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  1. #1
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    Definitive Word on Lipo Storage Mode vs. Full Charge?

    I'm hearing two different "facts" on the proper care and feeding of our beloved Lipo batteries:

    1) You can "store" your Lipo battery for a long time at a full charge without damaging the battery. The ONLY voltage level that can hurt your Lipo is if it gets too low.

    Or,

    2) You should NEVER "store" your Lipo battery for more than a day or two at full charge, as this will damage your battery and shorten its life. ALWAYS store your battery at around 3.8v/cell if not using it within 24hrs or so.

    Now, I've heard both of the above stated "facts" from various people in the know, who swear by it. People who've been in the RC field for many many years.... So is there a definitive, 100% fact, not just opinion, available on this whole "storage mode" versus "full charge is fine" debate?

    And if #2 is true, exactly why and how would having a fully-charged Lipo battery sitting for a few days damage it in any way? Everyone agrees that going too low on voltage is death on a stick for a Lipo, but I'm still confused by the full-charge vs storage mode issue.

  2. #2
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    Never heard of the storing it full.. Everything i have read always recommends against it. Of course my local hobby shop sells them and tells people you just charge them and go. After i seen a friend of mine being told that i told them to go online and research them a bit. Shot me a email saying they were going to stick with nimh for now and read more on lipo until they were comfortable. So that may be were the full charge idea is coming from hobby shops not giving people all the info they need to make a informed desision

  3. #3
    Marshal ksb51rl's Avatar
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    This is what Traxxas has to say on the matter, and since this subforum is only for Traxxas-branded batteries...
    Traxxas-Battery-Basics
    Quote Originally Posted by Traxxas Battery Basics
    NiMH, NiCd, LiIon, LiFe, and LiPo
    These terms refer to the materials and chemistry within the battery. Nickel batteries (NiMH, NiCd) have cells with the familiar “cylinder with a button on top” construction and a metallic case. Lithium batteries (LiPo, LiIon, LiFe) are usually constructed of flat cells stacked together. The cells may be encased in heat-shrink to form the final pack, or enclosed in a “hard case.” Traxxas Power Cell LiPos use a “semi-rigid” design that is durable and allows greater battery capacity in a pack of a given size.

    NiMH = Nickel-metal hydride
    NiCd = Nickel Cadmium
    LiIon = Lithium Ion
    LiFe = Lithium Ferrous Oxide
    LiPo = Lithium Polymer

    Capacity
    A battery’s capacity refers to the amount of energy the pack can store. Think of capacity as your model’s gas tank; the greater the capacity, the larger the gas tank, and the longer your model can run per charge. In addition to giving your model a longer run time per charge, using a pack with greater capacity also increases “punch,” the feeling of power you get when your accelerating from a standstill or out of turns. The large number (3300, 4000, 5800, etc) on your LiPo battery refers to its capacity in milliamp-hours (mah).

    One milliamp is a thousandth of an amp, and amps are the measure of load or “current draw” on the battery. To convert milliamps to amps, divide by 1000; for example, 7600mah is equal to 7.6 amps. Milliamp-hours, or amp-hours, refers to the amount of current draw the battery can sustain for one hour. To continue with the example of a 7600mah battery, it would handle a load of 7600 milliamps (or 7.6 amps) for one hour. Since your powerful Traxxas R/C vehicle will likely draw more than 7.6 amps, it will run less than an hour per charge. The important thing to remember is this; the larger the capacity number, the longer your run time.

    Voltage
    The more voltage a battery has, the faster your car will go. Battery voltage is determined by the number of cells in the battery. Power Cell NiMH cells deliver 1.2 volts each; a 6-cell pack has 7.2 volts, a 7-cell pack has 8.4 volts, and an 8-cell pack has 9.6 volts. LiPo cells have higher voltage: 3.7 volts per cell. Because of this, they need fewer cells to provide the voltage needed for high-performance R/C. Power Cell LiPos are available with 2 cells (7.4 volts) and 3 cells (11.1 volts).

