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Battery error - cell broken
350 1 2018-4-15
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Deanneat
lvl.1
Australia
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Ok - first post here

got the dreaded battery error the other day, out of warranty (actually just on the 12 months old) 3 charges total, cell lost. So googled lots, read lots, warranty, 6 months..... don't fly with bad cell blah blah blah - well, decided to pull the thing apart - and not just a "Oh well - lets do a you-tube on blowing it up"

I am putting together a "Why" this has happened - will post it up when finished, but decided to post up some preliminary findings.

so removed the outer case, made a balancing cable to plug into my iCharger 206B and off I went
3S 11.1V - reported back 12.59V equates to 4.19V per cell - so 3 x fully charged cells

Alarmed with "BATTERY VOL ERR CEL CONNECT" after 6 seconds
checked - 4.19V, 0V, 4.19V - yep cell missing

must be something I did.............

hmmmmmmmm, so soldered my balancing cable to the top of the moterboard (battery, not DJI LED motherboard) thinking the little connections were faulty, got the same report...........

OK so not the motherboard, not the cables, must be the way it is constructed.......... lets remove the cells from this little motherboard

Now metal long nosed plyers, metal screwdriver........ ohhhhhhhh so careful I was knowing I have 3x LiPo fully charged cells waiting to have some fun doing a thermal runaway in my workshop

Managed to remove it (with very little damage) and inspected all 3 individual cells - guess what - perfect

DJI use a spotwelder like everyone else in the industry to weld the cells to each other and to the board with very little solder (except the individual cell reporting and the combined battery leads)

There it is - a high impedance spot welded joint, purely a DJI construction fault, with no warranty and of course deniability.......... I just wonder how many of these are out there ...............

here is a close up ............. Hey DJI - you owe me a battery & your spot welding is horrible (but I'm sure you already know that)

I am going to put it together without the DJIA70-1 motherboard as this is the problem and will post up my efforts

at USD$100 each - if you have some, post them my way - might have to fix them and keep them

rsz_dji_bat_error.jpg
dji batt bits.jpg
2018-4-15
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Bekaru MP UAV
Captain
Flight distance : 15513100 ft
South Africa
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well done - good investigation. thanks for the pics and good run down/explanation. i am a firm believer that there is more to unexplained drone losses than simply 'user error'.
2018-4-15
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