Zippy Flightmax / Turnigy lipo testing

[methods]

These packs are meant to ride inside of violent RC airplanes that flip and flop the packs around in every orientation you can think of.
RC punishes these packs 10 fold what we could ever hope to do with bicycles.

I once had a 4S 2200mah pack fall 150 feet to grass field.
No damage other than a little dent. Still use the pack.

-methods

 

[Hyena]

What, no posts to this thread in a week, whats going on ?

I just noticed hobbyking have these little 4S monitors for $2.30 each. $7 for cell level monitoring of a 12S pack ain't bad. Yeah they're not as good as a BM6 but for a fraction of the price if you're reaaaally tight they're better than nothing.

http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=4176

They've also got these new 6S cell log style monitors that do voltage discharge curves which is pretty cool for $22 if you're into that sorta thing
http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=10348

Also, my last order put me over the line. Platinum, bitches
Now I get cheaper lipos, but I already have more than I can responsibly use... :lol:

 

[methods]

I have a datapoint:

Scenario:
3 packs in parallel.
Tied at the balance taps and at the main leads.
Say 1 set of the main leads disconnect but all the balance taps are still connected.

There was some worry early on that this situation could cause balance taps to melt.
I argued that they would not.
Well - that is how I have been riding my bike for 2 months

No change in performance
No sign of overheated JST connectors or balance wires

Literally did not even notice

Caveat - 2 in parallel is 10Ah @ 20C is a pack that is rated for 200A.
Under even my worst dynamic loading the pack was not drooping more than a few volts at 24S
Lower C packs under heavier load may not be so forgiving.

Test at your own risk

-methods

EDIT: Clarification: One string of 24S disconnected while 2 strings of 24S remained connected.

 

[mwkeefer]

What, no posts to this thread in a week, whats going on ?

I just noticed hobbyking have these little 4S monitors for $2.30 each. $7 for cell level monitoring of a 12S pack ain't bad. Yeah they're not as good as a BM6 but for a fraction of the price if you're reaaaally tight they're better than nothing.

http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=4176

True they are better than nothing and for 7.00... I can't think of a better option.

They've also got these new 6S cell log style monitors that do voltage discharge curves which is pretty cool for $22 if you're into that sorta thing
http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=10348

Forget those... stick with the CellLog8's ... they have a day worth of memory, can be connected to the packs in series (isolated) without damage, they are uber accurate (+- 1mv in my testing of 3 units), they have a trigger for LVC and HVC alarms which are programmable and I think they are 27.00. Oh yea, you can just import data into PC using LogView and the standardized comma delimited format.

Also, my last order put me over the line. Platinum, bitches
Now I get cheaper lipos, but I already have more than I can responsibly use... :lol:

Welcome to the club, it's about time! biatch = |P

 

[johnrobholmes]

Just went browsing around, the 25c turnigy is in stock and cheap, getting 5 more packs for myself.

http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=8586

 

[recumpence]

I just ordered six for the Catrike.

Matt

 

[GGoodrum]

This is the cheapest I've seen the Zippys at, but the 6s-5000 20C Turnigys are still a bit less for me. Has anybody ever seen any significant difference between the Turnigys and the Zippys?

 

[johnrobholmes]

It is kinda sobering to realize what else I could have bought with $500 :lol:

 

[vanilla ice]

Yea like an older scooter or small motorcycle..

 

[methods]

Being an "early adopter" of technology has its costs...

Getting a good price by being "part of the problem" has a whole different set of costs.

I will gladly pay my dues to be part of the solution instead of part of the problem.


-methods

 

[Hyena]

Yeah I've got half a dozen of those 25C zippys. I haven't put many charges on them yet but so far they dont seem to stay as perfectly balanced at the turnigys. I'm splitting hairs, but after charging on a SMPS with no balancing the zippys show a delta v of about 0.03-0.04v and the turnigys are around 0.01-0.02.

