Power inverter advice...

Christo

I'm hoping someone can help me turn a miserable past two weeks into something better…

So as an underpaid, overworked music teacher I was looking forward to our mid-year four week holiday. Plans were to catch up on some work, spend some time on my composing hobby, practice lots of piano and visit some friends I haven't seen in ages.

The Friday that the school closes I get that "coming-down-with-something-feeling", but it feels very mild and I'm still optimistic (despite the fact that one of my music co-workers were visiting with family the week-end prior whom all got sick and tested positive for Covid, and she was ill for the first half of the week and we passed lots of test papers back and forward for end-of-term moderation.)

Comes that night I got a fever which basically lasted for three days and kept me away for as many nights. Next day it was fever all day and deadly tiredness. The Sunday the throat ache started. Seven straight days with the worst sore throat I've had in years followed.

As bad as this was it wasn't all. We're no strangers in South Africa to load shedding where we'd sometimes not have power for two to four hours a day due to failures at power stations and what not. Basically as a result of a decade of state capture where our previous criminal president of the country appointed his crooked cronies in key positions at all state enterprises which includes the power utility which followed ten more years under Apartheid-free SA where the government in a bid to win votes sacked all the previously experienced (white) engineers and craftsmen to appoint under-qualified black personal. So with all the robbery and maintenance failure coupled with our ongoing population explosion our power network is extremely stretched.

Just as the holiday started the workers at the national power supplier embarked on an illegal strike action which only got resolved a day or two ago (with a resulting backlog in work that seems to have no end in sight).

So on top of feeling miserable I had to endure between four and six hours without electricity for the past two weeks.

The only bit of good news I had was a sizeable tax refund which I did plan to use to stop a few holes but will probably have to be spent on some sort of power back-up system. (Luckily I have that available now.)

I need some advice on the power requirement I'm looking at…

I basically want to be able to run my laptop, my monitor (I cannot work on a 13" screen when working on big orchestra scores), my WiFI router and especially my electric piano (Yamaha P-250) for up to about four hours.

Keep in mind I'm not at all technically minded.

My piano has a late at the back that says 230V 79W~50Hz

From what I understand one get these battery trolleys with an inverter that you charge at the mains and then that automatically kicks in when the power goes out.

But they come with different capacities and I don't want to get the wrong thing. I'm not sure what info to give to some store attendant with regards to my electrical piano. Most people get these to keep there PC's and TV's going I guess…

I'll appreciate anyone with knowledge or experience that can give some advice.

QuasiUnaFantasia

Here in Denmark we call such a thing by the very un-Danish name: UPS (uninterruptible power supply). You can probably do with an offline one, which kicks in immediately if the power supply stops. There are more expensive types that improve the quality of the power, but that is probably not what you are after.

MacMacMac

A computer UPS isn't made to run for four hours. It's meant for brief power outages.
You'll need a commercial grade device. Very expensive.

Instead, get a gas-powered generator.
Use the generator to feed a "proper" UPS.
Add up the total power consumption of your devices and get a UPS that can deliver more than that.

The UPS will clean up the "dirty" power that the generator provides.

Note that if you use a regular UPS, it will run off the mains when power is available.
But since that power is coming from the generator you'll be getting dirty power.

So ... when I say "proper" UPS I mean that a UPS that runs on batteries at all times.
When power is available the battery charge is maintained.
And the power drawn from the battery will be converted to "clean" AC for your devices.

Del Vento

MacMacMac Add up the total power consumption of your devices and get a UPS that can deliver more than that.

This is the key aspect. Example:

Laptop: 120W (call it 150W)
Piano: 79W (call it 100W)
Monitor: 80W (call it 100W too)
Router -- do you need it? If power is out, probably internet is out too regardless
Lamps: 20W (call it 50W, and it's assuming you have LED, otherwise much more)
Additional stuff you may need and have not thought about: 100W

Total FOR THIS EXAMPLE: 500W. If you want to run it for 4h, multiply 500 times 4 and you get 2kWh. Do your math with your actual numbers, always round them more (but don't overdo that, otherwise the result would be "a whole nuclear power plant 😉 )

