[Chiuso] Uninterruptible power supply  

Re: Uninterruptible power supply

I considered batteries, then bought a small ups...
the ups is a very tidy solution. and there is no need to worry about modifying things.
also I can use the printer anywhere where as with a battery solution you would have difficulty moving the printer...

Joan

Re: Uninterruptible power supply

With battery you will get very variable power on heaters with unexpected results. I would not go this way. Use the UPS.

Re: Uninterruptible power supply

Michael

Yes, you could run off batteries - the RAMBo has an upper voltage limit of 28V I believe.

However, as David says, the problem is with the heaters which are powered from the input voltage line and you would probably end up blowing fuses on the RAMBo.

So, your options realistically are either UPS or to use a 12Volt battery with a buck and boost converter which should be capable of supplying at least 25 Amps (30 A would be preferable).

Peter

Re: Uninterruptible power supply

Use a UPS and use a back up car battery for the UPS, that way if he UPS looks like it will run out of back up power before your print is done you can connect in a out side battery to keep the UPS going.

Re: Uninterruptible power supply

What size UPS is required for the Prusa i3 MK2 ?

What is the maximum power consumption, when heated bed and extruder and fans and stepper motors are all in full action?

Re: Uninterruptible power supply

And is a true sine wave inverter required or will a cheaper 'modified sine wave' do?

Re: Uninterruptible power supply

I bought a Powercool 1200va UPS, seems to work Ok...
like this http://www.box.co.uk/Powercool_Smart_UPS_1200VA_1359075.html

another site says it has a squarewave invertor... so I guess it's more mangled sine wave than modified sine wave...

I have no idea how long it will run for, on the battery...

I don't particularly want to risk running it flat and ruining a print...

the datasheet says it is OK with generators... if that's a consideration...

regards Joan

Re: Uninterruptible power supply

Here is how to use an Uninterruptible Power Supply to stuff up a print:

1) Realise that the UPS draws quite a bit of standby power, even once the battery is fully charged.
2) Do the smart thing and turn the power to the UPS off when not using the printer for a couple of days.
3) Do the not so smart thing and turn on only the UPS when you start your next print.
4) Measure a hitherto seldom mentioned calibration dimension of the 'Benchy" : How thick does your printer print the Benchy when it is not connected to the main power?

I would of course NEVER do such a stupid thing, 😳 but if I had done it, theoretically, then the Benchy would have grown to 2.90mm thick before the power failed.

The UPS that I would have used (if I had done such a silly thing) is the CyberPower Bric 850VA / 510W.

😀

I got it from Officeworks (Australia) and it works quite well so far.

Re: Uninterruptible power supply

These things happen. Like clearing the blocked U bend on the sink And then tipping the waste water into the same sink. Before reattaching the U bend... 8-(

Joan.

Re: Uninterruptible power supply

When the mains fails, it is often not clean. Auto reclose breakers on High Voltage network etc. Maybe eventual lockout on permanent HV fault. LV faults may blow your your local substation fuse. Transients on the LV feed to your house. Whatever event the delay in the uniinterruptable power supply to take over will wreck a print, so don't bother. Waste of money. We have a realible supply here, and I live in a rural Town.

If the printer remembered where it was before the glitch maybe have saved the day. We need stepper feedback and true position information. And other parameters ie hotend temp and bed temp before carrying on with a print.

Re: Uninterruptible power supply

W...
...
Whatever event the delay in the uniinterruptable power supply to take over will wreck a print, so don't bother. Waste of money. ...
...
....

I don't think so. Time will tell, because power outages are not all that uncommon where I live. Lots of thunderstorms.

Re: Uninterruptible power supply

Agree totally with Michael

We have overhead power lines and thunderstorms twice a year. I have my printers powered via an APC UPS (3000) which also provides power for my server and workstation. I have never lost a print due to momentary power outage (there are many of these) nor any short power cuts.

Only time I lost a print was when I didn't check the provider's web site and they had a planned 12 hour cut on a Saturday. The UPS did manage to last for almost 4 hours though...

