# 12v to 440v step up

Discussion in 'General Electronics Discussion' started by supak111, Nov 9, 2012.

1. ### supak111★ƃuᴉɯǝɥɔs sʎɐʍlɐ★

334
4
Apr 29, 2012
Hey guys I need to step up 12v DC to 440v DC what would be the cheapest best way to do this?

I need the 440v DC to be at a decent amps. I'm using a 12v DC car battery and its rated at 950 cold cracking amps.

Cheapest way I can think of doing this is to buy a cheap 12DC to 220v AC inverter and then rectify the 220v AC to 220 DC, but this still only gives me 220v DC not 440v that I'm hoping for.

Any ides are appreciated. Thanks again.

2. ### Harald KappModeratorModerator

12,465
2,987
Nov 17, 2011
Use the inverter plus an additional 1:2 voltage transformer: 220 V * 2 = 440 V

Harald

3. ### duke37

5,364
772
Jan 9, 2011
Or an inverter followed by a voltage doubler consisting of a capacitor connected to the junction of two rectifiers and then a reservoir capacitor.

Or build your own inverter using an old TV line output transformer core.

4. ### Miguel Lopez

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Jan 25, 2012
Rectifying 220V AC will give you around 300V DC. Anyway, less than you need.

Rectifying 440V AC will give you around 620V DC, I think this will not help neither.

What do you mean with "decent amps"? A number would help.

Best regards

5. ### duke37

5,364
772
Jan 9, 2011
The voltage that you get from rectifying a sine wave into a capacitor is Vrms* 1.414 which is what Miguel has calculated.

Some inverters (the simpler ones) give out a square wave where the Vrms, Vmean and Vpeak are all the same so you will get no higher voltage on rectification.

Will this be continuous? Your battery will not last long if you are taking say 200A to give 5A out.

Last edited: Nov 9, 2012
6. ### BobK

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Jan 5, 2010
If by decent amps you mean at least 1 Amp, you will need to draw about 40 Amps from your battery. The Cold Cranking Amps is what the battery can supply for 30 seconds, so I don't think that figure is of any use to you.

How much current do you need and for how long?

Bob

7. ### supak111★ƃuᴉɯǝɥɔs sʎɐʍlɐ★

334
4
Apr 29, 2012
The more amps the better (10 would be great) but I'd say 3amp at 440v at least.

Building a coil-gun/linear motor so the 450v 16,666uf cap will be discharging in FAST pulses. I need a power supply that can recharge my cap ASAP since I want the cap to pulse/discharge as many times as I can get it to do so in 1 second. The more powerful my power supply the more pulses per second I will get out of the cap. 1500-2000w power supply would do but of course a 5000w would just be more beneficial not necessary tho.

MY SETUP:

high amp 12v car sound battery ---->
high power 220v inverter probably not signwave since I don't have crazy amount of money for the project ---->
220v to 440v??? maybe volt doubler like suggested above. Price, easy of installation, size??? ---->
once I get the 440v at 3amp+ I just rectify it and connect it to my cap.

And I know drawing lots of amps from a 12v battery will make it drain super fast, its OK I just need the battery to last 5-10 minutes at the high pulse discharges I'm talking about. I will invest in a "12cell evo2 lithium battery" 20ah 13.6v 410cca.

Like I said my main problem is getting upto 400-460v DC with at least 3+amps. Keep in mind it needs to be as cheap as possible and not too big nor heavy. My 12v lithium battery is light, inverter already a bit heavy, and then I still need to double my voltage coming out of the inverter

8. ### CocaCola

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Apr 7, 2012
What kind of capacity does said battery have? As has been said above you are going to have to draw a HUGE amount of current from it to get what you want out... I suspect your battery will puke in this application long before you get anywhere...

Even with that you are in puke territory... To get to [email protected] you are going to have to drain a 12V battery at about 100+ Amps continuous, a battery like the above might last a minute or two at that drain level, just taking an educated guess...

Last edited: Nov 9, 2012
9. ### supak111★ƃuᴉɯǝɥɔs sʎɐʍlɐ★

334
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Apr 29, 2012

12cell evo2 lithium battery" 20ah 13.6v 410cca.

3,635
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Apr 7, 2012

11. ### supak111★ƃuᴉɯǝɥɔs sʎɐʍlɐ★

334
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Apr 29, 2012
Well the battery is rated at 410 cca so it can deliver 410 amps for full 30 seconds. Even 30 seconds is enough for my project. Also I'll be pulsing the amps into the Cap so battery will last even longer.

I've determined I have enough battery power for now. I can always add a few more batteries later. I just need 440v DC at 3+amps.

12. ### CocaCola

3,635
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Apr 7, 2012
Well you might want to actually lay out all the details of what you need vs changing them with every post, because my reply was to your post above mine where you said...

13. ### supak111★ƃuᴉɯǝɥɔs sʎɐʍlɐ★

334
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Apr 29, 2012
Yea I was kinda guesstimating when I said 5-10mins, didn't really think at the time that the battery will actually go much quicker.

14. ### CocaCola

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Apr 7, 2012
To charge the cap up to [email protected] will take the same amount of power (1320 Watts) from the battery whether you pulse it or not... Yes, the slower you pulse it the slower it will drain the battery but the slower it will charge the capacitor as well... You are not creating any additional energy by pulsing you are just stretching out the delivery and charge time... Yes, at the end of the day you might get a little more out of the battery at a pulsed discharge (because it won't puke as fast) but we are splitting hairs in this case...