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Batteries Lipo Battery C Rating Explained

Discussion in 'Electronics' started by Tony, Jun 30, 2018.

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  1. Tony

    Tony Administrator Staff Member

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    Here lately I have been receiving a lot of questions on if a higher C rating will hurt an ESC or a Motor. More specifically I have been asked if an ESC can handle say a 70c rated battery if it is only 35 amps. I'm hoping this video can help clear some of that up. I know those of us that have been in the hobby for a long time know what C rating is, but there are some that have never heart about a C rating.

    I remember getting back into the hobby and hearing things like mah, c rating, s rating, oh yea, there is another c rating, kv (which still doesn't make sense why they call it KV and not RPV...) and so on. These things are confusing and this video will hopefully clear that up for the newcomers to the hobby.


     
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  2. Smoggie

    Smoggie Well-Known Member

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    Nice video Tony. Also maybe worth throwing out there that there is a lot of exaggeration when it comes to C rating. All the independent tests show that no LiPo battery has a constant genuine C rating much over 30.
    As there is no industry standard way to measure C rating then manufacturers can pretty much make up their own numbers. As higher C numbers make the battery 'better' in the eyes of the buyer and make the battery sell for a higher price there is a big temptation to inflate the C number. There are even batteries out there advertising 150C which is just complete BS.
     
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  3. Tony

    Tony Administrator Staff Member

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    As I was editing this video, I thought the exact thing you just mentioned. All a manufacturer can do is discharge tests on a pack or packs and give a rough number. However, maybe the next batch has a slightly higher IR than the last pack which will result in a lower C. I will make a followup video to this one explaining exactly this. Thanks Steve for reminding me.
     
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  4. D.O.G.

    D.O.G. I Support Rc-Help! Rc-Help Supporter Goblin 380 Supporter

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  5. rdsok

    rdsok Well-Known Member

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    I'm waiting on those four million C rated batteries... but our full sized electric car issues would be solved at that point. Although I doubt I'd want to pick them up very often... PS, Tony, expect a call from Elon Musk from Tesla on those 4M C rated batteries. LMAO

    Since we're dealing mostly with aircraft and to some extent it also applies to ground vehicles and water craft... Using batteries that are well over the required amperage needs of the craft is inefficient since the batteries will be heavier. The higher the C rating, the more the batteries weight. Having that additional weight will also affect the load on the motor/esc... so in that sense it may cause some issues ( but I doubt it'd overload them still ).

    As for some companies over rating their C ratings... It happens, it's been happening since the beginning of time that some unscrupulous people want to exaggerate their products they are selling. I always think of the audio industry when it comes to this and how they say their stereo or speakers are X watts when they aren't, but it's everywhere. Like everything, if you deal only with reputable companies, it shouldn't be an issue.

    Final point... I probably wouldn't recommend talking about watts ( power ) while you discussing C ratings which are about the amps the batteries can supply or be charged at. Not so much because it isn't related since A x V = P... but it'll just confuse them if they are going to have to do any calculations to find out what the potential wattage a battery can supply at a given C rating. I'd keep it simple and just directly relate the C rating you are talking about to the amperage being used/charged. Keep the wattage talked for a more advanced video when talking about Ohm's law etc.
     
  6. Tony

    Tony Administrator Staff Member

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    Randy, I'm waiting for those 4MC batteries as well hahahahaha. However, about them being heavier, I have not seen much difference between 25's and 45's in the 3S 2200 packs, but that could also get into what Steve was talking about with them over rating the discharge capabilities of the packs. And I'm good without a call from Musk, I will take his money, but yea... lmao.

    But you are right about keeping it simple. The KISS method. Keeping wattage out of the equation is a good idea and I shouldn't have even mentioned it in the video. This was a spur of the moment video after some questions over the last few weeks regarding the exact same thing each time asking if a higher C would damage their ESC or their Motor. But as stated, I will be making a follow up video to squash some things mentioned about the video.

    And Ivan, sweet deal. Are we going to see some more videos from you now that you have a working computer again?
     
  7. murankar

    murankar Moderator Staff Member Armed Forces

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    If you have it use your telemetry. That will tell you what you need in a battery. Then again that's if your telemetry does the battery stuff. The only reason why I have 45c on my 570 is because 35c was out of stock.

    Other things people get carried away with is to much motor for their needs, which drives the need for a big esc which in turn drives us to 45c and up.

    Nick Maxwell flew his Raptor E700 at 1900 rpm and flew a castle 120 on his setup. This guy could kill a raptor in a heart beat too. His nickname was Nick smackwell.
     
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