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rogthewookiee
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Portable UPS

Tue Jun 07, 2016 12:14 pm

In about three weeks my wife and I are moving to West Africa. We've been told to expect poor grid level power.

We will be using laptops so I don't need a long run time from a UPS. The feature that i'm most interested in is protection from brown outs. From my research so far, that means getting one with an "interactive" or "stand-by" topology.

We will have to check it on in our luggage so light weight is critically important.

This EC350G Cyber Power looks like the smallest i've found so far.

What would be an ideal device would be a power strip with a super cap in it, but i've not seen anything like that for sale. (maybe I should do a kick starter?)

any suggestions?
 
localhostrulez
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Re: Portable UPS

Tue Jun 07, 2016 1:09 pm

You're forgetting a big one - check the outlet voltage in West Africa. It's probably 220V, not 120v, so a surge protector meant for the US won't work.

(Your laptops, however, quite likely don't care about 220V. Check their power supplies to be sure.)
 
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Re: Portable UPS

Tue Jun 07, 2016 1:29 pm

Arguably a laptop has its own UPS built in.

Do your laptops have swappable batteries?
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SecretSquirrel
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Re: Portable UPS

Tue Jun 07, 2016 1:36 pm

A laptop has it's own built in UPS. It's called a battery.

Brown outs are dangerous because as voltage drops, the current drawn by a power supply will increase to maintain the same power output. You can exceed the rated current capacity of cheap equipment or drive power supplies out of regulation. A short term drop likely won't cause an issue. A long term drop under high load will either blow a fuse or cause the supply to shut down.

A good power supply will actually work just fine through a fairly significant brown-out. My laptop power supply (Apple) is rated 100V-240V. Since most of Africa is a 220-240V grid, such a supply would continue to work at less than 50% of nominal line voltage. Beyond that, things will likely just shut down.

Note that the UPS you linked is designed for a 240V grid. It expects 120V input. CyberPower doesn't make a deskside UPS that supports anything other than 120V input. APC does make one: APC BK325I. One other thing to consider. If you are going to be there more than about two years, you will need to be able to source replacement batteries. They are likely to cost as much as the UPS does.

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Re: Portable UPS

Tue Jun 07, 2016 1:42 pm

Get a DC-DC converter and get a cheap car battery and charger there ;)

Edit - like others have said, might want to confirm typical powerline voltage ad frequency over there. NA homes are typically 120V/60Hz, whereas a bigger part of the world is 220V/50Hz. Probably need a plug adapter also.
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Re: Portable UPS

Tue Jun 07, 2016 1:48 pm

An example that shuts off power in the event of a brownout: http://powerguard.com.au/prod/plugin/pgdo3702.html
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rogthewookiee
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Re: Portable UPS

Tue Jun 07, 2016 2:37 pm

The country is Liberia, which uses 120V and standard Edison plugs. (Still might get some adapters for regional travel.)

The computers are a Dell XPS13 and a Surface Pro 4. So sadly no replaceable batteries. I'm leaving my desktop behind.

I have the Dell power supply handy and it is also rated for 100-240, at 45W. 100V from a 120V source would be a 17% drop in voltage and a range of 4.5A to 0.2A right?. (P=VI) I do have a 1000W dimmer available that I could use to find the minimum operating voltage I guess. I've worked as a theater technician for several years, so i'm pretty familiar with the physical infrastructure of power deliver and my undergrad degree included a ton of physics for the equations. However, i've not had to deal with this particular phenomenon!

Maybe it would have been better to lead with asking how to protect power supplies from voltage fluctuation? Or if they need protection?

I do love the DIY idea!
 
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Re: Portable UPS

Tue Jun 07, 2016 3:04 pm

I mean, I've seen switching power supplies (for electronics) that worked fine during a 70V brownout (might've been 50V on the other phase). But I don't think I'd feel comfortable regularly subjecting them to this, if I were you.

That said, here's the thing - cheap UPSes just run your stuff off wall power normally, and quickly switch to battery when needed (i.e. quickly enough that your computer won't notice). If you take a cheap square-wave one and plug a fan into it, this becomes evident (normal operation on wall power, runs terribly when you switch to battery). The pricier ones do sine-wave.

The even pricier ones, as I recall, isolate you from the grid entirely and run everything through the battery, all the time, for maximum reliability - which might be good if you really don't trust the grid power. (http://www.apc.com/us/en/faqs/FA157448/)
 
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Re: Portable UPS

Tue Jun 07, 2016 3:24 pm

Buy a couple spare Dell/Microsoft power bricks while you're still in the US. The Dells can be acquired cheaply off eBay. It would be a potential pain to source a replacement if local power quality issues blew out one of them.

Note that 350 VA units, like the CyperPower you linked, tend to use a 40Ah battery which is lighter in weight, but also a whole lot shorter on breath, compared to the 80Ah battery which is used (as a single or multiples) in nearly every other type of larger-capacity UPS I've seen from 500VA desk-side units to 3kVA server rack units. My assumption is that the larger size would be easier to source if a replacement is needed.
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Re: Portable UPS

Tue Jun 07, 2016 6:44 pm

ludi wrote:
Buy a couple spare Dell/Microsoft power bricks while you're still in the US. The Dells can be acquired cheaply off eBay. It would be a potential pain to source a replacement if local power quality issues blew out one of them.

