UPS | Extending the backup run-time of a UPS with an external deep-cycle battery.

Papa Smurf

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I have done this but it comes at a risk.
UPS charger takes longer to recharge your batteries after a power failure and in return runs hotter.
You risk electrical failure/fire.
For me so far so good, been running this setup for over 5 years now
However I don’t run UPS at home if I am not there to monitor situation
IMG_1664.JPG
 

*Zealot*

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I have done this but it comes at a risk.
UPS charger takes longer to recharge your batteries after a power failure and in return runs hotter.
You risk electrical failure/fire.
For me so far so good, been running this setup for over 5 years now
However I don’t run UPS at home if I am not there to monitor situation
View attachment 619072
That's exactly what I am looking for - I am thinking along the lines of only connecting the charged up external bank once Eskom is off and UPS running. When Eskom is restored, I will disconnect the bank and charge it myself with a standalone charger so that the UPS does not have to charge it.

Excuse my ignorance, but please explain the 96v limitation - Does that mean I can have any size battery as long as the voltage does not exceed 96v?
The UPS itself has 8 batteries and the external battery module has 16 batteries, this totals to 24 - You mentioned I only have 16? Are the rest for reserve then?
 

Jola

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I have also added a larger battery as above, but am well aware of the additional load on the charger circuitry.
 

thechamp

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The 96V battery means that batteries you connect should be in a configuration that gives you 96v, that is eight 12v batteries. What you have now are three sets of battery banks each bank connected in series to give you 96v, those three set are probably connected to each other in parallel(mantaining the same 96v) to increase the run time.
 

*Zealot*

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The 96V battery means that batteries you connect should be in a configuration that gives you 96v, that is eight 12v batteries. What you have now are three sets of battery banks each bank connected in series to give you 96v, those three set are probably connected to each other in parallel(mantaining the same 96v) to increase the run time.
Thanks :D
Would the 8 big batteries then make it go "KABOOOOM!" as discussed in the previous thread, or can I get away with it by closely monitoring the temperature?
 

Papa Smurf

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That's exactly what I am looking for - I am thinking along the lines of only connecting the charged up external bank once Eskom is off and UPS running. When Eskom is restored, I will disconnect the bank and charge it myself with a standalone charger so that the UPS does not have to charge it.

Excuse my ignorance, but please explain the 96v limitation - Does that mean I can have any size battery as long as the voltage does not exceed 96v?
The UPS itself has 8 batteries and the external battery module has 16 batteries, this totals to 24 - You mentioned I only have 16? Are the rest for reserve then?
IMO I cannot say what will happen when mixing existing new batteries with older batteries.
I just as a rule of thumb never do it as there will be resistance in the array of older batteries depleting quicker than newer ones.
I do not know enough on this subject.
I have always purchased UPS's and on day 1 gutted them and threw away the batteries. Then add new big ones externally.

If you want to add to your existing array you need to chat to someone that has more experience in this field. I dont want to give bad advice and you go kaboom
 

thechamp

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Thanks :D
Would the 8 big batteries then make it go "KABOOOOM!" as discussed in the previous thread, or can I get away with it by closely monitoring the temperature?
There is a big potential of it going KABOOOM! The smaller batteries are going to be overcharged while the system is battling to charge the bigger ones, the only way to go about it is to remove the smaller batteries altogether from the system. I think the 96V UPS is just a waste, just get yourself a 24V UPS and use the same batteries.
 

thechamp

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IMO I cannot say what will happen when mixing existing new batteries with older batteries.
I just as a rule of thumb never do it as there will be resistance in the array of older batteries depleting quicker than newer ones.
I do not know enough on this subject.
I have always purchased UPS's and on day 1 gutted them and threw away the batteries. Then add new big ones externally.

If you want to add to your existing array you need to chat to someone that has more experience in this field. I dont want to give bad advice and you go kaboom
It is not just mixing old batteries with new, but also mixing different battery capacities.
 

Geoff.D

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Thanks :D
Would the 8 big batteries then make it go "KABOOOOM!" as discussed in the previous thread, or can I get away with it by closely monitoring the temperature?
You MUST maintain the battery voltage that a UPS is designed for. You can never connect any other battery system except a 96V setup to the Powerware unit you have.

