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Forum Index : Solar : is 600 watt inverter too much power?

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bobt
Newbie

Joined: 26/12/2009
Location: Australia
Posts: 17
Posted: 03:39am 10 Jun 2010
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G'day everyone,

I recently brought a 600watt pure sine wave inverter,

and alot of my appliances use only around 50 & 20 watts or even 5 watts,(except the 32"lcd tv and xbox360)

1)if im using say only 5 watt appliance, am i wasting the inverter power on such small
watts usuage from the 600 watt inverter?

2)how much watts or amps do the inverters use
for their pull out of the batteries?

3)would a smaller inverter be better for the
small appliances?


thanks
bobt
 
VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539
Posted: 05:55am 10 Jun 2010
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Hi Bob

I just checked on a 12 volt 600 watt inverter I have and it uses 6 watts at idle and with a 125 watt load it uses 140 watts, it won't hurt the inverter doing this but it does drain the battery a bit faster but nothing comes for nothing.

Your smaller appliances may be better run direct off battery power with a suitable voltage regulated power supply but there are still losses.
Your 600 watt inverter will use about 70 amps out of the battery at full load.

I checked a 300 watt inverter I have and it idles at 5 watts and full load 36 amps so no great gain there and it dosent have the starting reserve power of the 600 watt unit for heavy instantaneous start currents.

Volts X Amps = watts

Watts / Volts = amps

And allow 12 - 20% for conversion losses from battery to the applience.

All the best

Bob
Foolin Around
 
VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539
Posted: 06:46am 10 Jun 2010
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Hi Bob

I found the circuit for a good low loss regulator that's simple to build and works in switch mode.

Page 19 has the variable voltage version.

2010-06-10_164456_LM2576.pdf

This will run your small appliances with minimum losses direct of the battery.

Item number: 370147451142 this is a suitable toroid inductor for the regulator. Do a search on the ebay number.

All the best

Bob


Edited by VK4AYQ 2010-06-11
Foolin Around
 
bobt
Newbie

Joined: 26/12/2009
Location: Australia
Posts: 17
Posted: 10:39am 10 Jun 2010
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g'day VK4AYQ,

thanks for the info on the step down regulator box,
i will certainly look into that.

I do have a few items i run directly of 12v, ipod charger runs directly to a battery
via cigarette adapter ,
which i just plug postive to the top and negative to the side,

i do that for my AA/AAA battery charger as well.
unfortunately there is still at least 3 items i use regulary that i cant use
a DC equilivant.

cheers
bobt
 
VK4AYQ
Guru

Joined: 02/12/2009
Location: Australia
Posts: 2539
Posted: 11:41am 10 Jun 2010
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Hi Bob

OK mate sounds like you got it mostly under control but Im sure that if you have any more issues there will be someone to help on the forum.

All the best

Bob
Foolin Around
 
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