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Old Jan 21, 2012, 11:11 PM
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New 6s Zippy from HK takes 98 minutes to charge at about 1c ? Bad cell ?

SO I just bought 3 zippy 6s 45c 2650mah batteries from HK. I've only used them two cycles. Both charge cycles one takes 50% longer than the others to charge.

Bat one takes 65 minutes at 2.2 amps
Bat Two takes 65 Minutes at 2.2 amps
Bat three takes 98 minutes at 2.2 amps.

I've only ran two really easy flights through each one, only down to 3.7-3.8 volts on each cell (I have a digital voltage "tester" mounted to my 500)


Hmmm, should I try and run a few more cycles through the 3rd one, see if it starts to balance better, or should I attempt to exchange it? I've never tried to exchange anything with Hobbyking, let alone a battery. There are no low cells before, after, or during flight, but the only reason it would take so much longer is a cell or two that's slow to take a charge. I have a Thunder T6 multi charger, no real diagnosis with it.

Thoughts?
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Old Jan 21, 2012, 11:43 PM
RC Helicopter Pilot
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United States, CA, Westminster
Joined Mar 2010
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You are running those new packs a bit low.
I try not to go below storage for the first 5 cycles.

Measure the voltage of the at last pack.
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Old Jan 22, 2012, 02:55 AM
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Good luck exchanging it. Between shipping and the policy, it's not really consumer oriented.

http://www.hobbyking.com/hobbyking/s...po_policy.html
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Old Jan 22, 2012, 05:35 AM
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Quote:
I just bought 3 zippy 6s 45c 2650mah batteries from HK
and you purchased these to save money not obtain the highest quality LiPolys available correct?

Stop the charge when the cells are = > 4.15 ea. and fly them.

Charles
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Old Jan 22, 2012, 09:20 AM
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Did you check the individual cell voltages?
Sounds like one or more cells are much lower in voltage than the others in the pack. That causes a lot of effort on the part of the charger to balance charge the pack. It has to spend a lot longer time doing it.
I have had to charge a individual cell for a while to bring it up closer to the same voltage as the other cells in the pack. But you have to be extremely careful charging a individual cell to avoid accidental short circuits.
They don't do a lot of quality control, if any, on the cheaper packs, so they seldom come balanced already from the vendor. You need to balance charge them and do something to get any cells that are way off to be near the other cells in a pack before you can fully charge them up.
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Old Jan 22, 2012, 09:35 AM
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Sounds like a weak cell for sure. Individual cell voltage after use and when charging if you get all other cells to 4.2 do you recall where the voltage is on the last cell?

When you buy from HK at their discounted price your not paying for a warranty. I buy many from them and ocassionally get one with a weak cell, such as 4.2, 4.2, 4.2, 4.2, 4.2 and last cell at 4.11 and it takes forever to charge, and usually never gets to 4.2 In HK standards this is not a defective pack, basically it has to have a completely dead cell. So its a gamble but your paying usually less then half the cost of a quality pack. Just have to accept it when you buy from HK that if its not a good cell match you pretty much eat it.
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Old Jan 22, 2012, 04:30 PM
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I had this same thread posted on another site. Thank you for the replies, I really appreciate your opinions, and sorry for the delay in getting back. I've decided to live with it.

I've now read the Hobbyking return policy for lipos and realize it's just not worth it. I didn't know anything about their policy, I do now. It's obvious they had issues with customers returning batteries that they the customer had damaged, I think the current policy is reasonable other than having to pay for all the shipping if it's a defect. I had a new zippy 3s once that had a broken solder joint from new, I repaired it myself, but they obviously missed checking that one. If I had to pay to ship that battery, I'd be pretty peeved. Buying from Asia in general is a crap shoot, the safest venue is through eBay in my opinion, but the markup on eBay is significant. I sell online for a living, everyday I have to decide if I should insure packages or not, in most cases I don't insure. From not insuring I've saved thousands of dollars and only lost hundreds from loss or damage. Buying a battery from Hobbyking is similar, in that I choose the less expensive battery, save 500% over more expensive choices and eat the losses from poor quality control. In the end I save, but I have to cover my own losses. I get it.


I agree, a low cell. I have a T6 multi charger, it does nothing in the way of diagnosis, but I can watch individual cell voltage when charging and the are all even (within a few hundredths of a volt) I can check the resting voltage and it's even, and I can watch the cell voltage under a load with my cheap digital cell voltage "tool" that I have mounted to the frame, it's even then too. I don't have a way to check IR easily. I've had lipos act simular to this and get "better" I'll just hope this is one of those cases.

