Buying a UPS

[furpile]

So much for powering my adsl router tonight, after an hour Telkom died. Seems the DSLAMs batteries are worst than my UPS. Back to expensive 3G

That's a whole different problem. On the weekend my modem ran for 3 hours on the UPS, but when the power came back on the internet died. Took Telkom a day to get the exchange running again...

 

[atomcrusher]

Bottom line is you can never have enough batteries.

That's what my wife used to say years ago when I did regular military call-ups

 

[akescpt]

That's what my wife used to say years ago when I did regular military call-ups

coming back home must have been fun though.

 

[Gaz{M}]

Great informative answer! Many thanks deweyzeph

Except that the figures given are too high. There is no way a desktop PC would draw 500W continuous unless you are gaming with a very powerful graphics card.

Also, laptops can draw around 30W. Check the power brick. It should have a wattage on there.

I would estimate your entire setup would be:

Laptop: 50W
PC: 200W
Router: 12W

Total say 300W rounded up.

All 3 use switched power supplies, so should run off a decent modified sine wave inverter, but you may as well get a pure sine wave inverter of around 1KW because I'm sure you will want it later.

204Ah x 12V x 80% efficiency x 30% discharge = 587 Watt hours of power.

So your two batteries will give you almost 2 hours of backup (587W/300W) and last many years at only 30% discharge.

But something to check is, what is the battery capacity at the current draw you are expecting of it. You can't draw 50A from a 102Ah battery and expect it to last 2 hours. Most batteries are quoted at the 20 Hour rate, in other words, it will supply a total of 102Ah over 20 hours (5 Amps per hour x 20 hours). But the capacity will be much less if you draw higher currents.

The datasheet will tell you the effective, lower capacity in Ah at the current rate you are going to draw (300W/12V = 25A). Look for the capacity at 25A. It may be only 80Ah or less.

This is all very confusing I know, but it is worth understanding to save yourself money in the long run by ruining expensive equipment.

 

[mister]

Thanks for that post Gaz - I was not aware of the need the capacity for the current rate you plan to draw

 

[The Thug]

Thanks for the informative post Gaz.

 

[DominionZA]

Except that the figures given are too high. There is no way a desktop PC would draw 500W continuous unless you are gaming with a very powerful graphics card.

Also, laptops can draw around 30W. Check the power brick. It should have a wattage on there.

I would estimate your entire setup would be:

Laptop: 50W
PC: 200W
Router: 12W

Total say 300W rounded up.

Sounds right.

I have been doing monitoring on my setup using a watt meter plug. Plug watt meter into socket, multiplug into watt meter, then devices.

I am running the following and pulling a constant 250W.
Quad core Xeon with 6 drives. This is my download and Plex server.
Netgear 16 port rack mounted switch.
Asus RT-N66U router/wifi
Linksys/Cicso WAG120N for ADSL

The above hits around a constant 130W.

Then I added my dev machine.
i7-4790 with 2 x 23" displays plus logic speakers. This takes it to 250W total.

Only problem for me is I cannot find another inverter/charger. So got 4 deep cycle batteries sitting here doing squat.

 

[DrJohnZoidberg]

Just ordered another one of these APC's for the office. http://www.wootware.co.za/apc-back-ups-rs-br900gi.html

Very happy with this unit so far.

Still waiting on battery replacement for one of the other units which I'm told will be available next week.

 

[PostmanPot]

Just ordered another one of these APC's for the office. http://www.wootware.co.za/apc-back-ups-rs-br900gi.html

Very happy with this unit so far.

Still waiting on battery replacement for one of the other units which I'm told will be available next week.

I was looking at one of these BR900GIs, but couldn't justify the cost for my needs.

Went with the RCT 2000VA Line Interactive. http://mybroadband.co.za/vb/showthread.php/622463-RCT-Line-Interactive-UPS-Quality/page2

I'd be interested to know the battery setup in the APC? Anyone know? http://www.apc.com/resource/include/techspec_index.cfm?base_sku=BR900GI

The RCT has 2x 12V 9Ah batteries.

 

[DrJohnZoidberg]

I was looking at one of these BR900GIs, but couldn't justify the cost for my needs.

