Zippy/ Flightmax / Turnigy/ Blue lipo testing (pt 2)

[El_Steak]

if the pack is still holding charge? i would reseal it with glue (i use hot glue on mine)

Yes I've read about your piercing/sealing of puff packs. It tried it and no luck, the cell won't charge, even though its actual voltage was 3.90, when hooked up to the iCharger, it would mark it at 4.16V (max voltage cutout) and would shunt it while charging the other cells.

The only way I can charge it is if I parallel it with healthy packs. I guess the healthy cells lower the total resistance and allow the charger to get a proper reading on the cell.

I then remembered the iCharger as an internal resistance measure mode. Ran it and the 5 normal cells in the pack read 1 or 2 mohm while the damaged cell reads 135 mohm !

RIP cell #2

 

[El_Steak]

Just finished operating my pack. Eventhough they were not pierced, cell #1 and #3 were badly dinked so I also took them out.

Its actually pretty easy to do. First I removed all the solder on the connections using a 60 watt iron and a solder pump. To make sure I didn't short out 2 cells with the iron, I covered all connections with tape.

Then to separate the glued cells, I dripped a bit of ethyl alcool (standard drugstore "rubbing alcool") between the cells and _slowly_ pulled a thin plastic ruler all the way down the cells.

HK has some Turnigy 3S 5000Ah 25C packs in stock so I'll order one and solder it back in. They are pretty expensive at 36$ though. I wouldn't go through all that trouble if HK had some 6S packs in stock...

Do I need any special solder for those tabs?

 

[Hyena]

Yep, sounds like you've done a fuseable link.
I posted about the same thing a year ago in the old thread.

el steak, glad you got to the bottom of the problem. It's certainly reassuring to know that this was user error and not something we might expect to randomly start seeing in our packs. As AJ said try sealing it up, although if you've lost the solvent out over time it may be not be recoverable.

Oh yeah, and I too nearly bought those 3000mah zippys! I was planning on making a 15S emergency pack for if I get stranded.
I decided against it in the end when I got to the checkout and HK policy now shows that you have to pay the higher EMS shipping fee for lipo, and I didnt really need them anyway. But yeah, tis good price.

 

[mwkeefer]

Steak,

Wish I had caught ya before surgery - I would have tried to remove the puff (AW style) and then sealed them up again and seen if they managed to hold their charge a bit better... If my understanding of the physics of LiPo is right (and I love ES cause if I am wrong, someone smarter than me will come along and correct me) - the air getting into the cell through that hole was actually what was causing the cell voltage on #2 to drop...

Well you did the surgery and it looks pretty darn well done (better than my first disassembly)!

Wineboy,

No worries... break out the HD soldering gun I told ya you would need, AW (I think it was AW, memory goes this time of night) above is 100% right and no worries, we have all done it at some point or another - how are your fingers?

The repair should take about 15 minutes including re-wraping the pack.

To worries about how reliable dinged, damaged, etc stuff is at 1C charge rate and 3C discharge... I had a pack bounce off the rear of my 20" nova about a week ago (18S2P) at about 30mph as I made a left turn through what I can only describe as Asphault Mogules (to my little 20" tires)... the pack was in a topeak handlebar bag I converted to a trunk (sort of)... When the bag hit the ground the pack came out of the bag and bounced and slid into a curb. I thought I was done for... ran to the pack to get it out of the road and waited, waited, waited for it to get warm, hot and catch fire - this thing has physical dents in some of the cells... nothing happened.

Put the pack back on the bike and resumed my ride. Upon returning I checked for punctures, there was a tiny little one.. sealed it with glue, checked the balance it was ok and so I charged it at 1/2 C - now 325 miles (and about 10 cycles) later - the cells all hold perfectly at 4.15/4.16 after even a full 24hr on the shelf, no puffing and no reduced capacity.

I'm beginning to wonder if all the hype about Lipo being "delicate" is bs or at best just a fact of yesterday which no longer holds true but... is still carried on as truth?

