UPS Battery Replacement Question

JJRM

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Hi guys, so my UPS packed up recently but didn't really pay attention to resolving until now. I use it just to keep my router and phone running during outages/loadshedding. Its seems the batteries are shot (see Yuasa battery pic attached). I have 2 new 12v 12Ah batteries which was never used (see CSB battery pic attached). Would it be safe for me to remove the old and try using one of the new in its place?

I understand performance might be affected but if I can make use of these new unused batteries, it is better than nothing.

The UPS is a Tescom 2kVA line interactive, about 3 or 4 years old.

Much appreciated! IMG_20190322_153719.jpegIMG_20190322_153734.jpeg
 

thechamp

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Awesome! I suppose runtime will be shorter than normal?
Not necessarily test it and see for yourself. I don't quite understand the 45w rating but I doubt those two batteries are much different in terms of capacity.
 

JJRM

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Not necessarily test it and see for yourself. I don't quite understand the 45w rating but I doubt those two batteries are much different in terms of capacity.
Will do and revert. The angle of the original picture I attached wasn't that great because the old are actually two batteries (in series), while the new is just one. I'll try nonetheless 1553265128795.jpeg
 

thechamp

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Oh? that is a little concerning, hang on a little bit before you hook it up, is that black battery a 24 or 12V battery?
If it's a 12V as written on the labeling it won't work on a 24V UPS.

I see in the OP you said you have two of those, they must be connected in series similar to the old ones.
 

Daruk

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Oh? that is a little concerning, hang on a little bit before you hook it up, is that black battery a 24 or 12V battery?
If it's a 12V as written on the labeling it won't work on a 24V UPS.

I see in the OP you said you have two of those, they must be connected in series similar to the old ones.
Yeah, the old ones are outputting 24v as he said. Make sure you have 2x 12v batteries in series to make 24v.
Personally I think UPS' are inefficient for that kind of thing - you're converting 12v to 240v and then back to 12 / 9 via the power supply. It's probably more efficient to just switch over manually to battery and power it directly then back to mains and charge the battery when the power comes back on. I'm likely going to do that with my router setup. Just need to find a good charger with auto-cutoff...
 
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JJRM

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Oh? that is a little concerning, hang on a little bit before you hook it up, is that black battery a 24 or 12V battery?
If it's a 12V as written on the labeling it won't work on a 24V UPS.

I see in the OP you said you have two of those, they must be connected in series similar to the old ones.
The black battery is a 12v. Yes I have 2 of the black ones so can easily connect it in series just like the old ones. Primary concern is just making sure I don't blow anything because of stupidity.

Obviously because of the different size, it won't fit inside the UPS itself but I'm sure I can make a plan.
 

thechamp

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The black battery is a 12v. Yes I have 2 of the black ones so can easily connect it in series just like the old ones. Primary concern is just making sure I don't blow anything because of stupidity.

Obviously because of the different size, it won't fit inside the UPS itself but I'm sure I can make a plan.
Connect the two in series, measure the voltage, you should get something around the 25.3 to 25.6, connect the UPS and sit back to admire your work, easy peasy, lemon squeezy, nothing will go KABOOOM!
 

JJRM

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Connect the two in series, measure the voltage, you should get something around the 25.3 to 25.6, connect the UPS and sit back to admire your work, easy peasy, lemon squeezy, nothing will go KABOOOM!
Awesome. Thanks for the help. Will test it out and post results here later
 

JJRM

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Yeah, the old ones are outputting 24v as he said. Make sure you have 2x 12v batteries in series to make 24v.
Personally I think UPS' are inefficient for that kind of thing - you're converting 12v to 240v and then back to 12 / 9 via the power supply. It's probably more efficient to just switch over manually to battery and power it directly then back to mains and charge the battery when the power comes back on. I'm likely going to do that with my router setup. Just need to find a good charger with auto-cutoff.
Good idea. In my case though that will mean buying a charger and making up different power cables with the appropriate connectors for the devices I want. I'll get to that when I have a chance.
 

Daruk

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Good idea. In my case though that will mean buying a charger and making up different power cables with the appropriate connectors for the devices I want. I'll get to that when I have a chance.
True, it will be a bit of work by comparison. The UPS will have that charging circuit built in, though not sure if it's independent or part of the main board - probably the latter. My thinking is to get a few gel cells like the ones you have and dedicate one per device I want to run - DSTV, router, Raspberry Pi, etc. with a small home made charge circuit for each one so that it's constantly powered by battery and the battery is constantly trickle-charged while there's power and then it switches over to full charge after a power outage when Eskom is back on.
 

Koosvanwyk

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It should work. The old batteries where 4Ah, so the new ones will last longer BUT check that the UPS is strong enough to charge the to 100%
 

thechamp

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It should work. The old batteries where 4Ah, so the new ones will last longer BUT check that the UPS is strong enough to charge the to 100%
Would you be kind enough to explain how you got the 4ah?
 

Koosvanwyk

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Would you be kind enough to explain how you got the 4ah?
The numbers of watts is equal to amps multiplied by volts.
Volts = 12
Watts = 45
Amps = 45 / 12 = 3.75
I did the calc while typing the original response in my head, therefore rounded to 4
 

thechamp

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The numbers of watts is equal to amps multiplied by volts.
Volts = 12
Watts = 45
Amps = 45 / 12 = 3.75
I did the calc while typing the original response in my head, therefore rounded to 4
So 45w per cell should not imply that it should be 4Ah multiplied by 6 cells that a battery has to give us 24Ah?
 

Koosvanwyk

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Missed the "/ cell" part !!. Problem is that the 12V is the total while the watts is per cell, so the formula used is incorrect. Google search reveals that it is 8.5ah.
 

JJRM

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So after leaving it charging a few hours yesterday, I was happy to see that it charged up to 90%, that is until our load shedding slot began a short while ago. Sadly though, my UPS isn't switching over to battery when it loses AC power. Might be a fault on my UPS itself. I'll probably have to look at a new UPS. Happy I've tried at least. I've read up somewhere about little UPSs for CCTV which can also be used for just running a router. Any suggestions or experience? IMG_20190323_084230.jpeg
 

thechamp

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So after leaving it charging a few hours yesterday, I was happy to see that it charged up to 90%, that is until our load shedding slot began a short while ago. Sadly though, my UPS isn't switching over to battery when it loses AC power. Might be a fault on my UPS itself. I'll probably have to look at a new UPS. Happy I've tried at least. I've read up somewhere about little UPSs for CCTV which can also be used for just running a router. Any suggestions or experience? View attachment 636886
Does it sound like it's trying to switch over? Mine does not want to switch back to AC, I can hear the relay clicking but it just dors not stay on AC.
 
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