By January 2008 we realised that we are in for serious loadshedding in the long term. I then knocked together a little UPS with a 1500Watt pure sine wave inverter, charger and two 105A.hr batteries. That was before LED lights and batteries in garage door openers and gates. It served us very well until 2012 when we built a new house and wired it for having a UPS. Essentially we have 2meters of cabtyre coming out of the wall in the garage with a blue standard 3pin plug top (like the plug end of an extension cord). This is connected to all the consumers needing UPS during loadshedding. The plug can go into a generator, an inverter or into a nearby standard outlet point. But we typically have an inverter/charger system between the blue plug and the wall outlet. If in the rare case that the inverter may smoke, the blue plug goes straight into the wall. Because we are talking of loads well under 3000 watt, the blue plug and wiring through the house is 1.5mm2.

Today we have a Victron MultiPlus 1600VA installed as the inverter. 12V with 3off 105 Amp.hr batteries. (Why only 12V? Because sometimes a battery is taken out for camping and the home system keeps going on 2 batteries.) The biggest consumers are 2 Bosch fridges, 9 fluorescent lights that really should have been changed to LED by now, and 3 ceiling fans connected into the light circuits. A desktop computer, inkjet printer, 2x modern flat TVs, router/modem, 2x MiBoxes, soundbar, all lights in house (LED), burglar alarm, outdoor beams (another reason for 12V), gate and garage door motors, sewing machine, cell phone chargers, bedside clock/alarm, outdoor braai rotisserie motor and lights, mosquito repel devices. This is a long list of consumers, but only a small amount of them run at the same time. The obvious stuff that's not on the UPS circuit are microwave, oven (we have a gas hob, no plug outlets above counters in kitchen and scullery, pumps, air con, towel rail or ceiling heater in bathroom, plug outlets where heaters, vacuum cleaner, hair dryers may get plugged in.

Have never had the Victron trip or even give an alarm.

Using an energy meter, our consumption at the blue plug is 210 Watts for most of the day, rising to 700 Watts in the evening. The peak hold function of the watt meter shows 1200 Watt over a week, but the sampling rate of the Watt meter is unknown. If the fridges are taken off the UPS circuit, the peak during a week is 800 Watt.

I can thus highly recommend the Victron MultiPlus 1600VA for this application. It really is a simple DIY job - the most work being the wiring of the consumers back to the UPS. However, a word of caution; the Victron must be set up (via special cable, software and laptop) to work correctly with your battery choice - check that the seller is happy to do this for you.

Edited September 26, 20204 yr by Gerald_D
make it clearer

Some more detail about installation; links for Inverter spec sheet and Watt meter

Comments re Victron;

When loadshedding ends, the Victron takes about 5-10 seconds to decide that Eskom is really back and only then switches Eskom power back on. It does this seamlessly and I suspect it may be syncing with Eskom before it switches. This delay is great because it is known for the Eskom network to be shaky when it returns and that some home appliances don't like this shaky period. However, when Eskom fails, there is a tiny glitch when the Victron kicks in. Supposedly 20milliseconds and it is only visible on fluorescent lights, nothing else.

The Victron is the most silent brand that I have used for this application (have assembled 11 similar systems for friends and family). Hum noises of all systems were minor, but the fans were of varying design and noise level. Noisiest was Meanwell TS1500 where the fan runs even under no load when the temp is over 25C. The Cotek S1500 was rather good with low-noise fans coming on only when they really had to. WRND has very noisy fans coming on above 500W irrespective of temp. I have very seldom noticed the Victron fan running, and then only at a low level.

Victron does not have a power outlet socket like most of the other brands. Actually a good thing because the other brands force you to buy Schuko or British plug connectors. Victron allows/requires cabtyre connections for input and output and that is why I have a standard plug outlet behind the Watt meter.

This Victron's battery charge side is the best I have yet seen in a UPS. Dear old Eskom forces 2 requirements on us; a. quick battery recharge times when loadsheds are close together and b. months of battery storage/maintenance when there are no loadsheds. The Victron handles both these requirements very well. The charge current is very high - so high that most customers probably want it limited to a lesser value. The Multiplus 1600 can charge 70 Amp at 12V, ideal for 4off 105 A.hr batteries. My system mostly has 3 batteries and only 2 batteries when I go camping, so I have had the charge current limited to 60 Amps (30% of battery C value). Then for the storage times, it effectively has a 4 stage charger - after floating the batteries at 13.8V and detecting no load for 48 hours, the float voltage drops to 13.2V for a week (after which it does a full charge cycle again). These numbers are all adjustable with a laptop/software/special cable.

From the Victron's spec sheet it can be seen that it will drain a 12V battery system down to 9.5V before it cuts out. This is considered to be too deep down for common lead acid batteries where the generally accepted number is 10.5V. Again, this number can be adjusted with a laptop/software/special cable. Be wary of buying a Victron at factory default settings and then connecting a couple simple lead acid batteries. . . . . they will be force fed at 70 Amp and drained down to 9.5 volt.

Quote

the blue plug and wiring through the house is 1.5mm2.
 

Personally for the extra safety factor I would have used 2.5mm wiring.

But that's just me.😇

I hear you. At some plug outlets I pulled a second twin+earth through the conduit to feed dedicated UPS modules. See pic, some modules will be blue colour, on the UPS. Feeding a 1.5mm2, and making all the extra module connections in the 4x4 wall box was easier that way. Remember that the whole UPS circuit is behind a 15 Amp breaker near the Victron.

(Not at home now, so I stole a pic off the net - I sometimes have the modules on the left as blue UPS)

My biggest loads are the fridges, and the cabtyre supplied with them is only 1.0mm2

Edited September 28, 20204 yr by Gerald_D

In the post above I showed MajorTech's Veti modules, but I much prefer Onesto's Matrix or LeGrand's Ysalis ranges. Modules make a very neat installation. I can think of nothing worse than power trollies and extension cords!

Nice clean setup. Can you please share your wiring diagram of how everything is interconnected?