APC sua1500 overload with no load atached

[Ordinary]

Hello guys , here brings me problem with the APC ups 1500VA , I would love if you can help me to fix it, i saw couple of threads with similar things here.

Problem is this, when i press power button and he start self-test, it will light up overload led even if there is no any devices attach. The only way to turn it on is by interrupting the self test by disconnecting from the battery and AC, and when i connect it again, first battery than ac, it will start without a self test and work, but when i disconnect AC he will automatically overload.

I also notice when he start self test that there is no volt drop from a battery and he also do not charge battery as well.
I do not have 2x18Ah, so i try him with new 2x7Ah (24vdc), and 2x14Ah, i think that small battery capacity is not a problem.
When he is turned off, i do not have 230v or 0v on exit, instead i have 150v.
I try changing small 22μF caps, because i find in couple of threads that this can solve a problem, but did not help

Here is video what is going on.
https://www.youtube.com/watch?v=lBZ99vrc9kg

[sam_sam_sam]

Re: APC sua1500 overload with no load atached

Here is what I would do

Check the secondary section of this battery back up for a shorts
Or

You could be having a feedback circuit problem which if this case could be a problem find out what wrong with it

If you have a good source for getting capacitors I would recommend replacing all capacitors that are less than 200uf

Are there any capacitors that looks like they are leaking or have popped there tops or the bottom
If you find any of them that have these kinds of problems replace them

[petehall347]

Re: APC sua1500 overload with no load atached

first check batteries ..then check current sensing circuits . might be high ohm resistor or something silly .

[Ordinary]

Re: APC sua1500 overload with no load atached

@ sam_sam_sam
Thanks for replay, i do not have leaking or popped caps. Can you give me little more info how to check secondary section of battery back up, i have only multimeter and basic knowledge of electronics, but i can handle to find short circuit if that is a problem.

@petehall347
batteries are new, but with smaller capacity, i think that UPS should work on them but it will not have long autonomy. How to check current sensing circuits?

I will post image of board, it's easier to locate

https://i.imgur.com/zRqjmV1.jpg

https://i.imgur.com/yP4Vqn6.jpg

https://i.imgur.com/6ljQqES.jpg

[petehall347]

Re: APC sua1500 overload with no load atached

have no idea how to check .. sorry ..
but it must have some current sensing with a resistor or something to measure voltage drop and work out the current .

[sam_sam_sam]

Re: APC sua1500 overload with no load atached

What are the part numbers on the IC chips that are mounted on heat sinks

[Ordinary]

Re: APC sua1500 overload with no load atached

HRF3205
N236
GL

[sam_sam_sam]

Re: APC sua1500 overload with no load atached

HRF3205
N236
GL

Very nice photo can you please post another photo of the board from the top of the board so I can see the part numbers of the IC chips thanks

[Ordinary]

Re: APC sua1500 overload with no load atached

I see only mosfets on heat sink, here is board from a top.
If you can't see just tell me ic number on board and i will wrote part no.

[sam_sam_sam]

Re: APC sua1500 overload with no load atached

I would check all of the IC chip on the heavy duty heat sink ( mosfets ) for shorts and if in doubt to weather or not they are good I would consider replacing them and go from there also if it has transformer that is by itself I would also check it with a ring tester

What brand of capacitors did they use on this board

[petehall347]

Re: APC sua1500 overload with no load atached

150v on output when off is very odd ..was thinking stuck relay but why 150v ?

[sam_sam_sam]

Re: APC sua1500 overload with no load atached

You could be right about the relay > that my question also why little bit more than half the power of what line voltage should be

[sam_sam_sam]

Re: APC sua1500 overload with no load atached

150v on output when off is very odd ..was thinking stuck relay but why 150v ?

But what happens when you put a lamp load on it is still 150 volts

[Brucetafer]

Re: APC sua1500 overload with no load atached

I just went through this as well with a 1500 Pro, It ended up being a fried bios chip, as when the batteries go bad they tend to cook themselves trying to run at super high resistance and low voltage and spikes.. I talked to APC for over an hour and thats what we came up with. Boards are super cheap to replace online if you can match your unit.

[sam_sam_sam]

Re: APC sua1500 overload with no load atached

I just went through this as well with a 1500 Pro, It ended up being a fried bios chip, as when the batteries go bad they tend to cook themselves trying to run at super high resistance and low voltage and spikes.. I talked to APC for over an hour and thats what we came up with. Boards are super cheap to replace online if you can match your unit.

If this is the case then this is a VERY poorly designed board
APC use to be a very good company I wonder what has happened to them