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Tx Battery Failure

PostPosted: Thu Dec 30, 2010 11:47 pm
by Boxhead
Hi Bruce. Mate not here about the Assan module, thats for another time. I did the the Lithium Ion batt mod using ( Trust Fire Batterys from Deal Extreme ) a while back and to date not a problem with 2 Tx's I modded ( an Imax and a Flysky Tx ) but this morning was different. I got my Easy Star ready for flight, alls well. Battery voltage on the Tx screen reading 7.2 Volt, motor controls check, time to fly. About 1min 20 sec into the flight I lost all control of the aircraft as seen in the video.
Tried frantically with the controls and nothing. After the plane had hit the deck I stared down at my Tx and I had a blank screen. Mmmmm.... not good. All switchs on the radio in the same position, especially the on/off, still in the on position. So I left the Tx as is and picked up my plane, disconnected the plane batt and got back to the car. Nothing that cant be fixed. After investigation ( after checking soldering joints, plugs etc , they were fine) I found that the Battery pack of the Tx was reading 3.6 volts. I plugged another set of the same Batts into the Tx and all was fine with the Tx. After checking each cell individually one cell was reading 3.6v and the other was reading zero. Seems one of the cells had died. The Batt's themselves have been charged 4 times since installation. Not the right circumstances but I was glad it was over the park not over a houses etc. their was no warning. I have pictures showing the cell counts but their to big to up load.

This is not a down play on the mod or the Batt's for that matter as I have probably had well over a 100 flights each on both tx's with out a hitch but to bring it to your attention and the attention of your readers. I hope I'm the only one this happens too. Hopefully I caught the only bad cell out there. If the cell was dieing I would have picked it up but it just went with no warning.


Re: Tx Battery Failure

PostPosted: Fri Dec 31, 2010 8:44 pm
by RCModelReviews
So long as you bough the "protected" ones, the cells have an automatic disconnect circuit built into them and it sounds as if yours may have been *way* out of balance, causing one cell to go flat/disconnect before the other.

You might want to add a balance lead to the pack and balance-charge them to be safe.

I did a lot of testing and found that even after 30 recharge/discharge cycles, my cells were still pretty much in balance so didn't bother to include a balance lead when I did the project. I'll add a note to suggest that people check the balance occasionally.

Re: Tx Battery Failure

PostPosted: Fri Dec 31, 2010 9:06 pm
by Boxhead
Bruce, it might be worth a picture as well on hooking up a balance lead. I for one have no idea how too. They were the protected ones that I bought as well.

B :D x

Re: Tx Battery Failure

PostPosted: Fri Dec 31, 2010 11:59 pm
by TG72
Here is a tutorial by Bruce balance lead is included!