Thanks for your prompt responses and guidance.
was wondering If you could enlighten me regarding a peculiar problem
related to No Load/Low Load Auto Shutdown phenomenon of UPS Circuits.
have two UPS'es that are rated for 360 Watts. Unfortunately both have a
load sensing mechanism thanks to similar micro controller circuit.
The battery back up time is fine if load is greater than at least 60-80 Watts.
I only tend to use a humble 10 watt power WiFi Router with the UPS.
This tiny load is considered insignificant and ignored by the UPS
circuit during power cut and it initializes a no load auto shut
countdown of 300 seconds (5 Minutes).
After the auto shutdown I
can again restart the UPS, it beeps a little and gives another
extension of 5 minutes .. and so on..Collectively it can give back up of
at least an hour, except for the 5 minute interrupt sequence which
Can I trick the circuit somehow to extend the time during no load ?
read in an "Ancient book" that No-Load Auto Shutdown could be disabled
by biting off a resistor in the load sensing circuit of UPS. I have no
idea which resistor could it be ..
Pardon me for the multiple shots,I tried to give a better view..
through an external circuit arrangement, because trying to modify the internal circuitry could be risky, unless you are absolutely sure about
you can make a 4 minute 555 IC relay timer
circuit with a 2 second ON time and 4.8 minute off time. and connect a
25 watt bulb load at its output relay via the UPS AC...so this timer
will switch ON for a second or two and connect the load to the UPS,
forcing the UPS to extend and reset the output switch ON timing every
after 4 minutes for the next 5 minutes.
I hope this might help.
Thanks for the guidance,it worked..
I followed the second half of your suggestion about using a 25 watt load and it served my purpose to a significant extent.
I connected a 25 Watt Bulb to the UPS, now it gives a run time of almost one hour and 10 minutes,
Have been using cum testing it for the past 10 days..and feel highly pleased..despite it being little inefficient.
Now coming back to the 555 timer, I found the IC on ebay, How do I program the timer for 2 second ON and 4.8 Minutes off ??
Any special equipment needed ?
adjusting the 555 circuit you can take the help of any "online 555
calculator" and set the values of R1, R2 and the C of your circuit
accordingly by matching the results presented by the software, through
some trial and error.
There's another similar but more efficient method that can be tried using an IC 555 astable and a triac, as shown below:
The above circuit will rapidly switch ON and OFF the load (25 watt bulb) at the indicated rate (2.4 seconds OFF, 0.03 seconds ON) keeping the load just dimly lit, and also tricking the inverter to "think" that the inverter is loaded, preventing the auto shut down.