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    GA vs 25R

    How does The Panasonic GA compare to the INR18650 25R? I’m interested in maximum cycle life. Thanks

    #2
    Depends on the discharge rate you are aiming for. A cell optimized for high output could provide more cycles than one optimized for high capacity IF you are using it for this task.

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      #3
      You lost me. I want a battery that will last for many cycles. For example, my 2 year old PF battery is still going strong, while my 2year old NCRB batteries are shit.

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        #4
        Right..well that's what I'm saying. Ncrb was a high capacity, low output cell. It was a great cell for its time but these days I would not recommend unless the pack configuration is high enough to spread out the current significantly. Otherwise it gets hot and this kills long term cycle life. The exception being if you don't regularly pull much current from it but just use for low performance bikes.

        GA has struck a much better balance between performance and capacity, and stays significantly cooler. 25r has double the rate but less capacity. Which might be worth it if significantly cheaper or if you need that sort of output.

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          #5
          So, the higher rate discharge of a 25r should give it more cycles than a GA? Given the application is the same for bothe, heavy pedicabbing demand.

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            #6
            Not necessarily, but there are some instances where this is the case, yes. Whether that is the case for you in particular depends on how much current the controller is set to pull, as well as the number of parallel strings in each of our hypothetical packs.

            I know this is a lot to take in, and I don't know what your controller is, so let's just stick with some common examples.

            BBSHD KIT @ 30A

            Comparison:

            * 52v GA Shark (uses a 4p configuration providing 13.5ah)
            * 52v 25r triangle (uses 5p configuration providing 12ah)

            Specs for GA give us 10A per parallel string so max recommended continuous discharge of 40A on 4p shark. Since BBSHD would be pulling less than this we are well within Panasonic's recommendations which is good for getting lots of cycles, it will stay cool during use.

            Specs for 25r give us 20A per parallel string so max recommended continuous of 100A on 5p triangle. If you were actually pulling anywhere near this amount of current then it makes a lot of sense to go with this battery as it will give you more cycles. For example a Cyclone with 4000w ASI controller will pull a ton of amps and would trash the shark pack relatively quickly but it would be fine with the 25r pack.

            Conversely, if you do not need that much current then the 25r pack provides a heavier battery with less range for no good reason and should choose the shark instead.

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              #7
              The 25R is a great cell, but...it is not famous for long life. During its short life, it is good for high amps from a small pack. If you have a large pack and need average amps, just get a long range cell, like the GA.

              The GA cell can also be beaten to death if you over-stress it, but...if you consider it's 10A rating only for temporary peaks, you can get a long life out of them. My favorite cell is the 30Q. It has decent range, and...even if I don't draw high amps? whatever amps I draw will run cooler than the GA cell at the same current.

              For long life charge to 4.0V per cell (80%), but even if you insist on charging to a higher level, make 90% you max (4,1V). If you charge to 4,2V just because you can, you will erode a significant part of the cells life, and you will NOT get any extra range over a 4.1V charge...

              https://www.electricbike.com/how-to-...-battery-last/

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                #8
                Thanks for the help guys. So for powering a BBSHD on a pedicab, heavy use, 12 hour days etc... The GA is the way to go? I use 52 v 20ah battero
                Last edited by ePedicab; 03-29-2018, 08:15 AM.

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                • paxtana
                  paxtana commented
                  Editing a comment
                  Probably the way to go, yes. Lots of parallel strings mean it will stay cool at 30a, and the high capacity may help you to maintain a lower average depth of discharge.

                #9
                20-Ah using a 3500-mAh cell is 6P. If you are drawing 30A from the pack as a temporary peak on occasion, then that is only 5A per cell. The GA cell will do quite well at that current. Normal cruising will be roughly half that rate, maybe 3A per cell...

                Make sure to only charge it up to 4.1V per cell. Technically that is 90%, but due to the odd shaped discharge curve, you really only give up 1/17th of the range. Charging to 90% can double the life of the pack. There is no problem charging to 100% if you use the pack right away, but...if you store it at 100% (4.2V per cell) then that erodes its life. https://www.electricbike.com/how-to-...-battery-last/

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                  #10
                  Thanks for all the help. I went with a LunaCycles 52V 28Ah.

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                    #11
                    One more quick question:
                    For the initial charging of my new battery 52V 28Ah GA; I should charge it to 100% and then leave it connected to charge for a couple hours to balance it ?

                    Thanks

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                      #12
                      Nice choice that's my personal favorite battery, practically limitless capacity.

                      Once the charge cycle is done it won't matter if you leave it connected to the charger or not, it can only balance so much in a single charge anyway and you really need to do multiple 100% charges in order to fully balance. Only need to drop by one or two volts then put it back on the charger at 100%

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                        #13
                        It wouldn't hurt to balance charge it once a week, orno even once a month. When using every day, charge to 80% right away when you get home for the night. That way you have a lot of miles on tap as soon as you wake up, but...it is not sitting overnight at full charge. Then, the next morning, set it to charge to 100% when you get up, so it's topping off while you get some coffee and breakfast.

                        A quality pack on a quality charger is very safe (I have two packs and two chargers from Luna), but...99% of the time, any problem from the pack is because of a BMS failure that allows one or more cells to overcharge above 4.2V per cell...ie...NEVER charge ANY pack to 100% when you are sleeping.

                        Luna has been very good about standing behind their warranty, but even if they are certain to replace a failed charger, you should have two because this is for your business. Use the lunagizer with the 80/90/100% settings in the evening. Then get the smallest, cheapest charger for the 100% charge in the morning.
                        Last edited by spinningmagnets; 04-03-2018, 11:01 AM. Reason: speling

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