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A UPS is an Uninterruptible Power Supply that provides backup power when the main power source is lost. Questions on repairing commercial ones are generally off topic.

11 votes
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Can I connect a capacitor in parallels to power supply of a router

Yes, but ... . A capacitor can help as you suggest but it may need more than that. Restating Steven's formula - a Farad will supply one amp for one second with one volt of drop. So 10,000 uF ( = 0.01 …
Russell McMahon's user avatar
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7 votes
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Fixing APC UPS buzzing noise

Applying EHT to far end is to be frowned on - you should not have any EHT in a UPS. … If it's confirmed that the cap's at fault, could I put in the 20uF 250V pedestal fan capacitor on the APC UPS board and expect it to have no detrimental effect on the UPS? …
Russell McMahon's user avatar
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5 votes
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Effect of Battery charging with un equal batteries in parallel

During UPS operation you want the combined energy of all batteries (of course). …
Russell McMahon's user avatar
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3 votes
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How long will laptop run from UPS?

UPS Battery = 12V, 30 Ah. UPS available energy = 12 x 30 x 0.8 = 278 Watt.hour Laptop battery = 14.6V. So N = 4 as 3.6 x 4 ~~ 14.6 Laptop battery capacity = 4Ah (on battery). … Laptop power use = Laptop battery energy / hours operaing = 48/4.5 = 10.666 atts = say 11 Watts UPS runtime - UPS energy/Laptop power = 278 Wh/11 W ~= 25 hours This is longer than a UPS will …
Russell McMahon's user avatar
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2 votes

Solar Charge Controller as "UPS"?

Designing a quality solar battery charging system CAM be as simple as connecting the right COTS components together - BUT knowing how to design to use the COTS parts can be a challenge in itself. Many …
Russell McMahon's user avatar
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0 votes
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Temporary (just 2-3 second) 5V Power Backup for Raspberry Pi

Capacitor: The voltage on a 1 Farad capacitor will drop 1V in 1 second with 1A load. So eg for 100 mA load and 3 seconds holdup for 1V drop you need 1F x 3s x 0.1A ~= 0.3F. More mA or time or less …
Russell McMahon's user avatar
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0 votes

UPS for ESP32 Microcontroller

The easiest approach is to use a capacitor that will power the system during the changeover period. For capacitance C farad, time t seconds, current i amps and voltage drop V volt C = t x i / V …
Russell McMahon's user avatar
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0 votes

Diode rating for a UPS project with extra battery

I_diode mex >= Power_UPS / V_UPS >= 50A An ultra-low Rdson MOSFET used as a diode gives the best results. A MOSFET can provide Rson of < 1 milliOhm at 50A. V drop < 0.05V. MOSFET loss < 2.5W at 50A. …
Russell McMahon's user avatar
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