Noob question about power usage

[Anthony5]

In my house I have pre-wired a few lighting circuits so that I easily can install a UPS on them in case of power outage. Those lighting circuits are all 220V and use 7-11W power saving lamps.

 

Currently I haven't installed a UPS yet as my understanding is that if I want to use it for an extended period of power outage would need an inverter with external batteries.

 

Since I recently switched the perimeter wall lights to 12-24V LED lamps I was now questioning myself, if I should do the same with the internal lighting, would the simple PC UPS output last much longer?

 

I'm confused because of the wattage would be about the same, though it would be 12V instead of 220V, but at the end of the day the transformer is still fed by 220V.

 

So what's the verdict?

[Lamkyong]

sorry UPS =  ????

[Anthony5]

Uninterruptible power supply

[Naam]

29 minutes ago, Arjen said:

The easiest "UPS" is a battery charger what charges your batteries, and an inverter big enough to supply your entire house, or the part you feel you need always electricity. This is not cost efficient, but easy to make.

that kind of power supply is not "uninterrupted". when there's a power cut the supply is "very much interrupted"

[Anthony5]

Think you misunderstood my question.

 

I have certain circuits in the house that are correctly wired to connect a UPS. Those circuits are now 220V with power savings lights 7 - 11W, but I know how to change them to LED 12 -24V DC 7-11W.

Of course the LED will be powered by a 12-24V power supply which requires 220V. During a power outage the UPS supplies 220V to the power supply that feeds the LED's

 

So my actual question is, does the 12-24V LED circuit use less power from the UPS, so will the batteries last longer, than if a regular 220V circuit with similar wattage lamps.

[impulse]

From a practical standpoint, a lot would depend on whether those lighting circuits are completely isolated from all the other wires in the house, and whether the existing wires are of adequate size to feed them with 12V or 24V.

 

LED lights run off a relatively low voltage.  Even if you run them on 12 V, they have internal resistors that drop that 12 V to 3-7 V (+/-), depending on the color of the LEDs.  If you're feeding them 220V, they have resistors, capacitors and inductors to change that 220 AC to 3-7V DC.  (Each color has its own optimum voltage)

 

If you have 200 watts of LED lights and feed them 12V, the wiring has to be adequate to handle 200/12 = 16.7 Amps.  If you feed them 220V, the wiring has to be adequate to handle 200/220 = less than one amp.  So you can use much smaller wires if you feed them 220V.   

 

In both cases, you'd be pulling 200 watts from the UPS, so the difference in battery life would be slight.

 

For my money. I'd keep them standard at 220V, which won't require any wiring changes at all.  Install your UPS, compare it with Naam's photo of his setup and call it good.

 

Outdoors is different because of the safety issues running 220V through wires that may become wet and frayed.  12/24 volt systems are a lot safer than 220V if you happen to clip a wire with the lawn mower or 9 iron.  (Edit: or if the dog happens to pee on an exposed connection.  Happened to my dog in an apartment complex and it could have killed him)

 

[Anthony5]

OK, I jumped the gun with my previous, now deleted, post.

 

I think Impulse has just answered my question

 

If you have 200 watts of LED lights and feed them 12V, the wiring has to be adequate to handle 200/12 = 16.7 Amps.  If you feed them 220V, the wiring has to be adequate to handle 200/220 = less than one amp.  So you can use much smaller wires if you feed them 220V.   

 

In both cases, you'd be pulling 200 watts from the UPS, so the difference in battery life would be slight.

[Crossy]

To answer Anthony's original question.

 

A 5W 220V LED will consume about 5W, a 5W 12V LED will also consume about 5W. There is no appreciable difference in power consumption, so no saving to be made there.

 

Using 12V or 24V LEDs will allow them to run directly off a 12/24V battery, if you keep that topped up with an automatic battery charger then you have a truly uninterruptible power supply. So long as the charger can keep up with the power drain when the lights are on you're good to go.

 

If you have regular long outages you should make arrangements to avoid the battery going into deep-discharge which will significantly shorten its life.

 

We have a computer UPS with external batteries, it keeps some lights on and works a fan should we decide not to run the genset at night.

 

[Naam]

9 hours ago, Anthony5 said:

So my actual question is, does the 12-24V LED circuit use less power from the UPS, so will the batteries last longer, than if a regular 220V circuit with similar wattage lamps.

according to sparky mathematics the result is the same as you are drawing the same amps no matter what voltage you use. negative is when using low voltage that you have to increase the wire diameter. it's most probably more convenient to add battery capacity.

 

OOPS! Crossy beat me to it.

[Daffy D]

"We have a computer UPS with external batteries, it keeps some lights on and works a fan should we decide not to run the genset at night"

 

Crossy have you just connected extra batteries (car battery) to a normal computer USB?

 

I thought of doing this to give extended black out time but I read somewhere (could have been on here) that adding extra batteries would over load the USB charging system 

 

I'm no expert in these matters but I would have thought the charging system would automatically compensate the load of extra batteries.

 

 

 

[Crossy]

@Daffy D  Yes, removed the (dead) internal batteries and hooked two truck batteries outside (it's a 24V UPS).

 

The internal charger peaks at a couple of Amps, so after an extended outage it does take some time to re-charge, I have a smart charger which I fire up to boost the batteries if they need it.

 

Much depends how often it gets used, if you have regular outages then an external charger is a must or the batteries will gradually get lower and lower until they die

[bankruatsteve]

I've read of plans to use the USB port for charging but don't know of any computers that do so yet.  I believe Crossy is referring to charging his UPS batteries.  (?)

[Crossy]

1 hour ago, bankruatsteve said:

I've read of plans to use the USB port for charging but don't know of any computers that do so yet.  I believe Crossy is referring to charging his UPS batteries.  (?)

 

I assumed it was a typo.

 

You cannot push power into a USB port and expect to charge a PC battery, a phone or tablet is a different animal, plenty of power banks on the market to do just that.

[Daffy D]

"I assumed it was a typo"

 

Yes my bad 

 

I blame the spellcheck

[skojevac]

Hi there, I have a question that's not really relevant for the topic, but I hope someone can answer.  I have a four-wheeler that I do not use on a regular basis and its battery tend to run down after sitting unused and there is a small home ups that's been sitting on a shelf for a long time and I thought perhaps to convert it to a car battery charger. I would take the battery out ot the ups and stick another meter or so of wire with alligator clamps at the end.  So the question is how feasible and how safe this setup would be?  I red it may not be really recommended to use regular car lead acid battery with ups, but I would not use it as a power source, only as a charger. Would the ups internal electronics be able to charge 75ah battery, and if so, what's the danger of overcharging? I would install additional circuit as a protection from such scenario. I was thinking about this 12V Protection Module.   . Is this possible and doable? tnx!