Trying to identify a rechargeable battery
If this is what you are dealing with

https://radioskot.ru/FOTO35/zamena_svincovykh_akb-1.jpg



Then this page will help you.  

The original battery is a 4V 800 mAh lead acid one. 
Details here and available
4V 800mAh Lead Acid Battery Rechargeable Flashlights Electric Mosquito Trap Battery 32 * 22 * ​​65mm Free Shipping.
BUT replacement with 3 x NimH as per the above webpage is strongly recommended.

https://radioskot.ru/FOTO35/zamena_svincovykh_akb-9.jpg