Note that 350 VA units, like the CyperPower you linked, tend to use a 40Ah battery which is lighter in weight, but also a whole lot shorter on breath, compared to the 80Ah battery which is used (as a single or multiples) in nearly every other type of larger-capacity UPS I've seen from 500VA desk-side units to 3kVA server rack units. My assumption is that the larger size would be easier to source if a replacement is needed.


You are missing a decimal point in your battery ratings. The originally linked CyberPower apparently uses a bog-standard 12V 6Ah sealed lead acid battery. Your average car battery is going to be between 40 and 80 amp-hours.

Back to the original poster. My take? Buy one extra of each power brick, toss them in you bag and don't worry about it.

--SS
 
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Re: Portable UPS

Tue Jun 07, 2016 7:46 pm

As most have already said, don't try to take a UPS with you, your device already has a battery. Save the weight for more useful items. You've already indicated your devices don't have removable batteries. Bring spare power adapters and a small AC inverter. Use the internal battery and fall back to the inverter as backup when your utility power fail. Once you get there, IF you find power really is a problem, try to find either a big sealed lead-acid battery (gel or AGM) or a car battery. The car battery might be your best bet: It can be used, not good enough to reliably supply the current to start a car but still plenty good for 30-40 Ah of backup usage under a 30 to 65 W load.
 
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Re: Portable UPS

Wed Jun 08, 2016 10:52 am

It probably won't apply to your case if you're just using it to survive through brown-outs, but be aware that a normal car battery will discharge pretty fast by itself (in on the order of a week or three). If you're looking to store power longer than that, or can't keep a charger on it, it will discharge and potentially ruin the battery. For longer term storage, you will have to use a deep-cycle battery instead of a standard car battery.
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localhostrulez
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Re: Portable UPS

Wed Jun 08, 2016 12:25 pm

I think it's longer than that - I.e. A car has standby draw of its own, and you can leave it for a few weeks without issue.

But yes, car lead-acid batteries have considerable self-discharge (that's the term you're looking for). And honestly, their typical use case is providing a ton of power for a very short time (starting the car), then being charged back off and staying that way for the rest of the drive - not really what you're looking for. I've seen people run inverters off a battery itself though.
 
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Re: Portable UPS

Wed Jun 08, 2016 12:46 pm

SecretSquirrel wrote:
You are missing a decimal point in your battery ratings. The originally linked CyberPower apparently uses a bog-standard 12V 6Ah sealed lead acid battery. Your average car battery is going to be between 40 and 80 amp-hours.

Good catch, yes. I was thinking in particular of the UB1280 (12 V, 8.0 Ah), which is used in dozens of UPS models and is available pretty much everywhere (in the US, at least).

I've even seen some older APC desk-sides where the 350VA and 500VA models looked identical other than the model number, but the lesser model used the smaller battery.
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Re: Portable UPS

Wed Jun 08, 2016 1:20 pm

localhostrulez wrote:
And honestly, their typical use case is providing a ton of power for a very short time (starting the car), then being charged back off and staying that way for the rest of the drive - not really what you're looking for. I've seen people run inverters off a battery itself though.


Lead acid batteries can be optimized for different things: high amperage, deep cycle, etc. For power backup I think you usually stick with deep cycle batteries. OP, as others have said, don't take a UPS with you. If you need additional backup power for computing, consider a lead acid battery with a car inverter (though if you're not familiar with electrical things, be careful! 12V doesn't harm you but lead acid batteries can crank out tons of amps, so a short can easily cause a fire!). Marine batteries are usually built to more rigorous specs than your standard car battery. Or at least they're bigger.
 
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Re: Portable UPS

Wed Jun 08, 2016 2:31 pm

Hmm, relevant post in another thread: viewtopic.php?f=3&t=117613&view=unread#p1309797
 
rogthewookiee
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Re: Portable UPS

Wed Jun 08, 2016 4:15 pm

Thanks for all the responses!

I'm not sure what part of that other thread was relevant? Other than I can just RMA the PSUs and not tell them where they were killed?
localhostrulez wrote:
Hmm, relevant post in another thread: viewtopic.php?f=3&t=117613&view=unread#p1309797


Apparently I was wrong, and things are 220V. Almost all power is coming from generators, not the grid. Does that change anything?

I guess i'll try and find a 220 surge protector.

It still seems like some kind of power conditioning would make things function smoother? I'm not really worried about not having power, if it goes off then I probably don't need to be getting work done.
I'm most concerned about harming the power supplies or the computers!

In summary, sag on a 220V supply should be handled just fine by a PSU that accepts 100v-240v. The major fear then is still surges above rated voltage. Is that correct?
 
