32 minutes ago, KLEVA said:

@nick9 - Referring to your original question - I have done similar myself on almost all my UPS's at home, but it's the charger that's built into the UPS that is the issue. Most home/small UPS are 12V or 24V (usually 24) with two tiny 7Ah or less batteries. My own logic, with only experience and history of failures, is NEVER go more than double the built in Ah, and only with a decent quality UPS.

So, for example, I have a 2kVA ups that came with 7Ah batteries, which lasted less than 10 Minutes under near full load. Replaced the batteries with 14Ah and my time has jumped to 25min (mainly because the Voltage detection of the UPS can't kick in as quickly). I have tried on another UPS to go to 30Ah batteries, but they cannot recharge properly and eventually a circuit in the UPS died and popped the whole thing after a week.

If you are going to do it, only go double the internal batteries, and on a decent UPS. the cheapies/chinese stuff just can't handle the charge current.

Another alternative, which is only heresay since I haven't done myself - Get a seperate charger for the batteries, and then break or use a diode to prevent the UPS from trying to charge the batteries. Then apparently you can use huge batteries. Again, this is heresay from someone I know, but I have never seen their setup (or needed to try, since I have full house solar now).

This is the route I took many years ago. I used a 1.2KVA UPS with two large truck batteries (nice AGM's didn't exist yet). I had a separate 10A trickle charger on the truck batteries with some relays in between to disconnect the big batteries from the inverter when eskom came on, and switch on the trickle charger. The problem was that if there was a long period of power interruptions (they didn't call it load shedding back then yet) it wouldn't fully charge between power outages. This was remedied by hooking up some thick (not the thin R400 type) jumper cables to the bakkie and idling the motor for a bit when needed. I also had to add some fans to the UPS as it overheated (as per @plonkster explanation above)

Want to Achieve a Longer runtime on Home Office. Using an APC 2200va (2,2Kva) UPS which gives me about an hour runtime with current Load. (Current Load is 2 x HP mini Servers, A PC, Laptop, Screens and networking kit – routers, Fiber CPE, etc etc)

Is it Possible to have a “Power Cart” (Battery Bank and Inverter) during a Power Outage powering the APC. In effect the APC will be seeing the equivalent of Eskom/Wall power during outage from Power Cart. – Looking at using an Inverter that does not have an integrated charging circuit.

So on Eskom outage, wheel power cart to Office and disconnect UPS from wall and connect to Power Cart. – Due to APC one hour runtime on batteries, load will not see a disruption

Reason for looking at doing this. Have periods of unreliable power on Eskom line – Lights will flicker, TV restart etc etc, but UPS keeps PC’s Stable – i.e. want to keep UPS to protect Load. (It is an “önline” APC UPS)

When no Eskom outage power cart then connected to separate charging circuit in garage using a charge controller etc.

Taking this approach, a modified sine wave inverter should be sufficient, keeping costs down, allowing for funds to be spent on Batteries.

My thinking is that 4 x 102AH deep cycle batteries with a  24v 3KVA Inverter will give me an 8 hour runtime at least. I would also imagine that the Inverter kva spec should be higher that the UPS kva spec

Your thoughts, is this doable – is there any theoretical/Electrical reasons why it will not work.

Power-Cart-Concept.pdf

On 2018/12/28 at 9:47 PM, CarGuard said:

Your thoughts, is this doable ...

It depends on what UPS you are using because one UPS cannot feed another UPS. 

That is unless you use a online UPS.

Their chargers can take a wide range of whatever incoming power and charge the batteries, having no effect on the output at all.

50 minutes ago, The Terrible Triplett said:

It depends on what UPS you are using because one UPS cannot feed another UPS. 

That is unless you use a online UPS.

Their chargers can take a wide range of whatever incoming power and charge the batteries, having no effect on the output at all.

Basically looking at feeding the UPS with an Inverter, only when there is no Eskom Power.

My Current UPS is an Online UPS (APC 2200i) - the plan is to feed it with an Inverter and battery bank only when Eskom is down.

So the Inverter will not be in battery charging mode

The only charger working will be the UPS in that it will be getting power from the Inverter (With Eskom Down).

See PDF attached to my original Post

 

14 minutes ago, CarGuard said:

Online UPS (APC 2200i)

Make 100% sure it is online, for I see it may be line interactive?

https://www.apc.com/shop/za/en/products/APC-Smart-UPS-2200VA-LCD-230V/P-SMT2200I?isCurrentSite=true

 

Cannot comment on the pdf. What I do know is that I also fed a UPS from a inverter / Eskom by switching between the two.

It does work BUT a lot of articles like this: https://www.power-solutions.com/pressroom/newsletter/2013/09/top-4-reasons-you-should-never-daisy-chain-ups-systems

Therein me stressing the point that the UPS being fed by whatever source of power makes no difference if it is a online double conversion UPS. They can take a wide range of foul input power. The caveat on "whatever source of power" is cheap generators. They can damage the APC online double conversion battery charger.

