Wiring a Small Inverter ..................

[Ralph Johnstone]

............. Never really had much use for one but the day has finally arrived.

I already have a small 75 W inverter which suits me perfectly for charging cell phones, IPods, and other small loads. However, the one further thing I really want out of life is to make my specialty Belgian waffles while on the hook in the middle of nowhere up north. For this, an electric egg beater is mandatory for beating the egg whites to a froth.

The beater I will be using draws 1.15A or 138W at 120V while beating egg whites. The inverter is rated at 300W max and 240W continuous service so I'm comfortable there. The efficiency of the inverter is 85% (hopefully). This means I will have to supply around:

138W / 12.5V (average) / 0.85 = 12.9A or realistically, more like 15A to beat egg whites for two or three minutes.

To keep the inverter happy, the wiring will be rated for 300W / 12.5V / 0.85 = 28.2A

Now for the problem . My main DC breaker is 50A and the largest individual circuit breaker on the panel is 15A. Given these limitations, what is the best way to protect the wiring to the inverter .............. an in-line fuse buried behind the electrical panel in a rat's nest of wiring , a stand alone circuit breaker mounted all by itself for all to puzzle over, or is there something a little more professional ?

Thanks as always for your help.

 

[Maine Sail]

............. Never really had much use for one but the day has finally arrived.

I already have a small 75 W inverter which suits me perfectly for charging cell phones, IPods, and other small loads. However, the one further thing I really want out of life is to make my specialty Belgian waffles while on the hook in the middle of nowhere up north. For this, an electric egg beater is mandatory for beating the egg whites to a froth.

The beater I will be using draws 1.15A or 138W at 120V while beating egg whites. The inverter is rated at 300W max and 240W continuous service so I'm comfortable there. The efficiency of the inverter is 85% (hopefully). This means I will have to supply around:

138W / 12.5V (average) / 0.85 = 12.9A or realistically, more like 15A to beat egg whites for two or three minutes.

To keep the inverter happy, the wiring will be rated for 300W / 12.5V / 0.85 = 28.2A

Now for the problem . My main DC breaker is 50A and the largest individual circuit breaker on the panel is 15A. Given these limitations, what is the best way to protect the wiring to the inverter .............. an in-line fuse buried behind the electrical panel in a rat's nest of wiring , a stand alone circuit breaker mounted all by itself for all to puzzle over, or is there something a little more professional ?

Thanks as always for your help.

Wire it direct to the house bank with its own fuse and battery switch or add/replace a breaker to the panel in the size you need.. Running an inverter off a panel switch often results in voltage drop that causes the inverter to drop out early if the inverter draws enough while other DC loads are on...

If you want it to power the ships AC outlets then it gets more complicated.

 

[Ron20324]

Put one of the beaters in a cordless drill.

 

[Bill Roosa]

or you could try:
https://www.google.com/search?q=man...oDKWH0QGb-4HoDw&ved=0CEMQsAQ&biw=1400&bih=856

 

[finding41]

It only takes a few minute with one of these. Really.
Your not going for stiff peaks like for moraine.
The cordless drill idea is brilliant.

 

[Tom G P-21]

What are you using for a waffle iron?

If its electric then it will probably have more of a load than the beater. If you are using a cast iron camp style iron over a propane stove then you should be ok.

 

[onecoolair]

I keep a stainless steel bowl on board and a stain less whisk like in picture. Which works pretty good.
Also I have seen 12 volt appliances such as blenders before. Don't remember off hand were. Try looking around first and see what you find.

 

[Ralph Johnstone]

You May be on to Something ..................

Put one of the beaters in a cordless drill.

................... except for the sawdust and metal chips (from previous jobs) falling into the egg whites :cry:.

 

[Ralph Johnstone]

For Belgian Waffles .....................

If its electric then it will probably have more of a load than the beater. If you are using a cast iron camp style iron over a propane stove then you should be ok.

.................... it MUST be a cast aluminum waffle iron for either gas flame or electric stove top elements. I find the electric waffle irons can't supply enough heat to brown the outside and leave the inside moist .

 

[Ralph Johnstone]

This May be A Good Alternative ................

I keep a stainless steel boil on board and a stain less whisk like in picture. Which works pretty good.
Also I have seen 12 volt appliances such as blenders before. Don't remember off hand were. Try looking around first and see what you find.

................ if I can find a battery operated mixer. The battery can be recharged on the little 75W inverter. Also saves pulling wire behind the liner and other related problems. Thanks.

Crap :cussing: ........... now I've got to find something else for a winter project .

 

[Ralph Johnstone]

But Isn't This ...........................

It only takes a few minute with one of these. Really.
Your not going for stiff peaks like for moraine.
The cordless drill idea is brilliant.

................ why the good Lord gave us electricity.

Absolutely, the peaks must be stiff to get enough aeration when the beaten egg whites are folded into the batter .

 

[Stu Jackson]

.................... it MUST be a cast aluminum waffle iron for either gas flame or electric stove top elements. I find the electric waffle irons can't supply enough heat to brown the outside and leave the inside moist .

Ach, there's always pancakes.