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Re: Portable UPS

Wed Jun 08, 2016 4:58 pm

rogthewookiee wrote:
It still seems like some kind of power conditioning would make things function smoother? I'm not really worried about not having power, if it goes off then I probably don't need to be getting work done. I'm most concerned about harming the power supplies or the computers!

The transformer in your laptop power brick IS a power conditioner. IMO, you're overthinking this. Just make sure you've got spare power supplies for the laptops and you should be good. They'll also help with generator power, as gen sets (unless really high quality/expensive ones) tend to be stepped square wave output instead of sine wave output.
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Re: Portable UPS

Wed Jun 08, 2016 6:39 pm

Hey guys, the car battery suggestion was based strictly on availability and cost. Yes, they are far from optimum, being designed to supply 600-800 amp surge, and not designed to be deep cycled. However, they're just about as common as could be; and, if availability or cost are an issue then finding a cheap used battery might be an option. Certainly a better option than trying to source a UPS in the U.S. to ship to western Africa, given the shipping cost will likely be on the same order as the purchase cost, and given that the UPS might not make it through customs and on to its final destination.
 
localhostrulez
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Re: Portable UPS

Wed Jun 08, 2016 8:27 pm

Captain Ned wrote:
rogthewookiee wrote:
It still seems like some kind of power conditioning would make things function smoother? I'm not really worried about not having power, if it goes off then I probably don't need to be getting work done. I'm most concerned about harming the power supplies or the computers!

The transformer in your laptop power brick IS a power conditioner. IMO, you're overthinking this. Just make sure you've got spare power supplies for the laptops and you should be good. They'll also help with generator power, as gen sets (unless really high quality/expensive ones) tend to be stepped square wave output instead of sine wave output.

Yeah, but are those power bricks routinely *meant* to deal with dirty power like that? Some UPSes out there might be...

I think a basic surge protector certainly isn't a bad thing to have, regardless.
 
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Re: Portable UPS

Thu Jun 09, 2016 7:31 am

Captain Ned wrote:
They'll also help with generator power, as gen sets (unless really high quality/expensive ones) tend to be stepped square wave output instead of sine wave output.


You're thinking of an inverter generator. For those not up on portable generator tech, an inverter generator is effectively a UPS front end being feed by a generator back end. It lets the designer use a high frequency AC section and decouples the engine speed from the AC line frequency. In a "direct" generator,

http://powerequipment.honda.com/generat ... -generator
http://www.jkovach.net/projects/powerquality/

Not that it is of any help to the OP, of course as he may be stuck with what ever is there. That said, a cheap UPS is likely to work even less well with crappy generator power. They aren't designed for that. A laptop power brick is about as forgiving a switching power supply as you are going to find. The front end is going to directly rectify the incoming AC to DC without going through any sort of transformer. The only thing on the front end that will be sensitive to crappy power is the power factor correction components. From the point at which the power becomes DC, incoming wave form no longer matters. For a switching power supply, over voltage is more dangerous than under voltage, especially with a 220V input. The main storage capacitor on the input side will have a maximum voltage rating. A significant over voltage could exceed that rating and shorten its life span.

All the concerns of the OP are valid, but the solutions to them, if needed, are not something you buy without knowing exactly what type of problem you are needing to solve and a likely not something you can just "throw in your luggage".

Best of luck in your adventure.

--SS
 
rogthewookiee
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Re: Portable UPS

Thu Jun 09, 2016 8:17 am

Thanks SecretSquirrel! and everyone else

I'll try and remember to post a photo of whatever the power situation is in a month just for fun!
 
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Re: Portable UPS

Thu Jun 09, 2016 8:23 am

SecretSquirrel wrote:
Captain Ned wrote:
They'll also help with generator power, as gen sets (unless really high quality/expensive ones) tend to be stepped square wave output instead of sine wave output.
You're thinking of an inverter generator. For those not up on portable generator tech, an inverter generator is effectively a UPS front end being feed by a generator back end. It lets the designer use a high frequency AC section and decouples the engine speed from the AC line frequency. In a "direct" generator

I based that on the fairly old generator I have at home. When I have to use it, the circulator pumps on the furnace are really noisy as it's pretty clear that they aren't seeing a sine wave.
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Re: Portable UPS

Mon Jun 13, 2016 7:39 am

Would be rather odd for an electromechanical generator to put out a squarewave, but it isn't hard to imagine one putting out a sinewave that is "dirty" enough to make some devices unhappy.

Regarding the OP, yeah a UPS seems like overkill unless extended outages are the norm. However, some sort of power conditioning would probably be a good idea.
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Re: Portable UPS

Mon Jun 13, 2016 8:51 am

just brew it! wrote:
Would be rather odd for an electromechanical generator to put out a squarewave, but it isn't hard to imagine one putting out a sinewave that is "dirty" enough to make some devices unhappy.


It's more like a small engine, driving a car alternator, being rectified, then driving an inverter. Removes the need for the engine RPM to be controlled and matched to line frequency. If you have a full sine wave inverter on the front, the power coming out is world's better than your bog standard portable generator.

--SS

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