4S A123 Saftey test, first broken RDlohr mount!

[Cryofix]

These batteries rock, Kama1 and I were out flying at our local field when we should not have been especially with T-rex 450's nice day, a bit cold but the wind was about 20-25 mph, one look at the wind sock and we should not even attempted it, however we did.

Wind was blowing strong east and you could really get the bird crankin when you caught the wind in that direction, I was nose left had just come across me at about 40+ mph, I began to bank right about 8 foot off the deck, added some rudder and then caught a gust of wind that kicked the tail up and sent the bird straight into the ground nose first. Impact was major, it left a 2 inch hole in the ground, I hit so hard I bent my motor mount, broke my RdLohr Gyro mount that was screwed into the frame, the gyro and mount kicked the rx forward as it came into the frame, the impact snapped my CF tail boom at the block, canopy was in about 4000 little parts, cracked my upper frames, and all of this happened with the A123 pack hitting the ground first.

Collected all my scraps, looked the battery over and there was no damage what so ever, there was dirt wedge an inch + into the battery, brought it home, dropped it on the charger, 6 minutes later at 9.9 amps and 932 mAh from my 6 minutes of glory, it was back and fully charged, went out and test flew it today and still runs like a champ.

The more I use these batteries the more I like them, my lipos are starting to find there way into things other that my heli, like my TX :D

[No_Gassers_Here]

Where do you get them puppies?

[Cryofix]

Ebay search: dewalt 36v

[No_Gassers_Here]

so do you butcher up the pac and make your own?

[Cryofix]

yea its so easy its not funny to make 2 4s packs all you gotta do is cut 2 connectors, and solder on deans and balance taps.

[No_Gassers_Here]

hell I got a 36v dewalt batt in the garage I only use the drill a few times a month so I can live with one batt for the drill. at what rate do you charge? and the last ? I promose is there any mod to the trex .what I mean is when I go A123 can I still use the lipos I hve now or is it one or the other? thanks

[Cryofix]

with a 4s A123 you will be running 13.2 volts not 11.1 so you need to make sure oyur ESC and motor can handle the bump in power, also it is recommended that you use a BEC.

There is no other changes needed in elctrical, I made a small mod to my frame and posted pics in another thread I will have to dig up the thread, it was very easy also, I moved my esc and bec to the side instead of on the bottom plate, and then dropped my battery tray straight down, this fit my A123 cells and allowed the canopy to fit easy.

I charge my A123 cells at 9.9 amps which is about 4.5C for a 2100 lipo A123 cells are made to charge at 10C and last for over 1000 cycles.

You can use lipo or A123 without having to change anything as long as you are setup for A123

[No_Gassers_Here]

cool thanks I'll give it a try.

[Finless]

Cryo.... Like the 600 posts I got a bunch of FLACK for about A123's.. I need to see some good vid or something about how these cells work... I saw your pictures and WOA man it looks heavy! REAL HEAVY!! If it provides the power great but:

THIS THREAD IS USELESS WITHOUT VIDS :)

Bob

[smw]

The A123 cells have a different max charge voltage than LiPoly cells. 3.6v for the A123 compared to 4.2v for LiPoly. So the A123 cannot be charged with a standard LiPoly charger. At least this was my understanding from threads from RcGroups Battery forum.

I looked into the A123's because I needed a 7cell pack for a 60 size pattern plane. I went with Emoli cells taken from a Milwaulkee V28 battery pack. They can be charged on a standard Lipo charger (TP 1010). However, like the A123's they are both big and heavy.

[kama1]

bob.
the batteries look heavy...but the bird takes it with out a problem.
when Cryofix and I fly together once the canopies are on you cant tell hes not running lipos.

the power his batteries have is sick.
flips,rolls and loops with out a problem.
might be a wieght issue with hard 3D but at this point they sure are sweet.
with the current flying skill level he gets near double the flight time .
with a good charger and 2 or 3 of these things there is no down time waiting for charges.
its all stick time once he gets to the field.

once we figure out how to shut the suto focus off on his camara we will get some vids for ya.
the stuff we have recorded now is pretty poor quality.

oh and yes we had no bussiness being out there with that kind of wind.
after his nose dive i soon followed with a inverted nose dive.
gust of wind flipped my bird over and she went in hard and fast.
if we had 2 crispy cream boxes would of made getting the stuff to the car ALOT easier.
few hours later bolth birds were repaired and ready to fly
:mrgreen:

[Cryofix]

Bob I am writing the video to hard disk now =)

[tele]

opps sorry didnt see this

becarefull there are two types of dewalt batteries out there A123 ( M1) and Emoli see my other posts of details.

and yes they are heavy don't know how they would go for 3d on the t rex but for bigger birds like the Lepton, EP8 ( a great bird!!! ) and the t rex 600 these cell rock!!

[rdlohr]

Wow! Thats a heck of a crash! I know you were able to reuse the gyro mount but I'll send you a new one if you want. You took enough of a beating on that crash!

Rick

[torkboy]

^^^ nice pic rick.


Wow that must of been a wild crash to break that thing!

[rdlohr]

^^^ nice pic rick.

Thanks, MComet made it for me. I love it!

[RC Accessory]

For the people who would rather not tear up a DeWalt 36V pack and would rather buy the A123 batteries ready to go, RC Accessory is now carrying the packs in several capacities and pack shapes.

Announced earlier on Helifreak. Thanks.

http://www.helifreak.com/viewtopic.php?t=26948&highlight=a123

Evan Chapkis
RC Accessory, Inc.

[prototype3a]

Just so people know... you can buy a "developer kit" from A123 systems directly which includes 6 cells with tabs and some other junk for ~$120 with each additional set $110. Still a miserable price compared to a 10 cell dewalt pack from ebay for ~$110.

[ShuNut]

I've been watching the info on A123's for a while now for my big heli that i should be getting next year......... opps it now 2007 so i should say... the heli that i hope to get sometime this year ...but have read on the forums about a few ppl using them on the T-Rex 450, this is great news....

...with a 4s A123 you will be running 13.2 volts not 11.1 so you need to make sure oyur ESC and motor can handle the bump in power, also it is recommended that you use a BEC....

So has anyone tryed A123 cells with A STOCK Rex ? Would the stock stuff handle the 13.2V ?
I hope so as i'd love to try these out... Lipos are just toooo expencive man.

Thx

[No_Gassers_Here]

well the specs I'v seen say the can handle it but I am not going that route I will runn a BEC just to be safe.

[spork]

I've got some A123's on the way. Initially I plan to run without a BEC. I'll let you know where the smoke comes from.

[tele]

:lol: :lol: :lol: :lolol