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Old Nov 16, 2012, 12:57 PM
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Taiwan, 北市
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Yup tks! I actually did the Google search already and it seems the consensus is that you can charge a LiFe with the Lipo setting, but you just need to be very careful about manually ending the charge at 3.3V (rather than the default Lipo setting of 4.2V). I just wanted to confirm that this is true

Also since both HS82MG and HS85MG servos are rated for 6V, I assume they won't burn up with the 6.6V LiFe pack?

Best,
Kevin
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Old Nov 16, 2012, 01:00 PM
Proud RC Addict
United States, UT, American Fork
Joined Nov 2009
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Well, I had a beautiful maiden flight and it flew like a dream.

Until the end...

E-Flite Habu 32 Crash - Maiden Flight Meets Light Pole (0 min 48 sec)
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Old Nov 16, 2012, 02:10 PM
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Joined Sep 2011
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Oh man... It hit that post hard on the wing I guess, sucks! Sorry
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Old Nov 16, 2012, 02:18 PM
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Yeah, frustrating that it was so close to missing all together. Probably only nicked 1cm or so on the tip of the wing. I should have flown higher on the go around I guess. Oh well. I'll rebuild it and try again next week
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Old Nov 16, 2012, 02:29 PM
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United States, MA, Holliston
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Quote:
Originally Posted by kchen95 View Post
Yup tks! I actually did the Google search already and it seems the consensus is that you can charge a LiFe with the Lipo setting, but you just need to be very careful about manually ending the charge at 3.3V (rather than the default Lipo setting of 4.2V). I just wanted to confirm that this is true

Also since both HS82MG and HS85MG servos are rated for 6V, I assume they won't burn up with the 6.6V LiFe pack?

Best,
Kevin
Actually, 3.3V is the nominal voltage and I believe LiFe/A123 packs normally terminate at 3.6V/cell. Almost all chargers have a LiFe setting, do your self a favor and take the time to figure out how to get your charger configured correctly for Life/A123..

As for your servos, look up the ratings, if they say 4.8V - 6.0V (4 or 5 cell) operation they should be fine with an 2S LiFe pack which has the same voltage characteristics as a 5 cell NiMH pack..
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Old Nov 16, 2012, 05:29 PM
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Joined May 2004
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Quote:
Originally Posted by kchen95 View Post
Yup tks! I actually did the Google search already and it seems the consensus is that you can charge a LiFe with the Lipo setting, but you just need to be very careful about manually ending the charge at 3.3V (rather than the default Lipo setting of 4.2V). I just wanted to confirm that this is true

Also since both HS82MG and HS85MG servos are rated for 6V, I assume they won't burn up with the 6.6V LiFe pack?

Best,
Kevin
You can use one of these on your LiPo charger to charge LiFe packs. I had one for awhile before I bought my FMA charger. They basically cutoff at the proper voltage just as you are thinking. Problem is, at $40, it's almost better to get a charger if you are planning on using LiFe cells going forward. Hot off a charger, a LiFe pack is charged to 3.65 volts/cell but they drop fairly quickly to 3.45 volts/cell. Problem is, they stay at that level or very close to it until falling off a table. So your servos see fairly high voltage for the entire discharge cycle. I've used 6V rated servos with LiFe packs but it is a little hard on them.
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Old Nov 16, 2012, 08:47 PM
Mile High EDF
United States, CO, Denver
Joined Jul 2011
918 Posts
I use a life on all my jets, my receiver puts out 6 volts , regardless of weather it's fully charged or not, fully charged is 7.2 volts. I have telemetry Hooked up and you can see volts on receiver . HK has some really nice nanos 20-40c http://www.hobbyking.com/hobbyking/s...dProduct=28656, I've found that almost all chargers will charge life batteries, the cheap one from eBay works great $20.

