Lights Flicker on UPS with Laptop

I am experiencing a weird flicker on energy savers. When the (desi) UPS is on battery power and when the 4th gen intel processor laptop is connected, lights flicker whenever I open a new tab in browsers or cpu usage increases.

I know these news processors adjust power draw based on cpu usage dynamically but why would that cause lights to flicker?

One of my friends experienced the same issue last year when he bought a 3rd generation intel i7 processor laptop. This wasn't an issue with 1st generation i5 laptop, however.

Anyone experienced the same issue? Thoughts?

Edit: This should have been under "Engineering" forums. Getting rusty after being away for so long.

^ The power drawn by laptop charger is in the shape of irregular pulses rather than a repetitive waveform. Sometimes when you make activity on laptop, the peak power drawn by the laptop and in turn by the charger is high (may be >5-6 Amps for 30 m Sec) and your desi UPS is not able to handle it. As a result, the UPS misses some cycles so you see flicker.

Ijaz, thanks for the explanation.

Excuse my ignorance here, but the charger is rated at 230-240vac 2.0A. Are you sure it can do 5-6A? I have a 2kva desi UPS - is it about the capacity or the ability to handle current fluctuations that would be the issue? i.e. whether I should upgrade to higher capacity or just switch to a pure sinewave UPS like CyberPower?

Peak current demands of chargers, fridge compressors (while turning on) are way high than average values. However I guess it may a problem with your UPS which can't supply the required peak current of short duration and starts missing cycles. Most probably a badly wound main transformer inside UPS.

You can try identifying the problem as follows:

Does this happen only when laptop battery is discharged? Or it also happens even when laptop battery is near full and AC power is connected to UPS output ?

If it happens in both cases, it could be some issue with your charger because at near full battery, the peak load demands by the laptop should be met by the battery.

It happens in both cases, whether the battery is full or discharged. Since getting a charger seemed like the cheaper fix - compared to switching the UPS, I have tried that. Sadly that didn't fix it.

So I am guessing it's probably the UPS then.

[quote=", post:, topic:"]
Peak current demands of chargers, fridge compressors (while turning on) are way high than average values. However I guess it may a problem with your UPS which can't supply the required peak current of short duration and starts missing cycles. Most probably a badly wound main transformer inside UPS.
[/quote]

That's interesting. I always [wrongly] assumed the numbers mentioned are the maximum rather the average. Thanks for the troubleshooting.

Guys Where are you going come back to the point..

@Ijaz : Any idea if this UPS would be able to meet such demands: http://www.cpsww.com.pk/support/download/datasheets/CPS1500PIE_Datasheet.pdf ? I can't seem to find the peak load mentioned but I think you mentioned you had access to one of the CyberPower inverters in the past.

I am considering getting that or http://www.cpsww.com.pk/products/accessories/eps/cps2200eilcd.htm

Before you invest on a new UPS (just for this flickering issue), I would suggest to do some more test.

Can you take your laptop with charger to a friend's or some family member's place where UPS is already installed? Turn off the main switch on that place and test it on that UPS. This will clarify the situation further.

Any UPS (above 500W) should be able to handle your laptop charger. I am really wondering as to what could be the problem in your UPS. I think your present UPS can be repaired.

As I see you are in Rawalpindi, so you are invited on a cup of coffee along with your UPS and laptop+charger. Maybe I can fix your UPS quickly :)