Step down converter

mountainman

Would it be possible to temporarily  run a 12 volt inverter from a 24 volt battery with a 24-12 dc-dc converter?

mcgivor

The cost of the DC-DC converter,  a high current model, would likely be more than that of an inverter designed to use 24V and would do so without the inherent losses of the converter, I would think. 

mike95490

Sure, it's possible, as long as the DC-DC step-up converter can supply the surge demands the 120VAC inverter needs, without the whole system crashing.  But it's not likely going to make you happy unless you are working with less than 50 watts

mountainman

I'm just trying to power up a 32" led TV with a
300 watt inverter until  my new 24 volt inverter comes.
I have a 30 amp 24-12 converter.

mike95490

if you have it, sure, try it.  It either works or won't.  But spend $$ to get parts to try it, and not simply getting the right voltage inverter is wrong.

mountainman

Ok so far it is works. Thanks.

mountainman

I wanted to double my panel watts from 500 to 1000 (4 250 grid tie) 
 To keep my existing mppt controller.
I rewired my 4 Gc Batteries from 12 to 24 volts. 
 I Got a 24 volt 300 watt inverter for ac.
For 12 volt rv pump and led lights I used a 20 amp  24-12 step down converter. 
 For 10 days without the converter my 12 volt usage was 880 wh. 88 wh avg.
Using the converter for 10 days 1550 wh
155 wh avg.   
~.60℅ efficiency to get 12 volts from a 24 battery.
With this 12 volt converter led  lights are not as bright and it takes longer for the full size toilet to fill. 

I see there are also 24-13+volt converters
I'm sure the lights would be brighter
 but would the higher voltage converter possible be more efficient?

BB.

Efficiency is a function of design, and to a degree, how you use the converter.

If you have a 4kwatt converter, and use mostly 50 Watts 90% of the time, the 40 Watts minimum power loading of the converter becomes a major factor.

Can you measure the current in vs current out? Measure no load current draw, measure average current loading and such.

If you use power 4 hours per day, but run the converter 24 hours per day can also be a power suck.

Bill

jonr

All other things being equal, a 24V to 13V converter is just slightly more efficient than a 24V to 12V converter.    As Bill says, far more important is the design and size.

mountainman

I leave the converter on 24 -7. It's main purpose is to supply the refrigerator propane solenoid.   And rv water pump.
A couple led lights and occasionally stove vent fan.
With everything on at once I measured 133 peak watts on 12 volts over 10 amps.
I didn't see any 15 amp converters
So I went with  a 20 amp.
With double the array watts from 500 to 1000 by switching to 24 volts.
A loss of ~3 watts per hour from the converter will hardly be noticed.