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Battery life?

Discussion in 'Phantom 1 Discussion' started by Joesrevolution, Apr 14, 2015.

  1. Joesrevolution

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    Hi guys,

    Been flying for a fairly long time now. Still at a bit of a loss when it comes to batteries though.
    I have not been taking as much care with them as I should have been (leaving them with charge in etc)
    I have a cpu balance charger now so can now put them into storage mode. However a few of my old batteries must be starting to die because of this now...

    http://www.flytrex.com/mission/quadcopter-joes-fc40-joseph-somerwill-gkr2EJFV/

    See the voltage on this flytrex. It dropped very fast straight away so I guess that means that the battery is on its way out?

    I guess what I'm asking is, is there a way to determine how much life the battery has left in it other than estimating based on flight times and flight voltages? I have a battery checker which can see individual cell voltages. Will this tell me anything?

    Thanks in advance!
     
  2. Pilot_FML

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    Even if your batteries show the correct cell voltages after a full balanced charge, they may not be flight worthy. The true test is whether they can hold their voltage while under load (i,e. flying).
    If even one of the three cell voltages drops quickly after you start flying your battery isn't repairable and probably should not be used any more.

    Keep your batteries healthy by slowly charging, only storing at recommended voltage levels and by continually monitoring individual cell voltages. If just one cell begins not to charge to its correct voltage the battery is beginning to age and you should be cautious flying with it and even consider replacing it.
     
  3. Joesrevolution

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    Thanks!

    That said the longest I have ever left a battery fully charged is about 3 weeks. How much damage am I likely to have done? Is it dead or Will it just not last as long?

    Regarding the Flytrex report, looking at the voltage would you say its dead? It was at 87% having been left at full for a long while before I partially discharged for storage but cancelled it based on the time it seemed to be taking...
     
  4. Pilot_FML

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    3 weeks is a bit long but not necessarily very bad for your battery. Gauging what damage (if any) has been done while fully charged for that length of time is difficult to assess. Every battery is different so hard and fast rules can't be applied. The only way to really tell how healthy a LiPo is, is to put it under load and monitor how evenly and fast the voltage drops. Without knowing this particular battery's voltage under load history, I couldn't comment how bad its health is!

    I personally wouldn't rely on Flytrex alone to determine battery health. The flight I see here had a sizable voltage drop right after takeoff but the drop corresponded to a climb in altitude which puts a lot of stress on a battery. Typically, LiPo's suffer damage if you also discharge them too low. Look at the attached link to get a better idea of the 80% rule.

    https://sites.google.com/site/tjinguytech/charging-how-tos/80-rule

    Bottomline: I wouldn't necessarily dispose of this battery but only use it with caution. Measuring after flight voltages (read up on resting voltages) is something you might also consider doing.... there's no other way to see if your LiPo is gradually or quickly dying.
     
    #4 Pilot_FML, Apr 14, 2015
    Last edited: Apr 14, 2015
  5. IflyinWY

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    Which battery are you using?

    The MultiStar 4000 was less than $30 last I looked.
     
  6. Joesrevolution

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    Cool, thanks for the response.

    I do usually adhere to the 80% rule and have never gone below 3v per cell.

    I use 2200 Overlander batteries mostly.

    Have a couple of 2900 ones now which give me 8 mins with my fat pig set up.

    Will my un modded bay take a MultiStar 4000 do you reckon?
     
  7. Pilot_FML

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    Once you go below "3.7v" (80% rule) per cell you are beginning to permanently damage the LiPo.

    The damage gets worse even more quickly (i.e. not a linear change) as you continue dropping further below 3.7v.
     
  8. IflyinWY

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    Nope, won't fit as far as I know.
    I took a Dremel and removed a bit of the opening in the body. Piece of cake.
    You're calling the bird a "Pig" makes me think you should strongly consider the additional weight before going to a heavier battery.
    Whenever I place the 10C 4000 battery under a heavy load, at my altitude of 5 to 8,000 feet, it can't keep up. The bird still flies, but I get flashing red lights which indicate low battery. I can fly nice and easy for a few seconds, and it recovers to flashing green... :)
    I have yet to hear of anyone having issues with this problem, at or near sea level.