 

[Benny17441]

I would recheck the calculations if I were you. An appliance rated for 1.15A at 120V will draw 11.5A at 12V. If you factor in a 15% inverter inefficiency your draw will be closer to 13.23A which would translate to close to 1600W. In addition an electric motor may require from 2 to 5 times the power required to run it just to start it. On the other hand I find it unlikely that a small egg beater would be rated for 1.15A at 120V. Dorm refrigerators with a compressor are usually rated between 0.95A to 1.1A at 120V. In the past I have used a 1500W/3000W inverter to run such refrigerators. With an inverter of 240W of continuous power you could only run a load of around 0.16A at 120V. Check the specs on the actual draw of the appliance.

 

[Ralph Johnstone]

Please ..........................

Ach, there's always pancakes.

...................... I try to maintain an air of civilization when out on the water .

 

[Ralph Johnstone]

Fortunately Benny ............................

I would recheck the calculations if I were you. An appliance rated for 1.15A at 120V will draw 11.5A at 12V. If you factor in a 15% inverter inefficiency your draw will be closer to 13.23A which would translate to close to 1600W. In addition an electric motor may require from 2 to 5 times the power required to run it just to start it. On the other hand I find it unlikely that a small egg beater would be rated for 1.15A at 120V. Dorm refrigerators with a compressor are usually rated between 0.95A to 1.1A at 120V. In the past I have used a 1500W/3000W inverter to run such refrigerators. With an inverter of 240W of continuous power you could only run a load of around 0.16A at 120V. Check the specs on the actual draw of the appliance.

................ you don't suffer from OCD (obsessive compulsive disorder) the way I do.

I used a DC voltage average of 12.5V rather that just 12V for round numbers and this gave me 11.04A. Factoring in the efficiency of 85% gave me the 12.99A which is still close to your 13.23A. However, what caused me to down another couple of Valium is your jump to "close to 1600W" . I know this is just a typo for 160W, or mebbe you're just messin' with my OCD :naughty: ?

I think small appliances like egg beater are notoriously inefficient ($$production costs$$) because of the very short operating times they see. Small dorm refrigerators are probably regulated to be more energy efficient because of their 24/7/365 operation. Yes, yes, it's OFF/ON operation for whatever time that works out to be. However, in this case I did measure the amperage with a Fluke clamp on and the amps were actually the 1.15A as stated. Interestingly, the beater has a rating of 200W and after playing around by holding the shafts with a wet dish rag, I never got much above 1.5A. I'm sure this thing would be quite suitable for mixing asphalt .

Like you, I also worried about start up load but started the thing repeatedly, and quickly, and saw no overload alarm indicator on the inverter. Like most situations, the start up period is just too quick to cause problems. This thing is temporarily laid out on the boat with wires hung everywhere (like jungle vines) for testing.

Still not clear on your statement that "In the past I have used a 1500W/3000W inverter to run such refrigerators." when the load of the single refrigerator is around 1.1A X 120V = 132W or are there other electrical loads on the inverter as well ?

 

[Clark]

Benny, I think you got a little '0' happy . . .

I would recheck the calculations if I were you. An appliance rated for 1.15A at 120V will draw 11.5A at 12V. If you factor in a 15% inverter inefficiency your draw will be closer to 13.23A which would translate to close to 1600W.
160W, not 1600.
In addition an electric motor may require from 2 to 5 times the power required to run it just to start it.
Yep, that's called inrush
On the other hand I find it unlikely that a small egg beater would be rated for 1.15A at 120V. Dorm refrigerators with a compressor are usually rated between 0.95A to 1.1A at 120V. In the past I have used a 1500W/3000W inverter to run such refrigerators.
A 1500W inverter is loafing to provide 120V @ 1.1A (~150W)
With an inverter of 240W of continuous power you could only run a load of around 0.16A at 120V.
Why? 120V @ .16A is only about 23W even considering 85% efficient. Did you mean 1.6A?
Check the specs on the actual draw of the appliance.

Good idea . . .

 

[Benny17441]

OK, you got me. Freudian slip of the old gray matter better known as brain fart. Kidding aside, this I know to be true; the conversion factor between 120V and 12V is 10. 1.15A at 120V = 11.5 A at 12V. Add the anticipated innefiency factor of the inverter at 15% and you get a total draw of 13.23A at 12V. Perhaps by accident your figure of 12.92A was close. Now for the brain meltdown I did try to convert 12V amps by using 120V. In the past I had used 1500W continuous 3000W peak to run a dorm refrigerator and had forgotten why. I have now reviewed the figures and remembered I had done it to have ample capacity to start the compressor and be able to run TV and a DVD player. It was nice because I could also run a small microwave. Getting back to the issue I concur that the power usage will be about 160W and that the 300W inverter should be able to run that concrete mixer. Do hardwire it directly into the batteries and fuse the positive terminal. A 12V plug into an existing 12V circuit may not allow the inverter to produce maximum power. If you use the mixer for a continuous 2 minutes you can anticipate the discharge on your batteries to be close to an insignificant 0.5 a/h. Our refigerator in the hot climate would consume around 3.5a/h. Sorry about the mix up and thanks for being kind about it.

 

[joker460]

Also try to keep the 12 volt wiring as short as possible to reduce losses.