To nano-tech or not to nano-tech

[Science Faction]

HI all,

In January I purchased 18 x nanotech 6S 25-50C 8AH blocks and they all arrived very well balanced at 22.9V.
I built 2 x 18S 2P packs with an 18S 60a BMS for some friends.
I have just been using 3 packs in an 18S 1P config in a backpack for myself.
Bad news, first after only 150Kms, not even 5 or 6 cycles and no hard work, 40Amp max draw, my 3 6S packs have gone puffy.
Yesterday one of my friends packs stopped charging so I pulled the batteries out of the box and of these 6, 1 was puffy and 4 were a little puffy and 1 normal.
One pair of paralleled cells had dropped to 1.8 V.
They were in position 13 in the BMS.
This is the first cell from the positive output of the 18S battery pack, ie closest to the bms in terms of current flow.
So i got a little suss on the BMS.
I replaced the dud cell packs with two of my 6S packs with matching voltages to each other and the other 4 packs and charged them to 76V.
These BMS's max out at 4.26V
The pack charged normally with all the cells resting on 4.21 - 4.22V with a max delta V within each 6S being 15mV.
I unplugged the cellogs and in the morning checked the cells again to find that the cells in position 13 had dropped to 4.17V, witha deltaV in that 6S pack of 54mV.
So I can't blame the nanotech's for the dud cell just yet, as it may be the BMS.
Will keep you posted.
I am going to investigate the other 18S 2P pack today.
I found this thread after this problem arose and i so so wish I had seen it before I ordered what I though were a higher quality product than the zippy's, although Lukes comment about the change in quality was in Feb and after I had ordered anyway.
I just hope like others i can get warranty.
I believe it is totally inexcusable to reduce the quality of a product especially when it is marketed as the premium product.
Cheers
Paul

 

[neptronix]

Hence the term - Battery murdering system....

 

[deVries]

Luke; what's the reason? bad cell rate getting up there with the Non-nano, or worse? higher IR?

Failure rate used to be very low, now it's poor. Cycle life used to be very good, now it's poor. They used to very very rarely puff or self-discharge, the recent batches seem to frequently puff or self-discharge.

They used to be the best of the RC LiPo, now they still have killer performance, but I've seen poor reliability and cycle life, where as the early ones would last for years of hard abuse.

Hey Luke, love your race vids...

I read on ES that you spec'd batteries from Korea for the Zero bike company you work for. Any chance we can get the batteries for a reasonable price?

Can you give us more info about this battery please, sir.

(Btw, for those with bad LiPo cells HK does sell cells individually now, so it is possible to replace cells or build your own packs.)

 

[Science Faction]

It's looking more like the BMS with the delta V increasing to 113mV after the second night.
The second pack and BMS are performing normally and all cells are within balance to 9mV.
There were no puffy cells amongst those 6 x 6S packs.
Paul

 

[mauimart]

After reading the feedback I received in this thread I decided on the cheaper 20C cells. I really did not need the high discharge rates of the nano's and as such the extra cost could not be warranted. I purchased 6 bricks of the 5Ah, 6S, 20C variety for a 18S2P pack. One of the cells in one of the bricks came in low and remained low after a few cycles. I have since shipped this battery back to HK (US warehouse). I'll let you know how the return process works out.

I am also logging all of the charge data for each charge cycle. If I am able to remain focused and stay the course I should be able to determine how many cycles are possible with these cells. My average commute consumes about 4Ah of the 10Ah total so I am expecting at least 300 cycles before things head south. I'm at about 30 now. Stay tuned...

 

[deVries]

Based on Luke's LiveForPhysics recent opinion/knowledge about the poor quality of Nano "x" months after its introduction I would not touch these ever again UNTIL proven with real data the Nano works superior with "x brand". The RC communities will find out for sure over time. Revisit Nano in 2013-2015 for some REAL PROOF. Frack the hype... Even Methods & LFP may have blown or inhaled some of that smoke. :lol: (Hey, I bought into that submarine hype Big Time. )

I own a lot of Nano from when it was first introduced. Mine are fine soooo far. 8)

But I won't be buying anymore Nano until I know a good quality & reliable QC source.

Warning: Rant about Quality Control...

Too bad HK fracked what looked to be the next best promising battery tech in the near-term. HK needed to source the REAL THING used on submarines *or* (only real option... :lol: ...) keep the QC at the highest standards. It's really not that hard for them to setup a lab & randomly test samples TO FAILURE to monitor what the frack is going on... End users ... especially RC & us guy's should NEVER have been or become the Lab Rats. HK must implement QC controls to snag the bad batches *before* ever being sold. And, it goes w/o saying HK should kick the asses of the QC battery departments that supply them. It's inexcusable these problems are not caught at the production factory before even shipping to HK. Frack them for not doing it, seriously! This is basic 101 production standards to test & verify every batch of material so it meets all specifications during manufacture *before* shipping to retailer/wholesale customers... Duhhh...

