Whistling Death

In the last 2 weekends I have had 2 ElectriFly 11.1 2100 mAh swell up. I have only put these through about 20 cycles(Fly/Charge).
1.I fly the H9 Mini Pulse PNP with a 450 BL Outrunner, 890Kv special PNP motor w/ 22A Brushless speed controll in it.
2. Great Planes Ulitmate with a Power 10 BrushlessL Outrunner Motor, 1100 Kv. and a Great Planes Silver Series 35A Brushless ESC 5V/2A BEC in it.
I am sure these batteries are shot, I just can't figure out why. I use a Hobbico Accu-Cycle Elite to charge them and use the Electrifly balancers to keep them balanced. I have done everthing by the book.
So all you experianced guys please help me before I have to go and buy 2 more $75.00 batteries.
I am thinking of going with Thunder Tiger since most of the guys at the field fly with them. Only thing tha sucks about that is I have all the electifly balancers that don't work with any other brand. THey are so expensive I just want to get every cycle out of them that is possible.

mrasmm

you can use that equinox just fine =) Just get the csrc v2 to tp adaptor cable at www.commonsenserc.com for about $3 bucks if you want to go with TP

about the packs, I'm guessing they are rated at 15C, so that probably means they are only good for about 12C actual. with a 35A ESC you could easily go over that #, with the 22A ESC you're probably ok.

How long are you leaving the packs at full charge? How fast are you charging? How hot are the packs when you get done flying? Are the packs actually balanced when you check it with your cellspy or dmm? How high is the voltage measured with your DMM after the packs are hot off the charger? Are you form charging the packs when you get them new? There's a few q's to start with =)

Whistling Death

The Batteries are 20C
Full charge for no more than a week.
20C batteries everyday charging at 10C
I never check the batteries after they are charged.
Normally they are right at 12.5 volts
I did form charge them

Funny, the manufacturers only recommend a 11.1 2100mAh battery but not what C rating you need.

Another thing, they recommend 2100mAh batteries. Does that mean they can only use 2100mAh or can I use say 2500mAh or even 3000mAh batteries.

exeter_acres

My Feedback: (2)

do you know what voltage the batteries are at when you finish flying....before you charge them?

Whistling Death

In the neighborhood of 9 -10 volts.

Everybody in my club is new to electrics. So this information will be good for all the members. That being said should we be checking the voltage right after charging and right after flying?

exeter_acres

My Feedback: (2)

thats a big neighborhood....

if they are all the way down around 9v UNLOADED.....then you are pushing them way below 9V loaded.....and that would be a no no....



also,,, you mentioned that you did a "form" charge... Please describe exactly what you did with this

Whistling Death

I used the default LiPo charge setting on the first charge, which is .30A and it took several hours for them to charge. I had turned it up to 1.0A, not to charge them too fast, hoping to get long life out of them.

exeter_acres

My Feedback: (2)

just making sure you weren't cycling them like Ni batteries as that is not recommended......

Hmmm... I think we need to know what voltage (via a voltmeter) the packs are at after a flight.......

Whistling Death

I am kind of afraid to fly with them now. Might they explode?

mrasmm

you say you are charging at 10C, if hat's true, then that is too fast =) it's probably not though. The fastest you want to charge is 2.1A, so your 1.0A charge rate will fit well within that. Most lipo's don't benifit too much (as far as cycle life) from anything slower than a 0.7C charge rate, or in your case 1.47A charge rate.

About the voltages, yeah, that's your prob right there, just as exeter_acres was sayin =). Your pack should be reading nominal unloaded after flying them, so for a 3s pack, you should be getting around 10.5 to 11.1 v or more after a flight without any load on the battery. That will leave about 20% in the pack. If that indeed is the kind of abuse the packs have seen, then I would get rid of them =)

http://thunderpowerrc.com/PDF/DISPOS...-BATTERIES.pdf

about the cycling thing, I'm not sure if I agree. I think it's good to cycle your lipo's when you first get them to form then or basically break them in. 1/2C (1A in your case with the 2100MAh pack) charge 2C (4.2A) discharge for 3 to 5 cycles. Maybe that's not what exeter_acres was saying though.

Also about the packs, yes you can fly a bigger pack, you'll just have to look at how much weight it is adding, and how well you want your bird to perform. If it flies real sporty and you're willing to give a bit of that up for a bit longer flying time, then yes by all means get a bigger pack. On the other hand if it is just putting through the air, then you'll probably not want to go with a bigger pack because it will add more weight.

Whistling Death

Great information, Thanks guys. Tell me this, have any of you ever had the shrinkwrap swell up on a lipo during flight from heat or any other reason?

mrasmm

I've had the silver coverings do a slight balooning effect when the packs are up to temp right after a flight. Within about 5 min though it's completely gone.. It's just very slight

Whistling Death

I went and flew my Ultimate today. After charging both batteries were 12.5+. After flying one was 10.5 and one was 11.25, each after a full 8 minute flight. No ballooning. Batteries seem to be ok after all.

jmir

My Feedback: (1)

When I first got into electrics, I purchased a Watt's Up wattmeter.
It really helps diagnose problems and it is very useful in determining whether or not you are operating within your power limits.
It comes with an excellent pamphlet including theory and how to use it.

http://www.powerwerx.com/product.asp?ProdID=3809