POWERRR!

[4Lmike]

I shall more than likely be investing in some lighting gear (300ws flash heads with stands etc etc) in the near future and have come across the issue of powering them when on location. I've noticed that these portable power supplys can be quite expensive (eg. http://www.warehouseexpress.com/buy-tronix-explore... ) so tried to find some alternatives. Does anyone know of any good reason why I can't use this ( http://www.powerinspired.com/product_info.php?prod... ) instead? It's a UPS designed as a backup for computers when the electricity dies, but essentially has the same power, or more, than the first example I showed you.

[AndWhyNot]

I think when it says backup time in the specification it means run time, at full load.

Check the description of this eBay item, the guy says it's been used for photo shoots: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&am...

[4Lmike]

AndWhyNot said:

I think when it says backup time in the specification it means run time, at full load.

Check the description of this eBay item, the guy says it's been used for photo shoots: http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&am...

hmm...I have a feeling I know who is selling that, given the user name

[AndWhyNot]

Yeah but we don't want your thread getting pulled for ads on PH do we, oh no, that wouldn't do.

[4Lmike]

anyway, back on topic, that looks pretty good but its still £200 compared to £60ish for the UPS I suggested. if that ups can give me the same power output and 1000 flashes from a 300ws flash head like the power supply in my first link then its a pretty good deal i would think. I'm really just wondering if theres something missing from the ups that means it wont be able to do the job of the other power supply?

[sgrimshaw]

At that price and intended usage I expect the batteries in the UPS are not designed for deep cycling.

As a UPS it's purpose in life is to supply power for a very short time, very occassionally.

The Portable Power Supply is designed to supply power, then be recharged frequently.

Compare the charge times and weight, and you'll see that there is a considerable difference.

My guess is that the extra money, and the main difference, is in much higher performance batteries.

[Simpo Two]

Well for £60, try it, and if it's no good sell it on eBay and then you know you need the proper one.

[matheson]

The Tronix is a good unit, I've had one a while now and use it with my Eli BX400s. Takes a good few seconds to catch up after full power shots, but it copes and hasn't missed a beat to date.

[AndWhyNot]

AndWhyNot said:

I think when it says backup time in the specification it means run time, at full load.

ie 3 mins

[4Lmike]

AndWhyNot said:

AndWhyNot said:

I think when it says backup time in the specification it means run time, at full load.

ie 3 mins

yes but it will only be at full load (750watts) for a split second each time the flash fires

[baz7175]

I'm not too sure the UPS is going to do what you want to be honest, they're designed to sit hooked up to mains supply and ONLY take over when things go up the left, once power is off they will continue to run until their internal battery packs die (as said previously this is normally only for a short period of time), the batteries will normally start to drop off as soon as you remove the power as the system is then in it's "need to run" mode, if you turn off the UPS the batteries may automatically discharge themselves, and honestly I personally wouldn't be for leaving it turned on and driving to a location for a shoot with it charged.

Put it this way, I've several thousand bucks worth of UPS on work systems (which basically have 12 massive battery packs each of which weighs around 6kg) and this ONLY supplies 4 PC's and a few small sub 50V components - I'm lucky to get 10-15mins run time out of this and it's pretty much up to the latest standards as far as performance.

I'm not saying 100% the unit you mentioned won't work for what you need it to do, but the typical use of a UPS is a non-movable backup for emergency power out situations to allow a short period of time to shut down sensitive equipment and systems safely.

[tog]

Why not just get battery powered lighting?

[MartinP]

The UPS is designed to be able to supply a large amount of power for just a few minutes. A power supply that can do that and also sit efficiently at a very low quiescent power state is more complicated. Given the relatively low cost of the supply you've highlighted, it will have been designed to be as simple as possible and I reckon that it would discharge itself pretty quicky even with no extenal load applied.

Had you considered a car battery and a chunky mains inverter? You'd probably be looking at a couple of hundred pounds though for a decent leisure battery (designed for repeated deep discharge use) and a powerful enough inverter. For that you'd be able to buy a couple of speedlights and radio triggers, which could be an alternative route...

Edited by MartinP on Thursday 6th January 10:28

[//dean]

Worth noting that a power supply for flashes MUST be Pure Sine Wave, or else you'll end up blowing fuses left right and centre in the flashes.

I have my petrol genny on ebay at the mo which is 1KW max output, worked an absolute treat for my 2x 400W flash heads, fog machine, battery charging, laptop charging etc etc. And it never runs out of batteries meaning an 8hr recharge, you just need to find a local petrol station.

[Simpo Two]

//dean said:

Worth noting that a power supply for flashes MUST be Pure Sine Wave, or else you'll end up blowing fuses left right and centre in the flashes.

That wipes out all the cheap 'suitcase' generators. Pure sine wave ones cost much more.

[matheson]

OP - if you're starting from scratch it might be worth looking for more info on the Calumet Genesis 300B Flash Head + 300 PowerPort Power Pack, or better go to your nearest store and try them.