streams and controller on battery backup?

[jeffbrig]

Roger, can you help me out on this one?

I know the streams run on a transformer, but I wanted to know if it is safe to run the system on a UPS type battery backup to maintain water movement in case of power failure. The battery backups produce an approximated/stepped sine wave, which is bad for AC drive motors, but I think will be ok in this application. Can you confirm?

Thanks,
Jeff
(currently waitlisted for a TS24 kit)

 

[rvitko]

It is fine to do this for the 6000 and 6100, they don't care so much about the Hz, it does make a bit of a difference but within reason it is fine.

 

[jeffbrig]

it does make a bit of a difference but within reason it is fine.

Can you elaborate on that at all? I admit, I don't know a whole lot about the streams, but I thought I read somewhere that the transformer actually drives the pumps with 10-11V DC. If that's true, I would expect the AC waveform to have zero impact on the pump motors themselves. Is there another factor that I'm not considering?

 

[rvitko]

The transformer produces AC voltage, a bridge rectifier inside the unit converts this to DC, when you convert AC to DC the total power is influenced by the surface area of the wave form being converted. That is why the US 60Hz models are 11 and 19V and still more powerful that the European models that are 50Hz and 12 and 20V. It is a modest difference but it does exist. I can't imagine this unit would be off by more than a couple Hz so I don't see it making any real difference.

 

[|\/|itch]

So two 6100 streams supposedly eat a maximum of 90 watts, right? At 120 volts, that's 0.75 amps or 750 milliamps. You would then need a 750 mAh battery backup to get an hour of runtime. Is that correct or is there some efficiency factor you have to figure in?

Mitch

 

[rvitko]

That is correct.

 

[jeffbrig]

At 120 volts, that's 0.75 amps or 750 milliamps. You would then need a 750 mAh battery backup to get an hour of runtime. Is that correct or is there some efficiency factor you have to figure in?

Not quite. The battery stores DC, and you're talking AC above. So, what you really need to know is the current that the converter has to draw from the battery to supply 120VAC @ 750mA. That's where efficiency comes into question.

 

[rvitko]

I thought the battery back up rating was at 120V? I mean the commercial UPS systems, what they give on the box is at 120V.

 

[jeffbrig]

They usually give a VA rating which reflects its capacity (as well as a wattage rating, though these numbers are never equal). While this suggests max output capability, it doesn't address runtime, which is where the battery capacity matters. The 750mAh mentioned above would be a puny battery. Assuming that's a 12V battery, that's very close to the total energy stored in 4 NiMH batteries in my digital camera (750mAh@12V vs. 1800mAh@6V). Not something that's going to run a UPS for long.

Fortunately, UPS batteries use lead-acid chemistry, which results in a heavy battery with huge Amp hour ratings. It wouldn't surprise me at all for a decent UPS battery to be rated at 20Amp hours or more, and bigger units have multiple batteries. Bear in mind that the load on a 12V DC battery to generate a 120V AC waveform would probably significant, probably close to 10A DC for each amp of AC current.

If the number mentioned above is for a 750VA backup supply, that would probably be a pretty good choice.

 

[gbtower]

I'm assuming that using a cheap inverter in a backup system would not be acceptable for the non-electronic streams. Anyone have a recommendation for a not too expensive inverter that would be safe to use?

 

[anthonyd]

Looking at the driver unit I see that it has three inputs from a center tapped transformer.

Further more looking inside the unit the three inputs are driven through a standard rectification circuit to produce positive and negative 12V (in the case of the 6000).

Simple electronic theory states that you could replace the transformer with two 12 batteries in series. The positive 24 volt side would be connected to the left most connector on the driver. The "series connector" (where the + of one battery is connnected to - of the other) could be connected to the center connection on the driver and the remaining negative connection could be connected to the last connector on the driver. You would then be supplying the driver with it's +12V and -12V required. The rectifier will just pass this current though without any hassels (except subtracting 0.6 volts from it). Then all you need it to provide the batteries with a constant charge and you can forget about the losses in the inverter.

Dont know what this would do for your warranty though, but then again running off an invertor might affect it too.!

 

[rvitko]

Actually the center pole is a common neutral and the outer poles are both hots.

gbtower- for a short term use like the average 4hr or so power failure it isn't a big deal to use just a UPS system.

 

[gbtower]

I'm assuming that what anthonyd is saying applies only to the electronic streams since my 6080 doesn't appear to have a separate transformer.

Thanks Roger for the reassurance. One of the reasons (although not particularly a large one) I wanted to go to the Streams is because they should run for a good amount of time on a backup. However, I will have to redo my current system since it would've been constantly running off the inverter. I have the charger connected to the battery, and then the battery to a basic portable inverter, and then whatever devices plugged into the inverter. This is on my smaller system, so the stream isn't yet incorporated. But looks like I'll have to get a switchable backup now for the bigger system. At least that is my understanding of what you're saying...

 

[rvitko]

I would just buy a computer type back up. They automatically turn on when power fails.

 

[anthonyd]

Rodger,

That is awhat I am getting at, if one applied +12v to one end terminal and -12V to the other end with a common ground connected to the center terminal you would achieve the same as using the transformer but with 12V battries instead. But I am sure Tunze will not condone doing this hey?

gbTower yes I was referring to the 6x00 series which use a transformer and untimatly use DC only.

 

[rvitko]

I think actually the 12+ from each battery would go to either end and the 12- of both to the center. We actually are working on a photovoltaic version for ponds but this might be a ways off, we kind of need to focus on what we do already and getting caught up. If you connect the negatve of one to the hot of the other you get a 24V system and 20V is the absolute limit of the Stream. And, no we would not condone this because their are too many risks if it is done wrong and also the hazard of lead acid batteries in general.