everydayflyer

I have studied all of the vendors graphs, read hundreds of post in many different forums on several different Users Sites including ,RCU,RC Groups ,Traxxas and a few smaller ones. I have read post by car /truck,aircraft ,fixed and rotory wing and even boat RCers.
I have read post of those charging at 6A,10A and even 25A and discharge rates from about 5C (12 min) runs to 10C ( 6 min). flights .
The one thing that remains a mystery is real cycle life data at rates other than 10C max..

I will start it off with my results to date.
I have a 3S which I have routinely discharged to 8 volts resting ,charged at 6-8.35A mostly at 8A plus. I have pulled 70A peaks from it and most runs have been in my CC Mamba Max 5700 powered Rustler. Most runs last 8 to 9 minutes so 7 to 8C average discharge rate.

I now have 60 cycles on the pack and it has lost next to nothing.
Discharges 20 and 35 were down due to pack being cool.

Second graph shows comparison of 3S A123 and GP3300 6 cell

everydayflyer

Sure good to see a post generate so much interest. I guess I am the only one around here who is putting any serious cycles on these cells.
Well I just completed discharge # 73 in my CC MM Powered Rustler and Dsch. #74 on my CBA so here is an update which shows that these cells do lose capacity if you run them hard / deep enough and charge them hard enough.


Voltage after charging 2,270 mAh on graph are incorrect. Those were the voltage after charging 100 mAh only. At the end of complete charge 3.512 / 3.517 / 3.502

I just hate it when I do that.

SS Pede

So it appears the drop in run time is modest compared to GP3300's, as one might expect for lithium cells. Are you charging any of your packs at the recommended charge rate? Maybe you can't do that perfectly if you don't have the "official" A123 charger. Or do you?

EDIT: Do you have any similar data from other lithium packs like some LiPo's? Charge/discharge rates might be different due to LiPo's lower tolerance for abuse. But a comparison would be interesting.

Marv829

I don't track my cycles. When I ran NiMh I usually replaced them every season or two at the most.

I had a cell getting very weak in one of my 3s packs so I took it apart and charged each cell separately with my Sonic charger. Then I discharged each cell separately at 10A with my ICE charger set to stop a 2v. The weak cell only had a capacity of 760mah. The other two were in the 2100+mah range. When I tore apart the Dewalt pack to build these packs the cell with the red wire on it was at ~1v. I don't know if this was that cell because I did not mark them at the time. So I took apart my three A123Racing 2s packs and tested each cells capacity the same way. I then turned them into 3s packs by matching the capacities as close to each other as possible. I ended up with one 2s pack matched as well. I ran that 2s pack tonight in my Rustler (MM7700, 14/87, 4" tires, 4v LVC). I did not time the run but it seemed longer than my ~6min run times I get with my 3s packs on the same setup. It was ~38° air temp outside (all components were at room temp, ~70°), after the run: Batt-112°, motor-86°, ESC-80°. I put the pack on the charger as soon as I could get it out of the truck. The start amps for the charge were +15A for almost 1min. I've never seen it that high before. It stayed in the 9A-11A area for most of the charge which took only 12min for the "Charged" light to come on at which there was 2155mah in the pack. When my meter showed 0A going to the pack about 2.5min later there was 2202mah in the pack. The pack was at 91° when I took it off the charger. Wow, who thought we would see the day where you could watch an entire charge cycle without toothpicks in your eyelids.

With the MM5700 in my Stampede I average ~9min runs also and much cooler temps all around with my 3s packs vs. 3s in the MM7700 Rustler, which is so darn tooting fast and powerfull on my back street.

Keep posting cycle data Charles. I want to see a 500+ cycles discharge graph.

Marv829

I forgot to put in the post that the pack with the weak cell took forever to charge because when the bad cell reached it's 3.6 volt first the charger slows way down to balance mode. It would still balance them though.

everydayflyer

I have lots of CBA test graphs of LiPolys on RC Groups Batteries and Chargers Forum in the Battery Graph Vault. Many of my Threads have life cycle test. The most cycles I have on a LiPoly is just over 400 but it has not been pushed nearly as hard as these A123 cells have.

Most LiPolys would not last 5 cycles if 30 plus C burst were pulled from them or if they were completely discharged even once. A LiPoly discharged to below 2.5 volts per cell will most often lose 20% or so capacity.

Believe me when I say that I have the proper charging / balancing equipment and know how to use it.

I have an Astro Flight 109 modified for A123 charging , I have a TP-1010C with Rev. 2.0D<Edit now 2.1A as I suggested some changes> firmware for A123 charging, I have four Thunder Power Balancers and a Hyperion Balancer,an Astro Flight Blinky balancer,a VamPower Balancer and several sets of Li-Po Balancers which were the first balancers every marketed.
I have many other chargers as well.
I have a CBA discharge test unit, a BNB Products BPR-100 In flight Data Logger and an Eagle Tree Micro Power in fligh Data Logger and should have yet another new Data Logger to test in another week or so.

I do not do much guessing when it comes to my batteries be they NiCd,NiMH,LiPoly or A123.

I am not easy to impress but these A123 cells are really impressing me.

Marv829

(O/T)

Charles, do you know how accurate the Eagle Tree brushless rpm sensor is?

everydayflyer

Once correct calibration factor is entered it is extremely accurate. It matches my Digital Optical Tach which reads exactly 3600 on a 60 cycle lite source.

jhouvener1

How about the e-moli battery? Has anyone used these as yet? Results?

