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Lipo Storage Charging - Discharge Amps?

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  • Lipo Storage Charging - Discharge Amps?

    I have a Revolectrix GT1200 charger powered by a DC 1500W 62A PS. I always Storage Charge down to around 3.8v per cell within a few hours after using my lipos unless they are at or near 3.8v after flying. The default discharge amp setting on the charger is 1A for Storage. However, it can be set to a max of 8A. If I set the discharge amps to 2 or 3A, I assume the Storage charge process would be somewhat faster. I also assume that would do no harm to the lipos since they would be discharging at more than 2-3A while flying. Are my assumptions correct?

  • #2
    I set the charger to storage charge, not discharge, at no more than 3/4 of its C rating. A 2200mah will be discharged at 1.9A or possibly 2A. While a 5000mah will be discharged at no more than 3A or 4A. The connectors, nor the batteries gets warm when discharging.
    So far I use this method and the batteries keep a consistent IR, discharge/charge evenly, and deliver good power. I have no scientific data its the correct way, but it does work for me.

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    • #3
      I have the Revo GT1000 Duo charger. In fact, I have 2 of them. When I discharge my batteries for storage, I discharge them at the rate that the battery size is. IE, if it’s a 2200mah, I discharge at 2.2A. If it’s a 5000mah, discharge at 5A. I haven’t detected any bad results by doing this. I’m not saying this is the right way to do it, so someone else may post up a different way. Oh, and I stop it at 3.8v/cell.

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      • #4
        Originally posted by xviper View Post
        I have the Revo GT1000 Duo charger. In fact, I have 2 of them. When I discharge my batteries for storage, I discharge them at the rate that the battery size is. IE, if it’s a 2200mah, I discharge at 2.2A. If it’s a 5000mah, discharge at 5A. I haven’t detected any bad results by doing this. I’m not saying this is the right way to do it, so someone else may post up a different way. Oh, and I stop it at 3.8v/cell.
        XV............Your examples and the other guys are basically discharging at a 1C rate which is no where's even close to taxing the LiPo especially if say most of the them on the market are 30-45C rated.
        On a conservative discharge basis I would safely use 10% of C rating whereas a 5000mAh(5Ah) 40C rated LiPo could safely without concern to IR issues get a 20Ah discharge (40C x 10% = 4C x 5A equals the 20A)
        For folks that don't have these Revo's which have the capability for higher discharge levels and don't want to be stuck in a time warp of discharging with the standard industry charger(even the higher power ones) go look at investing in the SkyRC BD200(see my recent thread on this) for discharging at time efficient levels.
        Warbird Charlie
        HSD Skyraider FlightLine OV-10 FMS 1400: P-40B, P-51, F4U, F6F, T-28, P-40E, Pitts, 1700 F4U & F7F, FOX glider Freewing A-6, T-33, P-51 Dynam ME-262, Waco TF Giant P-47; ESM F7F-3 LX PBJ-1 EFL CZ T-28, C-150, 1500 P-51 & FW-190

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        • #5
          Good info, OV. I just checked my charger and the highest it will discharge is 8.0A. I've always discharged at "1C" because that's all I was comfortable with without solid facts about the topic. I rarely have batteries that I need to bring back down for storage. The occasional time that I do, I just throw them into the plane in the basement and just run the motor at less than 1/2 throttle for a couple of minutes if I plan to use them again within days. If I decide to store them, then I put them on the charger and run them down to storage voltage. I kill them with DC light bulbs.

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          • #6
            there's no real industry standard guideline that I can find. but I always thought exactly what OV10 says. the batteries are being used at way more discharge than what a charger can do. I have packs that are capable of 60C constant and 120C bursts.

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            • #7
              I have only tried to discharge my 4s 5000mah in this way once. At present it seems that there is no problem, but there is no relevant information to refer to.

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              • #8
                As hard as the discharger will go. Recently got a 200W external discharger which will pull around 8A from a 6s pack. Makes a racket in the process.

                Regret waiting so long to get a nice discharger - don't think twice about charging the whole fleet of packs now because if the wind rolls in and we pack up early I don't have to spend 3 days getting them all back to storage.

                Some of my EDFs pull 140A at takeoff, 8A barely even fits on the same axis.

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