[NSRCA-discussion] Lithium Ion batteries

Thu Nov 30 12:51:30 AKST 2006

Stuart presented some great reasons for selecting Lithiums.  I also believe they are safer if you have the right charging equipment as you never go into overcharge and never build up heat.  Peak detecting chargers are known to miss the peaks (that occur as a result of heat) now and then and go into thermal runaway.  
I've been using Li-Ion and Li-Poly on my RC systems for many years and never remove them from the aircraft to charge them.  I do use a charger that tells me that they are charging properly.  It reads out number of cells, charge current, voltage, mAh and time charging.  If there were a problem I'd spot it and turn off the charger.
A word on regulators.  Make sure your system will work if one of your two cells goes to zero volts.  That means you want a low voltage drop across the regulator.
You guys obsessed with low weight, are probably already thinking about going with a single cell pack and no regulator.  I don't recommend it.

Jim O
  ----- Original Message ----- 
  From: Stuart Chale 
  To: 'NSRCA Mailing List' 
  Sent: Thursday, November 30, 2006 8:48 AM
  Subject: Re: [NSRCA-discussion] Lithium Ion batteries

  I am using the TP 900 mah batteries with a 6 volt regulator.  I doubt I will go back to Nicd or NiMH in a new plane.  Besides the weight savings they do not auto discharge as the others do so no need to quick charge after a couple week layoff.  A quick check of the voltage can tell you that they are charged if you want to check.  In my plane (electric) I am also seeing 50 to 60 mah used per 8-9 min flight.

  If you are really weight conscious as I was with the Pinnacle using heavier motor batteries you can clip off the charging lead from your on off switch as you shouldn't charge the Lipos in the plane. Saves another 5 grams or so J

  Stuart

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  From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Jay Marshall
  Sent: Thursday, November 30, 2006 10:21 AM
  To: 'NSRCA Mailing List'
  Subject: Re: [NSRCA-discussion] Lithium Ion batteries

  Ed's right. The disadvantage of LiPo's is that you have to remove them from the plane for charging - if you have any sense.

  -----Original Message-----
  From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Ed Alt
  Sent: Thursday, November 30, 2006 10:02 AM
  To: vicenterc at comcast.net; NSRCA Mailing List
  Subject: Re: [NSRCA-discussion] Lithium Ion batteries

  Vince:

  There's a charge jack for each battery.  One is via the switch and the other is a separate lead just for that purpose.  The only thing to watch for is that some chargers will not work properly if you charge both at the same time.  Some work fine.  The Hobbico Accu-Cycle Elite has definite issues and should only be used one battery at a time.  The problems with some chargers arise solely because of the common ground when two battery / switch harnesses are connected together.  The common ground can occur through the receiver power bus whenever two batteries are used and is the only drawback to a dual battery setup.  No matter how you do it, you have to watch for this condition.  

  I did some testing that was completely separate from the use of any regulator or switch harness.  On the bench, if you just have a battery on each port of the Accu-cycle Elite, if you just add a jumper wire between what they label as the negative battery leads, it has issues as soon as you try to start the charging of the 2nd battery.  If you measure the voltage between the two while they are charging normally, it typically shows about a 0.4 to 0.5V delta.  This would almost certainly cause either an early or late cutoff of the charging cycle if they were connected together - IF you could ever get the 2nd battery to start charging.  However, during it's battery detection phase, the charger puts out a large voltage difference between the two negative battery connections (ordinarily thought of as ground when installed in the airplane) and it goes into an alarm state.  I have heard that other charger chargers show early cutoffs when tried with dual batteries simultaneously charging, so the best advice is go one at a time or else unplug to charge.  With LiPo's, we should be unplugging and removing anyway.

  Ed

    ----- Original Message ----- 

    From: vicenterc at comcast.net 

    To: NSRCA Mailing List ; NSRCA Mailing List 

    Cc: Ed Alt 

    Sent: Thursday, November 30, 2006 6:24 AM

    Subject: Re: [NSRCA-discussion] Lithium Ion batteries

    Ed,

    How you charge when you use the two batteries with one or two switches configurations?

    Vicente "Vince" Bortone

      -------------- Original message -------------- 
      From: "Ed Alt" <ed_alt at hotmail.com> 

      Robert:

      You will get a lighter installation from LiPo's vs LiIon's.  I've heard that the LiIons stand up better to abuse if problems develop made during charging, but I believe that you are still supposed to observe the same precautions with either one.  Given that, I did switch to TP LiPo's when I built my Prestige's and they have worked out extremely well.  If you go with LiPo's, you can then afford (weight-wise) to do a simple, but very effective dual redundant battery setup.  I use a pair od 730 mAh packs and can go all day on that.  Check out the Tech-Tip at http://www.tech-aero.net to see how it's done.  It's even easier than pictured in those diagrams now that there is a dual failsafe switch and regulatior available in one package that operates off of just one switch.

      Let me know if you have any questions, but a pair of LiPo's and a PLR5-DR is the lightest and most reliable way possible to use LiPo's.

      Ed

        ----- Original Message ----- 

        From: Robert & Casey Green 

        To: NSRCA Mailing List 

        Sent: Wednesday, November 29, 2006 10:21 PM

        Subject: Re: [NSRCA-discussion] Lithium Ion batteries

        Dan, I am not planning on running electric, so I would like to know, do I go Litihium Ion, or Li-Poly.  My guess is Li-Ion because of the make up of the cell.  Not a big fan of Dura-flames, So I am intrerested in something different.   I have heard some good things about your batteries, and I would like to hear more.

        Thanks,

        Robert

          ----- Original Message ----- 

          From: Daniel J. Hamlett 

          To: NSRCA Mailing List 

          Sent: Wednesday, November 29, 2006 9:12 PM

          Subject: Re: [NSRCA-discussion] Lithium Ion batteries

          If you want more info about the fromeco battery and regulator, drop me a line.  I am a rep for them and will answer any questions that you may have.  I can also get you a great price on a set up.

          Dan

          mike mueller wrote: 

           Hey Robert I like these:

          http://www.aerographix.biz/fromeco_batteries.htm

           Run them with a 6v regulator. They will let you fly all day on 1 charge. Mike

          Robert & Casey Green <robcase1 at cox.net> wrote:

            Hey Guys, I am thiking about running lithium-ions batteries this year.  Besides duralite, is there anything else worth using.

            Thanks in advance.

            Robert

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