    C-Rating
    C is short for capacity. The load a battery can sustain is indicated as a multiple of capacity. For example, a load of 1C for a 7600mah battery is 7600 milliamps or 7.6 amps. A 2C load would be double the capacity; 15.2 amps (7.6 x 2 = 15.2). All Traxxas LiPo batteries are rated for 25C. For our example of a 7600mah pack, that would be 7.6 x 25 = 190 amps. How much amperage can be used to charge a battery may also be indicated as a “C” value. All Traxxas Power Cell LiPo batteries have a recommended charge rate of 1C, and a maximum charge rate of 2C. For maximum performance and longevity, charge at 1C whenever possible. For example, a 1C charge rate for the 5800mah Power Cell LiPo would be 5.8 amps. A 2C charge rate for the same battery would be 11.6 amps. An important note about C-Rating: Each battery manufacturer has their own formula and methodology for determining the C-Rating they assign to their LiPo batteries. For example, a Traxxas 25C battery evaluated using another brand's method of calculating C-Rating might be determined to have a 50C rating. For this reason, you should not compare batteries from different manufacturers by their C-Ratings.

    2S, 3S
    LiPo batteries contain 2 or 3 cells connected in series (S). So, a pack with 2 cells is a “2S” battery, and a pack with 3 cells is a “3S” battery. A 2S battery has 7.4 volts, and a 3S battery has 11.1 volts. If your vehicle or speed control is rated for “6S” and has two battery plugs (such as the E-Revo Brushless Edition), you can plug two 3S packs into it for a total of 6S. Two 2S packs would be “4S.”

    “Series” connection means the cells are connected inside the pack so the first cell’s positive tab is connected to the second cell’s negative tab. This combines their voltages; the two 3.7 volt cells deliver 7.4 volts combined. The other way to connect the cells is in parallel (P), which means the cell’s are tabs are connected “positive to positive” and "negative to negative.” This combines their capacities. If you look at the specifications of your Power Cell LiPo, you may see that your 2S pack is actually 2S2P, meaning it has two pairs of cells, each connected in parallel (2P), and the two pairs of cells are then connected in series (2S).

    Chargers for RC Batteries
    It is critical for the longevity of your batteries and your personal safety that you always use the correct charger or charger settings for your battery, and observe all the precautions outlined in your battery and charger documents. Traxxas offers the #2930 EZ-Peak and #2932 EZ-Peak 2amp chargers exclusively for use with NiMH and NiCd batteries ONLY. NEVER use a NiMH or NiCd charger to charge a Traxxas LiPo battery. Failure to use LiPo balance charger to charge LiPo batteries can result in explosion, fire, and personal injury! The #2933 EZ-Peak Plus can be used with all R/C battery types including Lithium batteries, but you must be sure to select the LiPo, LiIon, or LiFe mode when charging Lithium batteries. Always place your LiPo battery in a fire-retardant bag or case while charging. All rechargeable batteries should be charged in a charging bag or case.

    Storing Your Batteries

    ... LiPo batteries should be stored at 50% capacity. Store LiPo batteries in a charging bag or case. Do NOT store LiPo batteries discharged, as this will reduce battery performance and may lead to over-discharging if the packs are stored discharged for an extended length of time. The Traxxas EZ-Peak Plus makes it easy to store LiPos properly; just recharge the pack using Storage mode and it will charge the pack to 50% capacity.


    LiPos and Low Voltage Detection
    Over-discharging a LiPo battery will cause irreparable damage and may cause battery failure. To prevent over-discharging, only use Traxxas Power Cell LiPo batteries with an electronic speed control (ESC) that has a low-voltage detection system or alarm. All current Traxxas vehicles equipped with the XL-5, VXL-3s, VXL-3m and Castle Creations ESCs have Low Voltage Detection. Traxxas ESCs will show a green light to indicate Low Voltage Detection is turned on; the Castle Creations ESC will beep once for each LiPo cell it detects (for example, 4 beeps if you have installed two 2-cell packs in your model). The Castle speed control automatically activates its low-voltage detection mode when it detects it is connected to LiPo batteries. If you are uncertain about how to turn on and use Low Voltage Detection, consult your vehicle's manual or click here for some helpful support instructions. If you need further assistance, feel free to call 888-TRAXXAS. We're happy to help.