So you are stuck with adding "Sets" or "strings" of 8 12V batteries to the UPS battery connection.
Then as already stated the internal charger circuitry in the UPS has a limit regarding what it can deliver in terms of amperage at 96V. Therefore if you add larger batteries measured in Amp-Hours (AH), then the charger will simply charge those batteries at the maximum it can deliver, which means the batteries will take longer to charge after being allowed to discharge. The deeper the discharge the longer it will take.
Hence why we are all warning you that you can spend one H of a lot of money buying a larger battery bank and then find the batteries never reach full charge simply because the time between charge and discharge cycle is inadequate.
Now It depends on what batteries you can get and afford. If you want to stick to typical deep cycle 12V 102 AH batteries, it means you have to buy 8 of these and almost guaranteed, the charger in the Powerware system will burn out! The only unknown is how quickly!. Hence you will have to stick to matching the AH rating of the existing batteries in the units, or maybe slightly larger.

"Upgrading" UPS setups at 12V or 24V is marginally feasible as per Chuckymysters setup.

But note his warnings!. The charger will work harder and have more power loss, which manifests itself in the form of overheating and needs to be constantly monitored.

UPS systems are designed to provide you with only a few minutes of stby (measured in minutes rather than hours) long enough for you to switch OFF any critical devices, and that is all. Sometimes the UPS inverter/chargers have sufficient spare capacity in their designs to be able to charger larger AH batteries and that is what all these Heath-Robinson setups are about -- exploiting that spare capacity.

If you want hours of back up power, you need to go for a system designed to do that. It is NOT then called a UPS at all.
Rather dump that Powerware unit all together and spend the time and effort in researching and then buying a proper backup power setup as Dairyfarmer has done to suit what you want to do.

If the batteries in the Powerware system and the EBM unit are okay then use it as backup power for small things such as cellphone chargers, ADSL modems, Security systems etc until the batteries have to be replaced.

Based on the manual, The Power ware system has plenty of spare capacity in it to be able to drive a total of 11 sets of 8 9AH batteries before reaching its design capacity. in the manual, there is a table giving you the expected increase in standby times with each additional EBM you add.

The problem I have with this design is the added internal cable losses introduced through the daisy chaining cabling between the units! The last EBM added in this design will most definitely "never" ever be properly charged unless there are hours and hours of charging time available. Hence why tis is a really poor design to follow for a battery backup setup anyway, and just not worth the money spent.
 

*Zealot*

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There is a big potential of it going KABOOOM! The smaller batteries are going to be overcharged while the system is battling to charge the bigger ones, the only way to go about it is to remove the smaller batteries altogether from the system. I think the 96V UPS is just a waste, just get yourself a 24V UPS and use the same batteries.
Thanks :thumbsup:
That explains @Chuckmyster removing his batteries too and replacing with new larger ones.

Cost of replacing all batteries with new big ones on the UPS vs inverter setup with batteries.
I need a min of 2 hours with a 1500w load.

Thanks guys.
 

Papa Smurf

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Thanks :thumbsup:
That explains @Chuckmyster removing his batteries too and replacing with new larger ones.

Cost of replacing all batteries with new big ones on the UPS vs inverter setup with batteries.
I need a min of 2 hours with a 1500w load.

Thanks guys.
1500w load is massive, you need to reduce.
I'm running around 400 watts for load shedding off my 2 x 105Ah batteries and survive nicely without hurting my batteries.

Remember it is loadshedding, you just need to run the 'survival' stuff for the 2hrs
 

Geoff.D

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Voltage and Amp-Hour Arithmetic

In the simplest form, ignoring losses (internal resistance, cabling etc) and efficiency effects,

is as follows:

Identical batteries added in series with each other will increase the Voltage
BUT will maintain the AH rating
of the set of batteries.
In the EBM case, 8 (12v, 9AH) means the Voltage is now 96V (8 x 12), with a total AH of 9 AH

Identical batteries added in parallel keeps the Voltage the same BUT increases the Capacity of the "set" of batteries.
In the EBM case, 2 set of 8 batteries each at 12V 9AH means the voltage is 96V and the Capacity is now 2 x 9AH = 18AH
So, assuming no losses etc, 11 sets of batteries in the Powerware system means the Voltage is 96V with a total capacity of 11 x 9 = 99AH, which does not even match a 102 AH battery!