I think there may be a clue in the name of the device: "Uninterruptable Power Supply"...

Peter

Re: Uninterruptible power supply

+1

UPS can last long enough to cover all common power outages. In case of long outage (longer than one hour) it provides enough time for me to get mobile generator and plug the UPS into it to save valuable print if necessary.

Re: Uninterruptible power supply

David

Nigel is suggesting that switch-over from mains supply to UPS power takes too long and the printer will not be able to handle the split-second down time.

That is certainly not my experience with either computers, monitors nor 3d printers. My guess would be that his suggestion is based around cheap and nasty £50 UPS devices which most of us would not consider a workable solution.

Peter

Re: Uninterruptible power supply

Nigel is suggesting that switch-over from mains supply to UPS power takes too long and the printer will not be able to handle the split-second down time.
That is very unlikely to happen.
Switching power supply of the printer itself (without UPS) can withstand about 100-300ms of power outage, depends of actual power consumption. Any UPS should provide satisfying results as long as its output power is sufficient for the printer (250W).

Re: Uninterruptible power supply

There are different kinds of power supplies out there. Some are switching, some of them run the devices off of battery all the time and keep the batteries charged while doing so when mains power is available. It all depends on how much you want to spend for the UPS.

Re: Uninterruptible power supply

Yep how much you want to spend and how much your print time is worth? A good UPS (Uninterruptible Power Supply) will probably cost more than your 3D printer.

I never leave prints running when out of the house.

In the last 34 years that I have lived here in my rural town (overhead line network) I have had less than 10 power outages. A few seconds/ minutes to a max so far of 8 hours < on one Christmas Day. (Even in the so called England hurricane of 16th Oct 1987, we were off supply for just over 4 hours, only)

A UPS is a waste of money and they need maintenance, more money and if neglected!!!! why bother . Transients bugger up 3D printers more and get through UPS.

I know some countries like the USA and others have 3rd rate/world power supply systems. We Power Engineers built well here. A shame that our government lacks vision in the energy sector, and ignores the base load at their peril. Our margins are getting lower as more coal fired and nuclear powerstaions are due for retirement and come off the grid. (Hint... Renewables are not reliable coverage for base load, the wind doesn't always blow and the sun does not always get through a cloudy day when you need them most, ie weather is random, no way to cover realiably a base load)
Also renewables are paid to not generate via subsidies when over supply is concerned.

Often in the winter we have a countrywide anticyclone ie no wiind low sun angle and temperatures well below zero deg centigrade. That can last for many days. The base load generators would be the only coverage. ie fossil fuel coal and gas powerstations and fossil free nuclear power stations. Many due to be shutdown soon, here in the UK.

Re: Uninterruptible power supply

Yep how much you want to spend and how much your print time is worth? A good UPS (Uninterruptible Power Supply) will probably cost more than your 3D printer.

For the purposes of supplying a 3D printer for a few minutes a good UPS will only cost ~$100. Definitely NOT near as much as my MK2.

I never leave prints running when out of the house.

This is your choice. Staying at home or leaving has no bearing on when the power may go off. If your home or away when the power flickers or goes out for 10-15 seconds your print is ruined without a UPS

A UPS is a waste of money and they need maintenance, more money and if neglected!!!! why bother . Transients bugger up 3D printers more and get through UPS.

What maintenance? I check the battery on the 3 in my house monthly. That's it, no other maintenance is required.

I know some countries like the USA and others have 3rd rate/world power supply systems.

Wow! Do you even know the extreme distances that power has to be delivered to some parts of the US? Some of the extreme weather we have to deal with? 100F for 100 straight days in Texas. -10 to -50F in Minnesota. Here's a size comparison of just the state I live in...

Re: Uninterruptible power supply

If your home or away when the power flickers or goes out for 10-15 seconds your print is ruined without a UPS

Again, there are several factors that play into making this statement either true or false. Not all UPSs are made the same. Some are switching like this yes, but not all of them.