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groingo
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# Posted: 17 Apr 2015 11:55am
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I am using a 400 watt inverter that also has a USB port on it.
Am using the USB to run the heat circulator fan.
The inverter has a built in off switch which I think they all have but even when the inverter is switched off the USB power still works.
Anyone else try this and what does yours do?
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pizzadude
Member
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# Posted: 17 Apr 2015 12:34pm - Edited by: pizzadude
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I believe the usb output voltage is around 5vdc. It's transformed from the input voltage(12vdc I'm assuming).
If you were to open up the inverter, I'm sure you'd find the power switch controlling the inverted voltage only(120vac). The usb is transformed directly from the input voltage and may or may not be fused. Until the device is disconnected from the battery, you should always have 5vdc present at the usb port.
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MtnDon
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# Posted: 17 Apr 2015 12:52pm
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so it would be interesting to measure how much current is being drawn with the inverter "off" but still making 5 VDC available at the USB port.
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pizzadude
Member
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# Posted: 17 Apr 2015 01:03pm
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Yeah.
I'm sure the amp draw would be minimal, but still, any type of load will eventually drain the battery.
I'm not familiar with that sort of fan. Perhaps there is a nameplate rating on it?
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groingo
Member
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# Posted: 17 Apr 2015 01:08pm
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All I know is with the switch on in ready state it draws 0.250 amps, but I would think off means off....or should.
My question is non technical just curious, do yours do the same thing?
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pizzadude
Member
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# Posted: 17 Apr 2015 01:18pm - Edited by: pizzadude
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All inverters are equipped with at least one cooling fan. Some of which are thermally controlled. All others are constantly on, as long as the inverter is connected to a battery.
I have a 3000w to which the cooling fans are on all the time, whenever the switch is in the "on" position. I don't have usb on mine. When I turn the inverter switch to off, there is zero current. The fans are off with the switch.
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creeky
Member
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# Posted: 17 Apr 2015 04:30pm
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the dc circuit will be on its own no? i mean it's just a simple transformer. 12v dc to 5v dc.
the inverter shouldn't be involved.
pizzadude. ahahahahaha. sorry. cooling fans on all the time. sniff. wipes tear of laughter from eye.
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pizzadude
Member
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# Posted: 17 Apr 2015 05:12pm
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Quoting: creeky pizzadude. ahahahahaha. sorry. cooling fans on all the time. sniff. wipes tear of laughter from eye.
On my inverter, fans are on all the time.
Maybe I got a dud
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creeky
Member
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# Posted: 17 Apr 2015 05:59pm
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pay one way or the other
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pizzadude
Member
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# Posted: 17 Apr 2015 06:15pm
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Ok.....
Groingo, I'm curious..
Did you figure out what's causing the amp draw?
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creeky
Member
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# Posted: 17 Apr 2015 06:38pm
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 sorry. my inverter has a thermally controlled fan (in that the cpu watches various temperatures among many other variables) and it is off most of the time.
so I was bugging you for having a) a 3000 watt inverter. really. for what. launching the space shuttle?
and b) I checked my watch. it's 2015.
oh okay. and c) if groingo is running a 5v appliance at 3 amps he's drawing 15 watts of power.
and) I believe low cost dc to dc converters have a phantom load. but at that point. Pretty small draw?
which leads me to e) your second and fourth sentences in your first reply lead me to believe you might find a and b funny. eh.
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groingo
Member
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# Posted: 17 Apr 2015 06:50pm
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Here is the end result, keep in mind the inverter is switched off and indeed all 110 volt output is at zero, nothing hooked to 110 works but the USB port continues to be live.....not a big deal and no impact on the batteries just odd.
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creeky
Member
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# Posted: 17 Apr 2015 07:12pm
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as pizzadude pointed out. the USB runs transformed from 12v (your battery) to 5v (USB plug) thru a dc to dc transformer.
therefore: no inverter loss as it is separate from the ac inverter.
so the inverter can be off. doesn't matter. the dc transformation is a separate circuit altogether.
now speaking of end results. did i ever tell you about.
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MtnDon
Member
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# Posted: 17 Apr 2015 07:35pm
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Quoting: creeky the dc transformation is a separate circuit altogether.
Yes, but I wondered about just what loss there is asmany circuits don't go completely dead even when nothing is plugged into the outlet. Phantoms.
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creeky
Member
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# Posted: 17 Apr 2015 08:04pm
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now there's an hour of my life I want back.
I knew the answer was low, but how low.
so. dc/dc converters use a varying amount of power depending on watts used. kind of like electric motors they seem to need some power to get going. however.
12v to 5v 3 amps converter on idle should come in at .18w. Hey. We're big spenders. .2. or 1 watt every 5 hrs. call it 5 watts a day.
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pizzadude
Member
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# Posted: 17 Apr 2015 09:36pm
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creeky
No worries👋
I might be missing your point about my 3000w inverter tho..
My system is by no means top of the line. I currently have 5 deep cycle 12v marine batteries powering my 3000w/6000w peak inverter(paid$150 for it). The batteries are cheapies(65bucks apiece). But I've had pretty good luck with the brand. Someday I'll bite the bullet and buy a decent power supply, until then I'll get by with being cheap and stubborn ha.
I normally use minimal wattage off my inverter. Basically a light or two and a tv maybe.
There are times when having the extra power is an advantage tho too. I vacuumed out the cabin just the other day off my inverter alone. And when I'm feeling really lazy, I'll throw supper in the 1600w microwave. My inverter says "no problem".
I might have an outdated system and it might be a bit overkill, but it suits me ok.
Someday I'll upgrade. Gotta kick this stubbornness first😁
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morock
Member
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# Posted: 17 Apr 2015 10:57pm
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I would be interested the see what the draw is in idle mode. DC to DC converters are only 80% efficient at best and add a cost to the inverter. The easiest way and cheapest way to get from 12v to 5 v is a resistor network but would also waste energy. Most USB devices draw under 1 amp. Interested to see what the manufacturer went for in design though.
As a side note. You can't transform DC power through a conventional transformer, it only works for AC power. You need a DC to DC converter or some other technique, but not a transformer.
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creeky
Member
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# Posted: 18 Apr 2015 09:01am - Edited by: creeky
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ya. sorry. that was my bad. i was using transformer interchangeably with converter. dang.
thx pizzadude. cool hand. i had a 3000w to start too. I found the 35 watt (800w/day) idle draw hard to take during the cloudy months with short days. but we all start somewhere and usually it ain't on top of the mountain.
Quoting: creeky 12v to 5v 3 amps converter on idle should come in at .18w. Hey. We're big spenders. .2. or 1 watt every 5 hrs. call it 5 watts a day.
morock that's a 3 amp converter idle draw from a fairly decent converter available online.
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groingo
Member
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# Posted: 18 Apr 2015 12:05pm - Edited by: groingo
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Did a volt check with it switched off and USB port showed output of 5 volts, so opened the inverter up and sure enough it is a separate circuit, must be a reduction circuit, not enough power loss to be significant, if so I'd just put in a remote battery kill switch and that would resolve everything but no need, actually finding that leaving a small draw on the batteries seems to make them work better or it could be Creeky's poop that has distorted my brain!
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creeky
Member
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# Posted: 18 Apr 2015 02:07pm - Edited by: creeky
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beware the bokashi brain bending benefits.
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groingo
Member
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# Posted: 18 Apr 2015 03:41pm
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Yogurt, must have Yogurt and Jello.....mmmmm
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creeky
Member
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# Posted: 21 Apr 2015 03:57pm
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i waited.
chocolate puddddiiiinnnngggg
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