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Lipo vs Li-Ion

Discussion in 'Giant / Scale RC General Discussions' started by djmoose, Jan 20, 2014.

   
  1. djmoose

    djmoose 70cc twin V2

    Fromeco Relion 2600 - $38.50 EACH - 3.3 oz (because it's a real bad idea to just use a single JR connector...even with two batteries...)

    Glacier 30C 2200mAh 2S 7.4V LiPo - $15.50 EACH - 4.5 oz

    GForce 25C 2200mAh 2S 7.4V LiPO - $12.50 EACH - 4.2 oz


    I see no reason to use Li-ion packs as receiver power in high performance aerobatic planes.

    To me, the small weight penalty is worth the MUCH higher C rating and the over 50% price savings.

    I also don't believe in wasted C rating...it's always going to help. (read: you won't have to even worry about voltage drop under load as long as you're using good connectors)

    It would be a different conversation if comparable Lipos weighed TWICE as much....or weren't less then half the cost...but they don't and they are.

    THAT BEING SAID...quality Li-Ions in a warbird or scale project....I could see it making sense if you didn't mind spending the extra money for less power. (maybe if you needed to tuck the packs up in a hard to reach part of a scale plane)

    HOWEVER, I would never use Li-ions in a high performing aerobatic airplane with digital servos. (I welcome discussion, though....I could be wrong...)
     
  2. gyro

    gyro GSN Contributor

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    Cool, lets discuss.

    As mentioned previously mentioned, I just finished installation and flight testing on the @Fromeco Re-Lion Batteries in my 92" Edge... and I'm running 5 of the new Hitec HSB-9370TH DIGITAL servos.

    I previously used the two glacier 2s 2200 packs mentioned above, and they worked GREAT! However, I always needed to bring them in from the garage after going to the field, and they needed to be discharged if I didn't fly enough times to get the voltage down to 3.85v. Not a big deal though, and performance was excellent, no blowback, excellent system power, etc. I wouldn't hesitate to use them again in another 50/60cc, and I used them currently for power on my 30cc birds.

    I recently installed the two Re-Lion packs and a DCUP Cricket into my 92" and flew it this weekend. Everything worked PERFECT... no blowback, excellent performance. And when I was done, I put the plane away, and don't need to mess with the batteries, as they can stay in the plane, and connected with no problem. Yes, they cost a little more, but you get some convenience for that.

    Oh, and here is the flight performance demonstrated, and while this was a demo of the 24x9 Xion prop, it was on the 92" Edge with the Re-Lions:

    [video=youtube;suqNhbEoDXc]http://www.youtube.com/watch?v=suqNhbEoDXc[/video]

    I know @danielph is sponsored by Fromeco, and has lots of experience. Maybe you can weigh in Daniel?
     
  3. cardenflyer

    cardenflyer 70cc twin V2

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    1. Xion props are awesome.
    2. I have always used li ion batts. Mainly because I like the fact of using my 8ball checker to see the batteries loaded and they are a little safer than Lipo. I have a pair of 5200 in my 40% Carden and 104" EF Extra. Usually can get 8-10 flights pretty safe on both set ups.
     
  4. djmoose

    djmoose 70cc twin V2

    Li-on:
    Not needing to be at a storage charge when not in use. That's a plus.
    Weight = Small advantage here, not huge, but Li-Ion has the small advantage.
    Safety = Another small advantage here. However, Li-Ions CAN explode and vent like Lipos. Not sure what the Li-Ion advantage is...less fire? Will a puncture not necessarily cause flame with a Li-Ion? (honestly asking)
    C Rating = Lipos have the HUGE advantage here.
    Cost = Lipos have the HUGE advantage here.

    I'm not saying Li-Ions won't work in 3D models...I'm saying I can't see an overall advantage to using them all things considered. I'd love to hear more pros for Li-ion in large 3D planes.

    (and I love being proven wrong...because that means I've learned something)

    Some people might say that Li-Ions have enough c rating for 50cc+ models. Arron and Joe have used an eagle tree logger to log current draw and can have spikes up 20-25A on a 50cc plane. Granted, those are probably really small spikes, but voltage drop is voltage drop even for an instant. So....I don't want to HAVE to have a DCUP in my plane to feel good. (another $35, btw...I have several and like them...but they're not needed at all on my setups...they're just another layer of protection)

    To me, it doesn't make sense to pay more and be close with current requirements. I'd rather pay WAY less, and have more power then my electrical system will ever need. (and if you want to talk about getting that power to your servos correctly, I have a lot to say about that which would warrent another thread)

    just my thoughts...I'm not trying to be snobby...just explaining how I think things through and make decisions.
     
