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Old 04-22-2009, 11:16 AM
SportFlyer is offline
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Back at it again...
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Re: A123 Batteries for Dummies.

Forgive me if this has been posted before but I've read somewhere that the Triton 2 can charge A123's when set to the 6V lead acid setting. I remember reading that it would peak to 7.4V very shortly and then settle at 7.2V...Is this true ???

This was without any sort of "daptor" also...
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Old 04-22-2009, 04:53 PM
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Re: A123 Batteries for Dummies.

First failed a123...The story. I put a 101" plane together that had been sitting for a while. For the RX I dissassembled a 4s 1100 a123 pack I had made up for use in an electric airplane. I only used it maybe 4 times to see if it would work.
So I turned this 4 cell in to two 2s 1100 a123 RX batteries. Durring dissassembly I did let the wires short momentarily but figured it was too brief to worry much. I wired em back up, put them in the plane, charged them up with the cellpro and a day or two later went to the field to fly the plane. Only one battery was working hmmm... no juice at all in the battery. I figured I really screwed up a solder joint. But what the heck, I flew it on the one 1100 battery no problem for 4 flights and came home with after a good day of flying and dug into it to see what was wrong. Pulled the battery out and nadda, dead as a doornail. So that got me thinking my EF Yak running the single a123 1100 is not such a good idea.
A couple days later I was talking to TKG at CH and he told me about a tiny resistor thats imbedded in the + tip of the battery and when that blows the battery is dead.
Conclusion? Be very careful to not short the battery during construction or at any time, and run redundant batteries. That little timebomb could go off at any time.
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Old 04-27-2009, 05:34 PM
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Re: A123 Batteries for Dummies.

Speaking of failed A123 batts..........
I'm interested in what typical failures look like, open or short?
And, if anyone can remember or determine, what killed it?

I left an 1100 in a plane turned on for a week. One cell rcovered and had some voltage, one was shorted and has partially recovered. I charged the cells seperately to keep it out of the stupid safety charge mode and now I discharge, put in about 850mah and get obout 750 mah out. Not to good, I'm afraid to use it. I'll cycle some more and see if capacity improves.

I have taken apart 2 failures from friends who can't recall how/why they failed. Both had one cell open and would take no charge. I wonder if this was shorted like previous post?

would be interested to here of other experiences
thx
Gatorb8
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Old 04-27-2009, 05:46 PM
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Re: A123 Batteries for Dummies.

Does A123 have a 3000mah cell? A friend just got into this system and took apart a 36 volt dewalt battery to get the cells for his packs. The cell had some numbers on them to the effect .....30000. He called the company (A123) and they told him those are 3000mah cells. Anyone know anything about that?
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Old 04-28-2009, 11:10 AM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by Gatorb8 View Post
Speaking of failed A123 batts..........
I'm interested in what typical failures look like, open or short?
And, if anyone can remember or determine, what killed it?

I left an 1100 in a plane turned on for a week. One cell rcovered and had some voltage, one was shorted and has partially recovered. I charged the cells seperately to keep it out of the stupid safety charge mode and now I discharge, put in about 850mah and get obout 750 mah out. Not to good, I'm afraid to use it. I'll cycle some more and see if capacity improves.

I have taken apart 2 failures from friends who can't recall how/why they failed. Both had one cell open and would take no charge. I wonder if this was shorted like previous post?

would be interested to here of other experiences
thx
Gatorb8
I had an 8 cell MEC pack that worked for about a dozen flights and produced ~ 7 min./flight. Then, all of a sudden, on one flight the plane was flying fine for about 1-2 minutes and then it lost power as if the batteries were out of capacity but the power did not drop off drastically like usual. I checked the individual cells when I got home and found one cell had shorted. After closer inspection, I found a slight dent on the edge of the cell and figured that the cell had been dropped. I still have the cell and someday I will cut it apart to see what that dent did to the internals of the cell.

Now if I drop a cell, I run it through a few charge/discharge cycles to make sure it is OK.
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Old 04-28-2009, 08:26 PM
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Re: A123 Batteries for Dummies.

I tried to revive a batt that I left on for a week, no luck. When I charged it one cell was shorted at first, then would slowly take a charge, then got pretty hot. I unplugged it and an hour later it was still hot, I put it outside on the patio to cool in a safe place. Later I checked it and the voltage was below 1 V. 1 cell is toast. conclusion: don't forget to turn the batt switch off or 1 cell will toast.
Gb8
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Old 04-29-2009, 08:35 AM
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Re: A123 Batteries for Dummies.

So far, that seems to be the only method of killing a cell
The ones I have tried unsuccessfully to resusitate, had each ben held under a load for extended periods
The first times I had unexplained cell mismatch, ,had to do with the three wire charge setup -which was also used with a three wire switch -to the rx .IF a bind plug is added to this setup, then you get a full short!
The switches only ddisconnect the + lead so the signal and the ground were still connected . One cell would lose voltage slowly.
The best setup -I finally decided ( slow learner ) had ONLY two wires coming from switch to rx .
Once I make a pack -then cycle and balance it - I can leave it on th shelve or in a model for months -and the balance is spot on
My electric powered models with 4 or 5 cells - same thing
In my model,, the ignition requires 3 wires from switch to ignition, in order for the on internal tach info to feed thu switch to hand held tach.
In this case -Iadded a disconnect to the balance lead of the VPX cellfeeding the ignition
FWIW -the tach is reading 810 rpm at idle .
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Old 04-29-2009, 08:59 AM
JoeAirPort is offline
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Re: A123 Batteries for Dummies.

