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

The bulk charger is one offered on EV assemble. They can set it up for any cutoff, I chose whatever 4.1v x 18 is to save my packs for longer life.


Yep, 7 packs so we have one extra. Just in case of damage or otherwise bad luck.
 
No, a nimh charger terminates by detecting a voltage drop. Lithium needs a constant current constant voltage charger.
 
I did almost 25 miles today on my 24s2p 10ah pack. 100v at start and 86v at end of ride. Miserable day by he way!
 
i hooked up the trailer and went for a 5 mile ride, and tried to make sure at every 1Ah that i captured video of the CA displaying Voltage at 0A and 33A.
[youtube]jvz_9kMjQKQ[/youtube]
my 10Ah pack seems to be dying a lot faster!
lipo_600cycles.jpg
i've probably got some dead cells. how else can a 20s pack drop to 52V like that? when i hook up at 5s to charge, the low 'cell' (2.85) jumped way up to 3.3 and then it was the first one charged to 4.16 while the others were much lower...

more details, and some tests on individual packs/cells coming up.
 
Sorry to hear about your misfortune. I wonder whats killing your backs. Its either the amount you discharge or the rate you discharge. Even though a 1p configuration can power the bike its still raping the pack. Ive tried 1p even at 100v and it was happy to put it out and had no real sag but is it a cover for the abuse and hurt thats going on deep inside the pack. For a while I was doing 2p at 44v. Even with the 50A constant and 75-80A peaks its tickling the packs. Its about 5-7C on my 20-30c packs at 2p and 50-80A. 3p is a solid number for a pack. I find myself doing 70-80% DOD with a 15AH pack which is better than the full discharges I was doing at 2p. Also looking at the avg C rate on the pack in a 3p configuration its barely 3-4C per pack.
I think the cell c rate is a number that it can put out for short periods of time but shouldnt be asked to produce it constantly. I think we need to possibly derate the cells an try to use them at 25-50% of their advertised C rate if possible. Luke has already shown the saturation point on the nano cells we may need to find the same point for the regular lipo packs to see what their true ratings are. Ive read this thread in the past that certain packs were mislabeled and were able to deliver well beyond their rating in capacity and C rate.

To save the packs if that means more in parallel then so be it. Extra capacity never hurt and it keeps the stress down on the packs. Other than the initial parallel discharge harness I made and balance leads I made for paralleling the packs while charging it was pretty simple and straight forward after the work was done. Im following Docs foots steps for a 24s 3p. At 20lbs its light to my standards and MILES OF FUN! 1.5kw worth.

Also have you though about possible recompressing the packs. Maybe they are slighly puffed but you cant tell. When I complete my 24s 3p pack I plan to fully discharge the pack to where its soft. They physically get smaller and get a little squishy when discharged and put separators like Ypedal did to his and plastic hard case protection on all sides and compress the pack gently in a vice and wrap the packs with tape. That way they will constantly be under compression and should lower their RI. So that even at full discharge the RI should be lower than normal and when fully charge they will be virtually no RI to speak of. Which means less voltage sag.

Obviously that one cell is failing in your pack with it having a voltage way lower than the other but your cells are way out of wack on the discharged end of your pack. I see deviation on my packs on full discharge but no more than .25v. You have 0.5v and more. That cant be good. Check for any ding or damages maybe you have pinhole in the foil pouches and that cells is drying out or something.
 
GCinDC said:
i hooked up the trailer and went for a 5 mile ride, and tried to make sure at every 1Ah that i captured video of the CA displaying Voltage at 0A and 33A.
[youtube]jvz_9kMjQKQ[/youtube]
my 10Ah pack seems to be dying a lot faster!

i've probably got some dead cells. how else can a 20s pack drop to 52V like that? when i hook up at 5s to charge, the low 'cell' (2.85) jumped way up to 3.3 and then it was the first one charged to 4.16 while the others were much lower...

more details, and some tests on individual packs/cells coming up.
Click to expand...