They were $35 batteries, once in awhile I get a zippy with an issue. Initially I thought that all the inexpensive batteries were cells from the same source with different stickers (like gasoline for the most part IMO), but after trying most the less expensive brands, I've found Zippy to be the best as far as initial power, and life. I may have just had good luck with them, but I'm sold.


Thank you again for your input folks. I appreciate helpful replies with facts.
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Old Jan 22, 2012, 04:46 PM
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By the sounds of it if you do have a weak cell its not very weak. For future reference....if you do have a weak cell it could put your ESC into low voltage cutoff substancially faster, so you may wanna decrease your flight time with that pack till you know for certine if its back to normal. I dont know what you fly but the battery I had a bad cell in was one 6s pack in series for 12s on a heli...when it hit soft cut it still drops like a brick if your not ready for it. From 60' I got it maybe 10' from the ground. I never fly to softcut so it caught me by surprise. Needless to say I replaced that pack. If I was inverted or any closer to the ground it would have been devistating
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Old Jan 22, 2012, 05:02 PM
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Check the manual and see it has a way to adjust the CV cuttoff stage. Some chargers may label this as "faster" vs "accurate". Others allow to set the cuttoff current in C/10, C/20 etc. I found with some of the HK batteries, their sag behavior is very inconsistent across all cells. Using a more accurate CV cuttoff will cause it to spend alot more time in the CV stage.

I checked online for manual for your charger and could not find one. If you can find one, post a link and I'll look through it to see of the setting I'm referring to exists. If you cannot control the CV cutoff stage, Charles advice below accomplishes the same thing. Albiet more of a manual process. But also his recommendation to stop at 4.15v per cell will provide longer service life.

Quote:
Originally Posted by everydayflyer View Post
Stop the charge when the cells are = > 4.15 ea. and fly them.

Charles
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Old Jan 23, 2012, 10:53 AM
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Thanks Snoeshoe. I do time my flights based on resting voltage at the end of the flight, I've found that 4:30 is usually plenty of room for error, and gives me enough time to land even from far away before going below 3.4v even on the worst of my batteries. I set my esc to 3.1 LVC, I'd rather damage a battery than the model. I will check this battery after break in to see how it stands.

Thanks Gregor, This 200w charger is just like four imax b6 50w chargers in one case, appears to be the exact same firmware. They have three lipo charge options that I see. Charge, fast charge, and balance charge. With good batteries charged at one C, it usually one hour or less (most 3s batteries take about 50 minutes at a true 1c, with 6s I can only charge at a max amperage of 2.2 (50w charger) so as expected it takes a bit longer. I've never noticed any setting to change the end of charge current, but I will look over the manual. Thanks for taking the time to try and find one, I have a printed version I'll look over.
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Old Jan 23, 2012, 11:09 AM
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Gregor, I just read through the manual again, fast charge does not include balancing, I'd be leery of using this function with a suspected cell issue.
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Old Jan 23, 2012, 11:50 AM
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Quote:
Originally Posted by phranticness View Post
This 200w charger is just like four imax b6 50w chargers in one case, appears to be the exact same firmware. They have three lipo charge options that I see. Charge, fast charge, and balance charge.
I found manual for the IMAX and the charge setting I'm refering to is the "Fast Charging" lipo setting. In this setting the constant voltage (CV) stage is shortened. But its not clear of that mode includes cell balancing. If not, it would be very unfortunate and IMO a reason to replace the charger.
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Old Jan 23, 2012, 12:26 PM
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As far as i understand, there are few (if any) chargers that engage balance circuitry when in "fast" mode.

Mark
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Old Jan 23, 2012, 12:52 PM
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Quote:
Originally Posted by mrforsyth View Post
As far as i understand, there are few (if any) chargers that engage balance circuitry when in "fast" mode.
The fast mode I was refering to changes the CV cutoff current. So iCharger, Hyperion, Thunder Power chargers all disable cell balancing if you change the CV cuttoff? Are you sure about that?
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Old Jan 23, 2012, 01:27 PM
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As I know it, that is correct. I do know with absolute certainty that none of my 4 iChargers balance when charging in "Fast Charge" mode. iChargers will only balance with "Balance Charge" mode is selected. I cannot comment on Hyperion and TP chargers but I would suspect that they behave similarly.

That said, most chargers will still provide a measure of safety even when charging in "Fast Charge" or "Normal Charge" modes by monitoring all cells (with balance lead connected) and terminating before any single cell reaches an unsafe voltage. It's for this reason that I ALWAYS recommend that the balance lead be connected on EVERY charge, even when charging in "Fast" or "Normal" modes.

Mark
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