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  1. #1

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    Li-PO or NiCd Pros and Cons

    I am new into electric flight and need some advice. From what I read Li-Pos are lighter but more expensive than NiCds and require a specially designed charger. If I read the specifications correct a 2Ah Li-Po is about 10-15 oz lighter than a comparable NiCd. If the weight saving is that large I assume the power requirements for take-off and climp would also translate into lower currents and longered flight endurance.

    I s this reasoning correct? What are the cons with Li-Pos contra NiCd?

    Joje

  2. #2
    Foamaholic's Avatar
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    RE: Li-PO or NiCd Pros and Cons

    Reasoning is correct. That's why lipos are so great.
    Less weight = more power or longer flights.
    A good nicad charger will usually also charge lipos.
    The Triton charger is hard to beat for nicads, nimhs, and small lipos.
    Lipos also don't need cycling or topping off.
    http://electricnut.blogspot.com/

  3. #3

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: Foamaholic

    .......The Triton charger is hard to beat for nicads, nimhs, and small lipos.........
    What would be your choice of charger for numerous large Lipos?

    I am trying to educate myself about batteries. I come across the C-factor but have not been able to figure out what it refers to. If a Lipo can discharge at a 15C-rate how does that translate into Amp.? Do you know of a good site where one can learn more about the Lipo technology?

    Regards,
    Joje

  4. #4
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    RE: Li-PO or NiCd Pros and Cons

    AstroFlight 109 for large lipos. There are more expensive chargers out there but the 109 does most everything.
    Charges 1 to 9 cells at up to 8 amps. Been using one all summer and it's perfect.
    A battery rated at 15C means it can safely discharge at up to 15 times the battery's capacity in amphours.
    For example a 1500 3s1p rated for 10C can discharge at up to 15 amps (1.5 times 10), and can be charged up to the maximum rate of 1C, or 1.5 amps.
    A 3s2p can discharge at up to 30 amps, and can be charged at 3 amps.

    I found this handy chart at FMA
    https://www.fmadirect.com/site/fma.htm?body=Store
    http://electricnut.blogspot.com/

  5. #5

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: Foamaholic

    AstroFlight 109 for large lipos. There are more expensive chargers out there but the 109 does most everything.
    Charges 1 to 9 cells at up to 8 amps. .........
    Thanks, very helpful info. I believe I will be using two 1500mAh 3Cell packages in parallel for better endurance. If I am figuring right each package will carry half the load. If each package is rated for 8C discharge, that will transfer to 12A and I could draw 24A continuously, which would be 6A more than I need. Hence there is a margin.

    Can I charge the two packages simultaneously in parallel with 3A (2 x 1.5A) or do I need to charge each package separately or can I charge both packages in series with 1.5A?

    Joje

  6. #6
    Foamaholic's Avatar
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    RE: Li-PO or NiCd Pros and Cons

    Yes you can charge packs in parallel, two 10C 1500 packs at up to 3 amps. I do it all the time, but I make sure the packs measure very close to the same voltage first. Somewhere I read that doesn't matter because they equalize themselves but I don't take any chances with lipos. I am always neaby when they are charging.
    This is taken from the FMA site when you click on lithium batteries.

    WARNING
    Safety precautions
    for Lithium Polymer and NiCd cells/packs stocked by FMA Direct

    1. Never fast-charge any battery type unattended.
    2. Never charge LiPo cells/packs at any rate unattended.
    3. Only charge LiPo cells/packs with a charger designed specifically for lithium polymer chemistry. Example chargers include the Kokam USA, LIPO 402, LIPO 102 and LIPO 202; Bishop Power Products Apache S1215 and S1500; Great Planes Triton; and Schulze chargers with lithium charging capability.
    4. LiPo cells can ignite because of unmatched cell capacity or voltage, cell damage, charger failure, incorrect charger settings and other factors.
    5. Always use the correct charging voltage. LiPo cells/packs may ignite if connected to a charger supplying more than 6 volts per cell.
    6. Always assure the charger is working properly.
    7. Always charge LiPo cells/packs where no harm can result, no matter what happens.
    8. Never charge a cell/pack in a model. A hot pack may ignite wood, foam or plastic.
    9. Never charge a cell/pack inside a motor vehicle, or in a vehicle’s engine compartment.
    10. Never charge a cell/pack on a wooden workbench, or on any flammable material.
    11. If a cell/pack is involved in a crash:

    a. Remove the cell/pack from the model.
    b. Carefully inspect the cell/pack for shorts in the wiring or connections. If in doubt, cut all wires from the cell/pack.
    c. Disassemble the pack.
    d. Inspect cells for dents, cracks and splits. Dispose of damaged cells (see below).

