I have an electrical box powered by 120Vac, and want to have a red LED indicator light turn on if ever the 120V power is gone. A battery would have to be on stand-by to turn on this light.
My plan is to have the 120V terminals connect to a 24V battery charger charging a 24V battery, and a relay that closes contacts from the battery to the light, and probably a little piezo buzzer, powered by 24V, when no voltage is detected from the source. So the light & buzzer is like an error indicator. I called a battery supplier, they said it's better to use lead acid battery (b/c it's hard to get lith-ion phosphate batteries shipped) and a UPS board so that back-current won't occur just in case the 120V power goes out.
>What should I look for when charging this battery? What should I be careful of (too little voltage, too much, etc.)?
>Should I use a UPS board? What exactly do they do?
>What type of battery should I use that could last a few years?
My plan is to have the 120V terminals connect to a 24V battery charger charging a 24V battery, and a relay that closes contacts from the battery to the light, and probably a little piezo buzzer, powered by 24V, when no voltage is detected from the source. So the light & buzzer is like an error indicator. I called a battery supplier, they said it's better to use lead acid battery (b/c it's hard to get lith-ion phosphate batteries shipped) and a UPS board so that back-current won't occur just in case the 120V power goes out.
>What should I look for when charging this battery? What should I be careful of (too little voltage, too much, etc.)?
>Should I use a UPS board? What exactly do they do?
>What type of battery should I use that could last a few years?