Also another interesting thing I've noted in my 15S pack regarding balancing - I've put around 200 cycles on it now and I have it configured so I can discharge as either 15S2P or 10S3P. I have 2 lots of 5S packs soldered together to essentially make 2x 10ah packs and then a 2 5 ah packs that I either add in series or parallel when discharging. I never actually got around to using the 3P discharge lead as I'm never that far from home.

Annnyway, the 2 packs that I soldered together have stayed perfectly balanced over the 200 charges with a delta v of 0.01-0.02 after a full charge and have never once been balanced. The 2 individual 5S packs (that were always discharged in parallel) have slowly become less balanced with a delta v now of around 0.04-0.08. Thats still not the end of the world in terms of balancing but I thought it was interesting to note that having them permanantly hardwired in parallel (seemingly for the times when not in use) keeps them better balanced. I should also add that I never got around to parallelling the balance taps on these packs either, so its only the discharge leads that were soldered together.

 

[mwkeefer]

Yeah I've got half a dozen of those 25C zippys. I haven't put many charges on them yet but so far they dont seem to stay as perfectly balanced at the turnigys. I'm splitting hairs, but after charging on a SMPS with no balancing the zippys show a delta v of about 0.03-0.04v and the turnigys are around 0.01-0.02.

That's impressive... my turnigys at best of come out with .05v average balance, they are paralleled 5S like yours but I've also paralleled the balance taps.

Also another interesting thing I've noted in my 15S pack regarding balancing - I've put around 200 cycles on it now and I have it configured so I can discharge as either 15S2P or 10S3P. I have 2 lots of 5S packs soldered together to essentially make 2x 10ah packs and then a 2 5 ah packs that I either add in series or parallel when discharging. I never actually got around to using the 3P discharge lead as I'm never that far from home.

Annnyway, the 2 packs that I soldered together have stayed perfectly balanced over the 200 charges with a delta v of 0.01-0.02 after a full charge and have never once been balanced. The 2 individual 5S packs (that were always discharged in parallel) have slowly become less balanced with a delta v now of around 0.04-0.08. Thats still not the end of the world in terms of balancing but I thought it was interesting to note that having them permanantly hardwired in parallel (seemingly for the times when not in use) keeps them better balanced. I should also add that I never got around to parallelling the balance taps on these packs either, so its only the discharge leads that were soldered together.

I wish I was having your experience, in fact I assume I must have damage to 1/2 of the parallel pack becuase i watch the 15S2P self discharge quite a bit too much over a period of a few hours (.02v) and that's when i have disconnected all loads.

Im wondering - do you have a method of testing the IR of the packs? I know I have a few higher IR cells and can actually see the issue when I watch the charging process on the CellLog8 high detail screen... one or two cells in each pack seem to lag their neighbors (even though I balance the packs before charging).

Im going to break this 15S2P pack down tommorow and rebuild it (found a sweet new enclosure, will post more when/if it works out).

I should add that my packs from June... a few cells were damaged (my own damn fault) and I salvaged a 15S1P pack with cells having minimal puffing... they charge to 4.15 and balance out with .002 v without balancing, just once before using in new pack.) - this pack was run with its now dead twin for 3 months constantly and pushed far harder than it should have been.

The old pack is the first turnify 15C packs the newer packs are all 20C and don't seem as well matched - stil fine for eBike use to 10C or so... but I wouldn't push them much farther.

-Mike

 

[vanilla ice]

I will gladly pay my dues to be part of the solution instead of part of the problem.

Me too. Although I don't know that adopting cheap junkers headed for the scrap pile and getting utility out of them is really part of the 'problem.' I think buying a bunch of shiny new stuff you don't really need is arguably worse. ICE or otherwise.

 

[liveforphysics]

Im wondering - do you have a method of testing the IR of the packs? I know I have a few higher IR cells and can actually see the issue when I watch the charging process on the CellLog8 high detail screen... one or two cells in each pack seem to lag their neighbors (even though I balance the packs before charging).


-Mike

Cells that lag behind the others when charging are generally the best cells with the lowest Ri and/or biggest capacity.