The 2kWh is not a negligible amount for a purely battery-powered appliance. You can get it, but it's gonna be expensive, and batteries are not like diamonds (aka, they deteriorate and you will need to replace them at great cost). On the other hand, 500W is less than one horsepower, so very easily generated by a small internal combustion engine. Hence the suggestion that @MacMacMac gave

MacMacMac Instead, get a gas-powered generator.

which I second. However get a good one, with a 4-stroke engine. The 2-stroke engines are cheaper (if legal in your country), but they are more noisy (and trust me, even the 4-stroke ones are too noisy and I would never want to be near one!!!!!) they require more maintenance, they burn their lubricating oil, so they make the air quality miserable, right next to you, and you cannot store the gas+oil mix they burn for long, so it's a hassle.

MacMacMac Use the generator to feed a "proper" UPS.

I think this is overkill. The proper, battery-powered UPS would need to be able to provide those 500W, even if for just one minute or two. That is not a small amount. So you are ruling out the inexpensive ones. Plus, again, the diamond-priced but not diamond-lifetime-expected batteries. Main advantage? Not losing power at the moment of the power disconnect. Without one, power goes out, you lose power and stay without until you start the generator. Annoying, but not a big deal, since you have a laptop, in my opinion. Yes, the generator power can be dirty, but it may be good enough for most things and there are some with filters to make it cleaner. So instead, use the money for the UPS to get the best power generator you can afford:

best possible filters in its own power output, so it "cleans" its current
catalytic convert so it does not make your air quality bad
good muffler so it does as little noise as possible (which trust me, would still be TOO MUCH noise, and you will be glad when power is back and you can turn it off)
other bells and whistle as the manufacturer and you deem appropriate e.g. for monitoring its status remotely, starting it, etc -- think about the engine of your car vs the engine of your father or grandfather car: which one you liked better?

Best of luck, my friend.

Christo

Thanks for the replies all. As it is I'm counting down fifteen minutes to the next two hours in the dark (16:00-18:00) SA time.

I will thus read through all the suggestions at greater length at some stage.

The only two quick things is that a fuel operated generator is perhaps not an option since I live in a flat (the noise factor is why I have to rely on an electric piano to begin with)

Secondly (and I stand to be corrected), is a UPS like one gets for a PC not just an emergency back-up to give one time to save and back-up data, when an unexpected power outage occur? This is how I saw that type of thing being advertised (often with the explicit statement that it is not a back up power supply [to run for an extended period of time])?

I got about 600 USD in my tax refund and I was hoping to spent no more than two thirds of that on something like this, but I would rather pay more for something that would supply in my need (and that would at least last a couple of years).

My frustration with our current situation knows no bounds and there seems to be no light at the end of the tunnel - literally.

As I mentioned before it's basically just to keep the laptop and electric piano going. Even if for only two to three hours perhaps then.

This situation with our electricity is such a hassle. Imagine your power is out from 16:00 to 20:00 like mine last night. You just got home from work. So you waste time doing all sorts of things you didn't intend doing, and then when the power comes on again someone like myself (who is a morning person) feels like starting to wind down for the day. This morning again from 08:00 - 10:00. So effectively I can get nothing done.

Lights and cooking is not an issue as I have a gas burner and some hand held chargeable battery led lights to put around the flat. I don't own a TV so my laptop is not only my workstation, it also provides entertainment.

Del Vento Thanks for the useful suggestion as to how to do the calculations. I'm definitely referring back.

QuasiUnaFantasia

Maybe I'm just terribly behind the times, but I thought UPS's operated via coils (ie. electromagnetic storage of energy), not via batteries.

Del Vento

Yes, given the situation (I thought you had a single family house), I think you have to restrict yourself.

Rhodes74 Doesn't the laptop run on its own battery for some hours?

Put it in aggressive power-saving mode, if you can, forgo virtual instruments if you can, and use it only for the scores. Forgo the external display too if need be.

Rhodes74 If the piano has an internal power supply you might have somebody to install an DC input bypassing it.