    Never Use Damaged Batteries
    No matter which type of battery you use, you should discontinue its use if damaged. Never use a battery with frayed or damaged wires, or torn insulation. Never use a nickel battery if it is dented or has other physical damage. Never use a LiPo battery that has visible damage to its outer covering. Never use a LiPo battery that feels soft, or has swollen.
    Last edited by ksb51rl; 04-29-2013 at 10:54 AM.
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  4. #4
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    Is the nickel info correct, Stored fully discharged ?.
    I agree with the lipo info. Many moons ago the storage was about 80% but as time moves on more information and tests have shown about 50% is best.
    Problems.The manual's good starting point. Simple

  5. #5
    Marshal ksb51rl's Avatar
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    Quote Originally Posted by trax de max View Post
    Is the nickel info correct, Stored fully discharged ?.
    I agree with the lipo info. Many moons ago the storage was about 80% but as time moves on more information and tests have shown about 50% is best.
    Honestly, it's not what I formerly did. I don't run NiXX any longer.
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  6. #6
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    Thanks for the official recommendations from Traxxas on storage mode... but I still have a couple clarifying questions:

    1) What timeframe do they consider "storing your batteries"? I could see storing your Lipo's at 50% if not using them for a month or longer... but what about just a few days in between runs? Will a full charge hurt anything if it's used within 3-4 days? Or what about 24-48hrs?

    2) Is there any official word on how/why leaving a fully-charged Lipo battery for 24+hrs is bad for the battery?

    Part of my wanting to fully understand this is that my Lipo charger doesn't have a "storage mode" for charging/discharging, so after bashing my Pede with my Traxxas 2s 5800mAh Lipo, what's the best course of action to take that will extend the life of the battery, without too much unnecessary hassle? As long as the per cell voltage is less than 4v, but above 3.6, just leave it alone and don't do any charging? Or charge it up right after bashing to ensure the power doesn't drop too low over the next several days?

  7. #7
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    1) personally after each days use i put on storage charge, I never know if the next time i use them is the next day or the following week.

    2) due too the chemical reaction inside the lipo causes a quicker increase in the internal resistance from crystalite on anode or cathode. I'll have to look that one up.

    50% is where it's best at, but there is no rule why it can't be 70% or 40%. It just means instead of getting 500cycles from a battery you might get 350 cycles. Leaving more or less voltage, then the cycle life decreases.
    There is some manufactures ship with 4V some 3.6V. Ideally it should be 3.85V

    It's the disposal of the lipo's that i think everyone gets wrong even today after all these years.
    Last edited by trax de max; 04-29-2013 at 01:19 PM.
    Problems.The manual's good starting point. Simple

  8. #8
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Here is what I do...

    1) I storage charge/discharge them to 3.85v/cell if they will not be used within 3 days.
    2) If cell voltage is between 3.6-3.9v I will leave them if they will be used within 3 days.

    The longer they are left at full voltage, the less cycles you will get out of them.
    Whatever it is I just said... I could be wrong.

  9. #9
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    lets say a 2s 5000mah battery is 100% properly taken care of. Its stored properly, never left to sit more than 24hrs fully charged. What would the expected life of the battery be as in positive charge cycles? Also how many charge cycles does it loose as it sits charged? Like if i leave battery charge for 48hrs it will loose 20 charges as a example?
    " You just got passed by a Traxxas"

  10. #10
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    I have not seen a study on that, but here is a clip from my "LiPo 101" write-up:
    __________
    Making your LiPo's last
    I will just give an example of how much a small change in how a pack is taken care of can dramatically change how the pack behaves.
    Two identical packs were both charged and discharged in the exact same matter.... except one pack was charged to 4.20v/cell and the other to 4.10v/cell. This was done in a very controlled environment... NOT in an RC.
    After 500 cycles, the pack that was charged to 4.20v/cell had reached its life expectancy... it would not take more than 65% of its original capacity; meaning the LiPo was no longer able to be used safely.
    The pack that was charged to 4.10v/cell was still at 70% capacity after 1,000 cycles... so the .10v/cell difference more than doubled the life expectancy.
    __________

    If just .1v has that kind of effect on a LiPo... I can only imagine what storing at full voltage for extended periods will do.
    Whatever it is I just said... I could be wrong.

  11. #11
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    Does "Storage Mode" also Balance the batteries automatically or does your charger need to be set for that?
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  12. #12
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Depends on the charger.
    Balancing for storage is not really a requirement due to storage voltage being so vague.
    Whatever it is I just said... I could be wrong.

  13. #13
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    I think my first two lipo chargers balanced going from low voltage too storage, But not discharging from a higher voltage down over. But I have the new one to balance all the time.
    But as Jimmie says, it doesn't need to be excact on whatever the storage voltage is for the charger. All cells being equal saves time charging too full again.
    Problems.The manual's good starting point. Simple

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