Powering printers without mains

[Paul Frost]

I'm looking for advice/experience of using the common Epson splits printer without mains power.
I have a Belkin inverter rated for 300 watts (only if connected direct to the battery, 150 through the lighter socket).
The transformer for the printer says it's 240v 1.3A which I think equates to about 300watts, does that sound right?
I used it at a recent event but the inverter was constantly beeping a warning that it was not happy. I continued and ran it for about an 90 minutes and printed about 80 splits. The car battery sill seemed to have plenty of life when it came to starting.
How long would you expect a car battery to last with this sort of drain?

I am not very good at electrics so it would be good to know from someone who is.

I do have the battery printers that come with the SI schools kits but they don't seem to interface with a computer, unless anyone knows different?

[Spookster]

I'm looking for advice/experience of using the common Epson splits printer without mains power.
I have a Belkin inverter rated for 300 watts (only if connected direct to the battery, 150 through the lighter socket).
The transformer for the printer says it's 240v 1.3A which I think equates to about 300watts, does that sound right?
I used it at a recent event but the inverter was constantly beeping a warning that it was not happy. I continued and ran it for about an 90 minutes and printed about 80 splits. The car battery sill seemed to have plenty of life when it came to starting.
How long would you expect a car battery to last with this sort of drain?

I am not very good at electrics so it would be good to know from someone who is.

Power is voltage time current, so 240v x 1.3A = 312 Watts (so yes, you were about right)

A small petrol-engined car battery is rated at about 40 Amp Hours (Ah), and a big battery for a diesel-engined car is about 100 Ah. Running your transformer for 90 minutes at 1.3 amps has barely touched the battery capacity (1.3A x 1.5 hours = 1.95Ah).

Some clubs run their entire results system (laptops, printers, network) from a couple of batteries and inverters, which avoids the noise of a generator.

I do have the battery printers that come with the SI schools kits but they don't seem to interface with a computer, unless anyone knows different?

I think it's possible, but not easy. The schools kit setup is fine for training and activities, but if you want "proper" event results I'd stick to using laptops and normal splits printers.

[Zokko!]

I have successfully run two laptops and a thermal splits printer (a Star rather than an Epson, but with very similar power requirements) for many events, using a 300w inverter powered from a 110aH leisure battery. This avoids the possibility of flattening a car battery and allows the possibility of having download remote from your vehicle. I use a small folding trolley to transport the battery and all other kit if necessary.

It would appear that the limited capacity through your cigarette lighter socket is causing the problem. It may be worthwhile connecting direct to the car battery in future, if you don't want the bother and expense of a dedicated battery for the inverter.

[Paul Frost]

It was connected to the battery direct when it was beeping a warning.
Which I guessed was because the demand was right at its limit. The cables didn't get warm so I carried on.
Looking at getting a new inverter with a higher wattage I see that some are Quasi sine wave or sine wave or nothing, is this important?

[Spookster]

Looking at getting a new inverter with a higher wattage I see that some are Quasi sine wave or sine wave or nothing, is this important?

AC electricity ideally has an exact sine wave profile. An inverter creates a pseudo-sine wave profile out of the DC voltage, and some inverters do this better than others. Worst case would be an inverter that just created a square wave.

Having a profile that isn't a sine wave has the potential to damage whatever you plug into it. But if you're plugging a transformer into the inverter (as you would be, with a laptop and splits printer), that probably won't cause it any damage, whatever shape the wave.

[DaveR]

Short (not very helpful) answer:
I haven't tried this, but expect that the printer and battery will last for several hours, it depends how heavily it is used. Try it and see.



Longer (not very helpful) answer:

Yes, the 300W figure is about right. However it is probably the maximum that the printer will ever use and most of the time it will be using much less power. However it might get close to this at some points in the printing and that could be upsetting the inverter. Does it complain mainly when actually printing?

A small petrol-engined car battery is rated at about 40 Amp Hours (Ah), and a big battery for a diesel-engined car is about 100 Ah. Running your transformer for 90 minutes at 1.3 amps has barely touched the battery capacity (1.3A x 1.5 hours = 1.95Ah).

40Ah is a good figure, but the battery only produces 12V, so the energy stored is 480VAh (fantastic units but they'll do for comparison).
The printer needs 240V, so at maximum power it will consume 1.3*240=312VAh in an hour. So if the printer was operating at full power all the time it might last ~1 1/2 hours. In practice I would expect it to be a lot longer and a battery with more Ah will last even longer.


(As an aside: The inverter does the voltage conversion but even at perfect efficiency Volts*Amps in= Volts * Amps out, so to produce 1.3A at 240 V out of the inverter needs 26A at 12V from the battery)

[Paul Frost]

I was using with my VW transporter van, so probably a big battery.
It was beeping all the time, not just during printing.
I suppose a possibility is that it may be faulty.

[ifor]

How close was it to the liesure battery? How thick are the cables? You can get a significant voltage drop with longer thiner cabeling, they never realy suply these things with thick enough cables for anf length of cable run. As has already been said most the rating will be the max I would not expect you to see this in real life. I can run a laptop and a printer no problems off a 300W inverter. I have even had a laminater going as well and that dose actualy use power more continuasly.

[Paul Frost]

It was clipped directly onto the main battery under the bonnet, with about a foot of cable (as supplied with the inverter).

[Adventure Racer]

Just to go off on a slightly different tack - you suggest you had a transformer for the printer plugged into the inverter. What's the output voltage of the transformer?

[Paul Frost]

24v 2a
It's the standard power lead supplied with the printer.

[Adventure Racer]

Does the transformer get extremely hot?

How about one of these:
http://cgi.ebay.co.uk/120W-DC-Car-Charg ... 440wt_1165

[Paul Frost]

Not very, but warm.

[Adventure Racer]

Well it is theoretically a 250W heater you've got there (ie 12 of them for a 3kW bar fire).

No thoughts on cutting out the middle man by going straight from 12V to 24V? Far cheaper and more efficient than a more powerful inverter.

Coming back to the original issue, I suspect the problem might be that the "transformer" is an inductive load rather than a purely resistive one - this means that the waveform of the current doesn't follow the waveform of the voltage. Inverters don't really like loadings like that, hence why it's complaining.

[HOCOLITE]

I know nothing technical about these issues but the printers seem to produce a massive 'surge' sudden demand on the power, when the printer powers up our Belkin ****'s start to beep regularly. However the split printers don't cause that. We use a generator because of this. The inverter we have as an emergency never seems to be of any use. I suspect it is not up to the job