UPS Inverter Batteries

[aaron]

Hi Guys,

I was wondering if any of you had experience with UPS batteries. I'm considering buying a cheap 1500W inverter off of eBay. The problem is, well, I'm not really an expert, and there's no online documentation available, so I'm not sure what batteries are used.

I would assume (Gel) / Lead Acids and Valve Reg would all be fine, but I'd like to be a little more certain of it.

http://www.ebay.com.au/itm/360871044247 this is the inverter. It's cheap, but it's just going to be my new toy...

Thanks in advance for any help

[johansen]

that's not a ups but an inverter, probably modified square wave.

i do believe they make gel cells but there is almost no reason to buy them. AGM cells are the standard but the best kilowatt hours per dollar are flooded cells, and always have been.

[gxti]

It says sine output in the description, not that I necessarily believe it. It also says it has a charger, with the idea that you could use it as a UPS. Any 6-cell lead acid battery would fit the bill regardless of type. But probably the inverter is low quality, and the charger is going to be really bad.

Check this out for an idea of what can go wrong: http://ludens.cl/Electron/chinverter/chinverter.html

[NiHaoMike]

If it's for a stationary application, just get a deep cycle battery and call it done.

[aaron]

gxti: Holy shit that's bad.

I'm kind of in the same position though, I can't afford a good quality one. I'm still thinking of trying this one out but will absolutely pull the thing to bits first and take a look.

Also I don't plan on going anywhere near 1500W, probably morelike 500-600 max. But thought it would be better to buy something that's overrated for my application, seeing as it's only $90?

Thanks for the info guys. It is for a stationary application NiHaoMike so I'll just go with your advice

If anyone has any ideas on a reputable UPS/Inverter that would be fantastic, otherwise I'll get back to you on this particular one with some pics so you can judge for yourself. Maybe it will actually be decent. Doubt it though.

[nctnico]

Hi Guys,

I was wondering if any of you had experience with UPS batteries. I'm considering buying a cheap 1500W inverter off of eBay. The problem is, well, I'm not really an expert, and there's no online documentation available, so I'm not sure what batteries are used.

I'd get a used APC UPS and add batteries to that. This inverter from Ebay is more likely to be 150W. 1500W at 12V is 125A. No way those posts are going to handle that.

[aaron]

I think I've decided to just spend an extra $150, and get the 1000W Model from Super Cheap Auto. That way I can be sure it conforms to Australian standards. I spent a fair bit of time reading about all the dangers and problems with inverters from questionable sources. I suppose it's just not worth the trouble, or death.

Thanks guys.

[nctnico]

This thing?
http://www.supercheapauto.com.au/online-store/products/Calibre-Power-Inverter-1000W-12V-Pure-Sine-Wave.aspx?pid=222397#Cross

Looks like the same crap to me at 3 times the price. Those posts are not going to handle 1000W (83A @ 12V) either. For these power levels you need >25mm2 wiring and bolts to attach the wires to the inverter.

[NiHaoMike]

Ask around on the DIY alternative energy sites as for which inverter they recommend. At least if you buy local, you could do a stress test with a hair dryer and easily return it if it fails.

[Richard Head]

When you select the inverter just bear in mind the light load efficiency. Normally when operated below about 1/3 load the inverter efficiency drops off badly so don't overrate the inverter too much. Rather try to run it at 75% load or thereabouts.
Incidently, the same applies to petrol gensets. When they are operated below 50% load their efficiency is terrible.

Dick

[NiHaoMike]

The good inverters remain very efficient down to very low loads. They begin period skipping the main step up converters and/or start turning off phases.

[MarkL]

If anyone has any ideas on a reputable UPS/Inverter that would be fantastic, otherwise I'll get back to you on this particular one with some pics so you can judge for yourself. Maybe it will actually be decent. Doubt it though.

Like most everything else, you get what you pay for.  High power, quality inverters aren't cheap and it's one of those things I wouldn't mess around trying to find low-end bargains if you care about your house and/or whatever is connected to the inverter.

I've done some work in RE and I would recommend you take a look at Outback Power, Xantrex, and Exeltech.  They are all top-notch.  If you want to spend less, I've also used and can recommend Samlex inverters.  They don't have as many bells and whistles but are well made.  I've also heard good things about Magnum Energy inverters (Magnasine), but I haven't used them.

I'd stay away from "modified" sine inverters and stick to those that are true sine.  Most modified inverters actually output a square half-cycle pulse which can be hard on power supply input stages, and are definitely not suitable for anything that has an AC induction motor.

HomePower magazine (http://www.homepower.com) does periodic "reviews" of inverters.  You can go to their site and search on inverters.  I'm calling it "reviews" in quotes since they never seem to say anything bad about anyone (sponsors, you know...) but at least it's a starting place where specs are collected and tabulated from various manufacturers.

[MarkL]

And on batteries...

You haven't really detailed your power requirements beyond the wattage, but for smaller requirements I've recently discovered electric wheelchair batteries.  They are sealed, made to take mechanical abuse and deep discharge, and are widely available (especially the 12V 35AH versions, e.g. UB12350).