Complicated, unless you can find the right person. Easy if you know DIY -- but it may be a eyesore if not done correctly and may cause damages. How attached are you to this one instrument? If not much, consider stepping up or stepping down (selling or keeping this other one, as it best fit your needs). How about buying a VPC1 instead, which does not need power supply (it's powered by USB from the laptop, and has modest needs)? Definitely a step up in the action department from the P-250, but no internal sounds (needs virtual instruments from laptop). If that is not your cup of tea, how about one of the battery-powered slabs? The Roland JUNO for example. From the action perspective, I think that would be a step down from the P-250, but I am not sure (and it's probably a step up from the sound and workstation perspective, if you do that kind of stuff). I suspect you have many more options, just that you have to find details which are often considered irrelevant (battery and power supply specs)

Rhodes74 If not being playing loud. the piano will be surprisingly modest in power consumption.

Yes, and even less so if you are ok to using headphones. As a data point, I once used a power supply like the one described below (but with much smaller battery) to power my NU1 and a friend's JUNO for one hour. It worked just fine.

Christo I don't own a TV so my laptop is not only my workstation, it also provides entertainment.

But does the internet stay? You router is out, ok, and you could put on backup power. But do the internet providers have enough UPS to stay up during such a prolonged outage? I doubt it, so I think you'd be offline anyway (ok, you can use pre-downloaded content).

So in conclusion, consider also using that budget to improve your more-directly-musical gear, rather than the power infrastructure. Wouldn't that be more fun? 🙂
Also a new laptop, and/or second laptop battery if the current one is inadequate. You may still find that you absolutely need the battery-powered supply (e.g. for the external monitor), but if you have removed or greatly reduced the other needs, a wimpy one (those that sell for less than $100 in the USA and run of a relatively inexpensive car battery) may suffice [*]. Typical car batteries have 50Ah which means 600Wh which means can supply 100W for 6 hours (theoretically). Even assuming absurd 50% efficiency (it'll be better), you have 100W for 3h, which will be enough for a not-too-bright display which typically eats 50-80W and may have some spare capacity for something else not too hungry.

[*]: I am not recommending DIY, since some batteries require venting (do you have a balcony where you can place this thing?) but you can be successful with DIY if you know what you are doing or if you follow carefully instructions from a VERY TRUSTFUL source

Rhodes74

Doesn't the laptop run on its own battery for some hours?
So you only need to power the piano.
If it has an external power supply, just skip it and connect a small lion-akku instead.
If not being playing loud. the piano will be surprisingly modest in power consumption.

If the piano has an internal power supply you might have somebody to install an DC input bypassing it.
By feeding DC you avoid the losses of up/down conversion. Get a modest battery of fitting voltage and, most important, cycle-proof. Ignore the monitor for some hours…

-Rhodes74

MacMacMac

Rhodes74 Doesn't the laptop run on its own battery for some hours?
So you only need to power the piano.
If it has an external power supply, just skip it and connect a small lion-akku instead.
If not being playing loud. the piano will be surprisingly modest in power consumption.

How long will the laptop battery last? The OP lost power for four hours last night.
Will the battery hold up that long? Maybe.
Will it hold up that long even when running virtual instruments? Hmmm ...
The piano's average audio output is tiny, regardless of how loud you play.
The peaks are loud, but the average is small.
So the piano's power consumption won't vary much at all.
Power reduction from using headphones instead of speakers will be quite small.

Rhodes74

Del Vento run of a relatively inexpensive car battery

car batteries (and most lead batteries) are not designed for power cycles. Most of them break down at the first complete discharge.

-Rhodes74

Del Vento

Should be enough to extend battery life on a laptop and/or power a USB-powered piano such as the VPC1

Del Vento

Rhodes74 car batteries (and most lead batteries) are not designed for power cycles.

True, they should stay fully charged as much as possible, I had forgot about that in part of this discussion. Thanks for pointing it out explicitly!

Rhodes74 Most of them break down at the first complete discharge.

That is why I was not recommending DIY, to make sure the battery never discharges too much. That also mean that my back of the envelope math is wrong (since it assumed complete discharge), but the whole point remain: it's an option. I have used such an option for various purposes (camping, telescope nights, power outages). In my experience in practical use (not regular daily usage though), the battery lasts a few years.

