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

[dogman dan]

Wow!. you are so cool! I'll be back from my trip by the second week of August. I'll paypal you money for it now. If you ups it, nobody will have to sign for it, or if you mail it non priority. Send me a pm with how you want it paid for.

 

[mwkeefer]

Dogman,

If I UPS it now, it could sit outside your door in the sun and heat for days before you collect it... result could be another puffy pack. I'll ship it out 5 business days before your due back, should arrive just in time for your return or maybe a day earlier.

Pay me when you get back and receive it, I hate taking funds premature... too many bad things could happen

Not cool, just was in the same situation about 3 weeks ago but talked to my local post master and they held everything for me at the post office... even the EMS stuffs

-Mike

 

[TPA]

Thought I'd share:

I use an electric start push mower for the lawn. It used a 12v 4.5Ah sla for the starter. Every season the battery had to be replaced. The last one, I made sure to keep it charged at all times, but sure enough after a couple of months, it was not charging well.

So, I ordered me up a 4s 5000mah lipo pack (turnigy) in time for the start of this season. For all you Canadians, mowing season starts in March here, Eh, and lasts until the end of October. I made sure the pack was charged and balanced and rewired the mower for it (Andersons on the mower!!).

I have been mowing for 3-4 months now and the pack still reads 16.2V down from 16.8V in March, and has only been on the charger that first time.

Lipo FTW!

 

[mwkeefer]

TPA - thanks for sharing (god now I feel like I'm at an AA meeting)

Seriously though this raises a good and valid question in my mind (one I don't have the time to test)...

My dad has a 12V array of AGM SLAs (2S2P DECCA 6V AGM 200 AH)... which are rated at 1/20th C for 200AH capacity...

His use is a Prowatt 1000 (1000w continuous and 2000w peak) which means if he were to load it up to the hilt it would pull between 80 and 160A of 12v... For electrical code purposes, each 12v 200AH is isolated via a 12v 150A marine breaker...

The point is, I believe he paid 200.00 each for these batteries so figure 800.00 total and presents them (400AH capacity) with an average off grid load of just 30A @ 12v but peaks up to 80 and as high as 140 seen (think that's all the range I have for measurement)..

Let's assume I'm crazy or dumb enough to buy up 40 4S packs (5AH 20C) at 29.99 each (slow boat over) for a grand total of 1,198.00 + s&h from HK...

My capacity should be 200AH but that rating is a 20C rating right?... so pulling lets say 40A what kind of extended capacity may we see from this theoretical 200 AH 4S 40P lipo pack?

I get a full 5000 mah and then some out of 5AH packs used at 5-10C so what would the effect be discharging at 1/5th C?

-Mike

 

[KTP]

I just got my first batch of lipo in from HK...shame on you guys for making me so nervous! The packaging was excellent! My 5000mA 6s 25C Turnigy long packs were boxed, then double bubble wrapped, and then the whole package was bubble wrapped. Every cell tested great with my Fluke 289 meter and all of the packs were svelte. This first batch is going into a 14s2p pack for my 9C 6x10 on a recumbent trike...currently I am running 11s4p of sony 26650 VT LiMn cells (about 45V 8AH hot off the charger).

I have done a couple of rides now on the 14s2p. No deep discharges yet, started off at 4.150 +/- 5mV per cell, running the two 14s strings paralleled only at the ends, riding for about 15 miles with some pedaling, ending voltage of 3.955 +/- 5mV per cell.

Observation so far: Balance! I had no idea they would all discharge so closely to each other. I see now why some ride without a cell level BMS and just a LVC. Also, they seem to hold up a little stiffer than I had imagined...I was thinking they would drop down to 3.8V per cell fairly quickly, then hover there for 70% of the ride.

When my CA gets here I will run them down to 3.7-3.8 volts per cell and see what type of AH I can pull out of the long packs

 

[GCinDC]

I really wish I graphed the voltage when I first got my lipos, some 300 cycles ago. I'd love to see the following lines:

New Turnigy LiPo Discharge Curve: 1 Ah increments (x) Voltage (Y) @ 10A continuous, another line at 20A continuous, and other lines for 30A - 100A
Another chart, or just new lines for same loads w/ Turnigy/Zippy after 250 cycles, 500 cycles, 750, etc...

Anyone seen such charts?

 

[mwkeefer]

GCinDC,

Funny you should mention this...