New Habu up and running with tamjets struts and servo controlled front gear door
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Old Nov 16, 2012, 09:07 PM
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Taiwan, 北市
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Originally Posted by Sit-N-Fly View Post
You can use one of these on your LiPo charger to charge LiFe packs. I had one for awhile before I bought my FMA charger. They basically cutoff at the proper voltage just as you are thinking. Problem is, at $40, it's almost better to get a charger if you are planning on using LiFe cells going forward. Hot off a charger, a LiFe pack is charged to 3.65 volts/cell but they drop fairly quickly to 3.45 volts/cell. Problem is, they stay at that level or very close to it until falling off a table. So your servos see fairly high voltage for the entire discharge cycle. I've used 6V rated servos with LiFe packs but it is a little hard on them.
OK looks like I figured it out - my charger does have a specific LiFe setting I feel like I've read this somewhere before, but to make it perfectly safe on the servos that are rated for 6V, can I just not charge the LiFe fully to 3.6/3.65 and instead stop it at 3.0-3.3V? Or does this not make any difference?

Kevin
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Old Nov 16, 2012, 09:09 PM
Mile High EDF
United States, CO, Denver
Joined Jul 2011
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No difference , I've been flying Habu 32 for a year and F4 for 6 months on life and stock servos , not one problem.
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Old Nov 16, 2012, 09:17 PM
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United States, MO, Warrensburg
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Originally Posted by mulicheng View Post
Well, I had a beautiful maiden flight and it flew like a dream
Until the end...
Ouch! Sorry to hear about your Habu. I agree, they fly like a dream! Your next one will be even better.
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Old Nov 16, 2012, 10:54 PM
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Quote:
Originally Posted by kchen95 View Post
OK looks like I figured it out - my charger does have a specific LiFe setting I feel like I've read this somewhere before, but to make it perfectly safe on the servos that are rated for 6V, can I just not charge the LiFe fully to 3.6/3.65 and instead stop it at 3.0-3.3V? Or does this not make any difference?

Kevin
LiFe's are tricky to charge. I think you will find you only have 20-30% of the full capacity if you only charge to 3.0 v. Most of the capacity of the pack will be delivered on discharge before you notice much drop in voltage at all. My LiFe's charge to 3.6 V. As soon as you take them off the charger they drop to 3.3V. I haven't had any equipment fail on 6.6v. (Doesn't mean you couldn't, but I haven't seen it) If you are afraid to deliver 6.6v to your stuff I would find some other solution.
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Old Nov 17, 2012, 01:06 AM
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Originally Posted by jwjohnson View Post
LiFe's are tricky to charge. I think you will find you only have 20-30% of the full capacity if you only charge to 3.0 v. Most of the capacity of the pack will be delivered on discharge before you notice much drop in voltage at all. My LiFe's charge to 3.6 V. As soon as you take them off the charger they drop to 3.3V. I haven't had any equipment fail on 6.6v. (Doesn't mean you couldn't, but I haven't seen it) If you are afraid to deliver 6.6v to your stuff I would find some other solution.
Tks again for all the valuable advice from everyone! When storing a LiFe, should I maintain a particular voltage level? I know Lipo's should be stored around 3.8V; is there an equivalent for LiFe?

Kevin
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Old Nov 17, 2012, 05:23 PM
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United States, OR, Portland
Joined Aug 2011
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I know this is product specific but go here (http://www.lifesourcebatteries.com/receiver-packs.html) and pull up one of the manuals. It should help you with the care and use of LiFe batteries. I have used a LiFeSource battery to power a 50 size heli for a couple of years now. Only problem I had is it fried a Futaba servo that was rated at 4.8v. All my other servos that are rated at 6.0v are not having any problems. Just food for thought. Todd
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Old Nov 17, 2012, 06:38 PM
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It's worth checking your voltage out of your Rx. I put 6.6 nominal in and the RX steps it down by about 1to 1.2 volts. That puts most servos in the range.
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Old Nov 17, 2012, 10:33 PM
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Originally Posted by Tealc View Post
I know this is product specific but go here (http://www.lifesourcebatteries.com/receiver-packs.html) and pull up one of the manuals. It should help you with the care and use of LiFe batteries. I have used a LiFeSource battery to power a 50 size heli for a couple of years now. Only problem I had is it fried a Futaba servo that was rated at 4.8v. All my other servos that are rated at 6.0v are not having any problems. Just food for thought. Todd
Tks so much; this was exactly what I needed!

Kevin
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