Battery goes randomly goes between full charge an 0v - Page 1
Forum section: electronics / beginners

author: doitnowjust
author_rank: Newbie
timestamp: January 17, 2024, 05:53:00 pm
content: Hello,I have a new Li ion battery that is 14.4v, 6700mAh, 96.5Wh for a heavy duty cinema camera. I have been refunded for the battery and left with it. My goal it to try and fix it. Such a waste if its disposed of...When it arrived it would not work at all or charge at all.I fed it a low voltage overnight and now it goes between full charge and zero volts in the following way.When i measure 0v on the mulitmeter i put it in the charger for a couple of seconds then remove it, if it still measures 0v i do it again, after a few times i get a measures of a full voltage.I can then use it in the camera fine. however when i turn the camera off and then on again sometimes it will work and sometimes it wont and when i measure it again when its not working it is at 0v again.I tried discharging it to 14v and then charging it fully. It charged for about 150 mins the manual says it takes 300 minutes to charge.Any idea what i need to do to fix it as its very unreliable at the moment and i cannot use it. Shame .. when it works its fine.Here is a link to the batteryhttps://www.amazon.co.uk/Dot-Foto-Premium-6700mAh-Rechargeable-Battery/dp/B09Q97DJPK

author: Jwillis
author_rank: Super Contributor
timestamp: January 17, 2024, 08:29:56 pm
content: Sounds like a bad connection inside the battery or the Battery Management System inside the battery pack isn't working properly.

author: doitnowjust
author_rank: Newbie
timestamp: January 19, 2024, 10:59:39 am
content: Thanks for your reply.i need to find a way to open the battery case, then how would i test if its a bad connection or the BMS is faulty?if i need to replace the BMS how do i do that ?thank you!

author: perdrix
author_rank: Frequent Contributor
timestamp: January 19, 2024, 11:55:57 am
content: Don't touch it - claim against the warranty if it is new.

author: Siwastaja
author_rank: Super Contributor
timestamp: January 19, 2024, 11:58:32 am
content: +1 to get a new one on warranty. Repairing it would require significant expertise.

author: doitnowjust
author_rank: Newbie
timestamp: January 19, 2024, 12:00:30 pm
content: Thanks for your replies I should add I have been refunded for the battery the vendor doesn't know how to fix it and has left the battery with me. I do have some electronics knowledge just not about batteries repair. Any idea how I might go about opening testing and fixing this battery these are shown to waste it

author: shapirus
author_rank: Super Contributor
timestamp: January 19, 2024, 12:12:29 pm
content: To begin with, it depends on whether it is sealed (glued/welded) or can be taken apart without unreasonable damage.Pictures?

author: Jeroen3
author_rank: Super Contributor
timestamp: January 19, 2024, 12:31:19 pm
content: You areassumingthe BMS isn't just doing this because something is very wrong.Safest would be to recycle it. 96Wh is a lot of flames.But, you can pry open the ultrasonically welded box and harvest the cells perhaps.Discharge it first!

author: doitnowjust
author_rank: Newbie
timestamp: January 19, 2024, 12:32:02 pm
content: i read somewhere that you can use a scalpel to open it by cutting the glue seal.[ Specified attachment is not available ]

author: doitnowjust
author_rank: Newbie
timestamp: January 19, 2024, 12:35:32 pm
content: front side

author: doitnowjust
author_rank: Newbie
timestamp: January 19, 2024, 12:42:10 pm
content: thanks! How would i discharge it ? what voltage should i go down to ? and what do i do once i have it open?