[email protected]

everydayflyer

They are the same voltage as LiPoly 3000 mAh heavier and can only be used at approx. 40A max.
If you are really interested

http://www.rcgroups.com/forums/showthread.php?t=594726

however this really is the A123 Support Forum.

everydayflyer

I have a feeling my Rustler will wear out before the battery does. I mean I run this thing flat every run ,charge it at 10A while it is still warm and every recharge is right at 2300 mAh.and 17 min.
Dsch. 1 was 2,190 mAh # 54 was 2,150 # 74 was 2,110 & # 99 was 2,110 mAh.. All of these to a LVC of 7.5V (2.5 per cell).< Edit> CBA Discharge Test to 7.5V pack ran flat in Truck. MambaMax ESC set to LVC None and truck ran till it stops.

Charles

Marv829

Wow your on #99, thanks for the update. I have my LVC set to 6v (3s), would you recommend I increase that to 7.5v? Some of my packs seem to get more unbalanced then I would like and this can really slow down the Sonic charger. Would having the higher LVC help this at all?

-Marv

High Speed Dirt

Wouldn't one (long) balancing-charge after a day of use solve that problem?

Or does this problem occur after only a few discharges (when you're still flying or at the track)?

everydayflyer

Yes a higher LVC would help as data on the graph clearly shows however to me it is not a big deal.
My Thunder Power 1010C Rev. 2.1A charges at a reduced rate until the cells reach 3.0V and then ramps up. If I start a charge on a 3S that is at 8V OPV then the initial(reduced rate) charge takes approx. 75 sec. and then the ramp up to 10A takes approx. 2 min. more.

Charged to 3.65 per cell mine are balanced close enough without balancing. The TP 210V balancer when used balances during the charge so no extra time is required. My normal total charge time is right at 17 minutes.

Note the ET MicroPower indicates a little low on voltage. Actual max. voltage is 10.95.
The graph time past 17 min (end of charge) was recorded to show how the voltage settles down durning the first 5 minutes or so after charging.


Charles

reefboy

Thanks for posting your results and please keep up the great work! I have recently purchased a Dewalt pack off of ebay and plan on making a few 4s packs for my Zagi. I am hoping you continue with little degradation to the cells.

everydayflyer

One hundred and eighteen cycles and the last recharge took 2,311 mAh.. I keep pounding this 3S pack and it just refuses to give in.

Glacier Girl

My Feedback: (4)

EDF, kinda on the subject, as I'm just now getting into the A123's. I did Pmackenzie's hack on the 109 last night. Went with the 3 position switch so I can do the lipo, 1-9, and 10s A123's. Love not having to buy another charger.

IamDisaster

Why disassemble DeWalt packs? Cheaper way to get cells?

SS Pede

Yes.

everydayflyer

Great modification Pat came up with. I ended up with 79.8K tooal in mine for the 1-9 S charging and have been extremely pleased with it. Most I use my TP-1010C Rev. 2.1A as it will charge at 10A 1-5 cell and AF-109 is only(?) 8.35A with 3S and approx. 6.5A with a 4S.
My charge graphs on RC Groups

http://www.rcgroups.com/forums/showp...96&postcount=1

119 cycles on my 3S pack and still performing like new. Got to love these cells.Just completed a charge on AF-109 @8.35A,2200 mAh in 21 min.and I only charged at 3A setting durning Stage 1 .
Charles

everydayflyer

This 3S pack continues to amaze me. I run it flat ,charge it fast and it just keeps coming back for more.

Charles

Bthree

Been searching but with no result

Has a two cell version of the A123 pack been considered for a Gas powered Receiver pack, advantage would be to remove the 2 cell Lipo and inverter combo to produse 6volts used in performance planes keeping the setup simple

2300mah with a weight of just over 140grams seems like a reasonable combo for larger or many flight in a day modes

The big question is pack voltage which starts off at 7.2volts initial, thats high.

Current draw would not be expected to be high so pack volts are not likely to fall below 6 volts for the duration of the day.

Oppinions please and any practical experience

everydayflyer

Yes 2S A123s are being used as received packs.
A 2S pack charged to 3.6 per cell (7.2) quickly settles to 7 volts and drops a little more under load.
A 5cell NiCd fresh off of charge is as high or higher.

3S a123 numbers here.
http://www.rcgroups.com/forums/showp...96&postcount=1

At end of charge 3.585 / 3.571 / 3.60
7 min. later 3.483 / 3.468 / 3.483


There are tons more A123 data on RC Groups than here.



Charles

Bthree

True never considered that thankyou Charles

Red Scholefield

My Feedback: (9)

I'm flying A123 cells (from DeWalt 36 volt pack) in my Telemaster Electro, in a 4S2p configuration with AXI 2826/12, 13 X 6.5 APC E prop. I'm flying the parallel set up for the duration I can get and the Telemaster handles the 22oz nicely. So far I've logged 61 discharge/charge cycles since June 06. I know I'm not pushing these very hard and the discharges are never to Jeti Advance 40 low voltage cut off. Last check at 50 cycles there was no appreciable change in capacity (at 2.3 amps on CBA-II) . I'm using the same set up in three other 40 size models I've converted to electric and am getting very satisfactory performance.