eric.perry169gmail.com
 lvl.1
United States
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Follow up on screwing up my DJI Inspire 1 TB-47 battery:
To lead off, I had a bad cell reporting about .2 below the rest of the cells. I was going to attempt using a 798-DF13-7S-1.25C connector from Mouser's Website. I was unsucessful... The connector is almost right, but the pins on the battery board are rectangular and not square like on the connector. In my efforts to identify the ports on the battery board, i some how arced and fried something in the connector. This resulted in that specific pin reading 2volts below the actual reading for that cell... This also resulted in the smart board believing the cell was failing even more, and the battery was at like 5% based on the voltage reading.
At this point I had a full battery charged to 4.2Volts on each cell except for on, which read 4.0 volts. I'm Still figuring out how I can hardwire all the cells to the smart board connector (more on this later). At the moment, i need to discharge the cell to a safe storage level so that I can work on it at a later date, and not damage the cells. I've just gotten in FPV quad building, so I just so happen to have other LiPo packs around, and a balance charger, so I moved forward to mod the TB-47 battery to work with the charger.
With the entire pack stripped of all wires, I was left with only the cells and the battery board which links all the cells together in series (well a 6s2p orientation, or 6 groups of 2 packs in parallel, and those 6 groups are in series)
First I need to Identify the cells. Start with negative lead and identify which cell is which in searies (you'll see about a 4volt increase on the volt meter. I used the solder points on top of the battery board to accomplish this.
Second I need to order the right connectors for this. I chose to go with an XT-60 female connector and a JST 7 pin male connector. I took the XT-60 and solders black to negative and Red to Positive. Easy enough. Then I took the JST 7 pin connector. Mine had a red lead, which after checking the orientation in which it would go into my charger, was the correct lead to pair with the positive (red) side of the battery. I then matched each cell with a black lead, making sure that the last black lead (which lined up with my charger's negative pin) soldered to the negative (black) side of the battery.
With all my soldering, I wanted to verify that my solders were good, and the correct information was present. I took and multimeter, and I checked each pin on my balanced JST 7 pin connector to make sure it showed the 4.0-4.2 volts I was expecting. I also checked for continuity on the black lead to ensure I was all connected...
With this all connected, I went ahead and added some cheap electrical tape insurance over top of it all. I then plugge in my XT-60 on the charger, and followed that up with the JST 7 pin. And Perfecto! I got all my info. Each cell read out in the same order as the DJI app, and I'm now able to set the charger to discharge to a storage charge capacity.
My charger is discharging at 0.3A, so it's goign to take a while, but it's keeping the battery cool, and it's actually letting me do something about this....
Here's what I propose as a fix:
Leave the JST connector on it, perhaps shorten it up. Take the 7 pin connector that would have connected to the battery board (remember I have a bad connector on the board now) and cut it off. I'll take all the leads and solder them to a JST-7 femaile connector. Hoping I have enough room, I'll connect the two, cram them in the case, and put it all back together (removing the XT-60 and resoldering the battery terminal leads). This would allow me to service this battery again if the same issue happens.
The other solution if this fails, direct colder the 7 pin, and if that fails, I make a really expensive 6S2p, 2x3S2p , 2x6s, or 3x4S batteries for my new found quad hobby.





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