Electrical question, 220v storage

Captain Slow IRL

I'm a mechanical undergrad stuck with an electrical question; is it possible to take mains voltage, store it in a (battery or capacitor) and then run an appliance off it. The appliance would be disconnected from the mains at this point.

The idea is to use an electrical item away from a power source, for a short period of time.

enda1

Would the appliance need 220V AC power to run or is at DC powered device?
Like does the mains voltage usually get transformed down to something like 12V dc? (Example, laptop, phone etc.)

Captain Slow IRL

No, it's a large motor that runs off 220v.

enda1

Something like a UPS more traditionally for computer server use might be in order then, though rather expensive. Maybe someone knows of a more suitable alternative.

Would it be for long periods (more than 5 minutes?) What draw does the motor have? Is it for unplanned power outages? Will the motor need uninterrupted power?

GradEngineer

What is the rating of this motor?? A UPS would be the obvious choice but there quite expensive and once installed they are usually stationary! If the motor was small you could build your own symplified and manually operated UPS using a car/truck battery, trickle charger and sutiably rated inverter!

Captain Slow IRL

Apologies if I'm being vague, it's for a 3rd year project and I'm trying to keep a lid on it!

Essentially, what I'm wondering is if it is possible to store 220v in a compact and cheap way?

GradEngineer

Yep its easy and cheap if the load you need to supply is small and you dont need to run it for long!

What size is the motor and how long do you need to run it for??

With a 0.5 kW motor that only needs to be run for a few mins this is cheap and simple but as each gets larger the task becomes more expensive!

ciaranmac

Are you tied to a specific motor? If the project allows you to replace it with a 12v DC motor, you could use a car battery for storage.

Captain Slow IRL

GradEngineer wrote: »

Yep its easy and cheap if the load you need to supply is small and you dont need to run it for long!

What size is the motor and how long do you need to run it for??

With a 0.5 kW motor that only needs to be run for a few mins this is cheap and simple but as each gets larger the task becomes more expensive!

What are you saying I should using for storage, assuming it's only for a short period of time (5-10 minutes)

ciaranmac wrote: »

Are you tied to a specific motor? If the project allows you to replace it with a 12v DC motor, you could use a car battery for storage.

I was thinking of that at first, I just want to see what my options are before starting anything.

mawk

how much power does the motor draw. this is this most important question before any details can be given

are you talking a 1/4 horse or 35KW?

FoxT

Captain Slow IRL wrote: »

I'm a mechanical undergrad stuck with an electrical question; is it possible to take mains voltage, store it in a (battery or capacitor) and then run an appliance off it. The appliance would be disconnected from the mains at this point.

The idea is to use an electrical item away from a power source, for a short period of time.

1 - its a 3rd year project, not a major scientific breakthrough - so I suggest you'll get better answers if you can be more specific.

2 - the answer is YES. In principle, you can take energy from any source, store it, and apply it to any other sink, that you want.

3 - you can't store mains voltage, you can only store energy. The energy can be accumulated , stored, and delivered, in any way you need (e.g, thermal, electrical, chemical, mechanical, etc)

*takes off pedantic hat - but before i do, you deserve a spanking for such a vague question*

Broadly speaking, if you want to store electrical energy & deliver it elsewhere, you could rectify an AC power source & use the resultant DC to charge an energy storage device, such as a battery or capacitor. You could also, in principle, store the energy mechanically, for example via a pumped storage scheme such as the one at Turlough Hill.
Having stored the energy, it can be delivered via a number of ways - DC-AC conversion via inverters, use a DC motor to power an AC generator, etc.
The choice of energy storage method used will depend on factors such as desired capacity, cost, portability, ease of delivery, etc.
Efficiency is also important. Every time you convert something to something else, you lose something!


-FoxT

Captain Slow IRL

FoxT wrote: »

.......*takes off pedantic hat - but before i do, you deserve a spanking for such a vague question*........

You better be blond and female if you wanna spank me!

Thanks for the post, you've been very helpful.

FoxT

Captain Slow IRL wrote: »

You better be blond and female if you wanna spank me!

Thanks for the post, you've been very helpful.

Ha! I am neither

And, you are welcome !

Irish_Elect_Eng

Captain Slow IRL wrote: »

I'm a mechanical undergrad stuck with an electrical question; is it possible to take mains voltage, store it in a (battery or capacitor) and then run an appliance off it. The appliance would be disconnected from the mains at this point.

The idea is to use an electrical item away from a power source, for a short period of time.

If you are looking to create a proof-of concept prototype on a small scale you can use three readily available items to achieve this.

• AC Car Battery Charger.
• Car Battery
• DC Inverter

But as others have said, some detail would get you some good answers.

brandon_flowers

It is not that difficult but it depends what size motor you want to run. Power is key.

And what is your budget?

http://www.leisurebatteriesireland.com up in Newry should be able to help you as regards batteries, I would recommend an AGM battery if you need high power, you can get about 90Ah out of one of them. Can't remember the guys name up there now though.

Captain Slow IRL

I don't know what the budget is yet; I'm still dicking about with ideas so nothing is in stone yet.

Thanks for the link, there's some interesting stuff on the site.