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Inspire TB47 Over Charge Detected
323 8 2017-4-19 22:57:52
markfry
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United Kingdom
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Hello, is there a known solution to fix this error?

I have a TB47 battery with 52 charge cycles that has now developed the LED warning for "Over Charge Detected". The third LED flashes and charging stops at 90-95%. I have tried both 180W and 100W chargers, but the error remains.

It seems that the fifth cell is hitting the maximum charge before the other cells. It's not far off, maybe 0.05-0.1 or less from the other cells but it remains slightly higher during both charging and discharging.

The battery seems to preform fine, but that one cell always stays just a bit higher than the others. Built up resistance, maybe? Has anyone tried to bypass the smart board and directly balance the cells? It's quite frustrating because I feel that if this was a standard Lipo, a simple slow discharge/recharge cycle would probably correct the cell resistance. I have tried a few deep discharge cycles as described by DJI but that also hasn't fixed the issue.

Since the TB47 cells charge above 4.2V, are they effectively High Voltage Lipoly batteries (LiHV)?

2017-4-19 22:57:52
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Mark Guille
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Jersey
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When you say, you have tried deep cycling the batteries, how low (voltage) did you discharge them and how many charges ago?
2017-4-20 08:09:33
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markfry
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Mark Guille Posted at 2017-4-20 08:09
When you say, you have tried deep cycling the batteries, how low (voltage) did you discharge them and how many charges ago?

22.15, 8% and 22.0V, 0%... five cycles ago (the error was present before this and has been there for the last three charges)
2017-4-20 10:48:20
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Mark Guille
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Jersey
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markfry Posted at 2017-4-20 10:48
22.15, 8% and 22.0V, 0%... five cycles ago (the error was present before this and has been there for the last three charges)

First, I would try discharging it until it turns itself off then fully recharge. See if this makes any difference, I'm guessing it won't but maybe worth a try.
Secondly, if it is still under warranty, I would send it back, I'm guessing it's not though, so...
How confident are you about taking a battery apart?
Those cells need balancing. There are two ways of doing this, charging the cells with lower voltage or discharging the cells with higher voltage.
If you want to try this, let me know and I'll talk you through it, I will take one of mine apart and post step by step pics.

Mark G.
2017-4-21 22:11:06
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markfry
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Mark Guille Posted at 2017-4-21 22:11
First, I would try discharging it until it turns itself off then fully recharge. See if this makes any difference, I'm guessing it won't but maybe worth a try.
Secondly, if it is still under warranty, I would send it back, I'm guessing it's not though, so...
How confident are you about taking a battery apart?

I did the second deep discharge as you describe, running the motors until the battery turns off, but that didn't solve the issue.

I've taken the battery apart to have a look and I've also seen some examples online that show the cell solder tab layouts for charging/discharging individual cells. Another option I've been considering is to make up a balance lead so that I can do a proper balance charge using my iCharger. I'm not 100% certain, but I think a Micro JST 1.25mm 7-pin connector might do the trick (and then run that into a regular-sized lipo balance lead). Thoughts?

Cheers,
Mark
2017-4-23 08:13:53
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Mark Guille
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markfry Posted at 2017-4-23 08:13
I did the second deep discharge as you describe, running the motors until the battery turns off, but that didn't solve the issue.

I've taken the battery apart to have a look and I've also seen some examples online that show the cell solder tab layouts for charging/discharging individual cells. Another option I've been considering is to make up a balance lead so that I can do a proper balance charge using my iCharger. I'm not 100% certain, but I think a Micro JST 1.25mm 7-pin connector might do the trick (and then run that into a regular-sized lipo balance lead). Thoughts?

Hi Mark,

It sounds like you have done your homework and are comfortable having a go at this. Personally, I would try to discharge the overcharged cell, by creating a circuit with something like a bulb from a car tail light, regularly checking it with a multimeter until it reaches the same voltage as the others.
2017-4-23 09:24:39
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Skyclip
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Flight distance : 106052
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Germany
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Maybe you can find some additional hints here: http://www.pauljc.co.uk/2017/01/18/dji-inspire-one-battery-revival/
2017-4-23 09:35:05
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markfry
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Great link, I came across that while doing research on this issue.

Circling back a bit, since the battery is giving an official LED error code, I was hoping that there would be an official DJI fix... or at least some other known solution from within the Inspire community that was a bit more above board compared to manaully tweaking cell voltages, etc. Like, is there a way to force a DJI smart battery to self-balance?
2017-4-24 05:07:57
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DTK
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United States
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I am wondering whether charging these batteries are by way of balancing charger. These are expensive batteries and once one cell is out of balance with the 5 cells. A new battery is needed for replacement and that is really not acceptable.
2017-4-24 22:19:13
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