UPS inverters scaleability ?

Nuff

4) There are conflicting opinions about UPS inverters such as this.
http://www.ebay.co.uk/itm/400518403771?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
I have one similar but 1.5kw and it's been in use since 2009.
It's been coupled to 4 x 180 A/H 6v batteries and works but I'm being told it's probably highly inefficient.
They aren't intended for a large battery system but apparently have higher upper limit eg the 750XL is 2500VAH.
Has anyone got knowledge of these ?

techntrek

Re: UPS inverters scaleability ?

I've used several UPSs for years, much larger than the ones you've mentioned (see the link in my signature). There is no difference between "inverters" and "UPSs". The inverters which include battery chargers are no different than a UPS, except the battery is external to the inverter's case. The efficiencies are usually the same, in the mid-90's.

Usually with APCs you can search for them on the APC website and find the actual efficiency and other specs, but while I found the one you linked above, I did not find that info.

2manytoyz

Re: UPS inverters scaleability ?

I have a number of APC UPS units. The one MAJOR difference any of the ones I own, and even my smallest 400W inverter, is the UPS has no cooling fan. It was designed to run a matter of minutes, allowing for either a controlled shutdown, or a short blackout. Everything is crammed inside a case that has insufficient cooling for running longer than the internal batteries can supply.

Here's one of mine:







That said, it's easy enough to put the guts inside a different case, and add your own cooling fans.

Next issue is the built-in charger. Check the specs to see how many hours it takes to recharge the small internal batteries. That charger will be way too small for large external batteries. If you're using solar charging, in conjunction with the built-in grid charger, or another external charger, different story.

This one is the APC 700 model. Rated at 750VA (only 450 Watts). Great for a computer, TV, or AV gear. I believe the specification on the one you've linked to is only 500W.

In my line of work, I get lotsa free UPS units. Rarely have a broken one. Just need new batteries. Many owners aren't interested in doing that, so they give me free paperweights. Chances are good if you get a used one, the only issue is dead batteries.

I really only use UPS units as they were intended. Some of my appliances run from grid power, when available, and when the grid is down, an automatic transfer switch moves the loads to the inverter after 20 seconds. During the transition, the UPS enables a smooth transfer of power. Same again when the grid comes back.

My Xantrex ProWatt SW2000 PSW inverter was only $325. It'll run most any household 120VAC appliance without issue. Modifying an UPS can be a fun & educational project, but I wouldn't recommend spending a lot of time/effort/money on it. Pure sine wave inverters are now very inexpensive. I paid more for a 1500W modified sine wave inverter back in the mid 90s.

Good luck with your project!