What ever cell climbs the fastest during charging is the weakest cell. In this case, it's a toasted cell. :(
The bright side is, it's likely the rest of your cells are fine. If you're not at the limit of the controller voltage, you could just cut the shrink wrap on the connection side of the packs with the bad cell, solder right across it (after discharging it) to take it out of the series string, and then add in a little 2S pack at the end if your pack to make up for it. :)
 
Sorry guys. A lot of confessions here. It's embarrassing to report, but the pack has been operating like usual for the past several days, since I replaced a pack-side anderson... :roll: They melt so frequently for me, I just replace them when I need to. But in this case, I think one of the parallel charge connectors wasn't contacting it's pack-side mate, and that pack didn't get charged properly. But is that possible, if I was balance charging?? The uncharged cells must have sat so low... Maybe it was balancing overnight and still not charged up when I went for my test ride, and I didn't notice it when I disconnected... (credit to dbaker for the diagnosis!)
liveforphysics said:
What ever cell climbs the fastest during charging is the weakest cell. In this case, it's a toasted cell. :(
The bright side is, it's likely the rest of your cells are fine. If you're not at the limit of the controller voltage, you could just cut the shrink wrap on the connection side of the packs with the bad cell, solder right across it (after discharging it) to take it out of the series string, and then add in a little 2S pack at the end if your pack to make up for it. :)
Click to expand...
So if it's working fine, perhaps I brought it back from the dead? Surely it must have been close to 0V at some point. If that pack missed a charge, as I now suspect, it was probably close to 100% discharged, maybe 10Ah. Great tip though, LFP, for corpse carrying.. :lol:

I also must confess that it's my fault for riding (blind) w/o the BM6's. They've just been so temperamental, either because of crappy jst. I'd rebuilt a new DB25 dongle with brand new JST's, hot glued, only to connect it and hear beeping on a fully charged pack... one is plain bad, and another had been set to go off at 3.7V :roll: . But I just can't stand the sound of that beeping! Drives me mad! So I haven't used them.

And while I'm confessing: I'm probably closer to 500 50% DOD (whatever that means) cycles than 600... There, I said it! :mrgreen: I should also issue a disclaimer about anything else I may say! I'm just a noob at heart. :D Wow, it fees so much better to confess! :lol:
icecube57 said:
Even though a 1p configuration can power the bike its still raping the pack....
Click to expand...
Sorry, I think my label was misleading. The pack is 2p...
icecube57 said:
... recompressing the packs. Maybe they are slighly puffed but you cant tell. ... compress the pack gently in a vice and wrap the packs with tape.
Click to expand...
the packs are definitely puffy. i noticed that immediately when i opened up the pack. i hadn't used the fiber tape, but will do so from now on. but compressing them gently in a vice. LOL. should i wear a facemask when i do that?
 
Rode pretty easy for 12 miles. Used up 6.8Ah before I hit the cliff. End cells dropped to 3.14 at rest. Middle cells were up around 3.55...

Just curious: Do end cells get hit harder? The end cells on my ping went bye-bye too.
 
I have 2 comments to make about these lipo batteries.

1: My original 15S pack is still going strong and I've lost count of how many cycles it has on it now (over 500) It does sag a little more than it originally did but bulk charging to ~4.16v/cell and never balancing still yields 9ah when I run it right down.
All you sissies who are scared of lipo fires, here's a pic I took in a posh hotel I stayed at for work on friday night. Bugger paying $45/night for parking, I rode my bike, past the valets and parked it in my room, where I charged the pack overnight while I slept, a few feet from my face :mrgreen:

View attachment 12112010(002).jpg

2: On a completely different note, I just bought a new house and have been spending a bit of time there doing work on it before i move in. I left the radio on for tunes while working outside and when I came back to start the car the battery was stone dead - reading 8v. My phone was flat and I was a good hours walk in the summer heat from my current house where I have a battery starter jumper leads. Getting ready to leave my 8.5 month pregnant wife there and start walking I checked my tool box where I found an old 5S 20C turnigy pack. It was the first pack I bought from HK when they were released and it arrived with a DOA cell. I removed the dead cell to make it a 4S pack and taped it up in duct tape but never ended up using it so it sat in my tool box for over a year. I measured the voltage and it showed 15v, so pretty much nominal for the pack. I had nothing to lose so I thought I'd try jump starting the car with it. I had nothing but some 14ga aligator leads so connected one up, touched the other to the terminal as I told my wife to turn the key. The wire got red hot in my hand but a split second later the engine jumped to life like it way brand new

BOOYA! :mrgreen: :mrgreen: :mrgreen:


View attachment 13112010.jpg
 
Hi
Hyena looks like you do the same thing with dud packs as I do, once I found the thread on how to split bad cells out of a battery pack. I did not think adding 2 packs together was such a good idea but just removing would be ok.
As a result of this I have quite a lot of packs like that.I use 5 cell packs as well so with a few of the packs I removed 1 cell from, this I added to one of my main 20S pack to make a 24S pack, it works a treat adds just that bit of a boost to the system without requiring a controller upgrade.
The rest I use for other things including as a power supply for my iPad external battery, lights and by joining 2 together I have one big enough to power my notebook, for all 3 of these application's I needed to use a dc to dc converter like lyen sells.
All of the battery packs I split up get covered not with duct tape but with the 100 and 50 mm heat shrink from HK.
Geoff.
 