I just received 6 new 6S 5AH packs which will be run in 18S2P and monitored durring all charge / discharge cycles (once I get em together, probably after this weekend)

I've begun a log book, recorded the serial numbers, received voltage per cell and made the first cycle (automated) entry...

A pair of eagle tree loggers connected inline with 12S and 6S parts of the pack will provide me proper current / voltage readings... motor RPM, GPS data, etc - I can't get my accellerometer to work properly right now (AXI) which I had hoped to have done by now... it would be nice to measure torque

I'm open to suggestions (besides GFY) with regard to additional logging ideas, I had planned to use the CA for logging but at the rate my SD card shield (arduino) which takes raw TTL Serial and writes to card hasn't arrived and who knows when it will... I could bit bang it from an actual Arduino like I do on the linksys routers but... I'll wait for the protosheild, too much work to do

-Mike

PS: The 6S 20C turnigy came in last yesterday... I placed an order last night at 6PM EDT and received a shipped notification at approx 4:00 AM today (I was still awake) so it took them less than 12 hours to fill my order (10 to be exact) from placed to prepared for EMS Singapore... too bad they aren't shipping from HK anymore, these would have arrived Saturday.

PPS: The next 2 orders is comprised of 8x 6S 20C Turnigy for a 12s 4p rc build

 

[KTP]

Has anyone done a discharge graph for the 20C, 25C or 30C Turnigy or Zippy packs?

I went on two rides this weekend with my 14s2p Turnigy packs 5000mAH (10AH total). The first ride was from West Seattle down to Kent and back...about 52 miles total. Obviously I was pedaling but the batteries performed well, except that somewhere on the way back one of the connectors from a 14s strand came unplugged (probably during a hard bounce) and I did the last 15 miles on 14s1p unkowningly. I started the ride with all cells at 4.15 volts and ended the ride with one 14s string at 3.71 volts and the other string at 3.93 volts.

The second day I rode from Bothell to the Puget Sound past Ballard and back, about 43 miles total and the cells started at 4.15 volts and ended at 3.85 volts, all cells on both 14s strings within 3mV of each other (really impressed).

Anyway, still waiting on my CA, so I am unsure exactly how much I am pulling out of these packs. I am also not exactly sure where the "knee" is in the voltage curve for a certain current discharge...I am guessing it is just past 3.7 volts or so? Would you guys consider 3.7 volts to be fairly well drained? I was going to stop using the battery if I ever dipped below 3.6 volts, but I never got that low on either ride.

 

[knoxie]

Yes

I have done this also! if you havent already got one get either buzzers or a BM6 on each pack if you can, I have even had hard crimped Anderson conenctors loose the wire, it only takes 1 x conenctor to separate and then you could be in toruble.

Also there may come a point when you notice half way through the ride and then plug the half drained pack in to possibly much fuller pack :?

I have got 4 x BM6 monitors coming for mine so I can monitor each one 8) going to have a play with them to see if I can get all the outputs to switch a common alarm or brake line.

except that somewhere on the way back one of the connectors from a 14s strand came unplugged (probably during a hard bounce) and I did the last 15 miles on 14s1p unkowningly. I started the ride with all cells at 4.15 volts and ended the ride with one 14s string at 3.71 volts and the other string at 3.93 volts.

 

[BikeFanatic]

Yes I think 3.6 is a good stop point. I find that as cells drop to 3.65-3.68 some cells run out of capacity and drop to 3.3-3.5 --- the pack is becomes imbalanced as some cells have more capacity then others. I have over dc'd the packs beore but I bought the GT voltage analyzer from hobby city and it tracks the current cells voltage as well as the lowest voltage has an alarm too that you can set. Only 13.95 and I believe you can get away with two or use only on the LONG trps. Cheap shipping is available too i you order something light only

 

[El_Steak]

I bought 12 Turnigy 6s 5000ah 25C packs from HK in the last month. Been using them first in an 18s setup and now in 24s. I was lucky with my purchase, all packs were received with perfectly balanced cells. Never had a bad luck using them either, I charge at 4.16V and never discharge under 3.65V

Well, after a bit over 30 cycles, cell number 2 in one of my pack doesn't hold its charge anymore and its bringing its 2 paralleled friends down at the same time. This messes up the pack balance every cycle now to the point I had to remove the pack and "downgrade" to a 18s3p setup.