Christo

My laptop battery will last only about an hour. I can replace it comparatively cheaply, but I just cannot work on a 13" screen so running the monitor and my electric piano is my main need.

The piano is just for practicing with head phones. (Now during the holidays I planned to put in quite a few hours per day)

Below are some of the things which seem to fly of the shelves now with the current situation in South Africa (as they say, one person's need is another person's greed…)

with what it claims to be able to do…

Or it's this type of thing:

Or this…

The Gizzu thing is also available in smaller capacities (which I won't consider) and bigger (518Wh)

The concern with the full generator is the noise and with the Mecer inverter the longterm life and cost of the batteries.

With the Gizzu product using Lithium technology I suppose it will last longer, but it's perhaps the most lightweight of the three in terms of capacity.

Del Vento

Christo Below are some of the things which seem to fly of the shelves now with the current situation in South Africa (as they say, one person's need is another person's greed…)

Do you know the dimensions of these things? Do you really need the inverter? If you can power stuff in DC, you'll gain a bit of efficiency (in both energy/duration and in space/cost of the equipment).

Assuming the specs are accurate (which I suspect they are not), as @MacMacMac was saying the 300Wh Gizzu should have you covered. Probably they will produce more of a square wave than a sine one. How that is a problem? I suspect not much, since the power supply is going to simply make a DC from that, but I don't know for sure.

Is the currency more or less in parity with USD? That 26Ah @ 5V = 130Wh that I posted from Amazon, at less than $30 looks like a bargain…

My Dell monitor has an external power supply similar to some Dell laptops which runs at 20V. With a cursory look, I did not find any power bank at that voltage, but what do you need? At 5V (USB) and 12V (car) it's easy to find stuff, e.g.

The latter, if its specs are to be believed, is 72Ah @ 12V hence a whopping 864Wh at a cheaper price than the inverters, because there is quite less electronics and more efficiency (if my currency conversion is correct).

So, do you really need AC? I think you should try hard, e.g. swapping gear to answer "no" to this question. Also, you may consider separate power supplies for separate items, which may be cheaper and safer (if one breaks down, the others are still available).

Christo Lithium technology I suppose it will last longer,

Compared to lead and to Cadmium yes. But that too has a its own lifetime, and if you want to extend it, you have to keep it half charged and leave it at that…. So I'd say don't worry about that, perhaps just check the reviews.

MacMacMac

You really must first know how much power you need.

As for the items you listed ...

The Gizzu offers 296 watt-hours. Let's round off to 300 Wh.
That'll run a 100 watt load for three hours. Or a 300 watt load for one hour.
That's if the given device rating is honest ... which we don't really know.
Also we don't know about how clean the output is. Or maybe that's in the fine print, which I can't read from the pic.
If it's clean then this would keep you running for a while ... so long as you keep the load quite low.
But, as I said above, you need to know how much power you'll be drawing.

The Mecer is rated at 2400 VA (2400 watts). But it also says 1440 watts. That's curiously inconsistent.
In small print it says it will run for 8 hours at 150 watts.
I don't know your power requirements … but I think this is probably adequate for you.
But it also says that "this unit not suitable for use with an Apple iMac as they require pure sine wave".
In my book all laptops should be driven with sine wave. So I would not use this unit.
I'd use it with lamps for lighting, but not for electronic items.
It might work ... but I would not risk my devices to a cheap, dirty-power inverter.

I guess you'd rule out that Ryobi generator because of the noise.
But if I were buying a generator I'd also worry about the dirty electrical output.
If I could get clean output I'd buy one with a Honda engine.
Most other engines are crap. Also, Hondas tend to run a bit quieter.
All will require maintenance.

Christo

MacMacMac

Thanks for the response.

All other members' advice ia also much appreciated.

I would probably only want to run the laptop with its monitor at any given time OR the electrical piano. No need for everything at once since I can't be using it all at once.

If the Gizzu could let's say run this set-up for three/four hours it would suffice. It claims it can even run a small fridge (100W) for up to five hours (The info I posted previouslyfor the smaller model says three hours). Sorry for the small print.

This is also from their specifications for the 518W model. (A bit more detailed and perhaps easier to read…)