[NSRCA-discussion] Dodged a Bullet Today!!!!

[J.Oddino]

When I first got my 109 I was afraid to use it.  I didn't understand Phase
1. The manual says, "During Phase 1 the charger will continue charging your
battery for three minutes regardless of the battery voltage.  It acts like a
dumb charger during this first phase".  This sounded like a recipe for
disaster.  I also didn't like the idea of hitting the pack with 5 amp pulses
as it nears full charge.
After listening to Bob Boucher I now feel totally confident using it.  Phase
1 works exactly as the manual describes and therefore you need to be at a
very low current in Phase 1 if you want to top off a pack.  Any current that
lets the voltage equal 12.6 volts is too much (for a 3 cell pack).  Once you
understand that you are almost home free.  The remaining problem is the
cells must be balanced so one isn't over 4.2 while the others are at 4.1
volt.  Bottom line - don't use a 109 for topping off except at very low
current after balancing and watch the voltage.  When it gets to 4.2 volts
per cell stop charging.
I recently did something similar with my TP1010/210 charger/balancer.  I had
run some tests on the system in the plane and had taken out about 750 mAh
from the 5300 mAh pack.  I started charging at 5 Amps, the 1C rate, and
fairly quickly the charger shut down indicating that the balancer had
detected one cell going over 4.2 volts.  I was surprised that the charger
hadn't automatically reduced the current but then surmised that perhaps the
pack had not reached 42 volts even though one cell had reached 4.2.  I cut
the current down and topped it off with no further problems.
Clearly the charger with feedback from the balancer saved the day so the
question is, is it worth the cost?  With the 10s4p pack at about $620 the
answer is yes.
Jim O

----- Original Message ----- 
From: "Grow Pattern" <pattern4u at comcast.net>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Tuesday, March 21, 2006 3:04 PM
Subject: [NSRCA-discussion] Dodged a Bullet Today!!!!


>
http://www.rcuniverse.com/forum/m_4056141/anchors_4064428/mpage_1/key_/anchor/tm.htm#4064428See
picture on RCU.I had a bit of a set back today with my winter fun 40 sized
glow to electricconversion. I had wanted to try the Thunderpower 4200
instead of the Tanic3600. I set off to the field with a borrowed
Thunderpower 4200 mAh pack. Iset the Astroflight 109 to 2 Amps. It ent to
stage 1 and was calibrating toa 3 cell pack and was well on its way to
charging the pack, or at least so Ithought . I have done this topping-it-up
many times before. I set it on a 2Amp charge rate.I never made it to the
field. I heard a light "Phuttt!" about ten minutesinto the journey. I
stopped the van and ran back to the back doors. Thebattery was bloated and
looking bad. I grabbed the Deans connectors andunplugged it. Dangling it by
the lead and as far away from my face aspossible I lowered it to the
curbside.I then personally backed up and was about to move my van forward a
bit . (Ihad just put 3!
>  5 gallons in it!). Seemed like a good idea to get clear. Neverhad the
chance. The pack blew up in a ball of flame about a cubic yard insize and
proceeded to burn fiercely. I had grabbed the fire extinguisher butdecided
not to use it.The local police joined me for a while and seemed more
interested in theplanes in the back of the van than the charred remains. I
scraped all of thebits up to keep the country side pretty. Estimated that
the grass would growback soon, and went home.Fortunately I was able to get
it out of the van before it blew up intoflames etc.Long and the short of it
is. "Do not charge a fully charged battery with anautomatic charger"Dodged a
BIG bullet today.....Regards,Eric.P.S. If 3 fully charged cells = 12 V plus,
and 4 discharged cells = 12 Vplus, then how does the charger know which is
which?
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