Battery Amp Safety

[GrayG70]

Hi i have a question about Ampage and what exceeding them actually is -

I have a dual battery mode with 2 x 20amp batteries, Im running stagger fused clapton, dual coil, around 75 watts my mod shows the Ampage drain at around 20 Amps, so i turned it down a bit.
When my mod says 20AMps is what the drain is currently, is that the safe limit not to exceed, or because i have 2 20 amp batteries would it actually be doubled so i could indeed get it up to say 100watts and 30amp if i wanted too???, OR should i always stay below 20amp regardless of having 2 batteries installed.

 

[jwill]

What is the mod being used? I am assuming a regulated mod of some sort so please correct if otherwise.

Generally speaking a regulated mod will not allow you to set it up in a way that is beyond its capabilities. Running it high and hot will yield poor battery life but it should be doable so long as the mod allows it.

 

[GrayG70]

Hi thanks, Yes its a reg, The REV GTS 230w. I know the batteries are in series, so i was confused about it, i was assuming that 2 x LG HG2 batteries, 20A = 65watts x 2 = 130 watts. I may be wrong, but that was my understanding.
I ask not just because of battery safety but also because i dont want to damage the battery and shorten its life, any info would be appreciated.
I know my mod has BYPASS mode which i think allows me to use it like a mech, but ive never ever used that side of it, i get completely that regs are limited compared to mechs, as my next question was, can i run coils in series on my reg or do they have to be offset to use all 4 holes. When it comes to this side of it i get a bit confused.

 

[Mattp169]

regulated mods work differently.

The batteries supply a regulator. then that regulator outputs the power, NOT THE BATTERIES!!!

SO the display shows what the regulator board is outputting, NOT WHAT THE BATTERIES are out putting.

To understand what the batteries are outputting you must use what is commonly referred to as Watt's Law which is:
Watts/battery voltage/mod efficiency

so in a 2 battery mod you can have about 6.2V-8.4Vs now that also depends on the mod. Most mods cut off and stop working when the battery gets down t0 3.1ish Volts, some 3V some 3.2V I use 3.1V as an average

the mod efficiency is usually 90%. Some are a hair lower some are a hair higher. If you don't know what your mod is, which most of us do not know, then just use 90%

So at 75W
75/6.2/.9=13.44 amps

We use the lowest Voltage setting because that will produce the largest amps

So at 75 watts each battery will drawe up to 13.44 amps

That 20 amps you see on your display is what the regulator board is outputting to the coil not the battery to the board

 

[GrayG70]

Just to add, i have 2 x stagger fused clappys installed at 0.15ohm

 

[Kranky Kanger]

Okay this can be a bit complicated, but we'll keep it simple. I can't give you a definitive answer without knowing the resistance of your coil set up, but there are general rules of thumb when it comes to battery safety. It is usually not recommended that you exceed the continuous amp draw ratting of your batteries (to be on the safe side) in your case this is 20a. And no having dual batteries does not necessarily double your available amp draw. Batteries hooked up in series (almost all regulated mods) double your available voltage, but the amps stay the same. Parallel battery systems (many unregulated mechanical mods) the voltage stays the same, but the amps increase. From your description I am assuming (correct me if I'm wrong) you are using a regulated mod. With all that said it is possible to exceed the maximum continuous amp draw of your batteries without blowing them up. There is a difference between MCD (max continuous draw) and "pulse draw" . Pulse draw is actually what we do when we are vaping, we draw on the batteries for 3 to 5 seconds then stop. Stop, rest, repeat. Is it safe, yes for the most part, unless you go over the top with it. Pulsing a 20a battery at 25a is doable, pulsing a 20a battery at 40a is really not a good idea. Bottom line is, they'll get hotter than normal, and you will shorten the life of the battery significantly, but a good regulated mod will keep you from hurting yourself. As jwill noted, you'll be charging A LOT more often running them high and hot, and you will replace them more often. My personal recommendation is to stay at or below the MCD ratting of your batteries. It's safer overall and will help your batteries last longer, both in how often you need to recharge, and the batteries service life. If you want to be cautious then keep it 20a or below, if yoiu want to push it a bit that's your choice. But do become familiar with Ohms Law (find a good calculator online) and check things before hand. This is a good one I use, https://www.rapidtables.com/calc/electric/ohms-law-calculator.html . Stay safe.

 

[Kranky Kanger]

Just to add, i have 2 x stagger fused clappys installed at 0.15ohm

Having seen this I can tell you that you are already pushing your MCD. The calculated draw for .15 ohm at 75w is 22.3a. You're likely just fine. If your were going to push it to 100W on a regular basis I would bump to a .5 ohm coil to keep it on the safe side. Your call. Keep in mind that I am erring on the side of almost extreme caution. This is because I'm not certain of your experience level or the specifics of your set up.