 

[John in CR]

I can't believe people are talking about and actually shipping faulty lipo packs. Are these packs 100% discharged with the leads shorted, or can that even be done safely? Is it safe in a discharged state? Not only could you land yourself in jail with some hefty fines, but your negligence could also ruin it for everyone with rule changes prohibiting their shipment in the event of an event at a carrier. Your head is not on your neck just as a place your hair...use it.

Someone please get with HK regarding return/refund methods to come up with something that is safe and protects them from fraud.

 

[Ykick]

After reading the feedback I received in this thread I decided on the cheaper 20C cells. I really did not need the high discharge rates of the nano's and as such the extra cost could not be warranted. I purchased 6 bricks of the 5Ah, 6S, 20C variety for a 18S2P pack. One of the cells in one of the bricks came in low and remained low after a few cycles. I have since shipped this battery back to HK (US warehouse). I'll let you know how the return process works out.

I am also logging all of the charge data for each charge cycle. If I am able to remain focused and stay the course I should be able to determine how many cycles are possible with these cells. My average commute consumes about 4Ah of the 10Ah total so I am expecting at least 300 cycles before things head south. I'm at about 30 now. Stay tuned...

'been pulling 5-6Ah daily from my 10Ah Turnigy 20C pack for 2 years and well over 500 charge cycles. They're about 80% capacity compared to new but I'm not complaining.

I recently bought and started using CellLog 8S, the one with logging function. Pretty handy thing to use for discharge voltage sag logging. My hope is that it will allow me to better identify dying cells under normal operating loads.

Simply log a brick each trip to/from work and the subsequent bulk charge cycle. Dump that into Logview and it's all there to view any weird cell behavior.

 

[chilledoutuk]

I can't believe people are talking about and actually shipping faulty lipo packs. Are these packs 100% discharged with the leads shorted, or can that even be done safely? Is it safe in a discharged state? Not only could you land yourself in jail with some hefty fines, but your negligence could also ruin it for everyone with rule changes prohibiting their shipment in the event of an event at a carrier. Your head is not on your neck just as a place your hair...use it.

Someone please get with HK regarding return/refund methods to come up with something that is safe and protects them from fraud.

as long as the pack isnt puffing and you let it stand for a few days then it should be fine to ship back just because a pack is faulty in a consumers eyes does not mean it will burst into flames. it could be something as simple as a cell just not having the same capacity as the rest and being too much out of balance to use.

 

[John in CR]

I can't believe people are talking about and actually shipping faulty lipo packs. Are these packs 100% discharged with the leads shorted, or can that even be done safely? Is it safe in a discharged state? Not only could you land yourself in jail with some hefty fines, but your negligence could also ruin it for everyone with rule changes prohibiting their shipment in the event of an event at a carrier. Your head is not on your neck just as a place your hair...use it.

Someone please get with HK regarding return/refund methods to come up with something that is safe and protects them from fraud.

as long as the pack isnt puffing and you let it stand for a few days then it should be fine to ship back just because a pack is faulty in a consumers eyes does not mean it will burst into flames. it could be something as simple as a cell just not having the same capacity as the rest and being too much out of balance to use.

I never said it will, but it can. Non-faulty cells don't flame out without some form of abuse. Only a faulty cell can sit there for over a month after receiving the shipment undisturbed, in balance, in a temperature controlled environment, with no outward signs of being faulty, and do this:

 

[zombiess]

Eek. Scary pic to go with the story. So you received it, checked out OK initially and then it was just sitting there never been used and failed violently?
This kind of event always sits in the back of my mind.

Just more poor or non existent QC out of China I'm guessing. Scary thought if a pack on an airplane were to go causing a chain reaction.

 

[Science Faction]

After two more days sitting on the bench connected to the BMS the cell in position 13 has dropped to 3.89V and the deltaV is upto 277mV, so it looks like the BMS is the culprit on the dud cells.
No response from the BMS manufacturer yet.
It still doesn't excuse the puffed cells.
Methods did warn me that the nanotechs weren't worth the extra cash.
I can't imagine the Zippy's from HK are going to have a higher QC.
So
What to do?
What high quality LiPo alternatives are there?
I certainly would like whatever the Zero's are running.