Battery Brownout Protection (UPS)

[AlwaysRt]

I have asked questions in and started threads asking questions about pieces of this puzzle and thought a specific thread to show the result would be informative and also helpful. Like many in the Philippines I was dealing with frequent brownouts. In my case 75% 5-15 minutes, 20% 15 minutes to 2 hours, and 5% 2-8 hours. Because the majority of the brownouts I was having were so short I decided on automatic battery backup (UPS) vs a generator for convenience. The maintenance, fuel, and setup time required for a generator to get the power back on meant extra expense, dealing with no power every brownout, and 75% of the time the power would be back on anyway by the time the generator was ready.

1st purchase was a APC UPS 650 (325 watt modified sine wave inverter, 3 amp charger, and 9 Amp/hour battery). This was great as no flicker on TV when power went out, but turned out to be only about a 10 minute solution. Cost about p2,600

Then came all my questions and I eventually ended up with a 1,000 watt pure sine wave inverter with built-in 30 amp charger and a separate 170 Amp/hour battery. I do not yet know full run time as I set it up yesterday and only have had one 10 minute brownout so far. (I expect several hours) . Cost p7,000 for battery and p9,600 for inverter/charger.

Size comparison of both setups.

[Dave Hounddriver]

The battery looks much bigger in that picture than it does in the Facebook pic.  Looks like a great start to a fantastic setup (like adding a few more batteries and solar charging and high output inverter   

[AlwaysRt]

12 minutes ago, Dave Hounddriver said:

The battery looks much bigger in that picture than it does in the Facebook pic.  Looks like a great start to a fantastic setup (like adding a few more batteries and solar charging and high output inverter   

Adding batteries is simple so no problem there. If I have to find a 'mistake' it is in the sizing of my inverter.

Inverter thought process: First I knew the APC unit was 325 watts and worked fine for my LED TV, laptop, soundbar, and router. The only additional item I wanted to run was a floor fan. I also decided that since I was spending money that I didn't want to be wasted on something soon to be replaced, that I would get a pure sign wave inverter vs modified (think analog power the same as what comes out of the wall vs a square digital power source that some electric devices have problems with). Rounding up I would be covered with a 500 watt unit, and then doubling the size to 1,000 watts to be covered with more than adequate 'headroom'. Everything is great so far, here is the 'mistake'. After analyzing my last two electric bills, I found that I used 600 watts during a typical evening hour to run the entire house. Great! I thought, I can use this inverter to run the house if I want. Done deal and put on order.

Yesterday, as I was building cables and thinking about power requirements again, I wondered about my induction cooktop and countertop oven power requirements - WOOPS! Yes, my average power usage is 600w but both the cooktop and the oven are each 2,000 watt devices - so much for cooking when the power is out. I also will not be running the aircon (being installed as I type this) on this unit as it requires 940 watts (so I could but nothing else).

However, the final result is I more than met my requirement for internet, TV and fan. In fact if I want to, I can run the entire house (lights, ref, water cooler, laptop, internet, TV...) everything except for cooking and aircon.

[sonjack2847]

9 minutes ago, AlwaysRt said:

Adding batteries is simple so no problem there. If I have to find a 'mistake' it is in the sizing of my inverter.

Inverter thought process: First I knew the APC unit was 325 watts and worked fine for my LED TV, laptop, soundbar, and router. The only additional item I wanted to run was a floor fan. I also decided that since I was spending money that I didn't want to be wasted on something soon to be replaced, that I would get a pure sign wave inverter vs modified (think analog power the same as what comes out of the wall vs a square digital power source that some electric devices have problems with). Rounding up I would be covered with a 500 watt unit, and then doubling the size to 1,000 watts to be covered with more than adequate 'headroom'. Everything is great so far, here is the 'mistake'. After analyzing my last two electric bills, I found that I used 600 watts during a typical evening hour to run the entire house. Great! I thought, I can use this inverter to run the house if I want. Done deal and put on order.

Yesterday, as I was building cables and thinking about power requirements again, I wondered about my induction cooktop and countertop oven power requirements - WOOPS! Yes, my average power usage is 600w but both the cooktop and the oven are each 2,000 watt devices - so much for cooking when the power is out. I also will not be running the aircon (being installed as I type this) on this unit as it requires 940 watts (so I could but nothing else).

However, the final result is I more than met my requirement for internet, TV and fan. In fact if I want to, I can run the entire house (lights, ref, water cooler, laptop, internet, TV...) everything except for cooking and aircon.

That`s good to know, now you have found the mistakes I think I might be getting one.

[robert k]

I think it likely the aircon wouldn't start. They tend to draw much more to start than what they run at, possibly 3 times as much and your 1kw inverter even if it surges to 2kw would probably not like a 2.5kw load, even for an instant. Only one way to find out for sure though. Have extra fuses handy.

[AlwaysRt]

13 minutes ago, robert k said:

I think it likely the aircon wouldn't start. They tend to draw much more to start than what they run at, possibly 3 times as much and your 1kw inverter even if it surges to 2kw would probably not like a 2.5kw load, even for an instant. Only one way to find out for sure though. Have extra fuses handy.

I don't really see a need to power the aircon for now. I did not buy the batteries to run it (quick calculation says one battery would last only 1.5 hours or so) and I would not be able to run anything else. I have lived here several months without an aircon, been installed about an hour now, so not using it during a brownout is not a big deal for that reason also. Either way this inverter can handle the surge, if any, as it is rated for 3,000 watt overload for 30 seconds.