 

[Mattp169]

Okay this can be a bit complicated, but we'll keep it simple. I can't give you a definitive answer without knowing the resistance of your coil set up, but there are general rules of thumb when it comes to battery safety. It is usually not recommended that you exceed the continuous amp draw ratting of your batteries (to be on the safe side) in your case this is 20a. And no having dual batteries does not necessarily double your available amp draw. Batteries hooked up in series (almost all regulated mods) double your available voltage, but the amps stay the same. Parallel battery systems (many unregulated mechanical mods) the voltage stays the same, but the amps increase. From your description I am assuming (correct me if I'm wrong) you are using a regulated mod. With all that said it is possible to exceed the maximum continuous amp draw of your batteries without blowing them up. There is a difference between MCD (max continuous draw) and "pulse draw" . Pulse draw is actually what we do when we are vaping, we draw on the batteries for 3 to 5 seconds then stop. Stop, rest, repeat. Is it safe, yes for the most part, unless you go over the top with it. Pulsing a 20a battery at 25a is doable, pulsing a 20a battery at 40a is really not a good idea. Bottom line is, they'll get hotter than normal, and you will shorten the life of the battery significantly, but a good regulated mod will keep you from hurting yourself. As jwill noted, you'll be charging A LOT more often running them high and hot, and you will replace them more often. My personal recommendation is to stay at or below the MCD ratting of your batteries. It's safer overall and will help your batteries last longer, both in how often you need to recharge, and the batteries service life. If you want to be cautious then keep it 20a or below, if yoiu want to push it a bit that's your choice. But do become familiar with Ohms Law (find a good calculator online) and check things before hand. This is a good one I use, https://www.rapidtables.com/calc/electric/ohms-law-calculator.html . Stay safe.

ON A REGULATED MOD coil resistance has nothing to do with the amp draw on the battery. Only the Watts, current battery voltage and the mod efficiency determine the amp draw on your battery

 

[Mattp169]

Having seen this I can tell you that you are already pushing past your MCD. The calculated draw for .15 ohm at 75w is 22.3a. You're likely just fine. If your were going to push it to 100W on a regular basis I would bump to a .5 ohm coil to keep it on the safe side. Your call.

this is only on a mech mod, he is using a regulated mod so your math is wrong. Use watt's law not ohms law for regulated mods. It took me forever to understand this, but it is correct

 

[Kranky Kanger]

this is only on a mech mod, he is using a regulated mod so your math is wrong. Use watt's law not ohms law for regulated mods. It took me forever to understand this, but it is correct

Lean something new every day. I'll have to figure this out. Thanks.

 

[GrayG70]

Thankyou for the responses and help guys. ive got the idea now

 

[Mattp169]

Lean something new every day. I'll have to figure this out. Thanks.

I am not good at explaining WHY. I know it has to do with the fact on a mech mod you are drawing power directly from the battery to the atty which is ohms law
But with regulated mods what is happening is the power from the battery goes to the regulator board. The board then manipulates that energy by bucking or boosting to output to the atty So the power for the atty comes from the board. Meanwhile the board is only drawing the power from the battery as needed and its based only on the watt setting of the board

now whats important to remember here is the board is not smart enough to know what batteries you have. So say even at 75 watts and 13. whatever amps IF you have 10 amp batteries in there then that is BAD. At 200 watts in a 2 battery mod you are drawing upwards 26 amps (at full charge) and 35 amps (at low battery cutoff) So while pulsing at 200 watts will work and not instantly vent most high quality brand name 20-25amp batteries, you still shouldn't try to continually drain any set of 18650s at 200 watts

 

[Kranky Kanger]

I am not good at explaining WHY. I know it has to do with the fact on a mech mod you are drawing power directly from the battery to the atty which is ohms law
But with regulated mods what is happening is the power from the battery goes to the regulator board. The board then manipulates that energy by bucking or boosting to output to the atty So the power for the atty comes from the board. Meanwhile the board is only drawing the power from the battery as needed and its based only on the watt setting of the board

now whats important to remember here is the board is not smart enough to know what batteries you have. So say even at 75 watts and 13. whatever amps IF you have 10 amp batteries in there then that is BAD. At 200 watts in a 2 battery mod you are drawing upwards 26 amps (at full charge) and 35 amps (at low battery cutoff) So while pulsing at 200 watts will work and not instantly vent most high quality brand name 20-25amp batteries, you still shouldn't try to continually drain any set of 18650s at 200 watts

Yeah, I played with calculations and forced myself to think about it and that's pretty much what I came up with. The chip or board is the "fly in the ointment" so to speak. The thing I was having a tough time wrapping my head around was efficiency. But then I remembered that no circuit is 100% efficient, there are always line losses, power requirements for the board, display, etc. So .9 for efficiency started to make sense. So with a regulated mod the only role coil resistance plays is for calculating what voltage and amps to draw to fire the coil at the give wattage by the chip, I think. In theory anyway. I'm sure it's more complicated than that, but I'm starting to get a glimmer. Basically using an ohms law calculator tells you that you're drawing more amps off the battery than you actually are with a regulated mod because you aren't drawing directly off of the battery(s). And that's where I'm going to stop. Bottom line use the w/v/e calculation and compare against your batteries MCD. If you're at or below MCD you're good to go. Thanks Matt. Feel free to correct me if I'm all wet!

 

[Carambrda]