Power backup - regular outages - system losing efficiency - help

[pl8lad]

Hello, I live in Myanmar and there are 2 x 4 hour electricity cuts every day. I live in an apartment, I don't have any vehicle, but I'm curious about your battery powered inverter.   I'm not very good with electronics, and had a local engineer with me when I bought a Durasol Pure Sine Wave UPS series CD model 1500 VADSWL - 1700/24 volt inverter, along with 4 semi-truck trailer Varta Blue Powermotive N120 (150F50) 12V 120AH 800A batteries.  I was told they would not run the AC, but I have a small refrigerator & a small chest freezer, sometimes use TV & wifi, and fan, and at night, 1 or 2 lights   When I first got this set up, in Jan. last year it worked well, covering each 4 hour electricity cut, but over the last 4/5 months the useful time using the inverter has shortened, and it's now down to about an hour & a half.

All up the batteries & inverter cost me 2.4 million Kyats, about 750$US..

The reason I'm sending this message to you, is that you seem to have way more knowledge than I with this sort of thing, so I'm wondering if any of what I have makes sense to you.  It is not easy to find knowledgeable people here and I'm sure there are, but they may not speak English, and I certainly can't speak Burmese very well.

Anyway, any thoughts you may have would be very gratefully  accepted and whether you can shed light on my problem or not, I please accept my thanks for taking the time to read my email.

Ajarn Pete,

Yangon,

Myanmar.

[Crossy]

I suspect those automotive lead-acid batteries could be shot; they really are not intended to be used in a UPS type application particularly if they are not getting fully charged between outages. 

 

Any idea how much current is being dragged from the pack when discharging? What is the charge rate that your inverter can provide?

 

Can you survive a couple of outages without using the UPS so you can ensure your batteries really are fully charged?

 

Do you have / can you get a multimeter?

 

If we determine your batteries really are dead then: -

 

You really need deep-cycle (marine) batteries, and never go below 50% charge.

 

Can your inverter support lithium batteries? They would be a longer-lived solution.

 

Is it possible to get stuff mail-order and shipped into Myanmar? 

 

[Crossy]

I found a similar inverter to yours https://m.indiamart.com/proddetail/durasol-dsw1450-pure-sine-wave-ups-2850393422755.html

 

Max charge current is 8A which may not be enough to fully charge your batteries each time.

 

As above, try to do without power during a couple of outages to ensure you really are fully charged.

 

EDIT you are going to need at least 15 hours of charging with no discharge to get somewhere near full on the batteries.

[pl8lad]

Hello Crossy, and thank you for your quick reply.

I have been advised to get 2 bigger batteries, such as you mentioned, commercial boat batteries. I don't think Lithium batteries are available here, and importing things may not be allowed by the military here who are in charge of pretty much everything, It would probably take a lot of paper work, and a lot of tax/fees just to get permission for something like this.

The cuts are 1pm - 5pm then 9am - 1pm next day in cycles, but sometimes 5pm - 9pm, but not every day, so on other days, the charging time is 16 hours, but of course less when the extra cut off time happens. The pix below is my inverter, except that mine is half size vertically, the LED panel is the same, and the buttons below are the same.

Thank you for your suggestions I'll get the local engineer bloke to look at what you mentioned, he has a multi-meter,

 

--Any idea how much current is being dragged from the pack when discharging? What is the charge rate that your inverter can provide?--    Not sure myself, I'll try to find out.

Thank you again for your input,

 

[Crossy]

Does the LCD display tell you anything useful? Check the manual, it should have the maximum charge rate.

 

I would try running with no load for 24 hours, to ensure the existing batteries are fully charged.

[pl8lad]

There is a lot of info on the manual, but I can't find a max charge rate, but these are mentioned,

Battery, 100 Ah - 250 Ah.

Charge current, 15 +/- 2amp.

Fast charge current, 20 +/- 2amp.

Rated voltage (back up mode)230 VAC +/- 10%

Rated frequency (back up mode) 5oHz +/- 0.1 Hz.

Output, 90 - 290 +/- 10 VAC.

Frequency 41 - 65 Hz.

UPS/WUPS Mode selection, 180 - 265 +/- 10 Vac, or 90 - 295 +/- 10 VAC.

(Yes, you can see I'm a bit lacking when it comes to this electronic stuff.)

I will try your suggestion of leaving it to charge for 24 hours and see if that makes a difference,

Thank you again..