Charging and using my lipo  
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Charging and using my lipo - 6/11/2008 8:31:21 PM   
fosterp51


 

Posts: 8
Joined: 12/2/2007
From: Poterville, CA, USA
Status: offline 		Hello all, I'm new to electric flight. I'm flying a het f-18 with a 4s 3700mah 22c pack. I purchased a balance charger from ejf. My charger just shows me the voltage of the battery and how many mah's the charger has put in. I flew my plane for about 5 mins and my voltage went from 16.7v to 14.8v. The battery seemed to be about 120f when I was done flying. I'm just not sure on my charging rates or how far I can drain my battery too. I would appreciate your advice. Thanks Tim
       Post #: 1

RE: Charging and using my lipo - 6/12/2008 1:30:24 PM   
dignlivn


 

Posts: 554
Joined: 10/26/2005
From: Cullowhee, NC, USA
Status: offline


foster



How many mAh's did you put back when charging ?

Did you throttle back at all during the flight ( 5 min) ?

What brand lipo ?

Five minutes sounds about right, with no throttle management.

120 degrees is hot. more info on the lipo would help. Max. burst
rate etc. Pictures of plane etc. would help too. Cooling vents on
plane ?


Bob




(in reply to fosterp51)
       Post #: 2

RE: Charging and using my lipo - 6/12/2008 2:14:12 PM   
ADChobbystore



Posts: 1527
Joined: 5/16/2006
From: Rancho Santa Margarita, CA, USA
Status: offline 		A good practice is to try and stay above the manuf. rating on the pack, in terms of how low to drain it. If it is a 4s 14.8volt pack, try and always keep it around 14.8volts. This will help extend the life of the pack, and keep the performance level.

The absolute bare minimum recommended level varies from 3.0-3.3 volts per cell, depending on who you talk to. But if you constantly drain down to that level, your packs won't last as long, and the performance will suffer over time.

Your charger must have some sort of default charge rate if you don't see anything where you can adjust it? A little more info. on the charger would help. Standard practice is 1C for a charge rate, which is determined by taking the mah of the pack, and dividing by 1000 to get the charge rate in amps.

3700 / 1000 = 3.7amps - a good practice I like to follow is to charge at about 85% of the 1C rate, helps extend the life of the pack - 3.7amps x 0.85 = 3.1amps

As for your flight time and battery temp, it sounds like you are pulling too many amps from the pack, but too many variables could be in play, so a little more info. and pics would help.

_____________________________

"All About The WATTS!!!"
adchobbystore.com

(in reply to fosterp51)
       Post #: 3

RE: Charging and using my lipo - 6/12/2008 8:22:55 PM   
fosterp51


 

Posts: 8
Joined: 12/2/2007
From: Poterville, CA, USA
Status: offline 		My lipo is a fullymax 22c 3700 mAh 14.8 V 4S1P. Max 22C Cont./ 40C burst (max 81.4A Cont./148.0A burst). My charger is a Yuntong model # YT-0004s. It a balance charger for 1s to 5s 0.1A to 5.0A charge curent. I just charged my battery again after a 5 min flight. The starting voltage was 15.28v and I charged it for 55 minutes at 2.1A and it showed that it put in 1800 mAh, ending volts were 16.8v. I'm sorry but I currently don't have any pics. I'll try to get some. I have drilled three 1/8th inch cooling holes in the front of it. I drilled some holes in the back of it around the thrust tube for the exit. I have added about 18 " of wire to go from my esc to the battery compartment. I used 12 ga wire and dean connectors at the battery with bullet at the esc. Thank you for your help Tim.

(in reply to ADChobbystore)
       Post #: 4

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