    12. Dispose of cells/packs as follows:

    a. Discharge: with the cell/pack in a safe area, connect a moderate resistance across the terminals until the cell/pack is discharged. CAUTION: cell/pack may be hot!
    b. Discard:

    - NiMH: place in regular trash.
    - NiCd: recycle (cadmium is toxic).
    - LiPo: puncture plastic envelope, immerse in salt water for several hours, place in regular trash.

    13. Handle all cells/packs with care, as they can deliver high currents if shorted. Shorting by a ring, for example, will remove a finger.

    14. Always store cells/packs in a secure location where they cannot be shorted or handled by children.

    15. When constructing a pack, use only cells of the same capacity (mAh). During continued use of a pack, periodically check individual cells after discharge and before charging to verify cell voltages are within 0.1V of each other. If a pack has become unbalanced (i.e., cell voltages are more than 0.1V apart), restore balance by charging the cells individually to 4.2V before reconnecting as a pack.

    16. Using FMA's Safety Guard voltage limiter while charging series-connected packs is strongly recommended. Note that cells in a pack should still be periodically checked for proper balance.

    FMA, Inc. and KOKAM USA, its successors, heirs and assigns are not responsible in any way for any and all bodily injurie(s) and/or property damage that may occur from the use of or caused by in any way the lithium Polymer and NiCd cells/packs stocked and or distributed by FMA, Inc. and KOKAM USA.
    http://electricnut.blogspot.com/

  7. #7

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: Foamaholic

    Yes you can charge packs in parallel, two 10C 1500 packs at up to 3 amps. I do it all the time, but I make sure the packs measure very close to the same voltage first. Somewhere I read that doesn't matter because they equalize themselves but I don't take any chances with lipos. I am always neaby when they are charging.
    This is taken from the FMA site when you click on lithium batteries.........

    How does the real world match the theory interms of charging time? Does a 1C charge current in reallity also translate into one hour actual time?

    Joje

  8. #8
    Foamaholic's Avatar
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    RE: Li-PO or NiCd Pros and Cons

    No because there is some loss in the wires and to heat, so a completely discharged (3 volt per cell) pack takes longer, roughly 1 hr. 20 min. to completely charge.
    http://electricnut.blogspot.com/

  9. #9

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: Foamaholic

    No because there is some loss in the wires and to heat, so a completely discharged (3 volt per cell) pack takes longer, roughly 1 hr. 20 min. to completely charge.
    Again, very helpful!
    Thanks,
    Joje

  10. #10

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    RE: Li-PO or NiCd Pros and Cons

    You could take them off after an hrs. charge as they are about 95% charged. Charger shuts off every once in a while to read batt voltage.
    Gord
    Dreamed I was a muffler. Woke up exhausted.

  11. #11

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: Flypaper 2

    You could take them off after an hrs. charge as they are about 95% charged. Charger shuts off every once in a while to read batt voltage.
    Since charging batteries takes it's time I suppose it makes little sense to base a day of flying at the field on having the Lipos (or any batteries) charged as they are depleted. Maybe it makes more sense to invest in more battery packs and arrive at the field with a stack of 5-6 and call it the day then these are depleted. A solid Robbe Pro Home wall charger (about $200) has 4 separate charge outlets that EACH manage 9 Lipo cells.

    The main benefit with electro flight to ME is to b able to find a reasonable flying site near home. In that picture one could have a session in the morning and a second in the afternoon and charge batteries at home in between. One doesn't need so much gear to carry beyond the plane and the stack of batteries. Very little hassle to get some flying done.

    How do you experienced guys operate?

    Joje

  12. #12
    Foamaholic's Avatar
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    RE: Li-PO or NiCd Pros and Cons

    Now that I've gone all lipo I bought enough batteries to go fly until I'm worn out. Then I come home and charge them. With lipos I can let them sit charged until I want to fly again and go fly without having to top them up or cycle them. Makes it so easy, except for the time it takes to charge them. Sometimes I'll take my charger to the field and fly one then put it on the charger. Makes for fewer to charge when I get home. The great thing about lipos is you don't need so many because the flight times are so long. I often fly a while, land, take a break and fly some more, all on the same pack.
    http://electricnut.blogspot.com/

  13. #13

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    RE: Li-PO or NiCd Pros and Cons

    I take four 2100 ma packs for a GWS TM 400 and a Zero. Gives me almost two hrs flight time. plus three 730 packs for the Shock flier. Usually don't run them all out.
    Gord
    Dreamed I was a muffler. Woke up exhausted.

  14. #14

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    RE: Li-PO or NiCd Pros and Cons

    Your feedback is very encouraging

    It feels like a new dimension to model flight!!!
    Have you guys figured out how long a Lipo lasts in the real world.
    Again I ead something like 400-500 cycles or 3-5 years.
    Hand on experience is always a good supplement to the specs.

    No more messing with fuel, faulting glow plugs and neighbors complaining about noise.

