New battery warning.

[Dan Tandberg]

I recently ruined one of my Hacker A20-20L "Outrunner" class motors.
Here's how I did it. Two years ago I started running Thunder Power 2S
2200 eXtreme V2 LiPo battery packs on my smaller F5J contest ship. I
originally started with a 12x8 Aeronaut folding prop and this ran at
about 18 Amps. As my batteries aged, I gradually increased the prop
from 12x8 to 13x8 to 14x8 to 14x9 with the current staying under 20
Amps.

Recently I replaced the batteries with the new Hyperion G3 VX – 2S
2200mAh (35C). I was very happy when the sailplane climbed noticeably
better, but the motor failed after a dozen or so flights. I sent the
motor back to Hacker for repair, figuring that it just got old and wore
out the bearings or something, since it just got really noisy. (They
are graciously sending me a replacement at their cost.) The Hacker tech
called me up on the phone to see what had happened and he wondered if
the newer batteries had lower internal resistance and that I had run too
much current through the windings. They have apparently been seeing
other pilots with failures like mine. (He also very politely suggested
that I do a bit of testing with the newer batteries.)

When I tested the new Hyperion batteries with the 14x8 prop, the motor
was pulling 23.6 Amps, way over the rating of the Hacker A20-20L.


I think that Hacker Brushless Motors are an extremely good product with
wonderful user support. You should support them.
http://www.hackerbrushless.com/home.aspx


Moral of the story: "New LiPo battery chemistry may produce more heat
than height."





Dan Tandberg, M.D.
Professor Emeritus
Department of Emergency Medicine
UNM School of Medicine
Ambulatory Care Center 4-West
University of New Mexico
Albuquerque, NM 87131-0001
Internet mail: tand...@salud.unm.edu
HomePage: http://www.nmia.com/~tandberg
Department: 1-505-272-5062
BMSB-B65H: 1-505-272-8600
Fax 1-505-272-6503

[Carlos Reyes]

We have been using AXI motors in all of our testing. Bent shafts are extremely rare events. I've been very happy with them.

Given the budget in the project, we treat them as disposable commodities. No idea what the AXI repair service is like.

Carlos Reyes, AMA Scientific Leader member #4601
Author of RCadvisor's Model Airplane Design Made Easy and other books.
www.RCadvisor.com founder - Brainy calculator, so you don't have to be.

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[den...@aol.com]

Good work, Dan.

I have run the Hyperion 2200 35C a few times in my A20 20L/Electron with no problems but I won't be doing that again.  As you know I have been running the 14-9 for some time with three 2S TP 2100s in my Electron with good results.  I believe that this flying was at 20 amps for 25 seconds on average.

Dale

-----Original Message-----
From: Dan Tandberg <tand...@salud.unm.edu>
To: soa...@googlegroups.com
Cc: in...@hackerbrushless.com
Sent: Sun, Nov 22, 2009 9:36 am
Subject: [ASA] New battery warning.

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