  5. cardenflyer

    cardenflyer 70cc twin V2

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    Never had any problem ever. I've had 40% Cardens for 12 years now. Use to run just 6 volt nicads then with not one issue ever. I run High Voltage on my EF with TBM ions and have no problems at all. I'd honestly never run lipos over Li ions, even if they were in a used plane I bought. Just me, there's nothing I can do to make them fail or lag.
     

  6. I've been using Fromeco Li-ion packs in all of my GS airplanes for the past 6 years and have never had a single issue. In fact, I still have the original set of 2,600s that I bought from them and according to Mike at Fromeco, they're still in excellent condition. I have a set of 5,200s in my 104" Extra right now simply because it's handy to be able to fly all morning on a single charge. I have a single DC-Up in that airplane and am very happy with the performance. The DC-Ups weigh almost nothing and very effectively keep the voltage from dropping during high stress maneuvers. Once you've used most of the juice out of a Li-ion, there will be more of a voltage drop than you would see with a Li-po. There's no way around that. When running a pair of 2,600s in the 104, I start to feel a little less power from the servos after about 20-25 minutes of flight time, or half way through the third tank of gas. It's not bad, and most guys would not notice it. It is there however when you're doing snap rolls at 100+mph.
    All that being said, yes the Li-pos have the power advantage, but most guys are way to concerned about that. 3D flight doesn't take a bunch of power from the servos and the higher load spikes are really only seen during high speed aerobatics/XA flying.
    Battery choice is a decision that every pilot has to make, but I honestly believe that Li-ions are the safest way to go. Being able to load check the batteries really shows you where they're at and how much juice is left. It's also very handy as Gyro said to be able to leave the packs in the airplane all the time without worrying about discharging them to storage voltage.
     
  7. gyro

    gyro GSN Contributor

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    Ok, so reading what you've said above, the only advantage you mention other than cost (valid, but for some, cost is not the deciding factor) is the "C" rating, that you identify as a "HUGE" advantage.

    With a Fromeco ReLion, the "C" rating they advertise under their product specs is 11a (http://www.fromeco.org/Products/01FRC2600-100/). Since I run two of them, I think that means I'm able to handle a total load of 22 amps. You said above some pilots have seen spikes up to 25a, so 22a would seem sufficient to me. Add in the DCUP/Cricket capacitor, and those spikes are easily managed by the powerful capacitor bank.

    Based on the last flight with the 92" Edge and HSB-9370TH servos, (Brian flying in that video) the lowest momentary recorded voltage on the system under load was 7.1, which is satisfactory to me, since they're spec'd out at a 7.4 operating voltage. Additionally, since I'm running brushless servos that don't pull as many amps as other servos, I don't NEED a 25c capable battery.

    Now, if you're talking about an airplane in the 100cc class with 7 or 8 control surface servos, most people would opt for dual Relion 5200mah batteries, with each one spec'd at 22a max. Again, pairing them up should yield 44a, so I'm not sure that the LiPo's higher "C" rating comes into play here.

    To me, the huge "C" rating advantage you spoke about LiPos having is negated by using high quality Li-Ion packs, and even more so negated by using a DCUP/Cricket type capacitor bank, and thus leaving cost alone as the ONLY factor, with the Li-Ion packs having clear advantages in safety, storage, and longevity.

    What do you think?
     
  8. I'm using a Li-Ion on my first gasser and I've been putting it back to "storage charge" after I fly based on this reference:
    http://batteryuniversity.com/learn/article/how_to_store_batteries

    I didn't search the forums, but is it generally considered OK to leave a Li-Ion at a higher than "storage charge" for a long period of time?

    Marc
     
  9. gyro

    gyro GSN Contributor

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    Kurt and Mike at Fromeco are some pretty smart guys when it comes to electrons. Here's what they say about their Li-Ion packs:

    "Storage
    For prolonged storage, more than 2 months. Fromeco recommends that packs be discharged to a voltage of 7.4- 7.6VDC. For best results batteries should be stored in a cool dry place preferably 35 to 40deg. F."
     
  10. djmoose

    djmoose 70cc twin V2

    I think I'm going to do some research.

    I want to understand why people think Li-Ions are "safer" then Lipo. I know for a fact that Li-Ions are flamable and can explode when they vent. I'll try to find out more info on that.

    I also want to know about Fromeco's testing and 11A/22A findings. What stopped them at 11A and 22A? Was it voltage drop? Temerature range? How much? I mean we all should know that "C rating" is a rather unregulated term and there isn't a steadfast voltage drop and temperature range. I want to find out the voltage drop of Fromeco's 2600 Li-Ions versus a 25-30C 2S 2200 Lipo at 11A for about 5 seconds.

    I want to know about the Load-check that Fromeco recomends. Is this a Fromeco thing or a general rule for Li-Ion? I also want to know why we wouldn't do it with Lipo. Do we need to? Why or why not?

    These are the questions I have that have not been answered by pilots simply saying they've used them for years with no problems. I'll find out more.
     
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