I have 2 busted Lipo packs with busted cells, leaking electrolyte (I'll post more about them soon).

They are Turnigy 6s 5000mah 25C. Is it ok if I replace them with the Turnigy 6s 5000mah 20C packs? The 20C packs are around 40$ while the 25C are 60$.

My setup is 24s3p. The most current I'll draw is about 100amps in a short burst, but generally I stay around 30amps.
 
El_Steak said:
My setup is 24s3p. The most current I'll draw is about 100amps in a short burst, but generally I stay around 30amps.
Click to expand...
With 3p it won't be a problem at all, especially, since you only burst to 100amps & run at 30amps or less normally.

To extend lifespan, if that is a goal, then charge to 4.1v & discharge to 3.55v. Go to 4p if you need the range & want to extend lifespan doing those charge/discharge cycles I just noted. Keep dry in low humidity & charge at room temperatures -never charge even close to freezing.

You might (should :D , imo) get years of usage and a 1,000+ cycles... :twisted: :shock: :mrgreen: 8)
 
Yeah the C rating mismatch won't be an issue with the current you're drawing, especially considering the 25C packs have been used for a while and the 20C ones are new.

Did you physically damage the cells to get them to leak ? The only way I've managed to kill a pack so far is to get it soaking wet and it corroded.
 
Hyena said:
Did you physically damage the cells to get them to leak ?.
Click to expand...

At the beginning of summer I physically damaged a cell (puncture) and it caused it to puff (no leak I think). This time however I'm sure I did not damage them. The packs were well protected with double shrink wrap, a lipo sack, some foam padding and a wooden box. Everything really tight, no rattle.

That being said, I wasn't running an LVC :oops: protection. I wasn't drawing more than 75% capacity from the pack on my commute and thought it was safe. Now I realize that eventhough the cells were resting at 3.70+ after the commute, they might have dipped lower under power. Maybe this have caused the damage. Sure enough, I ordered 4 SMD LVC from geoff for next season.

Good news is I have good data now. I individually discharged all of my 12 packs with an external load using the iCharger 206B and recorded all the discharge curves in the LogView. It's quite interesting to see that health of each single cell this way. I have some great packs discharging 4600+ mah (from 4.16 to 3.5) and a few that have a cell that will take the plunge around 4000mah.

I plan on replacing the 2 worst packs with new ones and doing cell surgery on the few other ones with bad cells. I'll post more data in this thread later.

BTW, I have around 100 cycles on the packs (3000km)
 
El_Steak said:
I plan on replacing the 2 worst packs with new ones and doing cell surgery on the few other ones with bad cells.
Click to expand...
If you have the time to document that procedure with lots of pics and/or video that would be most excellent. :mrgreen:

I don't think anyone has documented LiPo cell repair/replacement yet??? :?

Thanks!
 
deVries said:
[

I don't think anyone has documented LiPo cell repair/replacement yet??? :?

Thanks!
Click to expand...

http://endless-sphere.com/forums/viewtopic.php?f=14&t=22650&hilit=re+sealing+lipo

KiM
 
deVries said:
If you have the time to document that procedure with lots of pics and/or video that would be most excellent. :mrgreen:

I don't think anyone has documented LiPo cell repair/replacement yet??? :?
Click to expand...

I think others have done it ( YPedal ? ), but I haven't seen the whole process documented.

I'm waiting on a 120 watt iron I ordered on ebay to get here. Sometimes stuff ordered from the States takes longer to get here than from China. I've been waiting for over 2 weeks and the iron was just in Ohio!

Here's a pic of the worst pack. Pretty much all the cells are leaking / busted / puffed. This pack was still holding its voltage and I could get over 3000ah out of it. It was in parallel with 2 healthy packs so I didn't really notice something was wrong by just looking at the voltages. From now on I will rewrap all my packs with clear shrink wrap.

BustedLipo.jpg
 
AussieJester said:
deVries said:
I don't think anyone has documented LiPo cell repair/replacement yet??? :?
Thanks!
Click to expand...
http://endless-sphere.com/forums/viewtopic.php?f=14&t=22650&hilit=re+sealing+lipo
Click to expand...
Thanks mate, that's how to do a quick-n-dirty de-puff. :wink:

Do the cells in series easily pull apart? Do you have to de-solder many connections to take apart any cell from the series connections? What solder device and what solder type do you use to solder the cell connections back together again?

I guess just taping and shrink wrapping is all that's needed to re-wrap or re-package the cells in the series configuration you want?

Anything else? :twisted:
 
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