I currently have a 2000 VA UPS inverter that is powered by a 24 volt battery. I want to increase my load capacity and was suggested to buy a 4000 VA system that runs on 48 volts. However, as I don't want to let my current UPS go useless, I was wondering if I simply bought another 2000 VA UPS inverter of the exact same model and an extra 24 volt battery to power it, will both of the UPS be able to support up to 4000 VA if their outputs (220 volts AC) were connected in parallel?

Let's say if the above works, are there any down sides to this compared to the single 4000 VA unit? Will the above be able to power a small 12000 BTU air conditioner or 11 cubic feet refrigerator and will it need any circuit breaker if one unit suddenly failed and output dropped to 2000 VA?


1 Answer 1


You don’t tell what UPS inverter you have, but I don’t think many models (if any) are able to be phase-synchronised. And if they’re not, you should not connect them in parallel : things won’t work fine as soon as they are out of phase, and you may even damage them if they lack protection. And even if they were phase-synchronise, you’d need to be sure that the current will be balanced between both UPS inverters.

If you have several devices to power, you may run two independent circuits (one connected to each UPS inverter). If you can’t, I’d suggest you buy a 4kVA inverter and ask your supplier to buy your 2kVA inverter back.

  • \$\begingroup\$ They do exist, as well as some high end motor-generator-inverter sets, but just like you say, if it's nit very expensive amd clearly states you can paralell them, you definitely can't. \$\endgroup\$
    – winny
    Commented Apr 9, 2017 at 8:56

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