I just did a big mistake tonight!.....

[Doctorbass]

While i work on discharging tests of my parallel multi-cell pack (for the 2000Wh), I just began to charge the discharged one from their previous capacity tests...

I charged 2 16p1s pack linked in serie and REVERSED THE POLARITY!!! :x :x

so the charger seen 2s16p and tried to charge them at -8.4V...

I just goes to watch TV a bit and when i came back, i just watched the voltage on the power supply and i saw 1.2V 10A

Immediatly i just immagined that it could be 7.2V but that i can't see the top horizontal led digit of the 7.. and i just looked at clooser to the display and realized that was exactly 1.2V !!!

Oh hoooo!.. I hust verified the polatity and .... you guess... + to -.. and - to + .. The pack was charging reversed and reached -1.2V !!!.. each 16p1s was at -0.6V!!!!!!!!!!!!!!!!!!!!!

I touched the pack and they was at around 40 degree C.. but no more!...


i'm very disapointed cause all my 10 x 16p1s pack was perfectly balanced to the same capacity!!.. that will be a big job to rematch other cells to the same capacity and RI than the 8 next pack!!!

Now the Pros: these Konion cells ARE SAFE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! THEY can be reversed and goes to reverse Without poping or exploding!! NO FIRE...

that's my 10% positive on that bad news....

Doc.. that will sleep with a bit of frustration tonight!

But.. I hear: stay positive big... . Stay positive.... :|

 

[CGameProgrammer]

But.. I hear: stay positive big... . Stay positive.... :|

You'll probably reverse polarity and accidentally stay negative.

 

[Link]

But.. I hear: stay positive big... . Stay positive.... :|

You'll probably reverse polarity and accidentally stay negative.

You are cold as ice.

Sucks that you'll have to redo the pack, though. Are you planning on taking apart the other packs and rematching the cells or are you hoping you'll be able to find enough cells to make another sub-pack that matches the capacity of the other packs?

 

[Toorbough ULL-Zeveigh]

When walking a tightrope sometimes you're gonna fall off.
We've all been there & done that.
I'm relieved & impressed how safe they actually are & want to thank you for sharing the benefit of your experience

 

[TylerDurden]

Throw away the TV.

 

[Ypedal]

DOH>...

Good opertunity to test abused cells tho.. might want to do this outside.. but will they still take a charge ?

 

[GGoodrum]

Oh, bummer, Doc. Good to know how safe they are, though. Eventually, know that will give you comfort.

-- Gary

 

[Doctorbass]

But.. I hear: stay positive big... . Stay positive.... :|

You'll probably reverse polarity and accidentally stay negative.

You are cold as ice.

Sucks that you'll have to redo the pack, though. Are you planning on taking apart the other packs and rematching the cells or are you hoping you'll be able to find enough cells to make another sub-pack that matches the capacity of the other packs?

I have 60 lbs of these cells so i'll be able to make nre sub pack that will match.. but in time, that's around 12h per subpack of work.. testing, matching, soldering, cuting tabs!!


Doc

 

[Doctorbass]

They are TOTALLY DEAD this morning.

I tryed to re-charge them at low A rate (like 100mA per cell) (1.6A ) on the subpack... but i kept in mind that even tough if thet would survive, i would not keep them for the pack.. that would be rediculous to keep them on a balanced pack!

After the charge began, the voltage slowly rise from 60mV to around 1.1V.. then the voltage rise become faster until it reach 1.4V.. and then... finally the slope change and it began to decrease!! faster and faster.. The heat increased a bit... just for fun, i decided to increase the current to see if the voltage could istop decreasing and increase again.. ... but ... nothing... it kepot a negative slope and felt to zero..

zero.. i mean.. 0.000000000000000000000V

Dead short!

that was a very strange phenomenum!.. that voltage step variation...

but anyway.. they are dead!..


But good news... in my optimization software, i submited to it only 320 cells out of 360... so i gave 40 left cells in that tested batch ready to built 2 16 cells subpack! I dont border if they have a bit more Ah or a bit les RI, all the rest of the subpack will be supported by it.

so i will need only 6-7 hour to spend to repair that error instead of 24!..

Doc

 

[steveo]

that sucks .. Just when you think your finished .. then you do something wrong it cost you more hrs in labour to fix..

I did something similar with my megapower charger ..

I tried discharging a cell on reverse polarity .. i saw some smoke come out of my charger .. i quickly disconnected.. no damage luckly ...


I double check every time i'm testing stuff ..

-steveo

 

[TylerDurden]

.. i saw some smoke come out of my charger .. i quickly disconnected.. no damage luckly ...

Smoke=damage somewhere... keep your eyes open each time you charge.
:?

 

[kbarrett]

.. i saw some smoke come out of my charger .. i quickly disconnected.. no damage luckly ...

Smoke=damage somewhere... keep your eyes open each time you charge.
:?

Ya let the magic smoke out of the magic elf box.

 

[Doctorbass]

The megapower charger is very strong!! I blew 3 fuses on it.. and i also replaced 1 times the original 20A by a 25 cause i had no 20A left.. and it blew.. !! The reason was because my previous 12V power supply dropped too low under 11V and it draw more current to do the 180W max it can do... so i changed the power supply and now i drive at 14V no prob.. the charger is in great shape and have no dammages!

But personally i think you can ameliorate the hest dissipation when discharging!.. the heat sink located on the back have not enough heatsink compound paste!.. between the case and the heat sink itself.. i added and the temp decreased by 10 degrees at 50W discharge.. I advice to do the same with yours! you will increase the life of it.

Doc

 

[jeffkay]

Wow, I did see a Pope's head once coming from the vent area of one of my cells but it went back in. If his legs come out first, it is a reversed cell for sure! ...Couldn't resist.
I will go away now.
Jeff K.