Dogman's 4S is due tommorow with 2 EMS shipments from HK (another 18S4P worth of 6S Turnigy Lipo) - which brings me to my final comment of the evening... After testing the Flightmax and the Turnigy 6S 5AH, the Turnigy will deliver more MAH (because it's under rated) but they are equally capable of 20-30C and if building parallel packs, the flight max are superb ( a bit smaller than the turnigys ) but for single P ebike packs of 5AH... I'm sticking with turnigy for those

-Mike

 

[AussieJester]

I'm beginning to wonder if all the hype about Lipo being "delicate" is bs or at best just a fact of yesterday which no longer holds true but... is still carried on as truth?

Definitely think this is the case, these modern day lipos are tuff critters!

KiM

 

[wineboyrider]

No worries... break out the HD soldering gun I told ya you would need, AW (I think it was AW, memory goes this time of night) above is 100% right and no worries, we have all done it at some point or another - how are your fingers?

It's nice to see one dissected. I started peeling off the blue shrink wrap yesterday, but I noticed a whole bunch of glue looking stuff? Acetone, distilled wine? Gasoline?

 

[docnjoj]

I believe that the consensus is that plain old rubbing alcohol works. Please don't waste the drinking stuff!
otherDoc

 

[GCinDC]

OK, I've got video of my CA during my commute and reviewed it to get, at every 1Ah interval, the V at resting and at WOT (45-55A):


Does anyone have similar data for new packs (or older ones?)

Note:
- Ambient temps during ride were 80F. I've noticed more slugglish performance when it was 95F+...
- The majority of my 315 cycles so far have used 50% capacity, ie 5Ah of 10Ah.
- Cells had only been charged to 4.08V before this ride. Usually, full charge set at 4.16V/cell.

 

[John in CR]

Nice work GCinDC. The packs are still looking great. I hope your cells make it to 3k cycles.

Hopefully someone else is running some at a bit more conservative top of charge voltage, so we can see some real world comparisons as these newer lipo packs age.

Lipo is getting so cheap, and seems to have gotten safer and more hearty. If the cycle lives consistently get out well into 4 digits along with improved shelf life, then it's time to start looking at a car conversion. Since I'd still use my car sparingly the car pack could be a major portion of the energy storage for the house too for going off the grid. Reducing those regular payments to the man to only for water, phone, and internet would be so sweet.

John

 

[swbluto]

I'm trying to predict what Ah you'd eventually "land at" at the cutoff voltage of 3.0 volt per cell.

At 74.1 volts, that means that the average cell voltage is 74.1/20 = 3.705 at rest.


According to this chart of thunder power lipo,

I'm looking at the top line because it's the closest thing to "at rest" and it appears 3.7V corresponds to 2.5 Ah, and it appears this particular battery would've hit 3.0V cutoff at around 4.5 Ah at the high discharge rate. Does that suggest your battery's capacity is (4.5 / 2.5) * 7Ah = 12.6 Ah when it's nominally 10Ah? I'm sure there's a part of the comparison that's not right but I'm not sure what... Have you run your battery to cutoff recently to check the Ah?

 

[BikeFanatic]

"After testing the Flightmax and the Turnigy 6S 5AH, the Turnigy will deliver more MAH (because it's under rated) but they are equally capable of 20-30C and if building parallel packs, the flight max are superb ( a bit smaller than the turnigys ) but for single P ebike packs of 5AH... I'm sticking with turnigy for those "

Hi Mike,
may I ask how many AH you get from a single parallel pack? I have Turnigy 25- or 30 C ( I use like 5 C as I have a 25 amp controller)I get max 4.4 AH ( aprox 200 watts) out of them if I stop when one cell hits about 3.5. I am running 12S1P. I am interested in others numbers. I have slightly overdischarged them in the past before I got my LV monitors, but only recently have hard data from cycleanalyst.

Edit : nice graph my numbers seem to coralate with that, the knee or drop off point is about 3.5 v per cell and 4.5 amp hours

 

[GCinDC]

Have you run your battery to cutoff recently to check the Ah?

Hi, yes, that time, I just ended my ride after 7Ah...