So, IF you were to replace the batteries in the Powerware unit with 8 102AH batteries you would have 96V and 102AH, which will probably mean the unit will already be running beyond its design capacity and will overheat.
 
Last edited:

thechamp

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Thanks :thumbsup:
That explains @Chuckmyster removing his batteries too and replacing with new larger ones.

Cost of replacing all batteries with new big ones on the UPS vs inverter setup with batteries.
I need a min of 2 hours with a 1500w load.

Thanks guys.
What are you going to plug in that demands 1500w?
 

*Zealot*

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Voltage and Amp-Hour Arithmetic

In the simplest form, ignoring losses (internal resistance, cabling etc) and efficiency effects,

is as follows:

Identical batteries added in series with each other will increase the Voltage
BUT will maintain the AH rating
of the set of batteries.
In the EBM case, 8 (12v, 9AH) means the Voltage is now 96V (8 x 12), with a total AH of 9 AH

Identical batteries added in parallel keeps the Voltage the same BUT increases the Capacity of the "set" of batteries.
In the EBM case, 2 set of 8 batteries each at 12V 9AH means the voltage is 96V and the Capacity is now 2 x 9AH = 18AH
So, assuming no losses etc, 11 sets of batteries in the thePowerware system means the Voltage is 96V with a total capacity of 11 x 9 = 99AH, which does not even match a 102 AH battery!

So, IF you were to replace the batteries in the Powerware unit with 8 102AH batteries you would have 96V and 102AH, which will probably mean the unit will already be running beyond its design capacity and will overheat.
Thank you kindly for your time Geoff :notworthy: I'm giving up on this and tossing the idea, will explore the inverter route as with @Dairyfarmer's project.
 

*Zealot*

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What are you going to plug in that demands 1500w?
Roughly calculated, but will decrease to stick within that load:
4 LED outside perimeter lights 10w each.
LED lights for 3 rooms
Burglar alarm
Server
Modem/router
24 port POE switch with couple IP cams
CCTV DVR
TV with PC
 

thechamp

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Roughly calculated, but will decrease to stick within that load:
4 LED outside perimeter lights 10w each.
LED lights for 3 rooms
Burglar alarm
Server
Modem/router
24 port POE switch with couple IP cams
CCTV DVR
TV with PC
And the wattage for the others?
 

Papa Smurf

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@Geoff.D nice post on #11 i missed it all together until now. But yes you are right, a UPS is designed to keep your computer running until you can save your files and switch off.
Not to run for an extended period of time.
DIY'ing with UPS's is risky as I know and I heed warnings to all that go down this road.
It can go kaboom.
As you mention rather invest in off-grid power solutions for load shedding times, there are plenty of cool things out there.
 

Geoff.D

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Thanks :thumbsup:
That explains @Chuckmyster removing his batteries too and replacing with new larger ones.

Cost of replacing all batteries with new big ones on the UPS vs inverter setup with batteries.
I need a min of 2 hours with a 1500w load.

Thanks guys.
What you illustrate here is why so many people are disappointed with their "backup LS" purchases done in a panic.
The first problem is the expectation that you can possibly afford to provide yourself with a power source so that life can continue as you are used. Unless you own a mint, forget it, you have to learn to compromise and reduce the load and understand the difference between peak (surge, startup loads) and average loads.

Next, you have to understand that the trade-off is always between backup time and load.
1500W at 24V means = 62 Amps! That is one helluva big battery setup you need! A 102AH battery string of 2 batteries will probably only give you 30 minutes standby time at best. So with a very simple calculation, that means you will need 8 102AH batteries to get even close to 2 hours of standby. ( very rough calculations).
Now you need a charger to be able to charge the 8 batteries in a reasonable time.
 
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