# power a power supply without an electrical outlet

#### jogpo

Joined Mar 30, 2013
3
hello,

i would like to use my 10A ajustable switching power supply in a place where there are no electrical facilities. Can i use a 220V inverter plugged on a car battery to power it ? How many watts this inverter should be rated ? in my case does it matter to buy one that output a pure sine wave ? will my power supply smooth it ?

#### ericgibbs

Joined Jan 29, 2010
16,389
hi jogpo,
Welcome to AAC,
What will be the PSU output voltage at 10Amps.??
E

#### Alec_t

Joined Sep 17, 2013
13,153

#### jogpo

Joined Mar 30, 2013
3
hi jogpo,
Welcome to AAC,
What will be the PSU output voltage at 10Amps.??
E
thank you, this is an 30V 10A ajustable power supply.

It's a QJE PS3010 power supply. There are no informations labelled on it except a sticker 5A fuse. When i google it i found this:
https://fr.aliexpress.com/item/33045460926.html

#### AnalogKid

Joined Aug 1, 2013
10,125
Seat-of-the-pants, ball-parky type numbers:

10 A at 30 V is a max output of 300 W.

It is a switcher, but not super efficient because it is adjustable. Figure 70% max, so that is 430 W. The user manual Specifications page might list its *best* efficiency.

With a 220 V output voltage, an inverter would have to supply 2 A continuous output current. For cooler, more efficient, and more reliable operation, oversize the inverter as much as you can afford.

Inverters are not very efficient, either, so again figure 70%. It needs 615 W input power, or 52 A at 12 V. That's a lot.

ak

#### crutschow

Joined Mar 14, 2008
30,801
What's the maximum combined voltage and current load you will be powering?
That will determine how big an inverter you need.

#### jogpo

Joined Mar 30, 2013
3
Seat-of-the-pants, ball-parky type numbers:

10 A at 30 V is a max output of 300 W.

It is a switcher, but not super efficient because it is adjustable. Figure 70% max, so that is 430 W. The user manual Specifications page might list its *best* efficiency.

With a 220 V output voltage, an inverter would have to supply 2 A continuous output current. For cooler, more efficient, and more reliable operation, oversize the inverter as much as you can afford.

Inverters are not very efficient, either, so again figure 70%. It needs 615 W input power, or 52 A at 12 V. That's a lot.

ak
thank you for taking the time to explain it. So according your statement 60A car battery plugged into a 1000W inverter should do the job.
And do i need a pure sine inverter ? or will the power supply smooth it ?

#### AnalogKid

Joined Aug 1, 2013
10,125
And do i need a pure sine inverter ? or will the power supply smooth it ?
No way to predict. My guess is that the PS will run ok, but the noise on its DC output will include noise components of the inverter's output waveform and its internal switching frequency.

ak

#### Irving

Joined Jan 30, 2016
3,132
thank you for taking the time to explain it. So according your statement 60A car battery plugged into a 1000W inverter should do the job.
And do i need a pure sine inverter ? or will the power supply smooth it ?
Don't confuse Ah with A.

A 60Ah battery is sized at the 20h rate, ie, 3A for 20h (though in reality you'll only get 60-70% of that). It can supply much more than 52A (starting a car is 150A+) but at that level of output you'll be lucky to see 20-30min before its too discharged to be useful.
Unless you can keep it charged, ie by running the car engine.