UPS battery etc

[quote=“blogger, post:20, topic:16417”]

First of all, in this whole thread, you have tried to prove that I am a complete jerk and at the end, you are expecting that I shall answer your question? Sorry, I won’t.

[/quote]

The only reason is that you were telling him wrong, and now I’ve got the reason too :) you are never in this stuff since 2008 so you think only relay is responsible for this :D and I wonder that you are being angry on me :) And he even don’t know that what his UPS is 12 volt or 24 volt, and without confirming each and everything you are saying it’s relay :D

If you tell me that I’m wrong, I’ll never mind. But you are…

Still my question is there will you please please tell me any such a battery?

And at last if you know basic stuff according to your needs, and you have a good man who design UPS- you can have a far better desi ups than these homage or aurora ones because these brands are not designed according to local load management of Pakistan. I've and ups since April 2009 and my batteries are same and it still gives me 3-4 hours backup. And the only one time repair charges were 100 rps, I changed buzzer and an led light in it since then....on my average load it draws 7.1 Ampere from batteries while on same load homage draws 7.4 Ampere. Now you decide yourself which one is better for my batteries?

We are here for discussion and corrections. But if you mind to know that you are wrong in some stuff, I'm sorry for that.

You remember few months back I was wrong on windows experience index about RAM score and I asked for you to correct me? I never felt bad to ask you....

I do not want to fight with you on what is correct and what is wrong. What I knew, I posted for others, If it is helpful then it is good otherwise, I am not forcing anybody to listen to me.

:(

[quote=“nvd650, post:13, topic:16417”]

Again you are giving strange statements? there is nothing like 1000 will only run on 2 batteries, you can run it on 4 batteries and even on one battery… basically it is volts that is calculated for number of batteries, is it 12 volt, 24 or 48 volts?

1000 watt UPS running on 12 volt will drain battery in lesser time as compared to 48 volt running on 4 batteries (assuming that capacity of one battery is 200 amph and of 4 batteries it is also 200 amph- 50 amph for each battery)

[/quote]

First, let me say you do seem quite knowledgeable on local UPS scene and I have learnt quite a lot from your posts here.

You are bang on the money when you say that a 1000 watts UPS can have 1 battery or 4 batteries.

However I couldn’t stop my self when I read that a UPS with single battery will drain faster than a UPS with 4 batteries. Key point here is that single 12 volt battery is 200 Ah and 48 volt are 4 times 12 volt batteries with capacity being 50Ah as well.

To elaborate, UPS is just a voltage conversion device. It takes energy and converts into another form of energy like every single ‘machine’ out there and spends a small amount of energy during doing that conversion.

So energy output = energy input - energy consumed during the process.

Lets assume a load of 660 Volts-amps (VA and watts are not same and I pretty sure you know the relation amongst them, so not going into that discussion), also assuming a UPS efficiency of 85% (just a figure, it can vary hugely from UPS to UPS but doesn’t really matter in our discussion).

Hence input power required by the UPS will be = 660 VA / 0.85 = 776 VA

So the batteries will have to provide 776 VA in all. It doesn’t matter if we have a single 12V - 200Ah battery or 4 batteries with 12V and 50Ah.

Calculations:

Battery currents

For 12 V = 776VA / 12 V = 64.66 Amps

since our battery is 200Ah, it will drain completely in (200Ah / 64.66A ) 3.09 hours. (Theoretical value ofcourse, the UPS will go on to low battery mode long before that :) )

For 48 V = 776 / 48 V = 16.16 Amps

Battery is 50Ah, it will drain in (50Ah / 16.16 A) 3.09 hours also.

The point to note is when you put four batteries in parallel connection, you can add-up the current to 200Amps, but the voltage remains the same i.e. 12 Volts.

If you put the batteries in series connection (which is our setup) you can only add-up the voltage to 48, but the ampere-hour rating will remain that of one battery i.e. 50Ah in our case.

This is assuming that the UPS has same efficiency at 12 V battery input and 48 V battery input.

Untill here it was pure physics; my opinion is that 48V batteries will last longer because it will draw lower current (64 amps vs 16 amps) and hence lower heat dissipation and other losses. However the gain may be very small and negligible.

Bottom line is: the two setups will always give you same battery drain time.

Cheers,

Joji

Joji thanks for the nice details but my point was something different. normally batteries available in market have also one other rating, for example you can have a battery of 200 amph /10A (they says it will give you backup if current being drawn by batteries is lesser or equal to 10A and if you draw more current from batteries then energy losses will increase. While batteries with more than /10A- like /20A or /40A will let you draw more current than 10A up to 20A and 40A respectively without extra energy losses in case of /10A battery.

