Confused - UPS Run Time

[Pho3nix]

Hi,

Got a 2000KVA RCT UPS and to my understanding it has 1200w capacity.
So how is it that when it has the TV, Router, CPE and Media Box it turns off after 30minutes.
With just the router and cpe, it lasts a couple hours which works but a little disappointed as my daily usage on everything listed above is 1kWh.

Am I confused or am I doing something wrong here.
Solar and all the other long term solutions aren't a possibility as I rethought the investment in this place since I'll be moving in a while.

 

[Geoff.D]

It all depends on what batteries are in the UPS. A UPS is NOT a backup power source. It is designed to provide power for long enough to switch OFF appliances.
What model UPS and what are the batteries that are available in the UPS?
1200 W is a rather poor output from a 2000 VA device BTW.
1200 W does not translate into 1200 Wh without knowing what the battery capacity is.

 

[supersunbird]

A TV uses a lot of power, so that's why. You'd need much bigger batteries.

 

[Speedster]

You are confusing volt amps / watts with watt hours. Volt amps (or watts) gives an indication of how much power the ups can provide while watt hours are how long it can provide that power for

 

[Pho3nix]

It all depends on what batteries are in the UPS. A UPS is NOT a backup power source. It is designed to provide power for long enough to switch OFF appliances.
What model UPS and what are the batteries that are available in the UPS?
1200 W is a rather poor output from a 2000 VA device BTW.
1200 W does not translate into 1200 Wh without knowing what the battery capacity is.

Look I know it’s not for long term usage and I mainly got it for internet and to charge phones but like I said when I looked at the kWh I use VS the W listed thought it would be decent for a little TV time at least.

How exactly would I check what batteries?

 

[Pho3nix]

You are confusing volt amps / watts with watt hours. Volt amps (or watts) gives an indication of how much power the ups can provide while watt hours are how long it can provide that power for

Fair enough.. could you help a heavily medicated guy with the calculation so I can check?

 

[supersunbird]

Look I know it’s not for long term usage and I mainly got it for internet and to charge phones but like I said when I looked at the kWh I use VS the W listed thought it would be decent for a little TV time at least.

How exactly would I check what batteries?

It's got 2 x 12v 9ah batteries. It cannot take bigger inside the casing.

 

[Geoff.D]

RTFM! The manual should tell you what the battery capacity is.
18Ah total capacity. assuming the load is 1000 W @ 220V and 100% efficient, that means at
a 50% discharge rate, the absolute maximum back up time you will get is 2 hours. The Tv could easily reduce that to 30 minutes or less.

 

[quovadis]

RTFM! The manual should tell you what the battery capacity is.
18Ah total capacity. assuming the load is 1000 W @ 220V and 100% efficient, that means at
a 50% discharge rate, the absolute maximum back up time you will get is 2 hours. The Tv could easily reduce that to 30 minutes or less.

How did you calculate that? There's no way you can run 1000W on 18ah for 2 hours. We're talking minutes.

Got a 2000KVA RCT UPS and to my understanding it has 1200w capacity.

That's the maximum load the UPS can be used for - not the battery capacity.

 

[REAList_1]

When you look at this you talk at least a 105ahr battery.
9ahr batteries are small.
The guys are right - a ups is designed for stopping a computer when you lose the 230v

 

[itareanlnotani]

2 x 12v 9ah

12 x 9 = 108 x 2 = 216Whr nominal capacity

What with efficiency and lead acid voltage droop, usable capacity is about 80% of that if you want to totally destroy the dead acid batteries, so about 170Whr actual capacity.

I'd suggest using no more than 100Whr usable capacity out of of that, as dead acid is ****, and doesn't like discharge > 50%ish, as battery lifetime will be heavily impacted (i.e it will die fast, and you'll have a useless paperweight that won't hold a charge) if you go further than that.

So, if your equipment rates at 1000w /hr, then this will give you 10th of that, or 6-10minutes odd of usage.

 

[RedViking]

You don't have enough batteries. Also a UPS with two small batteries is not meant to be used as backup power , depending on the UPS you are probably also running the batteries flat, which means they will be damaged by now and won't lost long.

Depending on the charger in the UPS, you can add more batteries.

