Inverter and blow dryers...

[misterW]

O.K., here's the deal:

I've used inverters before; used power tools off of one for years in the back of my truck.

So, when I began building my teardrop and my girlfriend asked me if she would be able to plug in and use her precious hair dryer, I said "sure, I don't see why not..."

That was before I found out her hair dryer was about 3x the wattage of any tool I had ever used (around 1850 watts). Is it possible to still do this by just using a high wattage inverter (say 2000 watts)? And maybe running the vehicle and charging the trailer battery while she gets herself pretty? Or am I likely to fry something?

As much as I would like giving her the comforts of home, frying the electrical system in the middle of nowhere for the sake of a hairdryer is not really worth it (at least in my book).....

Opinions?

[madjack]

...opinions...you asked...if she can't go without a hairdryer for a day orso, leave her at home with the dryer...you did ask...the dryer pulls around 15a of AC power...that equates to 150a of DC power...you would need to use 1ought welding cable as the connection wire to the battery...you are in the middle of Mother Nature...tell her to use Mother's method for blow drying her hair(the wind and sun)...just my opinion of course...and you did ask........
madjack

[teardrop_focus]

Opinions?

You asked...
Wait... lemme put on my flame suit.


Find another girlfriend; one who feels secure enough with her appearance to not need a freakin' blowdryer when camping.

[misterW]

Ha ha. Thanks, so far. To be more clear, I wasn't looking for opinions on the girlfriend, but rather on the plausibility of running high wattage appliances off an inverter (and, to be fair, she simply inquired about the possibility).

As far as calculations, is this the way one would go about this?

Lets say I want to plug an 800 watt device into the inverter. 800 watt/120 volts = 6.6 amps.

Now, what does that mean as far as the DC portion of the circuit -- the wire leading from the battery to the inverter? Does it mean that 66 amps (800 watts/12 volts)are going through it? And 66 amps would require gauge 3 cable (75 max amp rating)?

Is that right?

Thanks in advance!

[jss06]

Yes your math is correct. But you also need to take into account the efficency loss of the conversion. You will be lucky to get 85 to 90% efficeny. So your current draw in your example is likely to be closer to 75 AMPS DC.

[fromeo]

Can it be done? Sure.

Is it practical? That's a question only you can answer.

My wife is also rather fond of her hair dryer. When "camping" not having it is no issue. The catch is that we aren't always camping - sometimes we're using the trailer as a "mobile hotel room" where we need to go somewhere and NOT look like we're out camping.

To solve that problem I added a 400W inverter to the trailer. Found a small "travel" hair dryer for her that draws 300W on LOW. Current draw with the dryer operating on LOW is 27A DC (actual measured current). Seeing that she runs it only about 5 minutes per day, that equates to 2.16 Ah. Depending on your battery capacity and the length of your trip, that may or may not be a concern to you..

I could have gone with a larger inverter, but that costs more and invites more battery drain. The little one gets the job done and cost a whopping $29. The inverter is quite happy being fed through a few feet of 8AWG, again keeping the cost low.

Hair dryers aside, we have found the inverter handy to have around. One thing I am really fond of is being able to run a small crock pot (again on low) while en route to our destination. In the fall, when it's dark early, it's really nice to pull in, drop anchor and have dinner piping hot and ready.

- Frank

[misterW]

Funny you mention the crock pot, as that has been my plan since I began building the trailer. So the inverter was always part of the deal.

Also, as you mentioned, we wouldn't be solely using the trailer for weekend camping trips. Cross country trips where we check out some nice restaurants from time to time are also anticipated.

Stringing arc welding gauge cable back to the inverter seems ridiculous, so the question becomes how much do I scale down...

Key question for my decision: If the inverter has a larger capacity, does that mean that it would drain the battery more even when using smaller appliances, such as the crockpot or a fan? ie would a 2000 watt inverter drain the battery more than a 700 watt inverter when using the same 100 watt appliance?

[fromeo]

Stringing arc welding gauge cable back to the inverter seems ridiculous, so the question becomes how much do I scale down...

Key question for my decision: If the inverter has a larger capacity, does that mean that it would drain the battery more even when using smaller appliances, such as the crockpot or a fan? ie would a 2000 watt inverter drain the battery more than a 700 watt inverter when using the same 100 watt appliance?

There's much less loss when running 120 VAC vs. 12 VDC. So, when possible it is best to keep the inverter as close to the battery as possible and then run the AC over the distance. In my case, the inverter is within 4 feet of the battery bank and I use a 14/3 extension cord to plug the trailer into it. I call this the "poor man's transfer switch"

As far as efficiencies, they vary, but in general it seems that the smaller units are a little more efficent. Don't take that as gospel, but a reflection of my experience and those I have read.

If all I want to do is run the boob tube for a half hour to catch the 11:00 news, I'll use an $8 100W lighter plug-in inverter over the 400W one. Saves me about half an amp.

In any case, if it's not being actively used, it's switched off. No sense in having additional standby current draw.

- Frank

[nevadatear]

I wanted a hair dryer too, the one concession to civilization I wanted. So I bought a 12V hair dryer. No, it is not all that powerful, but it does the trick for me. I use the car battery and run the car for the 5 minutes it takes to use it, rather than use up the TD battery. here is one source http://www.12volt-travel.com/12-volt-hair-dryers-curling-irons-c-96.html

[madjack]

would a 2000 watt inverter drain the battery more than a 700 watt inverter when using the same 100 watt appliance?

YES...also, the drop across wiring is higher with DC power Vs AC power so it would be best to place the inverter as close to the battery as is possible, keeping the wiring short and using the longer wires(extension cord) on the AC side of the inverter..........
madjack

[teardrop_focus]

misterW

Ha ha. Thanks, so far.

To be more clear, I wasn't looking for opinions on the girlfriend, but rather on the plausibility of running high wattage appliances off an inverter (and, to be fair, she simply inquired about the possibility).

Forgive me; I was in a "mood".





Thanks for painting a more accurate picture. I can be a real pig at times.

[Shadow Catcher]

The Road Pro 12V hair dryer is 14A top of the page http://www.12volt-travel.com/12-volt-ha ... -c-96.html
Nancy when we are in a camp ground just goes to the bathroom and plugs hers in and most of the time we have 110.

[Danno]

I know that I'm Danno come lately to this thread, but my wife just got a new blowdryer that can be found at this link: http://www.sallybeauty.com/digital-hair ... =Hair09-03

It's cool because it has variable heat and blower speed settings. Minimum heat and speed yields 500w and highest speed and heat yields 1875watts.

much more reasonable wattage wise than some with just a low/high setting.

it's pricey, but she loves it and if you are camping at a place with electricity she can use the same blowdryer as when you are running off batteries.