Can I run electrical equipment off a battery?

[charlie10]

Hi

 

I want to start a hot dog business but to save money on gas heaters would it be possible to run a steamer (designed for normal household electrics) off any sort of battery? I'm looking for a way to move to different locations without having to be near a power source the whole time. Is there any sort of portable battery that I could charge overnight and then use to power a small hot dog cart?

 

Thanks

 

Charlie

[doG]

Sure. You will need either a DC heating appliance or an inverter to convert the batteries dc current supply to AC since normal household type appliances are designed to run on AC. The heating element in the unit probably doesn't much care if the power is AC or DC but any motors in the unit will only run on the type of current they are designed for. Many marines appliances are designed for DC. I think you will also find that they cost quite a bit more than AC appliances because of their smaller market.

 

FWIW though consider the average tailgater. They run their grill with gas or charcoal because it is convenient and cheap. I've never seen a portable electric grill. I suspect that's because of the higher cost of an electric grill plus the cost of a suitable battery to power it.

[swansont]

A car battery will be rated at somewhere around 100 Amp-hours. At 12V that's 1.2 kWh, or 2 100 W E-Z bake oven light bulbs for 6 hours, and is 4.32 MJ. Probably not enough for a hot dog steamer. The energy density of propane is ~46 MJ per kg, i.e. one kg of propane has ~10x the energy content of a car battery, using those numbers.

[charlie10]

What I want to power is This. So I just need to buy an inverter to convert the current? Is it that simple or ist there more to it? How long would a car battery power the steamer (in the link) for? Would a car battery be most appropriate? I don't know a lot about electricity hence why i'm asking on here! Thanks for the replies so far

[John Cuthber]

You could do it, the data sheet for the product says it's 260 watts.If your car battery has a capacity of 100 Amp hours at 12 volts it could store 1200 watt hours so it would run the steamer for about 4 or 5 hours but the efficiency of the inverter might take that down to 3 or 4 hours. You would need a bunch of car batteries and chargers to cover the working day.

I suspect the gas would be cheaper too.

[doG]

You could probably find a big enough deep cycle marine battery to get you through a day. They're available at 500AH or more and they're 12V so retail inverters are readily available. Some automotive batteries like forklift batteries are available at a 1000AH or more but are usually higher voltages, 36V and 48V are common and I've seen some that were 90V.

 

Another thing to consider is the weight of your power source if you are the propulsion source. Would you rather push around 10 car batteries or one bottle of propane gas?

[charlie10]

thanks for the replies, I've found this here, it says its 62 ah at 10hr rate does this make it 620 ah overall? Could you charge this from the mains after it has used its power or not?

[swansont]

thanks for the replies, I've found this here, it says its 62 ah at 10hr rate does this make it 620 ah overall?

 

No, it's 62Ah capacity (see the specifications tab); I think they mean getting that capacity assumes you are discharging uniformly over a period of 10h.

[J.C.MacSwell]

thanks for the replies, I've found this here, it says its 62 ah at 10hr rate does this make it 620 ah overall? Could you charge this from the mains after it has used its power or not?

 

It is still 62 amp hours, but based on steadily outputting it in 10 hours (so based on 6.2 amps constant) You would get more ah over a longer period (at a slower rate) but less if you discharged it quicker, due to the internal resistance of the battery using up more of the energy.

 

Since for this application you would be discharging it faster with a single battery you would get less than 62 ah.

Edited August 4, 2011 by J.C.MacSwell

[ewmon]

Calculate battery requirements using a five-step method working backwards from the device:

1. Calculate the total energy consumed by the device (volts × amps × hours = W∙h)
   
2. Calculate the total energy consumed by the converter (W∙h / converter efficiency, eg. 1200 W∙h / 90%eff = 1333 W∙h)
   
3. Calculate the required capacity of a battery based on converter input voltage (W∙h / volts = A∙h)
   
4. Adjust the required capacity based on discharge current, battery's Peukert constant, and Peukert's Law
   
5. Adjust the required capacity based on using only 80% of capacity (A∙h = A∙h / 80% or 1.25 × A∙h)
   

Also, instead of making steam that requires a lot of energy, hot dogs can be electrocuted, and all all the energy goes directly into the hot dog.

Edited August 4, 2011 by ewmon

[tomgwyther]

Wouldn't a little diesel generator be the simplest solution? Or if it's a travelling hot dog stall; i presume you have a car. You can get an inverter which plugs into the car's cigarette lighter. They cost about £50 ($75) and would easily run your hot dog steamer, plus a few other appliances.