To get an idea of Ri, apply a known current load while at nominal voltage and 70degF, observe the amount of voltage sag on the pack after 2-3 seconds for it to stabilize, then divide this number by the number of amps, and you've got Ri (V= IR). You want to check a whole big pack or battery array, just treat them like resistors aranged in the same groupings, and you can solve for average indivdual cell Ri.

 

[mwkeefer]

Luke,

Excellent info... I use my iCharger to quickly read off the IR of each sub pack (paralleled) individually.

I agree with the slower charging (not damaged) are going to be the better IR but somthing has to explain the mystery of dropping not the overnight voltage decay - were not talking LiFePo4 here and with no external drain... I assume I have a bad cell in one of the parallel packs (maybe more) and need to break it down to figure which one.

-Mike

 

[liveforphysics]

Luke,

Excellent info... I use my iCharger to quickly read off the IR of each sub pack (paralleled) individually.

I agree with the slower charging (not damaged) are going to be the better IR but somthing has to explain the mystery of dropping not the overnight voltage decay - were not talking LiFePo4 here and with no external drain... I assume I have a bad cell in one of the parallel packs (maybe more) and need to break it down to figure which one.

-Mike

Did the cells go from being warmer to cooler by chance? 0.02v is well inside the proper voltage change for going from a warm room to a cool garage for example.

 

[mwkeefer]

Luke,

That was the first thing I thought of but I've tested with the pack kept at a constant 72F (oven charger and temp probe) so that's not it. I really think one of the cells (or more) from my last batch of 6 x 5S packs is just bad and pulling down the other good side of the pack.

I'm trying to hold out for new packs > 5800mah but... maybe I will have to bite that bullet soon.

-Mike

PS: I have to order alot of packs just after christmas for a publicity trip from Philly to NYC on a single charge (114mi one way)

 

[recumpence]

Well, I now have 16 of these packs ordered for my next "Big" build.

Matt

 

[El_Steak]

How much are they for you "Platinum Members" ?

I'm just a lowly "Gold Member" and they are 64.42$

 

[MrKang]

How much are they for you "Platinum Members" ?

I'm just a lowly "Gold Member" and they are 64.42$

Platinum = 56.36

 

[MrKang]

Well, I now have 16 of these packs ordered for my next "Big" build.

Matt

That's the way ..ahha ahha i LIKE it !

hope you ordered them by several shipments...otherwise customs will love you with 16 Lipo's in a box !

 

[regmeister]

How much are they for you "Platinum Members" ?

I'm just a lowly "Gold Member" and they are 64.42$

Platinum = 56.36

The price went up as the stock diminished. They were quoting me $60.39 earlier, and I'm am a Gold member.

 

[Vanquizor]

If you aren't an UBER member and can settle with only 15C you're way cheaper building a pack with these:

http://www.hobbyking.com/hobbycity/store/uh_viewItem.asp?idProduct=6502&aff=150208

works out to $0.41/watt plus shipping.

 

[mwkeefer]

I think the 5000mah packs are similar in pricing at 20C/30C... the Zippys are good but for the size, weight and rating I will stick with the slightly higher rated cells (which will never see their limits, worst I have ever hit a pack is 10C)

A while back I looked into making a pack out of 2x the 2500 mah lipo but it just wasn't worth it in the end, too much trouble.

Good tip though for people just getting into Lipo or away from LiFePo4 (traditional LiFePo, 2.5-3C)

-Mike

 

[Vanquizor]

really boring day at work, so I tossed every poly pack Hobbyking sells into a spreadsheed and made the assumption that you would use any bonus points on the item in an order. A quick sort shows only 2 packs under $0.45/watt; the one I previously posted and this one which is currently out of stock:

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=8579&aff=150208

Many of the Zippys were under $0.50/watt including the 5000MaH 6s1p in 20C flavour, the 25Cvariant was just over the mark.


I assumed no relationship pricing or other discounts, so your milage may vary
but with a little creativity in the use of coupons even a first timer should be able to get under $0.50/watt shipped to your door.