Community Moderator Alumni are previous members of the Moderation Team, which ensures conversations are friendly, factual, and on-topic. Moderators are here to answer questions, escalate bugs, and make sure your voice is heard by the larger Fitbit team. Learn more
@Leyla2511 Thanks for joining the Fitbit Community! That is very strange! For some reason, is it turning off sometimes? It could be that the battery is not having proper contact with the tracker itself and that could be why the app is sometimes telling you that the battery is low and then full. Try the following:
The side spring may be bent as a result of improper battery insertion or pressure being applied to the back housing. Please verify that there is proper contact between the battery and the battery contacts inside your Zip tracker. You can do this by opening the battery door of your Zip, removing your battery, and ensuring that the silver battery tab located in the lower right half of your tracker is flush with the white box outline in the tracker housing. The process can be followed here: http://imgur.com/a/l1KwH
Hope this helps. Let me know how it goes! 
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Community Moderator Alumni are previous members of the Moderation Team, which ensures conversations are friendly, factual, and on-topic. Moderators are here to answer questions, escalate bugs, and make sure your voice is heard by the larger Fitbit team. Learn more
@BKJAJ Thanks for joining the Fitbit Community! That is very strange! Batteries on the Fitbit Zip should lat up to 6 months without having to replace it. Note that constant tapping on its display may drain the battery quicker.
To get the information you are looking for, please contact customer support. They will be able to give you the steps to follow.
Keep me posted!
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