I am using sealed Lead acid battery 12V, 2.3AH. If battery low circuit is NOT used, it discharges as low as 3V. Is it harmful? should I use low limit protection circuit? if yes, then upto what level?
An Automotive starting battery is permanently damaged and will have to be replaced if discharged below 11V (1.8V per cell); a "deep-cycle" battery shouldn't routinely be discharged below 10.8V, otherwise life will be shortened.
An Automotive starting battery is permanently damaged and will have to be replaced if discharged below 11V (1.8V per cell); a "deep-cycle" battery shouldn't routinely be discharged below 10.8V, otherwise life will be shortened.
I told you before, your 12V battery is knackered if it's discharged to 3V.
Send it away for recycling and buy a new one. Don't dispose of lead acid batteries in the household waste, they contain lead which is bad for the environment.
The minimum discharge voltage will be on the datasheet.