Hello,
I have four Zippy 4S, 3,000 mAh batteries.
Each one was used about twenty times and was never discharged below 14.8 no load volts and above 80% of nominal capacity.

From the beginning, each battery takes about 1.5-2 hours to charge from storage 3.8 V to the fully charged state.
I am charging at 1C using the computerized charger that does not allow for any form of accidental batteries abuse like overcharging, overdischarging, too high charge or discharge rate, wrong polarity etc. 1C is 3 Amps. so, even with charging losses reaching 20%, each battery should charge in about 1.2 hours.

The batteries do not show any signs of dying like swelling or/and getting very warm while being charged or immediately after flights.

Perhaps Zippy batteries, being of mediocre quality, simply are like that.
Perhaps...something else.

Thanks,
Matt

Watch your charger taper off at the end of charge.  The charge toward the end tapers from your chosen charge rate to a rate of C/5 -  C/40, depending on the charger and your choices.  That portion of finish charging is slow.  If you choose C/5 or C/10, finish is faster than tapering to C/20, the basic setting of many.  If you choose to stop at C/5 you get a bit less charge or amps into the pack.  As long as you are having over 20% remaining amps after flying, you can try changing the finish number for a quicker finish.  And yes, balancing can slow the charge especially if the cells are any out of balance.  Most Batteries claim that it is ok to charge faster then 1C.  I use 1C unless I am in a hurry, and then I may use 1.5 - 2C.  Others may go higher.

If you use a voltage tester, the voltage after C/5 may be a little less than 4.2V.

Basically, balance charging takes a while, and the more out of balance your cells are, the longer it's going to take.
What i do, is to make an adapter where i can access the individual cells. I charge them individually initially. Then they are,  or should be balanced.
The higher quality batteries have cells selected that are naturally balanced, and because of that,  will take less time to balance charge. That's a separate process,  so it costs more  to make packs.
If you want to field charge packs for a second flight of the day,  I'd skip the balance charge and just do a fast charge to the proper 4s voltage.
Kind regards,
Chris

Good find Matt.  I have an older charger that also has "fast charge" and it took me a while to figure that C/5 was the reason as the charge rate is still programmable.  It is "fast" because of the faster ending. 

Remember that when you charge them at C/5, the actual input charge may be a bit less.  Check voltage after off charge for several minutes.

Hello everybody,
I have made six flights with my eParrot today.
Four flights were 5 minutes each pattern flights, two were 4 minutes each and I used them to practice the wingover, square eight and hourglass.
These maneuvers, and especially square eight and hourglass, are consistently inconsistent and I have to improve them.

I have used four 4S 3000 mAh Zippy batteries for the pattern flights and two 4S 2200 mAh E-Flite batteries for the practice flights.

The no load cells voltages, measured about 1/2 hour after the flight #6 ended, were as follows:
4S, 3000 mAh batteries: range of 3.74 - 3.79 V for all cells where 3.74 V was the lowest and 3.79 V the highest no load cell voltage read by the LiPo voltage meter.
I wrote down the no load cells voltages for each battery and these numbers are available if anybody wishes to see them.

4S, 2200 mAh batteries: 3.75 - 3.77 V per cell with the same comment as above.

Charging: Fast Charge with balancing on my charger at 1C

4S, 3000 mAh batteries: range of 45-47.5 minutes for all batteries to reach 16.8 V displayed on the charger. Individual cells voltages: 4.19-4.20 V displayed on the charger. When the batteries were disconnected from the charger and LiPo Voltage meter was used, it showed the total voltage of 16.6 V for each battery and between 4.15-4.18 V range per all cells. Charging added between 2130 and 2217 mAh to the batteries what is acceptable from the 80% maximum discharge rule.

4S, 2200 mAh batteries Fast Charging process took 51 and 53 minutes to fully charge the batteries to the same voltage ranges like 4S 3000 mAh batteries. Charging added between 1750 and 1780 mAh to the batteries what is acceptable.

Conclusion: I will fly again on Thursday morning and will charge again on Thursday afternoon to compare the effects of both charging methods.

Thank you,
M

"Learning never stops - period"

 


 

Matt-

Any reason not to charge at 2C or even 3C? What is the max charge rate for those packs?
1C is rather conservative, especially since it is likely you won't actually be charging the 3000's at 9 amps; I'd bet they will be at the 4S peak voltage at a lower amperage as Tim Wescott alluded to above, and then taper down from there.
For kicks, after flying, why not try a 6A (2C) setting and see what they take. If my suspicions is correct, you might see about 4.5-5A starting charge, with a tapering down on the charge rate from there.

Good luck.

Chris,
Maximum charge rate of my 4S 2200 mAh E-Flite packs is written on the labels - it is 3C.
Maximum charge rate of my 4S 3000 mAh Zippys is not specified.

I will always charge at 1C as, putting aside all "maybes", "buts", "I am not sure but you should..." and "why don't you try this and that..", it is the safest charge rate for the LiPos.

I am fast charging now my four 4S 3000 and two 4S 2200 batteries after six flights today and will report the results.

Also: I have received the LiPo 150 Watts discharger ( http://www.myrcmart.com/rcx-3in1-battery-balancer-discharger-voltage-indicator-150w-discharging-p-4767.html) and it discharges fully charged 3S 4000 pack to the storage voltage in 17 minutes(!).

Please see the attached.
Thanks,
M

"Learning never stops and when it stops you are dead"

 

Thanks for the info on this.  Just ordered one.  Price is right if it works.   

I think most chargers are limited to 2A, so on a 4s pack that is about 33w only. That's a nice jump in speed for discharging.

My charger photo is attached.

I charge my 6S2700 batteries on a parallel board. I can do 6 6S's from discharged to full in 25 minutes.

I am now charging only to 4.1 volts..expect more life from them this way. It will be a while before I know if this works or not.

More importantly, what life were you getting from them at the full 4.2V charge? Obviously not what you expected or there'd be no cause to change what you're doing...

Maybe going to the HV cells at 4.35V/cell and undercharging those to 4.25V would be the hot ticket??

R,
Target