Backdoor

Hi all, Years ago i bought a vtbox dna 250 but one day i decided to don't use it anymore and i put it away with the battery low. After few months i've picked it up again and the dispay showed the message "weak battery" and i couldn't charge it. Now i bought a Tuglyfe DNA 250 and my question is: how to avoid this iusse (weak battery)? How can i set escribe to don't full discharge (or overcharge) the battery?