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Inverter Information

BLOCKBUSTER

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info@blockbusterdrain.co.za

Some tips on the purchase, installation and use of Battery Inverters for 220 Volts.

Inverter information on a plumbing site? Why you may ask? Well we provided some info on generators. but some of our customers favour the use of battery inverters so we thought that we would provide some basic information on them too. I have had about 20 years experience using big UPS systems and understand how these things work.

There are a host of advantages (over generators) to using an inverter system with batteries. They are not noisy and are clean, reliable and don't need much maintenance. They don't use petrol and oil and they can be hidden away easily. That's generally what the sales guys will tell you - all true.

There are however some issues that you need to know about in the generator vs inverter war. There are some pretty severe downsides that you often don't get told about!

These are as follows:

They don't always operate so well on or near full load. They can overheat and the battery life does not always compute to the given Camp/Hour rating. If you have 200 Amp/hour of battery you are not going to get 200 Amps for an hour. You are far more likely to get 20 Amps for 10 hours though. It wont happen either, but it will be closer.
There is a recharge time. You may need up to 24 hours to fully recharge the batteries. If you get load shedded twice in a row you have a problem. If you get shedded longer than your run time then you also have a problem :-).
The guys who are sometimes a bit cagey about the run time of these units. They say "3 hours", but this is seldom at full load. You need to be very specific when you ask questions about the run time.
These things are suitable in most domestic situations except if you want to run big loads like microwaves, kettles, fridges etc. A generator is a better bet unless you buy a really big unit with lots of extra batteries. Inverters work fine for a couple of lights and a TV or two.
The batteries wear out! They have to be replaced. It used to be every year but its longer now. This can add a big cost to running an inverter. The other thing is that the batteries are often not covered by the warranty - check this out too!
Most of them produce a square rather than sine wave AC. This is not generally a problem if you are running lights and TV's. PC power supplies work OK most of the time. You may pick up problems with some chargers (laptop) and motors though. The output of most little (>10kva)generators is also not great but at least it sort of looks like a sine wave albeit a very jagged one! You can buy inverters that push out a pure sine wave but they are more expensive.

The perfect situation is to have both! You run the inverter until the batteries are flat and then you charge the batteries with a generator. This is basicaly how big IT installations are set up. The moment the power fails the UPS inverter kicks in and runs the load off batteries. In the mean time the generator has been given a signal to start. The generator starts itself and feeds the UPS - when they are in sync with each other the UPS actually switches out of battery mode back to mains. When it's running on mains the batteries get charged.

Installation. If you require a big unit to be wired into your house then you have no alternative - consult an electrician! The smaller units simply "live" between the mains and the appliances. You plug the Inverter in and you plug the appliance in. When the power fails it switches to batteries.

Safety. Remember that you are dealing with 220/230 VAC and that this voltage is deadly. Cables must be in good condition and the earth wire must be operational - except in the case of some 2 pin appliances. Also remember that you are bypassing your earth leakage unit. If you happen to touch the output side of the inverter there is no eartk leakage relay to save you! Dont take them apart! They are particularly dangerous with the covers off.

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