Inverter for battery powered Coffee?

[kukla]

Hey everyone, heres the deal:

I have one of those fancy coffee makers where you put in the disk of coffee grounds and it spits out a hot cup of java in about 30 seconds. Needless to say, I really enjoy the appliance which is why I would like to put it in my locker at school. All of the details I have worked out, except I can't find a suitable inverter to power the coffee machine on batteries because it requires 1350 watts.

Will this work to power on batteries?

Will it be too expensive?

Do you have any other ideas that I could use to power the coffee machine?

After searching, I have come up with this which will reach up to 1000 watts if larger transistors and a larger transformer are used, but even then I wouldn't know which parts to use.

So can anyone help me out?

Thanks for your help,

Kukla

 

[audioguru]

Do you know how to do simple arithmatic?
1350W/12V= 112.5 Amps. A car battery might boil or explode with such a high continuous current. Maybe you need 2 car batteries in parallel to handle the high current. How will you charge them?

The inverter project you posted is a piece of junk and doesn't work. It blows up its capacitors because they are backwards and has a very low power output when it works. Larger transistors won't make any difference to its low power.

 

[kukla]

Wow. I'm glad that I got advice on this.

I have pretty much no idea what I'm doing.

Thanks audioguru.

 

[audioguru]

I have pretty much no idea what I'm doing.

No kidding!
It is a good thing that you asked.

 

[kukla]

Well I have obviously given up on my previous idea, but after some thought and a few google searches, I have come across a 12v coffee machine that is designed for use in a car. (What else?) This makes things easier, except it has one of those cigarette lighter plug in things, I don't know what they are called.

So I was wondering could anyone help me going about powering this coffee machine by battery?

Would this even be any more cost effective?

Would I just need another, different type of inverter?


Thanks alot for your help.

 

[audioguru]

The coffee machine that operates from the 12V lighter plug in a car needs a car battery to power it, not an inverter. How are you going to charge a car battery in school? It might last a week then you could carry it home for charging each weekend.

 

[Oznog]

But no 12v coffeemaker is going to make coffee with that speed. As a sanity check, look at the size of cable alone needed to pass over 1000W @12v. That would require 2 ga cable or better, and that's just to prevent the cable from overheating. The voltage drop is another issue. It is likely a 12v coffeemaker is made to comply with a more or less standard limit of 10 amps from the lighter socket, so it's 120W. This will mostly work, but it's going to be slow. There's a question of just how hot that water's going to be able to get even if you wait forever.

Actually it's not impossible. I have a big alternator that puts out like 130 amps. If the engine is running, and you have excellent connectors and HUGE cables running to a sizable inverter, this is entirely possible to run your badass coffeemaker. I've run a small microwave with the engine running. I've run a 6000 BTU air conditioner. Not at the same time of course.

 

[audioguru]

He could install a gasoline powered electric generator in his school locker to power the coffee maker.

 

[RODALCO]

Coffe maker

Hasn't the school got a powerpoint in the hall or locker room to use ?

Somehow the cleaners need access to 120 Vac for the vacuum.

Just my 2 cents worth

Good luck with your coffeemaker.

Good coffee is essential.

 

[jrz126]

Hasn't the school got a powerpoint in the hall or locker room to use ?

Somehow the cleaners need access to 120 Vac for the vacuum.

Just my 2 cents worth

I was thinking of that as well... If it only takes 30 seconds to spit out the coffee, then just find an outlet near by and plug it.

 

[Nigel Goodwin]

Why not just make the coffee at home and take it in a flask?.

 

[HarveyH42]

Wonder why there isn't some kind of portiable personal coffee maker. There must be some method of boiling water with reasonable sized battery power.

I work the early shift, and the vending machine is 50-50 functional, and doen't get serviced until lunch break for me. It's not the greatest coffee, but its not instant (sewage). My solution was to keep a jar of coffee in my locker, regular ground columbian coffee. When the machine is out of service, I heat water in the microwave, throw in three spoons full of grounds, and let it brew. The grounds settle to the bottom as the water cools to a drinkable temperature. Just like out camping.

 

[audioguru]

There must be some method of boiling water with reasonable sized battery power.

Nope.
Heating something takes power. Power is volts times amps. A battery must be pretty big to supply amps of current for a time long enough to heat a cup of water.

 

[Dr.EM]

Why not just make the coffee at home and take it in a flask?.

I do admire the logic in this suggestion

I expect you want the machine in the locker for a coolness factor, so you can open your locker and turn on this big coffee maker in there?

An invertor for that power level is unrealistic (if it is to be supplied from 12v at least). Supplied from a bank of 4 car batteries in series supplying 48vdc, possibly, but it is unusual and requires a bespoke design. Also bear in mind you would be generating mains voltages at high power levels which, although may not be referenced to earth (?) could still be fatal if the wiring wasn't suitably insulated.

Stick with Nigels suggestion , or use the machine from a wall outlet.

 

[Roff]

I calculated how many watts would be required to raise the temperature of 12oz (340g) of water by 75C in 5 minutes. I got 366 watts. This assumes that ALL the power goes into heating the water, and none is lost.
So, if you wanted to do it with a 12V battery, you would need about 30 amps (again, with no losses). To do it in 10 minutes would require 15 amps, etc.
Of course, the actual current would be more, or the time would be longer, due to heat loss.

 

[HiTech]

I agree with Nigel and besides, most schools forbid items that use heating elements and other potential fire risk devices. A good quality coffee thermos can keep the stuff warm for many hours. I use an Alladin/Stanley thermos during cold, wintry days in the woods when hunting. I've sat the thermos in the snow for over 10 hours and at day's end, it's still steaming hot, just like it was poured from the pot.

 

[Roff]

And, as we all know, the thermos bottle is the world's greatest invention.

 

[audioguru]

There is nothing like nice stale 10 hours old coffee!
I thought the school kid wanted fresh coffee. He should also grind it in his locker.

Hey. Why is a school kid drinking coffee?

 

[Nigel Goodwin]

There is nothing like nice stale 10 hours old coffee!
I thought the school kid wanted fresh coffee. He should also grind it in his locker.

Perhaps he ought to plant a coffee bush (does it grow on bushes?) in his locker?.

 

[Roff]

Perhaps he ought to plant a coffee bush (does it grow on bushes?) in his locker?.

You forgot the roaster.