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  • why are there MaH and A on my battery

    Hi guys, so i'm buying these --- 18650 3000MAH 35A --- Lion batteries to replace my acid batteries, on batteries you would see Mah or AH meaning how many amps in that certain hour, so what does it mean when it says this on a battery ? 18650 3000MAH 35A?

    https://www.ebay.com/itm/2-PCS-MXJO-...%257Ciid%253A1

  • #2
    They likely aren't 3,000MAH or 3AH, 35A is what you might get in a short circuit. With Li you are buying a dream.

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    • #3
      The 3000 mAh is the capacity of the battery. The 35A is a max discharge rate, usually a very short duration. The max continuous current on those batteries is 20A, according to the specs - this rate wouldn't be supported much longer than the 35A though.

      Comment


      • #4
        OK you want the real answer? Pretenders are guessing and muddying the waters. .

        mah = milli amp hours. Where the whole number 1 = 1000 mah. or 1 x 10-^3rd power = Milli or 1/1000th. In engineering we use scientific notation is used to express very large and small numbers. In this case makes a tiny battery sound larger.










        So 3000 mah = 3 Amp Hours. 3000 mah / 1000 = 3 If you like that then can I sell you some 300,000 micro ah batteries? Or how about a .003 K ah battery. All are the exact same size.

        35 is a C-Rate and with lithium 18650 cells means they can be discharged at 35 Amp which roughly translates to to C10 where C = the Amp Hour Rating of the battery. In this case 3 amps x 10 = 30 amps. At 35 amps is C 11.666666666667

        So it means 3 amps hours with up to max 35 amp max discharge current , or C10 aka 6 minute rate.

        3000 mah sounds like a lot more than 3 ah huh? They are EQUAL. On the flip side I have designed a many 48 volt 40 Kah batteries. Sounds small huh? If you call 115,000 pound battery small. Only Americans get confused by it.
        Last edited by Sunking; 12-03-2017, 06:24 PM.
        MSEE, PE

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        • #5
          Originally posted by Sunking View Post
          OK you want the real answer? Pretenders are guessing and muddying the waters. .

          mah = milli amp hours. Where the whole number 1 = 1000 mah. or 1 x 10-^3rd power = Milli or 1/1000th. In engineering we use scientific notation is used to express very large and small numbers. In this case makes a tiny battery sound larger.










          So 3000 mah = 3 Amp Hours. 3000 mah / 1000 = 3 If you like that then can I sell you some 300,000 micro ah batteries? Or how about a .003 K ah battery. All are the exact same size.

          35 is a C-Rate and with lithium 18650 cells means they can be discharged at 35 Amp which roughly translates to to C10 where C = the Amp Hour Rating of the battery. In this case 3 amps x 10 = 30 amps. At 35 amps is C 11.666666666667

          So it means 3 amps hours with up to max 35 amp max discharge current , or C10 aka 6 minute rate.

          3000 mah sounds like a lot more than 3 ah huh? They are EQUAL. On the flip side I have designed a many 48 volt 40 Kah batteries. Sounds small huh? If you call 115,000 pound battery small. Only Americans get confused by it.
          So, for all that explanation you'll get 10 EE-18 boys, which, by my reckoning == 1 "attoboy". Collect 10 EE 18 of those and you'll get an "O boy", the duck will come down and give you 50 bucks and a groupon, which, along with the 50 bucks, is good for a prostrate/balloon knot check from a small fingered Romanian midget with an attitude.

          I'm not sure an attoboy is a discrete, quantize-able amount or not. Since EE's are more cerebral than ME's, as may be obvious from this post, I leave that as a question for you to ponder. Just don't say I never gave you anything.

          https://www.solarpaneltalk.com/#

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          • #6
            Originally posted by AzRoute66 View Post
            The 3000 mAh is the capacity of the battery. The 35A is a max discharge rate, usually a very short duration. The max continuous current on those batteries is 20A, according to the specs - this rate wouldn't be supported much longer than the 35A though.
            Just to re-iterate, these cells are rated for only 20 A continuous discharge, a rate of 6.67C, the 9 minute rate. The 35 A on the label is a *pulse* discharge only, just a couple seconds at most. These cells are not designed to be discharged heavily at 10C or more, and definitely not short circuited... a dangerous overheating condition will occur, and long term damage done to the battery.