Friend of mine did that - I did warn him re. the cheap Builder generator he bought - he damaged about 4 APC online double conversion units over time - he did get them for free. :-) 

Classic, Eskom got it wrong about load shedding!

However, I feel that if by Sod's law I averted load shedding by stocking up on batteries, then it's money well spent.

https://mybroadband.co.za/news/energy/294672-where-is-the-load-shedding.html?source=newsletter

1 hour ago, nick9 said:

Classic, Eskom got it wrong about load shedding!

In Dec when their was a burp or two from Eskom. I got the impression that it was a "warning" to us all that Eskom is still around, "showing" us who is in charge.

There was talk about coal shortages, yet the coal suppliers responded in the media and said they have stock, it is just not collected.

Then in another article it was said that Cyril allegedly cancelled all the senior Eskom peoples leave, instructing them to go and visit all the power stations in person, in Dec.

On top of that big business like Anglo recently starting weighing in on electricity reliability and increases, warning of some substantial job losses linking that directly to Eskom.

And then we have State of the Nation address soon, where it is speculation that Eskom will be broken into 3 parts.

Ps. The Unions obviously say never, we will strike against such a split ... how the Unions figure their position, I have no idea. Eskom goes down, so do they.

Just in!!!

* WARNING *
ESKOM just announced that there will be national power outages on 29 ,30 en 31 February.
Reason for that is unclear.

Send this warning to everyone! 

Is it bad that I now *want* load shedding to kick in, at least a little, so I can use my lovely UPS kit??!! 😀

1 minute ago, nick9 said:

Is it bad that I now *want* load shedding to kick in, at least a little, so I can use my lovely UPS kit??!! 😀

Wait for 29-31st of Feb ... 🙂 

I also came here to see what others' thought about the idea of "upgrading" UPS units with larger batteries. I generally advise against this idea as well. Mostly, the effort is just not worth it.

I am going to if I may, refer guys to the power forum and this thread in particular for a "second opinion".

 

Just an update on this.  My company deployed APC UPS (brand new) with extended run capability and extended battery pack to keep routers running during load shedding to a large group of our staff.  Total cost of each unit based on my estimate is roughly R40k.

The feedback on our local mailing list is, everyone hates the APC unit, the complaints were:

1. Very noisy fan

2. After a few months it no longer lasted more than 20 minutes.

The decision was defended as by local IT as, we aren't experts and at the time options were limited.

Use it, don't use it.

Edited June 5, 20215 yr by Gnome

Hi. Old guy here. Edmund. NOT A TECHNICIAN NOT AN ELECTRICIAN. but I love to dabble. I have a 600va UPS. Been using for 10 years now....first battery 35ah lead acid car battery, used the UPS charger for charging. No cooling fan, ran great for 5 years until battery died...5 years? ....pulling pc and ADSL router just fine, UPS got warm. 4 years later.....SAME UPS......600va......105ah lead acid battery, pulling, in loadshedding of course, my cctv system only.....9 cameras, DVR, 12volt monitor, 9 channel PSU, switch, fibre router....router is for monitoring on the phone. UPS got hot, added  12volt cooling fan on the side with 9volt power supply to slow fan down a bit for the noise. Got addition 15amp charger which seems to charge at 7.2amps only but it does the job quick. You just need to switch over to the 15amp charger manually......the only manual thing. Almost forgot, it pulls about 3.7amps with the monitor OFF and 5.2 amps monitor ON. it was tested a month ago when one of our mini sub stations was sabotaged.....ran for 10.5 hrs when power was restored, so it could have ran longer. Thanks.

Help with UPS/Inverter setup for loadshedding

 

Hi I need some guidance whether my plan is feasible  
Long story short  
I have a RCT 2000VA UPS , and the batteries(2 x 12v 7.2ah in series) are dead I am planning on replacing the batteries With 2 x 12v 50ah batteries

Now I know the built in charger is too weak to charge them

By my calculations and other posts in this thread, it will take 2-3 days to charge them from empty on the built in charger

I will also add more cooling to avoid the overheating, maybe a heatsink and a few fans

 

So I am planning on getting an external charger, solar or Eskom to charge the batteries

Now to the main part and my actual question 

What I need guidance with

I want to connect the batteries to the UPS with a diode/s to stop the built-in charger from giving power to the batteries And then a diode from the batteries to the external charger to stop power from going back into the charger

The above is so that I can avoid having to unplug batteries charge and then replug them like suggested in other parts of this thread

Will this work?  So that I do not have to unplug the batteries, and can just keep it as a standalone low maintenance unit

Or must I rather add something like brad harrison connectors to the batteries unplug them to charge and then replug them after charging

Thank you in advance