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Thread: amps and batteries

  1. #1
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    amps and batteries

    Hey everyone, new time e-cig user here. I have most of the battery safety rules down pat but I'm getting some "conflicting" information on the amp limits (more specifically working out the total amp output from my setup). I currently have the odyssey kit which came with the 70 watt pegasus box mod and the triton 2 tank, and I'm using Samsung 25R batteries. I plan on using the 0.5 ohm clapton coils with the tank.

    Now as far as I was aware (according to some guides) you can use the ohms law calculator and give it the wattage and resistance and you'll get the amps. I punched in the rated wattage (45 watts) on the coil along with the resistance (0.5 ohms) and it came out as 9.4 amps and 4.7 volts. I'm getting a bit of confusion and lots of information at once so I might have overlooked something, but a few guides on battery safety mentioned the voltage of the actual battery when calculating the amps (I'm guessing the voltage of the battery would be what they refer to as nominal voltage?). The reason I'm confused is that I have no idea how (or if) to factor that in when working out the CDR of my setup.

    Basically I'm wondering, is my build safe vaping at 45 watts on 0.5 ohms on a Samsung 25R? And am I miscalculating the amps I'm putting out? I get some aspects of working this stuff out but all this information tends to get confusing when they present it differently or what have you.

    Thanks for all the help guys
    jacksonmate likes this.

  2. #2
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    For mech mods use ohms law.

    For regulated use watts law.

    Sent from my LG-H815 using Tapatalk
    "Vapers- The evangelical vegans of the smoking community"
    Quote Originally Posted by btobw View Post
    1 vote for DogMan because squonkers, dogs, chooks and brevity

  3. #3
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    Ah I see I guess I was looking at the wrong stuff. Is there a link to an easy explanation on working out the amps using watts law?

  4. #4
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    What doggy is saying, is you have to look at what the batteries are doing on a regulated mod for a given watts, it doesn't matter what the coil is doing when we are concerned with what's happening at the battery. This is because a regulated mod will take the battery voltage and boost it to up to 9 volts to achieve the desired power output.

    For this calculation we use the watt law which is W=VxA where W is the watts you have the mod putting out, V is the battery nominal voltage (3.75V) and A is the amps we need to find out.

    Transposing the equation to find amps, we get A=W/V.

    Since 45 over 3.75 is 12 amps, you can see your 20 amp batteries are well and truly safe at this power setting. The *only* thing that is the same on a regulated mod between the battery and the coil is the watts, which is why we have to go back to that to figure out what the battery is doing.
    DogMan likes this.
    Chris: Tobacco free since 17:00 15th March 2013.

  5. #5
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    Ah that makes perfect sense, so next time I want to adjust the wattage I can just plug in the numbers and use the formula. I'm happy to hear that my setup is well and truly safe, hearing about those batteries exploding really spooked me and made me second guess everything. Cheers for all the help guys

  6. #6
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    What Fabricator said plus allow some wiggle room (voltage boosting is never 100% efficient, some battery manufacturers rate optimistically and old cells don't deliver what new cells do) - but at the end of the day, as to whether the build is safe - it will be, as that is the whole point of using a regulated mod. Any half decent regulated mod will poll the cell frequently to ask if it is keeping up and will spit the dummy gracefully if it is not coping.

  7. #7
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    Quote Originally Posted by DynamicEgo View Post
    Ah that makes perfect sense, so next time I want to adjust the wattage I can just plug in the numbers and use the formula. I'm happy to hear that my setup is well and truly safe, hearing about those batteries exploding really spooked me and made me second guess everything. Cheers for all the help guys
    Yes, that equation will work for any single battery mod. Some mods are more efficient than others and as mathsguy said you have to figure this in. It's only important when you're right on the edge of what the battery is capable off though.

    There's another built in safety factor here, and that is that the 20 amp rating is for continuous current draw (according to both the manufacturer and Battery Mooch). Vaping is not anything like continuous use though, so even at 20 amps you are still pretty safe.

    Most problems with batteries happen for a good reason. Usually the user has stressed the battery in some way, or caused a short circuit. If you use a good charger and some common sense (like never using a battery with a damaged wrap, never use a battery that has been overheated, and never short the battery) you will probably never see a catastrophic battery failure.

    Another safety feature you have is that the Samsung batteries are IMR (manganese) chemistry, which is one of the safest lithium chemistries. It can be made to vent, but an actual explosion is practically impossible. Venting itself can be very bad if the mod can not let the gases escape fast enough or in an enclosed space, but it's a long way from explosion and fire.
    Last edited by fabricator4; 17-10-16 at 10:32 PM.
    merexy likes this.
    Chris: Tobacco free since 17:00 15th March 2013.

 

 

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