UPS (Invertor) Backup Increased

I have a invertor which is connected to a battery and our main for power backup. When i connect the negative terminal or positive terminal of battery to the main's ground the UPS shows fully charged battery and works like fully charged, but when i disconnect that wire it shows low charge and shuts down. what is the reason behind this. why its power increases when i connect the wire to main's ground?

Invertor's output is modified sinewave and there is no company name printed and its not locally made

Hi,

I am a bit confused. What you are referring is a power inverter right? One reason maybe is that it is broken. Have you tried testing the device, its voltage rating, etc.?

Thanks for reply. I am using word invertor instead of using UPS from the start. We use it as a power backup when Main supply is Off.I want to know that is there any way a power invertor can charge up battery using only neutral from the main power supply while the main power is off.

I am also confused about this problem

Hi there Imran,

If I understand correctly, you want to charge the battery through your inverter by connecting the main ground only[the main supply is turned off]?
If it is, it isn't possible.

Hope this helps.

Regards,
Justin

Hi imran akhtar,

I think your negative wire going to the bat is cut or any series resistor for the
current limiting in the negative line is open,that may be the reason when you
connect the bat negative to the gnd it works , the reason for the positive terminal ,
of the bat isolating and grounding can also show a status bat fully charged if the bat
is short ie means bat charge voltage negative supply reaches the osc/ invertor ckt through the short cond of the bat and the positive may be reaching the circuit directly from the power supply.