Replacing UPS batteries produce a spark

[Rom]

I'm having some problems with my PC's uninterpretable power supply. It came with two 12v 9Ah batteries that aren't charging anymore so I've decided to replace them with higher capacity batteries that are 12v 12Ah. The old batteries were connected in serial (plus to minus) but if I try to connect the new ones the same way it produces a sparks when connecting the last UPS wire to one of the batteries. The spark is about as big as the one that ignites kitchen gas burners, not too big but enough to startle me like a movie jumpscare. I thought the capacity doesn't matter as long as both batteries are 12v. Also they are bigger in size and don't fit the UPS case so I have to use them externally. I know nothing about electricity and, to be honest, it scares me. Any help will be appreciated.

 

[Wilko]

Hi - perhaps double double check the batteries are the same voltage as the originals and they are wired in exactly the same way as them. Given you now have batteries outside the case, how have you extended the leads? (i.e. any chance of short circuits? ) Are the batteries charged and the PC off? Perhaps post a few pics and it may assist understanding .

 

[telectrix]

is there any load on the batteries when you connect them?

 

[Deleted member 26818]

Is the UPS connected to either the mains or the computer when you are connecting the batteries?

 

[Rom]

The leads are long enough, so there was no need to extend them (just had to rout them from the back, through a vent hole).

 

[Rom]

The UPS is not plugged to an outlet and there's no PC connected to it. When I reconnect the old batteries (those that don't charge anymore) there's no spark.
I did some googling and on one of the forums they say that inverter's discharged capacitors may cause a load which produces a spark. Could it be the cause in my case? How do I safely connect these batteries?

 

[Rom]

Also the batteries are charged.

 

[Strima]

You need to check that the UPS is capable of maintaining higher capacity batteries as you may damage it.

 

[Rom]

The UPS instructions sheet says that the stock batteries should be replaced with the exact same ones. Guess now I can either buy two more 12v 9Ah batteries or a different UPS to use the 12v 12Ah batteries that I already have.

 

[buzzlightyear]

there my friend you have more on the new batteries 6ah more then you need replace with the same batteries .

 

[buzzlightyear]

Also the batteries are charged

they would be if they was not. then you would have to charge them up.

 

[DPG]

A small spark is probably nothing to worry about. Although the UPS is not powering a load, it will have electronic control circuitry trying to start up. Once connected, does the UPS start up OK? (ie. LEDs, LCD display etc.). If it does then I would try a small load on it and see if it functions correctly.

The above is assuming you are CERTAIN that your extended battery cables cannot touch either each other, or any metal work. Is the case plastic or metal where the wires come out to your batteries?

 

[Rom]

Once connected, does the UPS start up OK?

The UPS wasn't connected yet. Those sparks made me think I was doing something wrong so I didn't connect the batteries. Could this UPS be designed to only work with 9Ah batteries?

Is the case plastic or metal where the wires come out to your batteries?

The case is entirely made of plastic.

I've just noticed that the power switch was in ON position all this time. I'll gather some courage and try to connect the batteries when UPS is OFF.

Thanks a lot for the feedback so far!

 

[DPG]

Connect it up with switch off. Then power it up and see what happens. If all is OK then try it with a load.
The capacity of your batteries is not causing this issue.

 

[Deleted member 26818]

Also, connect the positive side first.

 

[DPG]

Also, connect the positive side first.

Doesn't really matter on isolated batteries/plastic chassis. More relevant to things like cars with a grounded chassis.

 

[Deleted member 26818]

Doesn't really matter on isolated batteries/plastic chassis. More relevant to things like cars with a grounded chassis.

Yeah, old habits die hard.

 

[Strima]

Also, connect the positive side first.

Unless it's a Triumph with a positive earth... I wondered why my new LED lamp would work...

 

[Rpa07]

‘Movie jump scare’ - I like that!