How do I invert DC 12V to AC 220-240V

[Declet Uche]

Please i need help on a simple method of converting DC to AC
The desired AC output is to power a mini laboratory incubator

 

[wolram]

You need to buy one of thees.
https://www.amazon.com/dp/B00M9XW8U6/?tag=pfamazon01-20
I do not know if 1200w is enough to power your equipment may be you can give more information on the power needed.

 

[Declet Uche]

Electrical 120V~ or 230V~, 50/60 Hz
1200w is enough to power it.
The main problem is that am working on a biological science research where i need to incubate a culture for 24hrs uninterrupted. Am from a part of Nigeria where steady power supply has been a big limitation. So i and my group ar work on getting steady power from a DC mains (batteries) to power the incubator.
Tnks. Will so much appreciate your contributions.

 

[Averagesupernova]

You want to err on the side of caution. If 1200 is just enough to power it then you should go with a larger inverter. Generally a larger inverter will not draw any more than a small one with the same load. It's better to have a large inverter do the job with ease than to stress a small inverter.

 

[Declet Uche]

You want to err on the side of caution. If 1200 is just enough to power it then you should go with a larger inverter. Generally a larger inverter will not draw any more than a small one with the same load. It's better to have a large inverter do the job with ease than to stress a small inverter.

So what's your suggestions, please am open to ideas

 

[russ_watters]

So what's your suggestions, please am open to ideas

Do you have the nameplate amperage or wattage of the incubator?

 

[Declet Uche]

Do you have the nameplate amperage or wattage of the incubator?

220V~240V AC
750watt

 

[Averagesupernova]

I don't know anything about incubators. Watch the specs on both the inverter and the incubator. Make sure the rating on the inverter you choose is continuous. Some inverters may have a 1200 watt spec for instance that is peak or surge. This means it can supply 1200 for a minute or so but only 800 continuously without interruption.

 

[johnbbahm]

You may be able to find an old computer UPS (uninterrupted power supply) with 220 output.
Many of the 5000 VA we used to use had 220 outputs.
Anyway someone handy with electrical could add to the batteries to extend the period of outage covered.
Another, maybe less expensive choice would be an Solar inverter, like a sunnyboy,
http://www.ebay.com/itm/SMA-SUNNY-BOY-4000-US-10-GRID-TIE-STRING-INVERTER-208-240V-/152484166863?hash=item2380c3bccf:g:7MQAAOSwsW9Y0WOA
I don't think it would care if the input was from batteries or solar, but you might need to research the subject.

 

[CWatters]

Can you tell us more about the reliability of the power grid? I think this might not be cheap to do.

Inverters aren't always very efficient. If we assumed 75% efficiency then 750W would turn into 1000W drawn from the battery. At 12V that 1000W works out at 83Amps.

If you need it to power the incubator for the whole 24 hours the batteries will need a capacity of just under 24 * 83 = 2000AH approx. You might even need double these figures as lead acid cells don't like being deep discharged frequently. If you regularly deep discharge them they loose capacity and life time. I think that's going to be quite a substantial and expensive battery. For reference a typical car battery is around 100AH.

You also need to think about how you can recharge the battery. If the power grid is only available for part of the day the charge current needed could be very large. For example suppose the grid is available for 6 hours a day then to recharge a 2000AH 12V battery in that time would require 2000/6 = 333A. That's a substantial charger.

 

[Declet Uche]

Can you tell us more about the reliability of the power grid? I think this might not be cheap to do.

Inverters aren't always very efficient. If we assumed 75% efficiency then 750W would turn into 1000W drawn from the battery. At 12V that 1000W works out at 83Amps.

If you need it to power the incubator for the whole 24 hours the batteries will need a capacity of just under 24 * 83 = 2000AH approx. You might even need double these figures as lead acid cells don't like being deep discharged frequently. If you regularly deep discharge them they loose capacity and life time. I think that's going to be quite a substantial and expensive battery. For reference a typical car battery is around 100AH.

You also need to think about how you can recharge the battery. If the power grid is only available for part of the day the charge current needed could be very large. For example suppose the grid is available for 6 hours a day then to recharge a 2000AH 12V battery in that time would require 2000/6 = 333A. That's a substantial charger.

Waoowh very detailed, thanks so much
Maybe i would rather sort out other ways to power my incubator

 

[Declet Uche]

But can someone/anybody please teach/explain to mi how i convert DC to AC
Am already conversant wit the AC to DC conversion

 

[darth boozer]

http://www.explainthatstuff.com/how-inverters-work.html

 

[Declet Uche]

http://www.explainthatstuff.com/how-inverters-work.html

Thanks a lot, it explains the history and ideology behind inverters, but no circuit of how to make one there sir

 

[davenn]

Thanks a lot, it explains the history and ideology behind inverters, but no circuit of how to make one there sir

surely you could have googled that ...
http://www.bing.com/images/search?q=basic+DC+to+AC+inverter&FORM=HDRSC2I would suggest you DONT even try building one yourself ... well not one over a few watts of capability
else you are likely to get into trouble

 

[Rive]

Thanks a lot, it explains the history and ideology behind inverters, but no circuit of how to make one there sir

You are asking about stuff with the target voltage at the level of the grid AC. You should just forget any homemade stuff and buy the ready-to-use components.

With the given parameters (length of supply time, power requirements) it is possible that you could do it cheaper with a simple portable generator instead of batteries.

 

[Windadct]

As far as the AH needed in the battery the incubator is not "on" 100% of the time. The heater will need to only supply the heat that is lost, and this is very difficult to estimate ahead of time. So experimenting with the " worst case" scenario over 24 hour period may be needed to select the best batteries. Also - adding insulation to the incubator will help.

So there should probably be a Duty Cycle type factor in this, "24 * 83 = 2000AH" should really be like 24 * 83 * DC = DC * 2000AH. The incubator may need a fan running 24 hours, but the heater will consume the most power. You may get away with almost 1/2 of this ~ 1000AH.

I doubt a solar inverter ( at least a good one) will work, as they use a MPPT control to get the most energy out of the solar panels, AND they do not like having people hack the system and add batteries. And - they are not cheap compared to a automotive type inverter.

Is this a school project?

 

[anorlunda]

For that number of kwh, and considering cost and complexity and criticality, I think that a gasoline powered AC generator is a better solution than batteries. As an added benefit, you could get a gas generator big enough to supply 2 or 3 incubators for only a small additional cost.