Or get something like this:
https://mybroadband.co.za/forum/threads/mecer-2400va-inverter-review.1015178/

 

[HeftyCrab]

Look I know it’s not for long term usage and I mainly got it for internet and to charge phones but like I said when I looked at the kWh I use VS the W listed thought it would be decent for a little TV time at least.

How exactly would I check what batteries?

That 1200w is the peak power draw which the UPS can supply. The amount of time you can draw that amount is determined by the batteries. I believe based on other threads here, yours has 2 x 9ah batteries.

Edit: see the other guys beat me too it.

 

[Mars]

I have a 2000va ups and it runs my pc, server (with two 600w power supplies and about 10 hdd's) a printer and monitors ect. for about 4 hours. The kicker is that I have two 120 ah batteries on it.

The 2000va or 1200w gives you how much load you can put on it. In other words its the back of the bakkie. The batteries are the fuel tank, that shows how long you can go with that load.
Obviously if you have a lighter load you use less fuel, but if you have a small fuel tank then you aint going far, no matter the load.

If your batteries are inside your 2kva ups then its only made to give you time to save and gracefully exit your pc. You could technically put a couple of 100ah batteries onto that ups and get a couple of hours tho you may have trouble with the internal charger if its only made for a couple of 7 or 9 ah batteries.

 

[alanB]

https://offgriddiy.co.za/calculators/battery-back-up-times/

 

[Pho3nix]

I have a 2000va ups and it runs my pc, server (with two 600w power supplies and about 10 hdd's) a printer and monitors ect. for about 4 hours. The kicker is that I have two 120 ah batteries on it.

The 2000va or 1200w gives you how much load you can put on it. In other words its the back of the bakkie. The batteries are the fuel tank, that shows how long you can go with that load.
Obviously if you have a lighter load you use less fuel, but if you have a small fuel tank then you aint going far, no matter the load.

If your batteries are inside your 2kva ups then its only made to give you time to save and gracefully exit your pc. You could technically put a couple of 100ah batteries onto that ups and get a couple of hours tho you may have trouble with the internal charger if its only made for a couple of 7 or 9 ah batteries.

Mind sharing how you added the additional batteries?
Have a spare UPS I can hack

 

[SauRoNZA]

Yes it has the ability to power 1200 watt of devices....it doesn't actually have a capacity of 1200w....much much less than that in fact.

1200 watt really just means it won't fall over if you plug 1200 watt worth of stuff into it. Then it should last all of 5 minutes so you can safe shutdown.

Basically you have too little battery for your purposes.

 

[Mars]

Mind sharing how you added the additional batteries?
Have a spare UPS I can hack

As long as your ups uses 12v batteries you can replace them with any other 12v battery. Assuming you have two 9ah batteries in series then you can replace them with two 105ah batteries in series. you would just need to change the cables for something a little thicker with connections to fit the new batteries. I would use at least a 4mm core. Usually the ups's have thickish cables, but theyre way to short. You can get 105ah batteries with m10 bolts made for backup purposes, but if you can't get those then the 105ah's with the normal posts also work, you will just need to get two terminals.

Then of course you would need a battery charger of some sort to help charge them in case you dont have the time to wait for the smaller internal charger to charge them.

If you use normal car batteries you just have to be aware that they may gas while charging, and that the gas is acidic, so it may damage electronics over a long period, so it would be worth putting them somewhere where you can vent them.
If you use the deep cycle 105's, or VRLA/AGM batteries then venting is not an issue, you could stick those in a cupboard.

 

[Gordon_R]

Just for comparison. Not exactly the same as your situation, but you have to add up the numbers, and cannot repeatedly use the full rated capacity of a lead-acid battery.

We had a technician in today to quote on our complex pedestrian gate, which has an electromagnetic lock, and continuously draws power. A battery backup for this will need a significant amount of storage, unlike the gate motor or electric fence, which only use intermittent power.

A small battery might work for a once-off 2 hour period, but repeated load shedding like we had last month, would kill a small battery, and end up causing more failures in the battery and loss of function. There are no cheap fixes, and lead-acid batteries are nothing like the Li-ion ones in your cellphone.

 

[Geoff.D]

I am surprised and alarmed to a certain extent that someone is of the opinion that an electromagnetic lock that requires continuous power to stay "locked" is a good idea! Surely, the lock should default to "locked" when the power fails or when the gates close and locks that no power is required to keep it locked. Power should only be required to open the lock?