If you go to metro, ask them aurora batteries of /20A or /40A and those are expensive than ordinary batteries.

So in short when you have 4 batteries of same capacity instead of one battery, then it will let you draw current up to 40 A and in this case when you run your UPS with more than average load, you'll get more backup time.

And this is also experienced by me myself :) and even when I connect 4 batteries on a 24V UPS.

[quote=“nvd650, post:26, topic:16417”]

Joji thanks for the nice details but my point was something different. normally batteries available in market have also one other rating, for example you can have a battery of 200 amph /10A (they says it will give you backup if current being drawn by batteries is lesser or equal to 10A and if you draw more current from batteries then energy losses will increase. While batteries with more than /10A- like /20A or /40A will let you draw more current than 10A up to 20A and 40A respectively without extra energy losses in case of /10A battery.

If you go to metro, ask them aurora batteries of /20A or /40A and those are expensive than ordinary batteries.

So in short when you have 4 batteries of same capacity instead of one battery, then it will let you draw current up to 40 A and in this case when you run your UPS with more than average load, you’ll get more backup time.

And this is also experienced by me myself :) and even when I connect 4 batteries on a 24V UPS.

[/quote]


Well you completely lost me here when you said "normally batteries available in market have also one other rating, for example you can have a battery of 200 amph /10A"



I did some googling but couldn’t find any such rating/specification on any of the battery models. Can you provide some specsheet that states this specification.



Some excide batteries spec sheets are linked below.



http://www.piranhaoffroad.com.au/index.php/default/cms/exide-battery-spec-sheet


http://www.ieeco.net/Exide_Battery_Data_Sheets.html#ups



You might be referring to the short circuit current, but it has nothing to do with back up time as far as I understand. Also the short-circuit current will be a lot more higher.


Also, on a separate note, you can’t just hook up 4 batteries on a UPS which was designed for a single 12 V battery even in parallel. Coz the charging side of the UPS circuit can’t handle the additional current requirement and the batteries would take too damn long to charge up.

Cheers,

Joji

Joji, thanks for your response, my fault, I was giving you wrong information, to be crarified please look at the images of the batteries in links below

http://www.rajaelectronic.com/item_detail.jsp?item_id=70&category=Maintenance%20Free%20Batteries&sub_category=null

http://www.rajaelectronic.com/item_detail.jsp?item_id=93&category=Maintenance%20Free%20Batteries&sub_category=null

What is this /10HR? Anyway I'll search again and will discuss with you:)

[quote=“nvd650, post:28, topic:16417”]

What is this /10HR? Anyway I’ll search again and will discuss with you:)

[/quote]

Capacity of a battery is always specified at a certain discharge rate. 150 AH does not mean you can draw 150A for 1 hour or 300A for 30 minutes. This 10Hrs means that you should draw that much current which does not cause a full discharge in less than 10 hours.

For example, a load of 10A on a 150AH battery will fully discharge the battery in 15 hours which is well above 10 hours. So this battery 150AH/10Hr can give you 150AH only if max load is 15A (which will cause a full discharge in 10 hours)

Above that load (or discharge rate), you will not get 150AH capacity.

[quote=", post:29, topic:16417"]

Capacity of a battery is always specified at a certain discharge rate. 150 AH does not mean you can draw 150A for 1 hour or 300A for 30 minutes. This 10Hrs means that you should draw that much current which does not cause a full discharge in less than 10 hours.

For example, a load of 10A on a 150AH battery will fully discharge the battery in 15 hours which is well above 10 hours. So this battery 150AH/10Hr can give you 150AH only if max load is 15A (which will cause a full discharge in 10 hours)

Above that load (or discharge rate), you will not get 150AH capacity.

[/quote]

I was really waiting for you :) now what do you say if you connect 2 batteries on 12 volt ups, it will increase backup time as now you can draw more current, or current drawing from one battery will now divide in 2 batteries?

My computer doesn't restart on homage 660 watts UPS.Its on wide mode though.

-

[quote=", post:29, topic:16417"]

Capacity of a battery is always specified at a certain discharge rate. 150 AH does not mean you can draw 150A for 1 hour or 300A for 30 minutes. This 10Hrs means that you should draw that much current which does not cause a full discharge in less than 10 hours.

For example, a load of 10A on a 150AH battery will fully discharge the battery in 15 hours which is well above 10 hours. So this battery 150AH/10Hr can give you 150AH only if max load is 15A (which will cause a full discharge in 10 hours)

Above that load (or discharge rate), you will not get 150AH capacity.

