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Author Topic: industrial grade ups...48 volt battery pack?  (Read 316 times)

WB7TDG

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industrial grade ups...48 volt battery pack?
« on: August 19, 2022, 10:45:28 AM »

ok fellow geeks...
I have a full sine wave industrial grade 1500 watts  ups that uses external 48 volt sla battery packs. each external battery container uses 8 12 vdc 9 ah agm batteries arranged in two 48 vdc strings. the system has served me very well, but am having to replace the batteries ever 3-5 years. I guess that's typical.
What I am researching is replacing those little 9 ah batteries with either a string of 4 35-50 ah agm, sla or wetted deep cycle batteries. Am also researching using a 48 volt lithium battery pack.
The system is next to an outside wall so ventilation is no problem.
What I want, when it comes time to replace the current battery system is something that will last me for at least 10 years or so.
advice anyone?
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NA6O

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Re: industrial grade ups...48 volt battery pack?
« Reply #1 on: August 19, 2022, 11:31:39 AM »

I went thru this with a big Tripp-Lite rackmount system. Against my advice, the owner added a huge array of AGM batteries… 1600 AH worth! They do work, but there’s two issues. First, the UPS doesn’t have sufficient charging current. Not even close. Even after weeks of charging, the array doesn’t reach float potential. So don’t get carried away with the quantity of batteries. Second, the RFI was horrendous. See my report at https://na6o.com/main/RFI_files/Tripp-Lite_UPS_RFI_Report.pdf

Do not use Lithium batteries on a system that doesn’t have a proper charger for that chemistry. They will promptly fail.

A modest capacity lead acid battery set should work reasonably well. There’s really no reason to spend more on AGM. Gel cells are the normal choice in fixed applications. And 5 years, yes, that’s typical. I’m not up on Li-based UPS systems other than the big ones associated with solar gear… Li is the only way I can see that would give you a very long service life.

Gary NA6O
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WB7TDG

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Re: industrial grade ups...48 volt battery pack?
« Reply #2 on: August 19, 2022, 01:10:45 PM »

very good Gary....nice to open up a line of dialogue on this...
each external battery pack has its own charger....but I find they tend to overcharge or cook the batteries....if I use the ups internal battery charger, I don't get the overcharge...IF the batteries are all the same brand and amp  hour and they are ALL replaced at the same time...
RFI...yep got it and still tracing it down. got one of those ac input rfi filters that come in a little sealed metal case somewhere in the shack. will see if installing that directly in the ups case to filter the a/c input will help.
my ups is a cyber power PR1500LCDRTXL2U. the ups is on its own individual 120 vac circuit breaker
will investigate gel cell batteries a bit further...
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WB7TDG

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Re: industrial grade ups...48 volt battery pack?
« Reply #3 on: August 19, 2022, 08:41:26 PM »

just got thru reading on the tripp-lite article.....will print that out...love that huge toroid!
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KB8VUL

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Re: industrial grade ups...48 volt battery pack?
« Reply #4 on: August 20, 2022, 10:52:48 AM »

Personal experience on AGM vs Flooded Lead Acid or SLA's
I work on tornado sirens that are battery powered at 24 volts.  So two 12 volt batteries.
For years we put standard deep cycle boat batteries in them and would get maybe 2 years of life from them.  Putting standard automotive batteries in them netted less than 2 years of service life from the batteries.
I switched to an AGM, specifically a DCM0075 from Interstate Battery.  We had contracts on a number of sirens that required them to be replaced every 3 years or as needed.  We missed that window once and left the batteries in place for 6 years.  When I pulled those batteries from service on the rotation, they were STILL at 95% capacity and are now 10 years old and are at 92% capacity.  And with your specific application where the batteries are constantly and properly maintained with correct charging, I would expect them to last just as long.  These AGM batteries are NOT an SLA and do hold up a lot better than SLA's or Flood Lead Acid over time. 
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KB8VUL

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Re: industrial grade ups...48 volt battery pack?
« Reply #5 on: August 20, 2022, 11:09:27 AM »

Now, something else with replacing batteries on a UPS and significantly exceeding the Ah rating of the original batteries.
SOME of those UPS units are designed with a battery capacity in mind.  Meaning that the heating of the internal components during operation from the batteries EXPECTS a certain amount of capacity from those batteries and for them to discharge within a certain time frame.  Meaning the batteries will go dead before the internal heating starts to be a concern.  If you have a UPS that doesn't have in the original design for additional battery capacity, then it very well may expect the batteries to discharge in a certain time frame protecting the unit.
Taking a UPS like that with 9 or 12 Ah batteries from the factory and putting a 75Ah battery plant on it may cause damage to the unit if the outage exceeds the expected time for the batteries to give up.  I have seen this happen and even did it a couple times not realizing what I was doing.  This is typically going to apply to the little UPS units that are 1500Va and smaller.  Once you get into the larger units that are 3KVa and larger (have a 20Kva on a 75Ah string that's 144 volts) there is less concern because those units all have external battery bank inputs for added capacity. 

And I will remind you, even if you are already aware, 48 volts and up with big batteries is BIG power availability, especially when it comes to things shorting out. Proper fusing and protection from contact by yourself or conductive objects is a MUST. I have plexiglass mounted to metal frames protecting my battery plants because of this.  My 12 volt plant is 750Ah with a 75 amp charger maintainer.  This feeds a repurposed 3 phase breaker panel that feeds power to the racks standard breakers for circuit protection and the racks have fuse blocks for the individual radios and equipment to protect that gear and wiring.  Don't screw around with this.  Big batteries will turn a number 2 wire into a red hot heat source in seconds.  And anything combustible will catch fire that it comes into contact with. 
 
