# is there a way to boost amps on a 12VDC

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#### Ralphr15

Joined Mar 4, 2016
1
I need a little help on a project im doing i have 2 AA batteries going into a .9-5 to 5VDC 500mA stepup into a 3-12 to 12VDC 1A stepup output how can i stepup Amps from 1A to 18A with out losing 12VDC

#### blocco a spirale

Joined Jun 18, 2008
1,546
Think about this: your power source is 2x AA cells, 12V x 18A = 216W.

Can 2x AA cells deliver 216W or 72A?

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#### bertus

Joined Apr 5, 2008
22,277
Hello,

A boost converter will NEVER give out more power than you put into it.

Bertus

#### AnalogKid

Joined Aug 1, 2013
11,045
To boost 3 V to 12 V is a 4:1 change. Because power does not happen by magic, this means that for every output amp at 12 V you need 4 input amps at 3 V; you need 72 amps of current at 3 V to make 18 amps of current at 12 V. Wait - power conversion circuits are not 100% efficient, so you actually will need over 90 A at 3 V.

As an off the shelf device or module or component, there is nothing you can buy that will do this. To design this from scratch and produce one unit is 1-2 months of total effort for an experienced designer.

You don't say how long your project needs to run on one battery charge. To put this in perspective, running 12 V / 18 A for a couple of hours takes a car battery. Attached is a datasheet for a sealed lead-acid battery that can hold its output above 12 V for two hours when delivering 15 A (not 18 A). It weighs over 50 pounds.

ak

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#### mcgyvr

Joined Oct 15, 2009
5,394
Wouldn't the electronics world be so much easier if it worked like those that skip over the absolute basics think it should work..

#### AnalogKid

Joined Aug 1, 2013
11,045
No.

#### Kermit2

Joined Feb 5, 2010
4,162
I got 11 gigawatts out of a lemon and a copper and zinc strip.
...or was that microwatts?
Oh well. Nothing but details. The important part is how I defied the laws of physics.

Always was a law breaker.

#### Alec_t

Joined Sep 17, 2013
14,314
You have to admire some people's optimism, though, with projects like this .

#### wayneh

Joined Sep 9, 2010
17,498
Studies have proven that pessimists are more often right, and I tend to admire being right more than optimism. Some optimism is useful at times, but it's usually a symptom of ignorance. Again, that's not always bad.

#### alfacliff

Joined Dec 13, 2013
2,458
its not pessamism, its physics and chemistry.

#### wayneh

Joined Sep 9, 2010
17,498
Limiting yourself to the facts is pretty much the definition of pessimism.

#### tcmtech

Joined Nov 4, 2013
2,867
Just put the voltage booster circuit in parallel with a current booster circuit. At no load you will have 12 volts and at a dead short you will have your 18 amps.

#### BobTPH

Joined Jun 5, 2013
8,967
Come on guys, you are not giving the OP the benefit of the doubt.

He didn't say how long or how often he needs the 216 Watts.

I can certainly build a circuit that runs on 2 AA cells that will give you 216W at 12V for 1mS every 10 minutes.

Bob

#### AnalogKid

Joined Aug 1, 2013
11,045
Limiting yourself to the facts is pretty much the definition of pessimism.
Not even close to true. Limiting yourself to the facts is one aspect of pragmatism.

Pessimism, like optimism, is not restricted to facts. In one sense it is anticipating the nature of something unknown (the future) based on an evaluation of what is known (the past and present). Aspects of the evaluation differentiate the two results. Both isms can be characterized as either faith or trust, depending on the nature of the knowns.

ak

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