            Real world bench test results of this particular cell are posted here.
            CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

            Comment


            • #7
              Originally posted by sensij View Post

              Just to re-iterate, these cells are rated for only 20 A continuous discharge, a rate of 6.67C, the 9 minute rate. The 35 A on the label is a *pulse* discharge only, just a couple seconds at most. These cells are not designed to be discharged heavily at 10C or more, and definitely not short circuited.........
              I was going too say pretty much the same thing, nobody really knows what some random Mfg prints on the label. Yes there are standards, but if they aren't followed, you can't rely on them being implemented. With so much counterfeiting and 800mA ups-man-ship "My cells are bigger than your cells" going on, beware.

              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

              solar: http://tinyurl.com/LMR-Solar
              gen: http://tinyurl.com/LMR-Lister

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              • #8
                Originally posted by AzRoute66 View Post
                The 3000 mAh is the capacity of the battery. The 35A is a max discharge rate, usually a very short duration. The max continuous current on those batteries is 20A, according to the specs - this rate wouldn't be supported much longer than the 35A though.
                Go it, so if my camera charger was 500ma...how would you calculate the discharge rate ?

                Camera charger AC 100V-240V 50/60Hz
                output DC 8.4V----500Ma

                and if it dosen't apply to this charger i gave specs for, then when would the 35A max discharge work ?

                Comment


                • #9
                  Originally posted by Tesla View Post

                  Go it, so if my camera charger was 500ma...how would you calculate the discharge rate ?

                  Camera charger AC 100V-240V 50/60Hz
                  output DC 8.4V----500Ma

                  and if it dosen't apply to this charger i gave specs for, then when would the 35A max discharge work ?
                  I'm not really following what you want to do. In the first post, you talked about replacing lead acid with these. Were you using the lead acid as an energy source to recharge your camera through an inverter, and then an AC/DC adapter? How many of these 18650 cells are you intending to use, in what configuration?
                  CS6P-260P/SE3000 - http://tiny.cc/ed5ozx

                  Comment


                  • #10
                    The battery charger puts out a maximum of one half amp (500 mA) at 8.4 VDC. This is the rate that current goes INTO the battery.

                    The power coming OUT of the battery has to do with discharge. The battery will supply [allegedly] 20A continuous or 35A pulse, in your case [camera] the continuous would never be nearly that high, and the pulse might be when your 10 lb flash goes off and starts to recharge.

                    Not sure what to say about charging an 18650 at 8.4 VDC. I suspect one of us is not quite getting the 'picture'. Picture, get it? I crack myself up.
                    Last edited by AzRoute66; 12-08-2017, 05:39 PM. Reason: Edit: Oh, I see, probably charging two batteries in series, such as you are most likely not removing them from the camera body.

                    Comment


                    • #11
                      Originally posted by Tesla View Post
                      Go it, so if my camera charger was 500ma...how would you calculate the discharge rate ?
                      Does not compute, nor does anyone need to know. A camera discharge rate is so low, it cannot be measured.

                      Battery capacity is specified in Amp Hours at some Discharge Rate. In the case of lithium, they fudge all the numbers. However 90% of all other batteries are rated at a 20 hour discharge rate. It is all extremely complicated math. It takes 20 years of higher education to understand if you are educated in the USA, 5th grade math in any other country. So here you go.

                      Amp Hours = Amps x Hours, or AH = A x H
                      Hours = Amp Hours / Amps, or H = AH/A
                      Amps = Amp Hours / Hours, or A = AH/H

                      So in theory lets say you have a 200 AH Flooded Lead Acid Battery at the 20 hour discharge rate. What does that mean. Well if discharged at the 20 hour rate it means 200 AH / 20 H = 10 amps, or it means the battery can supply 10 amps for 20 hours. However that is only theory because the same battery if discharged at say the 1 hour rate is only a 85 AH battery meaning it can only supply 85 amps fpr 1 hour or a 85 AH battery at the 1 hour rate. What happened to the missing 115 AH? Nothing, Peukert Law kicked in.