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KB8VUL

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Re: industrial grade ups...48 volt battery pack?
« Reply #6 on: August 20, 2022, 07:38:03 PM »

https://www.youtube.com/watch?v=DpQeDcEpEn0

48 volt and smaller systems in failure mode testing
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WB7TDG

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Re: industrial grade ups...48 volt battery pack?
« Reply #7 on: August 21, 2022, 09:21:53 AM »

this is getting very interesting!
My cyberpower ups is in a metal case..not plastic...and can use an internal 48 volt battery pack...however I do not use it....there is no protection, fuse or otherwise, from the battery pack to the ups.
my ups can use up to 6 external battery packs in metal cases, connected in series. output of each case has a circuit breaker and each internal string of 4 9ah is also fused. each case will hold 2 of these 48 volt packs and each case is equipped with its own battery charger. as can be surmised, these cases are heavy with fully loaded!
since I currently use just two of these cases I don't use the internal chargers.
each case has provisions for 120 vac inputs.
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KB8VUL

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Re: industrial grade ups...48 volt battery pack?
« Reply #8 on: August 21, 2022, 09:00:41 PM »

this is getting very interesting!
My cyberpower ups is in a metal case..not plastic...and can use an internal 48 volt battery pack...however I do not use it....there is no protection, fuse or otherwise, from the battery pack to the ups.
my ups can use up to 6 external battery packs in metal cases, connected in series. output of each case has a circuit breaker and each internal string of 4 9ah is also fused. each case will hold 2 of these 48 volt packs and each case is equipped with its own battery charger. as can be surmised, these cases are heavy with fully loaded!
since I currently use just two of these cases I don't use the internal chargers.
each case has provisions for 120 vac inputs.

Ok , good info. 
I would say that you would be fine to connect it to whatever capacity battery bank you wanted, as long as you didn't exceed the float current required by the battery plant.

The packs are internally fused I would guess creating a safety for shorts and the like.  Typically they are in line of the batteries somewhere.  APC likey to put them between the center of the battery string.  But I am betting it is somewhere within the packs.
And while the packs connect in 'series' understand that it's still 48 volts so teh packs are in parallel, maintaining the 48 volts to the unit.  I assume they just daisy chain together. 

Yes, I bet those are some heavy packs.  Four 9Ah batteries is gonna have some weight to it.

My big UPS (18Kva) is a bit different in that it runs 2 72 volt trays in series per level and has 5 levels and has a battery cabinet that will parallel with it that contains another 8 levels.  Of course I am not running any of the batteries that came with the unit because the dumb thing needs 60 7Ah 12 volt batteries to fill all the trays and I am NOT gonna spend that sort of money when I have a source of 75Ah batteries I can use. 
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WA3SKN

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Re: industrial grade ups...48 volt battery pack?
« Reply #9 on: August 28, 2022, 10:23:10 AM »

So what does Cyberpower say???
Your UPS consists of an inverter, batteries, and a rectifier system.  The inverter is rated at 1.5KVA. Not sure for how long... they are kinda "coy" about that.  But what load are you using?  How much power is actually drawn does come into play.
You have 12v 9ah batteries presently.  The rectifiers are designed to both float and recharge them.  Adding batteries will increase capacity but not recharge capacity.  I would expect a 5-7 year life for your batteries and since you are replacing more frequently your charge voltage might be a bit high... so what is it now?
Forget about other battery technologies and just "blueprint" what you are using now. I suspect you could go to 12v 12ah batteries and just adjust the float voltage a bit to get the 10 year life you want.  More than that and larger rectifiers would be needed, IE... a more expensive UPS.

-Mike.
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G4AON

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Re: industrial grade ups...48 volt battery pack?
« Reply #10 on: August 30, 2022, 03:43:48 AM »


While the original posting concerned UPS batteries, unless you specifically need mains to power equipment the vastly more reliable solution is to use float charged batteries.

On a hill top radio site that I used to maintain, there were three x 30A chargers in parallel charging a stack of sealed lead acid batteries with 24 Volts feeding a rack of six trunking radios.

Obviously if the mains failed the supply from the batteries continued. If a charger failed it could be removed without interrupting service. The system could operate using a single charger and they were “hot swappable”.

By comparison, equipment rooms using 5 KVA, or 10 KVA, UPS feed seemed to have a lot of failures that needed a system shutdown… they were nowhere near as robust as those 24V float charged systems.

73 Dave
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WB7TDG

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Re: industrial grade ups...48 volt battery pack?
« Reply #11 on: August 30, 2022, 09:30:06 AM »

for the radio station only...
any thoughts on 24 volt battery systems feeding one of those 24 to 12 volt regulators? I notice there are a bunch of them on fee bay and amazon.
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KC3TEC

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Re: industrial grade ups...48 volt battery pack?
« Reply #12 on: November 08, 2022, 08:09:11 AM »

3 to 5 years is the normal lifespan of the batteries under typical industrial scenarios.
"Power failures often occur more"
Typically they use a sealed gel battery due to offgassing during charge cycles
While a deep cycle marine or even an automotive battery would work and possibly last longer, they are a vented battery.
Due to offgassing (Hydrogen) in an enclosed space this presents an explosion hazard.
This is not a problem in a vehicle or boat due to adequate air movement and dissipation rate.
Yes those batteries will work but its not recommended for safety reasons.
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W9IQ

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Re: industrial grade ups...48 volt battery pack?
« Reply #13 on: November 08, 2022, 08:15:48 AM »

SLA (sealed lead acid) batteries have no off-gassing and can be tipped without any electrolyte spill. But the charging and supervisory circuit must support the chemistry.

- Glenn W9IQ
« Last Edit: November 08, 2022, 08:17:59 AM by W9IQ »
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.
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