplies, look at the server stuff, a lot of it is 48V, but there are some 12V units kicking around, some reading is required to figure out how to get them to power up, but I would be surprised to have to pay more then about £50 for hundred amps at 12V on ebay.

https://www.ebay.co.uk/itm/HP-ProLi...omputing_PowerSupplies_EH&hash=item462d7b16e1
Seems like a reasonable choice for all that you can find them cheaper on occasion, the hookup diagram is available with a little google fu.

Regards, Dan.
 
thordruid said:
Do you think it is possible to charge a 12V battery constantly from the generator and also draw power from that same battery? or is his dangerous and not possible?.
Click to expand...

Yes, electrically this is feasible. There may be hash coming from the generator, however. It could be audible.

It's also a question whether the 12VDC is in any way connected internally to the 220 VAC. If so then you have to be mindful what connections you make externally, which could create unwanted interacting loops of current.
 

Why convert 220Vac to 12Vdc only to convert it again to 100Vdc which was my original suggestion and is mandatory for these power levels. ( unless the user already has a 12V boombox Amp)

If this is the case then say so.

Cars operate with 3 phase regulated Alternator providing all the necessary power all the times except start the engine and buffer any current impulses such as A/C clutch. Ripple is only bad when 1 or more of 6 diodes is blown, the most common failure mode of alternators.

Car Alternators may be rated up to 120A at 14.2V for large cars and more in special cases which may not be enough and require an upgrade to power 2kW Amps with built-in DC-DC converters to 100Vdc.

( If the user really wants to use a mobile 12V 2kW amplifier, he needs a 2.8kW DC-DC converter for efficiency losses Which will be cheaper ? 14V @ 200A or 28A @ 100Vdc? or whatever voltage is used inside Power Amp.

( as previously mention redundant power sharing DC-DC converters would make more sense for reliability, but will need at least 10% preload for stability. )


The requirements , overall on this project, are poorly defined.
 

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