I've hit the cliff at around 9-10Ah for my 2p pack, so it's entirely consistent with this graph. I'll do it again soon to be precise. At the cliff, around 66V for my 20s pack, Voltage sag is sickening under load (WOT)... as is the fear that one cell could be far lower

I was however encouraged to see a consistent 5V sag under load. I think it was less when new though. And I think I spent most of my commute closer to 78-79V @ max Amps, rather than 75-74V...

 

[dbaker]

Do the Anderson voltage drops impact these findings?

 

[swbluto]

Have you run your battery to cutoff recently to check the Ah?

Hi, yes, that time, I just ended my ride after 7Ah...

I've hit the cliff at around 9-10Ah for my 2p pack, so it's entirely consistent with this graph. I'll do it again soon to be precise. At the cliff, around 66V for my 20s pack, Voltage sag is sickening under load (WOT)... as is the fear that one cell could be far lower

I was however encouraged to see a consistent 5V sag under load. I think it was less when new though. And I think I spent most of my commute closer to 78-79V @ max Amps, rather than 75-74V...

Okay, I thought you might have had per cell LVC protection through a BMS or LVC monitor. If you don't, then it's not wise to run near the cutoff due to sudden "unbalancing" towards the ends of discharge.

Anyways, as lipo ages (As do all lithium batteries) the internal resistance increases. I think I often hear that the internal resistance doubles within 2 calendar years (Presumably at "normal temperature"), and there's probably some increase with cycle life. But if you start off with "25C" batts to begin with, than 12.5C is nothing to sneeze at.

 

[GCinDC]

Okay, I thought you might have had per cell LVC protection through a BMS or LVC monitor....

I think I often hear that the internal resistance doubles within 2 calendar years

I use BM6's when I go for a long ride, and yeah, the beeping gets fast and furious as the cells drop. Maybe that adds to my discomfort... :lol: <EDIT: BTW, Obviously I stop at this point!>

Can't see how the andersons would affect the pack's capacity or voltage... though might just increase load when I'm melting them.

What is the most obvious effect/result of doubled IR? Voltage sag? Decreased Amps? Heat?

 

[swbluto]

What is the most obvious effect/result of doubled IR? Voltage sag? Decreased Amps? Heat?

Mainly, they'll sag more and the batteries will produce more heat at a given amount of current. If voltage sag nor battery heat has even been a slight concern to you to begin with, it's nothing I'd worry about though you might see slightly decreased performance at high current.

For the "ping users", it's kind of a big deal because that 2C battery than becomes a 1C battery and many use pings at its max.

 

[wineboyrider]

I wrote:I have 6 - 5s Flightmax 4400mah packs and one of them I got crossed with another and poof! Now I check the voltage on one of the packs and it's 0000 as in Zero :x :x
My fault for sure. I tried to hook it up to the Eco 6 Charger and it gives me a improper cell voltage.??

the white cell wire seems to be the problem I can read voltages from all the wires except the white wire?

Red to Black 4.2v
Red to Blue 9.2v
Red to white 0v

From the negative side:
Black to yellow- 4.6v
Black to white - 0v

So there is either a bad wire connection in the white wire and/or the cell leading to the white wire is bad?

Please help?

 

[BikeFanatic]

I wonder if you blew a fusable link like hyena posted a pic on this thread page 12.

I had a pack where the white wire was loose ---instead if taking the entire pack apart ---I opened the top where all the wires exit and examined the PCB board and the connections there. Sure enough there was either a loose wire and or a break in the continuity between wire connections. Just a little solder here and there and my pack is good to go.

JMHO, not an expert or anything, If you do need to do cell replacement surgery Probably a few folk here can walk you through it.

 

[texaspyro]

It's nice to see one dissected. I started peeling off the blue shrink wrap yesterday, but I noticed a whole bunch of glue looking stuff? Acetone, distilled wine? Gasoline?

If the cells are held together with an adhesive (i.e. double sided tape) one of the best thing to use is heptane. It causes adhesives to temporarily forget how to be sticky. Once it evaporates, the stickiness returns... amazing. It is very un-reactive and I have never seen it affect plastics, etc... YMMV. It is sold commercially as a product called UnDu. The "Bestine" brand of rubber cement thinner is heptane and costs a whole lot less than UnDu or commercial heptane.

