I have one Yamaha PSR 710 synthesizer. To protect it from electrical surges/voltage fluctuations and sudden blackouts, I have bought an APC 850 VA Home UPS (Pure Sine Wave). now I want to buy an appropriate battery (preferably EXIDE) to give the battery support. What specification of battery should I go for?. My synth does not have any extension, nor i would like to play it when electricity goes off. I only want to shut it down gracefully. hence battery back up required only for 5 minutes at a time. Please help.

 

According to the manual you should use a 12V standard (or deep-discharge) type lead-acid battery (not a Sealed Maintenance Free type). The smallest recommended size it will safely charge is one with a 80-100Ah capacity.