I'm looking to repurpose an old UPS that no longer has a functioning battery. I have a 55-watt, 220-volt table fan and I'm considering replacing the existing battery with a 12-volt, 7.5Ah battery. Since the new battery has a similar voltage but a higher amp-hour rating, how long can I expect it to power the fan? Is this type of modification feasible? Thanks for any insights!
1 Answer
Based on a rough calculation, your table fan consumes about 198kJ per hour. A 12V 7.5Ah battery has a total capacity of about 324kJ. If we factor in efficiency—let's say around 85%—that should give you roughly 1.5 hours of runtime powered by the new battery. Just keep in mind, real-life efficiency can vary a lot depending on your setup!
Appreciate the calculation! It might be worth looking into a smaller DC fan for outdoor use.
I'd say you're in the ballpark with your efficiency estimate—maybe closer to 80%, though.
If you're using a lead-acid battery, remember that typically only half of its capacity is usable. Just something to consider!