    Joje

  15. #15
    Foamaholic's Avatar
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    RE: Li-PO or NiCd Pros and Cons

    I've read that about lipo lifespan too. I've used them all last summer and this summer without any going bad or anything, and I fly a lot, usually every day. Of course other's results could vary.
    http://electricnut.blogspot.com/

  16. #16

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    RE: Li-PO or NiCd Pros and Cons

    I bought mine last year too. Flew all winter when the weather was good except for our winter funfly when it was 0 F . Batts. would run for five mins, didn't matter what capacity they were. Fingers only lasted that long before they went numb anyway Most of the guys with the alky burners never got them started. I remember those days. Good thing our clubhouse has a woodstove. I think about 25 members showed up.
    Gord
    Dreamed I was a muffler. Woke up exhausted.

  17. #17

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    RE: Li-PO or NiCd Pros and Cons

    Your original questions was lipo vs nicad, how about nickel metal hydride? They costs about same, usually less than nicads, are lighter and have very high discharge rates. The lipos are still better but the nimh might be a good alternate if price is and issue.

    Try the guys at http://www.unipros.com/cbpsite/loosecells.asp?session_id=188183 and compare the 1400, 1800 and 2100 red CBP to Sanyo nimh. A good example is the 1800 mah CBP 25 amp dishcarge at a cost of $2.50 per cell vs the Sanyo 1950 at the sames amps but a cost of $4.55

    One other comment about lipos, they usually wont' survive a serious crash and if the voltage drops below about 2.8 per cell they most likely can't be recharged again.

    Just my 2 cents worth!!

    Good luck

  18. #18

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: woodduck-RCU

    Your original questions was lipo vs nicad, how about nickel metal hydride? They costs about same, usually less than nicads, are lighter and have very high discharge rates. The lipos are still better but the nimh might be a good alternate if price is and issue.
    .......Good luck

    Thanks, I'll consider that.
    Joje

  19. #19

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: Foamaholic

    AstroFlight 109 for large lipos. There are more expensive chargers out there but the 109 does most everything.......................
    I was going to order an Astroflight 109, but read that you cannot feed it from an automotive battery. A special wall power unit is supposed to be needed. Is that right?

    If so, the Astro 109 appears pretty useless at the field if no AC main power is available.
    Is the info about the necessity of a special power unit correct?

    Joje

  20. #20

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    RE: Li-PO or NiCd Pros and Cons

    whilerunning a motorcalculator I noticed a significant impact on overall performance caused by choicing different brands of Lipos. Which brand of Lipos is considered to provide most bang for the buck?

    Joje

  21. #21

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    RE: Li-PO or NiCd Pros and Cons

    The Kokam have the highest discharge rate but are also the most expensive and heaviest. For my money I like the Thunder Power they have a great selection are reasonably priced and have good discharge rates.
    Also look at Poly Quest lipos from allerc.com

  22. #22

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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: woodduck-RCU

    The Kokam have the highest discharge rate but are also the most expensive and heaviest. For my money I like the Thunder Power they have a great selection are reasonably priced and have good discharge rates.
    Also look at Poly Quest lipos from allerc.com
    Where can one cut the best deals on Lipos?

    Joje

  23. #23
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    RE: Li-PO or NiCd Pros and Cons

    Hi Guys
    In this thread I notice some of U are having much longer life out of your lipo's than I am. About 150 to 200 cycles is all I get
    and there internal resistance go up. So they just won't put out the kind power I need for decent vert. or long term hovering.
    They Never really get warm, but I do run them down in about 14min even when they are new.
    conditions are: Tanic 830 ma 2p 10.5c batt, AXI 2208/34 with a 10X4.7apc prop, and an apache lipo charger.
    after 150 cycles they need replacing

    any ideas to extend there life would be appreciated.

    thanks Mike,
    Mike

  24. #24

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    RE: Li-PO or NiCd Pros and Cons

    hi, i love flying lipo too, it has all the benefit, the only concern is its life span, most of these lipos are said to have 500 cycle time, but from my experience, most of them would remain same performance (or discharge rate) in the 60-80 cylces, and from then onward, they start to deplete, those lipos life span could never exceed 100 cycles. does anyone have any good idea in keeping the life / or extending the life span of lipos ?? thsk

  25. #25
    Moderator Matt Kirsch's Avatar
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    RE: Li-PO or NiCd Pros and Cons

    ORIGINAL: Joje

    I was going to order an Astroflight 109, but read that you cannot feed it from an automotive battery. A special wall power unit is supposed to be needed. Is that right?

    If so, the Astro 109 appears pretty useless at the field if no AC main power is available.
    Is the info about the necessity of a special power unit correct?

    Joje
    Where did you read that? It's BS.

    An automotive battery is the CLEANEST, MOST STABLE source of 12VDC power available. There is absolutely positively no reason why the Astro 109 cannot be powered by an automotive battery.

    There might be an issue in a RUNNING car, due to the extra-high, unstable voltage put out by the alternator, but again, a regular automotive battery is perfectly suitable!


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