The faulty cell will charge up to 4.15 at the same rate as the other cells, but when I leave the pack sitting, it slowly loses its charge. It was 4.15V at 7AM, its now 4.04 at 7PM. The other cells in the pack are all still at 4.15V

Any idea if there is any hope for that cell?

I went to order a replacement pack from HK, but they are out of stock on the Turnigy 25C and 20C packs :x

 

[mwkeefer]

steak... can u do a 1a discharge to 3v via the balance taps? could tell if this is lost capacity and quantify it _

-Mike

 

[El_Steak]

steak... can u do a 1a discharge to 3v via the balance taps? could tell if this is lost capacity and quantify it _

-Mike

Yep, I'll try that, just need to rig some bulbs or something.

This morning the faulty cell was down to 3.94V all by itself. I'm curious to see if its going to slow down or stop at some point before going under 3V.

Is this what usually happens when you get a "puffed" cell ? My pack is double shrink-wrapped (thick stuff) and I can't see if there's any puffing without cutting it open.

 

[mwkeefer]

Steak,

Do the test... specifcally watch how long the cell remains above 3.7, 3.6v... do you have a way to track AH/WH used in the discharge test... it's what we are really after.

On the puffed symptoms... sadly there are many reasons (over charge, discharge, physical impacts, bad balancer, etc) which can cause the symptom... But yea over discharge would cause it faster than over charging slightly (4.22v).

I missed the config on your pack (how many parallel packs and paralleled how?) so I can't even venture a guess as to the nature... but I think you said it was cell #2 of the block of whatever... if it's more than a 1P pack - could be just one of the parallel cells in that arrangement is dropping / self discharging.

Another thing it could be (you are going to love this) is a mild short circuit (think moisture) which will increase the self discharge rate... Normally this would dry on it's own and the self discharge would end but.... In so much wrap I'm not sure the condensation (if any) has anywhere to evaporate to.

BTW: If you meant do puffed cells take a normal charge then seem to self discharge faster, yep... mine all do that (the really puffy ones) so the question is - Cause or Effect?

Liveforphysics, Methods, ZapPat, Jeremy Harris - these guys could all answer that question probably but I dont' feel even now I have sufficient test data to give a real answer

Hope it helps!
Mike

 

[El_Steak]

Thanks for your insight.

Do the test... specifcally watch how long the cell remains above 3.7, 3.6v... do you have a way to track AH/WH used in the discharge test... it's what we are really after.

No I don't, time to order a Turnigy Watt meter I guess. I also ordered a single cell charger to make the process easier.

I missed the config on your pack (how many parallel packs and paralleled how?) so I can't even venture a guess as to the nature... but I think you said it was cell #2 of the block of whatever... if it's more than a 1P pack - could be just one of the parallel cells in that arrangement is dropping / self discharging.

The entire pack is 24s3p (12 x 6s packs - 88.8V 15ah). The packs are paralleled at the cell level through the balance taps. To recharge, I reconfigure it in 6s12p and charge with a single RC charger (icharger 206B). I use a connector setup similar to GCinDC.

The bad cell is definately in a single pack. After recharging, I broke the parallel string, all packs kept cell #2 at 4.15 except for the faulty one which is still dropping in voltage.

Another thing it could be (you are going to love this) is a mild short circuit (think moisture) which will increase the self discharge rate... Normally this would dry on it's own and the self discharge would end but.... In so much wrap I'm not sure the condensation (if any) has anywhere to evaporate to.

That would be sweet for sure! I'll open up the pack tonight and take pictures.

 

[KTP]

Are these the 25C 6s long packs that were on flash sale? That is what I have built my 14s3p out of (with three 2s packs also).

I am starting to think it would have been wiser to build the pack entirely out of 2s packs, thus minimizing the pain of replacing a bad cell. The 2s packs seem to be in stock more often. Too bad I have spent my Lipo budget for the next few months already

 

[El_Steak]

Are these the 25C 6s long packs that were on flash sale? That is what I have built my 14s3p out of (with three 2s packs also).

No, they are the regular format 25C 6s. I might buy a 2s pack to scavenge a replacement cell from. Normally I wouldn't bother and just buy a new 6S pack, but they are out of stock of 20C, 25C and 30C

Which 2s pack did you buy ? couldn't find them in the 25C section. They really have to modernize that web site so you can filter by brand, size, capacity, etc.

