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Old Mar 14, 2009, 03:15 PM
PanterA
cory76044's Avatar
Godley Texas
Joined Nov 2008
71 Posts
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confused and drained!!!

Im having a tough time understanding how lipos work and figure what battery you need and how many to piggyback at one time. Most of the time I "get" new stuff very quick but I just cant seem to wrap my head around this. In simple terms how would you explian the subject or recommend a good site. I always try to think about water when dealing with anything electric and that always seems to open the door for me but not this time. Anyhelp would be greatly appreciated.... = Cory Cory=
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Old Mar 14, 2009, 04:50 PM
Lost in space
Jupiter FL.
Joined Sep 2006
374 Posts
Try this for starters,

Beginner's Guide to the Care and Feeding of Lipo Batteries

http://www.ampaviators.com/index.php...d=48&Itemid=27
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Old Mar 14, 2009, 05:25 PM
Wind blows
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Minneapolis
Joined Jan 2007
2,896 Posts
http://www.wattflyer.com/forums/showthread.php?t=31368
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Old Mar 14, 2009, 05:39 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,699 Posts
Quote:
Originally Posted by Laggard
This is an excellent article on electric powered flight how to's and why's.

I however feel his recommendation of a LVC setting of 2.75V+ is a little behind the current thinking based on the newer low IR cells. A LVC setting of 3.2V+ would be more applicable with the newer lipo technology. As you can see from this graph, the pack is completely drained at 2.75V. The plane would fall out of the sky before the LVC triggered. Even 3.3V is too low at low C-rate discharges.
http://enerland.com/upload/product/PQ-1800XP.pdf
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Old Mar 14, 2009, 08:32 PM
PanterA
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Godley Texas
Joined Nov 2008
71 Posts
Thanks for the help...I knew I would get turned on to some great info sites!!!! Much better!!!
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Old Mar 14, 2009, 09:00 PM
Elfi Flyer
Doug Sipprell's Avatar
Rock Hill, SC
Joined Oct 2002
5,545 Posts
I personally follow a rather simplistic approach to the care and feeding of my Lipo's. I presently am using Thunder Power almost exclusively, but that is by personal choice, there are other good brands available.

With respect to charging:

Charge at 1C or less. 1C = one times the capacity of the battery pack, expressed in AMPs. Example: 1320 mAh pack = 1.32 Amps. So, regardless of the number of cells, I charge at 1.0 - 1.10 amps which = 1000 - 1100 milliamps.

With respect to discharging rate WHILE IN THE PLANE, under max power, I follow the "C" rating shown on the label of the pack, usually 12C - 18C, which means (in this 1320 mAh example), 12 x 1.32 amps = 15.8 amps for a 12C rating, or 23.8 amps (18 x 1.32 amps) for an 18C rating. Use a power meter, such as the Astro Wattmeter, for measuring amps at wide open throttle while you are holding the plane (static load).

Another good rule of thumb: Believe only about 85% of the ratings supplied by the manufacturer/supplier, when it comes to the discharge rate.

Lastly, and sorry for the unsolicited lecture, don't recharge a battery when it is hot, use a balancer (if balancing is not already provided by the charger itself), and keep batteries up to room temperature when you put them into use. Cold Lipo's = lower voltage. Set the low voltage cutoff of the electronic speed control (ESC) to 3 volts per cell. Example: 6 volts for a 2 cell Lipo, 9 volts for a 3 cell Lipo, etc.

Oh yes, don't try to recharge a Lipo with a non-lipo type charger.

If you stay within these limitations, you should have no problems with Lipo's. I am still running packs acquired in 2005!

Good Luck

RD
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Old Mar 15, 2009, 09:48 AM
PanterA
cory76044's Avatar
Godley Texas
Joined Nov 2008
71 Posts
Thaks for the help. With a saturday night crash coarse its starting to come together. I am making this harder than what it is, there are so many warnings , I just dont want to burn the house down!!!
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Old Mar 15, 2009, 10:05 PM
Elfi Flyer
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Rock Hill, SC
Joined Oct 2002
5,545 Posts
Quote:
Originally Posted by cory76044
I just dont want to burn the house down!!!
Get a security letter box at Wal-Mart for $10. Great container for charging, carrying Lipos. I have two the them. Also, you can get a Lipo Sack, even easier to use.

RD
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Old Mar 16, 2009, 08:25 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,699 Posts
Quote:
Originally Posted by cory76044
Thaks for the help. With a saturday night crash coarse its starting to come together. I am making this harder than what it is, there are so many warnings , I just dont want to burn the house down!!!
Smart thinking cory. Better to ask before than after. Much cheaper too.

My batteries are always in a fire safe box except when in the plane. Cheap insurance, just in case. 5+ years now without an incident, but they do happen, even to the most experienced, so I keep them on a leash.
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