everydayflyer

Red I have a 4S pack which I charged to 18.25 (4.5625 volts per cell) after flight 44. Well approx. 4 months have passed and the pack now has 240 flights on it and I can tell the capacity is down a little.


I have a 3S which has been charged between 15 and 20 amp. averages (6-8 min.) and it shows signs of losing capacity also, however it does have 443 flights on it.


Charles

Red Scholefield

My Feedback: (9)

I guess everything has its limits, but I think we are all in agreement that A123 technology is far ahead of LiPos in the reliability, durability and cycle life department.

SS Pede

I'd have to agree with you Red. Also, I don't mind capacity loss as much as performance loss. I'll deal with slightly shorter run times after 300+ runs if the power output is still pretty good.

Does anyone have any thoughts on "effective" capacity of these cells versus LiPo and/or NiMH? A123 claims a 2300 mAh pack will run as long as a 3300+ mAh NiMH pack. I know A123 cells are light, with low internal resistance, but are these claims overblown? What sort of run time have people observed compared to similar capacity cells of different chemistries?

Red Scholefield

My Feedback: (9)

I think the claim that A123 2300 will run longer than a 3300 Ni-Mh is stretching it more than a little bit.[:'(]

andy38

I have a hxt-63-64b motor,sentilion-100amp hv speed control,2 6s1p a123 packs in series for 12s1p in a e-coverted 4*60.
Two 6s1p packs just fit where the tank was,tank floor still in pace,hatch in top of fuse.Duration is 6-7 minets with alot of full
power used, amp draw 35-40amps, bateries are only warm. I flew this plane for years with a OS91fX,even though it is heavier
it is more than a mach for the OS I think the larger 18-12 prop helps the perfomance alot.

everydayflyer

Myu gues is that A123Racing was making the comparison in RC surface vechiles. My traxxas Rustler runs longer on a 3S A123 the it did on a 6 cell NiMh 3300 or a 7cell Ni Cd 2400. the A123s are lighter and maintain volts under load better.

A Astro Flight Cobal 15 powered plane which I use to fly on 8-10 cell NiCds 1200-1500 mAh that was difficult to gey 3 min. acro batic flights with get good solit 7 min. flights with a 4S A123.



Charles

deVries

Hi Charles,

Great thread you started here. Looks like you're 'the man' when it comes to cycle testing these A123's. [8D]

Could you give us an update to where you are now, please.

Also, have you or anyone reading this thread found anyone else that has cycle tested further or longer than you have? Details, please.

What have you learned since your last post I quoted here?

Lastly, for someone trying to get maximum cycle lifespan from these batteries what would you suggest should be the maximum charge rate and discharge rate to use per cell? (If can't do per cell, then for whatever set-up you have then.)

TIA, deVries


Can anyone point to good data showing 'real world' cycle life at lower amp charge rates such as Brian suggests at 10amp or less?

Thanks!

everydayflyer

Max. cycle testing I am aware of is here however that was with single cells and not flight cycles.


http://www.rcgroups.com/forums/showthread.php?t=732148


Max. life see A123 spec. where they list 2.3A charges and 5A discharges= 1,000 cycle to 80% remaining capacity.. I do not wish to take an hour to charge and non of my planes ewill fly at 5A average discharge (30 min. flights).


My MUS 3S 2300 pack which I Zip charge at 20A (6 min) average now has 486 flights on it and is stilll delivering over 2000 mAh .

I know of no one with more actual flights on a single A123 battery. I have others with over 200 flights on them.


Charles

deVries

Thanks, A123 Cycle Man. [8D]

Do you think this reference to 2.3A charging is just because that's close to standardized charging rates when that graph/stats were made? Maybe 5A or 10A will do almost as well?

Also, I think you have been overcharging these a bit too. What voltage per cell do you think you can get away with without affecting cycle life much? I read it's supposed to help with balancing too. What's been your experience w/balancing?

Thanks for your interesting thread. I'm just getting into using these batts, so you have been very helpful. I really appreciate your efforts! TU

Red Scholefield

My Feedback: (9)

I have 151 cycles on two packs (run as 4S22P) discharge up to 34 amps, charge 3A on CellPro 4S. It has taken me 27 months to accumulate these for real life data point.

everydayflyer

Perhaps I am confused. I stated over 480 flights on a single 3S which has been charged at 20 amp. average (6 min. charges) and you want to know if I think charging slower will / would be better for cycle life.

I also provide a link to where single cell was cycled hundreds of times at a lower charger rate and lower discharge rates.

My opinion with these cells is same as with LiPolys. Charging them at higher rates does nothing like as much damage (life cycle wise) as abusing them during discharge and or storage.

Anyone who wishes to know how they would do being charged at X amps. and discharged at X amps. can purchase some cells and start testing.

I enjoy flying a lot more than bench testing myself.

FYI There is a lot more post , Threads, dat aon threse cells on RC Groups than there is here.


http://www.rcgroups.com/forums/showp...01&postcount=2


Charles

deVries

What I was trying to newbie-guess at was the reference you gave showing suggested maximum cycle life was attained by charging at 2.3A was really misleading in the sense that they chose 2.3A because it was a "standardized charge rate" back in the day 2006. With higher performance batteries, such as M1, charging it at 5A or 10A is not going to affect cycle life much at all. Agreed?

How many cycles would you consider fantastic charging at 20A as you do? ...and still have 80% of original battery capacity? 800? 1,000?

Also, I was hoping you would comment too about overcharging the batts to X voltage... what over-voltage could you get away with and not damage the cycle-life on these A123 Racing 26650?

EDIT: Thanks for your link in your post just above, because I read your answer linked from there already. It seems overcharging is no biggie, but just don't store the batts in an overcharge state or 'hold' the charge voltage past its initial charge.

Btw, I understand your need to fly beyond the bench, because you have sure gone way beyond the call of duty bench testing these babies.

Thanks for your reference link too, wow, now I've got some studying to do....

Thank you Charles. TU

everydayflyer

A123 Systems / A123 Racing is the one who prepared the 2.3c / 5A discharge tests / graphs.

Why they chose those rates would best be answered by them.

My Mini Ultra Stick 3S A123 battery has already surpassed my expectations. I see no measurable difference in capacity,performance or cycles being charge at an average 20A rate. I am sure not going to do 480 plus 1C charges and 5A discharges just to be able to do a one on one comparison.


Charles

Charles