I bought the ZIPPY Compact 2700mAh 4s 60c Lipo Pack for my KH250 build (and the FrSky voltage tel...

[G+_Steve Prior]

I bought the ZIPPY Compact 2700mAh 4s 60c Lipo Pack for my KH250 build (and the FrSky voltage telemetry sensor).  I balance charged the pack before I flew, then after flying for a few minutes the drone seemed more sluggish - I checked the battery and it seems that the first cell is down to 2.9V while the rest are above 3.5V.  This happened twice so far.  The battery hasn't been in a crash and has no damage.  Did I get a bad battery?

[G+_Steve Prior]

Thanks, and I watched the video, but I think this is a slightly different situation.  The video tells you how to charge one cell that's lower than the others to speed up the charging process.  But my situation seems to be that after the balance charge all cells start out at the same voltage, but one of them drops voltage faster than the others.  That's why I suspect a bad cell.

[G+_Quadflyingmedic]

Steve Prior looks like a bad cell. Have got a few batteries like that but they were cheaper batteries than a zippy. Can make it a 3cell if you are good at diy and need a 3 cell or try and contact |ho you bought it from and see if you can get a refund

[G+_Steve Prior]

Today I ordered a Turnigy 2200mAh 3S 25C from Hobbyking, so when that shows up I'll try to RMA the Zippy 4S.  Will see how the KH250 behaves with the lighter weight pack.  I HATE dealing with returning things.  At least I bought the 4S from Hobbyking's US warehouse so I don't have to return it to China.

[G+_Steve Prior]

Everytime I've flown with that pack that cell goes significantly lower than the others.  Today I flew and it ended up low, but after flying I left the telemetry hooked up for a while and now the cell voltage reads zero and my balance charger won't charge the pack at all.  2 days into the RMA process with Hobby King and the status is still "waiting for initial review".  I ordered a 3S pack which shipped today, but it looks like I'm grounded until it arrives.  :-(

[G+_Steve Prior]

Quadflyingmedic Looks like the manufacturer won't require me to return the bad battery.  Do you have a pointer to instructions on how to make a bad 4S pack into a 3S?

[G+_Quadflyingmedic]

Steve Prior I think there are a few vids on youtube. I have never done it just know it can be done

[G+_Quadflyingmedic]

[G+_Steve Prior]

Thanks, I'll give it a shot eventually.

[G+_Quadflyingmedic]

Steve Prior I have a 6 cell with a bad cell. I'm gonna make a 3s and 2s battery from them. One day

[G+_Steve Prior]

OK, this is getting strange.  I received a new 3S pack today, balance charged it and flew.  When I was done I noticed that the first cell was significantly lower then the other two.  I balance charged it again, flew and saw the same result.  One bad pack I can understand, but two seems like too much of a coincidence, though aside from the FrSky voltage sensor connected via the balance port there should be no way the quad's wiring could affect one cell more than another.  What are the odds that the sensor is draining the cell?  Any other good theories?

[G+_Steve Prior]

Only other theory is that the FrSky voltage sensor might be defective and misreading the pack.  Will measure next time with the balance charger and see if cell #1 is really lower than the others.

[G+_Quadflyingmedic]

Steve Prior may be on to something there. Seems strange if you did get 2 bad packs that the same cell would be bad!! If you have a volt meter you could check with that too

[G+_Steve Prior]

Didn't try with my meter, but the balance charger reads the voltages as 3.14,  3.37, and 3.48 after starting with a balanced pack and flying in my basement for a while.

[G+_Quadflyingmedic]

Are you runing any accesories off the balance port?

[G+_Steve Prior]

The only thing connected to the balance port is the FrSky SP-FLVS module you see in the picture above.  It's not running off the balance port, it's monitoring it.