 

[KTP]

Yet another batch of Turnigy lipo just arrived, all in perfect shape, 3.865V +/-5mV, bringing to total to about 1800WH. Still waiting on one more batch I need an intervention or something...

Note, the idea of shipping some foamy wheels to ensure padding wasn't so smart...the wheels are teeny tiny, and they just put them in with the Turnigy wattmeter I ordered. Perhaps a foam airplane wing or something would be better. The box was somewhat banged up but the batteries *seem* fine.

The turnigy wattmeter looks pretty cool...seems to register about 30mV less than my Fluke 289 when reading no load voltage..not sure if there is any way to cal it...a pretty solid little piece of kit for $23 though...

 

[wineboyrider]

Ianmcnally 2 wrote: I had a pack where the white wire was loose ---instead if taking the entire pack apart ---I opened the top where all the wires exit and examined the PCB board and the connections there. Sure enough there was either a loose wire and or a break in the continuity between wire connections. Just a little solder here and there and my pack is good to go.

Broke open the pack and measured the voltages from the pcb board and they are the same! I guess I'll break open the pack and look for the tabs. :?

 

[Hyena]

I've hit the cliff at around 9-10Ah for my 2p pack, so it's entirely consistent with this graph. I'll do it again soon to be precise. At the cliff, around 66V for my 20s pack, Voltage sag is sickening under load (WOT)... as is the fear that one cell could be far lower

Yep my pack with around the same amount of cycles on it is exactly the same - delivers to 9ah with a bit more sag than when new then falls off the cliff about 9.5ah. I agree the sag at the end is harsh, I've hit the cliff a few times and I usually feel it from the way the bike rides then look down to see the voltage has fallen through the floor.

 

[mwkeefer]

Hello all,

I just wanted to drop a heads up, for the first time in nearly 9 months - I got not one but 2 damaged packs in 2 seperate shipped orders... for those of you looking for a quick solution or cause: I broke my own rule and mixed motors into the shipment (I would guess since I never had a problem before this but I was lazy).

The first box was 2 x 8S 5800 mah packs - threw #1 on the charger but didn't get a low voltage warning, all seemed ok till end of charge when cell #5 read 3.9x volts while the rest were at 4.15. I suppose this cell has FAR more capacity or was at 3v not 3.7v when it arrived. It may not be a big deal - I'm about to do a 1A charge via balance lines to see if I bring it up it will stay at proper voltage.

Package #2 was 4x 6S 5000mah 20C turnigy packs and as always I connected it to the celllog8 to test it out of box - one cell was ZERO volts the other was 5+ volts... I follwed the balance leads and could see the blue line had come undone.

I've emailed HK about these issues and requested permission to simply fix the 6S pack since otherwise it appears fine.

Moral of the story - always add somthing more fragile than batteries (a prop, delicate little pieces, etc) to a battery order to make up extra shipping ability - never anything solid and heavy like motors. The 8S was likely somthing I should have caught and fixed before charging for the first time at 1/2C.

Hope this helps!

-Mike

 

[markcycle]

Well I'm happy to say I ordered 10 packs and all came in a timely manor packed better than they ever have, by far. No dead cells the packs are 5s 5ah 20C turnigy packs.

Just wish I could get them in bulk

All the packs charged up and are well balanced
I will be doing a load test on the packs before placing them in a series parallel configuration

My 3p 24S pack (made from 6s 5ah 20C packs) for a total of 100 volts and 15AH now has some time on it and I've gone through over 20 charge discharge cycles. In my dirt YZ125 motorcycle build it is just amazing pack, gives my 603 motor along with a Kelly controller the power to really impress. It stay fairly well balanced.

here is a link of my YZ125 with the pack
http://www.youtube.com/watch?v=oYIkQkJKHTw

Mark

 

[GCinDC]

found myself near the cliff again today so took some vid of the sluggish acceleration, individual cell voltages & effect of parallel charging...
[youtube]t8hHiAyrcjA[/youtube]