Went with the RCT 2000VA Line Interactive. http://mybroadband.co.za/vb/showthread.php/622463-RCT-Line-Interactive-UPS-Quality/page2

I'd be interested to know the battery setup in the APC? Anyone know? http://www.apc.com/resource/include/techspec_index.cfm?base_sku=BR900GI

The RCT has 2x 12V 9Ah batteries.

The batteries in this unit are 2 x 12V 7Ah, manufactured by APC.

 

[PostmanPot]

The batteries in this unit are 2 x 12V 7Ah, manufactured by APC.

Jealous.

Here's the OEM for RCT. http://www.voltronicpower.com/oCart2/index.php?route=product/category&path=37

 

[DominionZA]

I need someone in the know to advise me please.

If you read further back, I am getting hardly any backup time from these 102Ah batteries that I have hooked up to the EVO140 UPS.

Recap...
Ellies 102Ah hooked up to the EVO150. Pulling about 250W. 2 mins and the UPS starts going mad. Battery voltage measuring around 11.6V (from 13.6 odd).
If I disconnect everything and leave just the router and ADSL, I get 45 mins or so. Madness.

Thinking maybe the battery is defective, I tried the other. Same result. Then I tried one of the 70Ah batteries that the Ellies ones are replacing. Same result - just a little shorter.

What is causing the batteries to drain so extremely with hardly any draw on them? It is looking like the UPS is doing something - but I don't have a clue what.

Any ideas?

 

[DrJohnZoidberg]

Jealous.

Here's the OEM for RCT. http://www.voltronicpower.com/oCart2/index.php?route=product/category&path=37

Wonder if there is any difference between these battery packs with regards to recharge cycles.

 

[air]

Great informative answer! Many thanks deweyzeph

Thanks for that post Gaz - I was not aware of the need the capacity for the current rate you plan to draw

+1 - Thanks gents

 

[The_Traveller]

I need someone in the know to advise me please.

If you read further back, I am getting hardly any backup time from these 102Ah batteries that I have hooked up to the EVO140 UPS.

Recap...
Ellies 102Ah hooked up to the EVO150. Pulling about 250W. 2 mins and the UPS starts going mad. Battery voltage measuring around 11.6V (from 13.6 odd).
If I disconnect everything and leave just the router and ADSL, I get 45 mins or so. Madness.

Thinking maybe the battery is defective, I tried the other. Same result. Then I tried one of the 70Ah batteries that the Ellies ones are replacing. Same result - just a little shorter.

What is causing the batteries to drain so extremely with hardly any draw on them? It is looking like the UPS is doing something - but I don't have a clue what.

Any ideas?

did you buy lead calcium or lead acid ? if its the former, then unfortunately you've bought the wrong battery which is not meant to be used for applications like power backup.

Also what kind of charger do you have ? is It a built in charger or external ? you need to see what is the maximum charge current that your battery can handle.

Could also just be really crap batteries.

 

[The Thug]

Would the way your batteries are wired up impact on your backup time?

 

[The_Traveller]

Would the way your batteries are wired up impact on your backup time?

if the batteries are wired incorrectly then it will damage the batteries.

 

[The Thug]

if the batteries are wired incorrectly then it will damage the batteries.

Maybe that could be the issue with Mike.

 

[DominionZA]

did you buy lead calcium or lead acid ? if its the former, then unfortunately you've bought the wrong battery which is not meant to be used for applications like power backup.

Also what kind of charger do you have ? is It a built in charger or external ? you need to see what is the maximum charge current that your battery can handle.

Could also just be really crap batteries.

I don't actually know. All I know is they are deep cycle batteries.

The latest 2 are those Ellies 102Ah batteries that Makro are running a promotion on - if that helps.

Voltage measures around 13.5V when I turn off the juice and test. The UPS sucks them dry in no time though - but only a load of 250W.

 

[DominionZA]

Maybe that could be the issue with Mike.

It's a 12V ups, so testing just on one battery at the mo.
My 45 min runtime on a 40W odd load is with 2 x 70Ah wired in parallel to double battery and keep 12V.

It seems like the ups is doing something funky.
With my tedelex inverter I would last almost a day with these batteries.