                      Here is the deal. There are different battery chemistries. Each chemistry has it own application. A camera has almost no real demand for power, so it uses a lithium or alkalyne battery that cannot supply a high rate of power. An electric vehicle demands huge amounts of power and requires a special chemistry to deliver very high C-Rates.

                      I am not going to bother educating you, not my job. If you want a starter try this link as it defines some common terms. Read it then come back with questions. Or you can read what pretenders think.

                      OK the answer to your question is simple.

                      Camera charger AC 100V-240V 50/60Hz
                      output DC 8.4V----500Ma
                      Simply means the charger is 8.4 volts with a maximum charge current of 500 ma. So if the battery in the camera were 2 AH or 2000 mah and completely discharge would take 4+ hours to charge. 2000 mah / 500 ma = 4 hours.







                      Last edited by Sunking; 12-08-2017, 05:43 PM.
                      MSEE, PE

                      Comment


                      • #12
                        Thanks for everyone's feedback, my end goal is to take all electronics i use every day and build a solar panel and battery system for them, i watched a YouTube video of a guy with a camper that does just that, he used a camera charger in his description along with laptops, fans, heaters ...etc, so i used the camera charger.

                        But 18650's are awesome for holding charge and are lighter compared to traditional acid batteries plus maintenance free.

                        I fly R/C gliders that are electric and thought it would be cool to make one solar/battery powered , i mean i only get 20 minutes flight from one on a regualr LiPo battery so i can be that off if i do solar with batteries.

                        Comment


                        • #13
                          Originally posted by Tesla View Post
                          Thanks for everyone's feedback, my end goal is to take all electronics i use every day and build a solar panel and battery system for them, i watched a YouTube video of a guy with a camper that does just that, he used a camera charger in his description along with laptops, fans, heaters ...etc, so i used the camera charger.

                          But 18650's are awesome for holding charge and are lighter compared to traditional acid batteries plus maintenance free.

                          I fly R/C gliders that are electric and thought it would be cool to make one solar/battery powered , i mean i only get 20 minutes flight from one on a regualr LiPo battery so i can be that off if i do solar with batteries.
                          U-tube: The new Idiot's' bible.

                          Comment


                          • #14
                            Originally posted by Tesla View Post
                            Thanks for everyone's feedback, my end goal is to take all electronics i use every day and build a solar panel and battery system for them, i watched a YouTube video of a guy with a camper that does just that, he used a camera charger in his description along with laptops, fans, heaters ...etc, so i used the camera charger.
                            Good ole Youtube, the Idiots Bible.


                            Originally posted by Tesla View Post
                            I fly R/C gliders that are electric and thought it would be cool to make one solar/battery powered , i mean i only get 20 minutes flight from one on a regular LiPo battery so i can be that off if i do solar with batteries.
                            I fly 3D RC Planes and the last thing you want to do is use solar to charge your Rc LiPo batteries. Why would you want to wait all day to charge a battery? Even after a day may not be fully charged.

                            Our club does have a Solar Rig to charge LiPo batteries. I built and designed it. It is a 500 watt panel with a 24 volt 100 AH lead acid battery and uses PL8 Hobby Charger. The secret to it is the Lead Acid Battery, the panel cannot supply the 1300 watts the charger can demand. Trust me all us club members would throw that solar system away in a heartbeat for good ole AC power. With the solar system only one lousy battery can be charged up at a time. Does not work so good with more than one pilot trying to fly and charge batteries. The lead acid battery does the real work and charging.

                            The real solution to flying electric planes is to have 5 to 10 batteries and take them with you fully charged.
                            Last edited by Sunking; 12-17-2017, 11:55 AM.
                            MSEE, PE

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                            • #15
                              Originally posted by J.P.M. View Post

                              U-tube: The new Idiot's' bible.
                              Yeah I ripped you off. I like it.

                              MSEE, PE

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