 

[KTP]

Which 2s pack did you buy ? couldn't find them in the 25C section. They really have to modernize that web site so you can filter by brand, size, capacity, etc.

I had to buy 20C packs for the 2s, couldn't find any 25C except the nanotech stuff. They seem to discharge evenly along with the 25C longpacks...of course I am only pulling like 2C out of each pack on my 9C 6x10 on 14s

The zippy 3000mAH 5s 20C packs look really attractive at $0.32/watt on the flash sale..it is normally a $29 battery, not sure why they are quite that discounted...suspicious

 

[El_Steak]

Found the problem... my fault!

As you can see cell 2 is punctured and it puffed right around the hole in the pouch. Some other cells are also dinked, but not punctured.

The blunt weapon used to puncture the cell is the plastic Anderson holder clip at the bottom right. I know perfectly well how this happened, I was testing all sorts of motor cover drilling patterns to air cool my motor, and I had to often remove my rear wheel, the rack and the batteries.

I got lazy and didn't put the batteries in their protective Lipo sacks and box. Then I forgot to install that damn Anderson clip and it went to the bottom of the battery bag where it repetitively stabbed my LiPo pack. :x

Damn, I wish HK would have some packs left!

hummm, I could always ditch those 3 first cells and replace them with a 3s pack from HK (they have some in stock).

 

[KTP]

Well that makes me feel significantly better about my (currently perfect) 14s3p setup. I was disturbed by your description of a cell just suddenly failing in your 25C Turnigy, but now we see the cause.

This makes me wonder about a lot of the random reports over the years of packs puffing or smoking, or what have you. If we threw out the bad cells that were due to shipping damage, and the bad cells resulting from RC trucks and planes crashing, and the bad/puffed cells from very high discharge/charge rates, I wonder if the actual failure rate of 1C charged, 2C to 4C discharged ebike lipo packs would be extremely low. Also, it seems people are more likely to post when they have a problem than when they don't (which is one reason I am posting every time I get a shipment that checks out perfectly).

 

[wineboyrider]

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.??

 

[KTP]

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.??

Possibly the actual cell is ok and you just vaporized the wires inside the pack. have you taken off the blue plastic to inspect them?

 

[AussieJester]

Found the problem... my fault!

As you can see cell 2 is punctured and it puffed right around the hole in the pouch. Some other cells are also dinked, but not punctured.

The blunt weapon used to puncture the cell is the plastic Anderson holder clip at the bottom right. I know perfectly well how this happened, I was testing all sorts of motor cover drilling patterns to air cool my motor, and I had to often remove my rear wheel, the rack and the batteries.

I got lazy and didn't put the batteries in their protective Lipo sacks and box. Then I forgot to install that damn Anderson clip and it went to the bottom of the battery bag where it repetitively stabbed my LiPo pack. :x

Damn, I wish HK would have some packs left!

hummm, I could always ditch those 3 first cells and replace them with a 3s pack from HK (they have some in stock).

if the pack is still holding charge? i would reseal it with glue (i use hot glue on mine)
and keep using it with a watch ful eye...I have lanced and de-puffed near a dozen cells
and have a few dozen cycle through them now with good results...all my cells were
charged to 5v or close to hence the puffing...


All the best anywayz...

KiM

 

[wineboyrider]

Possibly the actual cell is ok and you just vaporized the wires inside the pack. have you taken off the blue plastic to inspect them?

KTP

No, but I'll try and do it tomorrow. Thanks for the tip! Sounds logical too. 8)

 

[John in CR]

The zippy 3000mAH 5s 20C packs look really attractive at $0.32/watt on the flash sale..it is normally a $29 battery, not sure why they are quite that discounted...suspicious

I saw that too. It looks like these Lipos are going to get down to my 20-25cents/wh number by Christmas. 55 of those packs are saying "Buy me John, buy me now." 3kwh - 20c - 46lbs - $1k is damn hard to resist. The only thing keeping me strong is knowing that soon enough it will be 4kwh - 30c - $1k. Well that and the fact that I have lots of batteries.

Who's going to be the first one to build a bike out of these lipo bricks? Lipo packs + fiberglass + epoxy + some carbon fiber to reinforce the critical areas = the Batt Bike. These smaller packs are perfect for the task because you can arrange them with the flat sides of the cells facing left and right and overlap them like bricks and create a really strong bike with very little added weight in bonding materials.

Anyone serious about ebike racing in events with a weight limit has to take a hard look at this route.