From your situation, it seems that the capacity of the rechargeable battery of your emergency light has become smaller.
If it is a lead acid battery, you will not you may not be able to repair it yourself and you can only replace it with a new one. Judging from your usage, you did not charge according to the instruction manual. Your battery is probably overused and not being charged on time. The lead-acid battery has undergone an irreversible chemical reaction, which means that. you cannot recharge it. It has reached the power that a standard battery should have.
If it is a nickel-cadmium battery (or a nickel-metal hydride battery or a nickel-cadmium battery lithium), it can always be repaired. Simply charge it according to the method described in the instruction manual.
I personally think your emergency light may be a lead acid battery. This type of battery isrelatively cheap and has no memory phenomenon. The downside is that he is very afraid of excessive discharge. Once over-discharged, it will not be charged in time and the battery capacity will decrease quickly until it can no longer be used.
I estimate that the battery of your lighting backup is of this specification: 4Ah 6V
It is available in the market and the price is domestically produced: 20 The price ranges from 30 yuan to 30 yuan imported: about 50 yuan.