Dick, amazing that the engine runs so well with the vent line plugged.
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Old 04-29-2009, 12:16 PM
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Re: A123 Batteries for Dummies.

Yes!
Except Iam using it as the fill line -the vent is a fixed line -facing the airstream.
crude but effective
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Old 04-29-2009, 04:06 PM
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Re: A123 Batteries for Dummies.

What's that blue thing behind the spinner backplate?
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Old 04-29-2009, 06:14 PM
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Re: A123 Batteries for Dummies.

The engine was moved forward as far as possible to improve prop efficiency-
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Old 04-29-2009, 10:10 PM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by dick hanson View Post
So far, that seems to be the only method of killing a cell
The ones I have tried unsuccessfully to resusitate, had each ben held under a load for extended periods
The first times I had unexplained cell mismatch, ,had to do with the three wire charge setup -which was also used with a three wire switch -to the rx .IF a bind plug is added to this setup, then you get a full short!
The switches only ddisconnect the + lead so the signal and the ground were still connected . One cell would lose voltage slowly.
The best setup -I finally decided ( slow learner ) had ONLY two wires coming from switch to rx .
Once I make a pack -then cycle and balance it - I can leave it on th shelve or in a model for months -and the balance is spot on
My electric powered models with 4 or 5 cells - same thing
In my model,, the ignition requires 3 wires from switch to ignition, in order for the on internal tach info to feed thu switch to hand held tach.
In this case -Iadded a disconnect to the balance lead of the VPX cellfeeding the ignition
FWIW -the tach is reading 810 rpm at idle .
Dick,
Thanks for the feedback. I use 3 wire charge switches and definately pull the balance pin out of the connector going to the Rx. I've been told "don't worry about it" but as you have discovered, there are circumstances that will cause problems. I don't argue much, I just go away.

I'm still trying to figure out my buddies batts that had open cells. May have been shorted batt leads but that is pretty hard to do and most people remember when they short batt leads and release 30+Amps .....
I suspect some chargers kill the batts too, not sure...
Gatorb8
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Old 05-01-2009, 09:29 AM
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Re: A123 Batteries for Dummies.

ok here are some more real world results. as i have posted in the past i used a dewalt pack and made 5 2300 packs with tp balance taps and ec3 connectors. i used a spektrum ar9100 receiver. i am running a da 85 in a 33% toc260 extra. i am running 3 2300 packs 2 for the plane and 1 for the ignition. i am aware the 2300 for the ign. is over kill but it was easier than reconfiguring the packs. i have now been using the packs for 2 months and aprox 50 flights. i fly imac and some basic freestyle. i fly 10-14 minute flights. i now fly 4 full flights and are only adding aprox 20% back into the plane. each time i do my test i have used no more than 25% of capacity of any 4 flights. ignition is a non issue as it basicly uses little or no mah. i have found the following practice to follow. while i am assembling my plane i have the charger plugged into a battery jump start box for a automobile . before i have finished putting my wings on all 3 batteries are charged. after i have done 4 flights i hook the charger back up. in the time i have bull s....ited between flights i have charged all 3 batteries. (less than 15 minutes). i will then fly 4 more flights and do the same. i always fully charge the batteries while i disassemble the plane and again it is almost always doen before i can completly take my plane apart. i am now building a new 35% h9 sukhoi and will do exactly the same for this one except the ignition battery. i was able to do 5 packs from the dewalt pack so i will use the remaining 2 packs for the plane and found bp hobbies has real a123 batteries on sale so i am going to grab a 1100. mah for the ignition. funny thing is how many guys say "your nuts" if you cant load test them i dont want them. well....guess what one has already ordered batteries and is jumping on board. thanks to dick i jumped in and made the swith and wont look back. also just a heads up if you look at bp hobbies web site there are some good deals on real a123 racing packs and chargers. looks like they may have banked on the electric guys to jump aboard and got stung. thet have some pretty sweet "make an offer" deal to get rid of them for those not confortable making your own.
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Old 05-01-2009, 01:01 PM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by ken crane View Post
also just a heads up if you look at bp hobbies web site there are some good deals on real a123 racing packs and chargers. looks like they may have banked on the electric guys to jump aboard and got stung. thet have some pretty sweet "make an offer" deal to get rid of them for those not confortable making your own.
I was going to get some 1100 cells from Hobby King and make my own packs but the BPHobbies deal is much better since I don't have to do any soldering. I have purged all my Lion packs for the giant scales and will never look back. Thanks for the head's up on the BPH deal.
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Old 05-04-2009, 05:58 PM
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Re: A123 Batteries for Dummies.

Quote:
Originally Posted by nordqk View Post
I was going to get some 1100 cells from Hobby King and make my own packs but the BPHobbies deal is much better since I don't have to do any soldering. I have purged all my Lion packs for the giant scales and will never look back. Thanks for the head's up on the BPH deal.
the last time I bought a123 1100's it was direct from B&D for $15 delivered for the vpx pack, I just add a jr connector and shrink wrap so the done deal is about $16.
$26.95 + shipping seems steep!
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