[/quote]

This actually makes quite a lot of sense. Very well put.

Now on a separate note, can anyone tell me whats the price now-a-days of that battery in the picture … the 150AH, maintenance free battery, I think I would like to replace the one at home with the maintenance free one.

[quote=“nvd650, post:30, topic:16417”]

I was really waiting for you :) now what do you say if you connect 2 batteries on 12 volt ups, it will increase backup time as now you can draw more current, or current drawing from one battery will now divide in 2 batteries?

[/quote]

When you connect batteries in parallel, you are increasing the capacity (AH rating) and effectively increasing the time in which you want to discharge them. So the current drawn by the load will be split equally between the batteries and batteries will be able to give you (near to) full AH rating.

Paralleling batteries has some problems too, for example there is always a small difference in the terminal voltages of even same brand/model batteries. For example if you use 02 batteries and one is at 12.75 Volts while other is at 12.68V, then the battery with lower voltage will act as a load on the battery with higher terminal voltage. A current will start flowing between them until the terminal voltage of both batteries come at same level.

Secondly, batteries don’t degrade equally. After some time, one battery will degrade more than others in the parallel battery bank and same phenomena will happen but on a permanent basis.

[quote=", post:34, topic:16417"]

Secondly, batteries don’t degrade equally. After some time, one battery will degrade more than others in the parallel battery bank and same phenomena will happen but on a permanent basis.

[/quote]

OK, got you, one more question here, let say one battery says for 2 years on a 12 volt UPS, what about if two batteries are connected in parallel to same UPS on same load? I mean what about the life, will it decrease a lot or only some fraction of 2 years?

@Ijaz Ahmed

would you please give some advice on maintenance free batteries i.e. what are advantages and where to get in Rawalpindi-Islamabad

also are there any good battery enclosures available, the ones in shops at college road are of very poor built

[quote=“nvd650, post:35, topic:16417”]

OK, got you, one more question here, let say one battery says for 2 years on a 12 volt UPS, what about if two batteries are connected in parallel to same UPS on same load? I mean what about the life, will it decrease a lot or only some fraction of 2 years?

[/quote]

Well, same load, same UPS but what about the capacity of the two batteries ? If you had previously 100AH single battery and now you connect 2 x 100AH batteries then you can expect increased battery life. But if you think to install 2 x 50AH batteries instead of single 100AH, there will be no difference.

Behavior of locally manufactured lead acid batteries is difficult to predict due to various compromises during manufacturing and (sometimes) poor quality control + various other factors. That is the reason one particular brand/model may perform excellent for me but might fail or will perform below average for other users.

[quote=“ZXCVB, post:36, topic:16417”]

@Ijaz Ahmed

would you please give some advice on maintenance free batteries i.e. what are advantages and where to get in Rawalpindi-Islamabad

also are there any good battery enclosures available, the ones in shops at college road are of very poor built

[/quote]

I bought 04 x DELCO 150AH maintenance free batteries (Korean brand) last year and they are performing excellent. There is no regular importer of quality MF batteries, I just got them from Melody Market Islamabad. Advantages are obvious, they are maintenance free and expensive.

If you want to invest in quality battery and want trouble free operation for a long time, you should invest in deep cycle batteries.

Regarding enclosures, I don’t know much. You can get them fabricated.

Never place the batteries on concrete floors or metallic sheet containers. Always thermally insulate the battery from its metallic container or the concrete floors.

[quote=", post:34, topic:16417"]

When you connect batteries in parallel, you are increasing the capacity (AH rating) and effectively increasing the time in which you want to discharge them. So the current drawn by the load will be split equally between the batteries and batteries will be able to give you (near to) full AH rating.

Paralleling batteries has some problems too, for example there is always a small difference in the terminal voltages of even same brand/model batteries. For example if you use 02 batteries and one is at 12.75 Volts while other is at 12.68V, then the battery with lower voltage will act as a load on the battery with higher terminal voltage. A current will start flowing between them until the terminal voltage of both batteries come at same level.

Secondly, batteries don’t degrade equally. After some time, one battery will degrade more than others in the parallel battery bank and same phenomena will happen but on a permanent basis.

[/quote]

This is quite a common issue which can easily be solved with using diodes (with appropriate current rating) so that there is no looping currents between the batteries. However in that case the UPS charging voltage will be needed to set higher due to a drop of about 1Vdc across the diode.

@Ijaz Ahmed

DELCO 150AH at what price and from which store in Melody?