Pairing “Hohm Life” batts w regulated mod, ohms down to 0.10.

[Dr. Seuss]

Hello,

I had a few things I wanted to run past someone with a better understanding of battery/ohms law etc, just for the sake of peace of mind.

One is, as I understand it parallel battery set ups, you add the amps, so 2 20 amp batteries can hit 40 amps right? The batteries split the ultimate total. Similar to how you split the ultimate watts total, so 150 watts would be split to 75 watts, per battery. Do I understand that correct?

Is there any easily visible cue for determining whether a mod is series vs parallel or do you just have to find the specs? I imagine stacked is pretty obvious as far as my understanding goes because they’re physically stacked. How could I tell visually if a mod is series or parallel?

Lastly, this is my main question and I think will be answered based off the answer I get for my first question but I wanted to run it by you guys to be sure. The mod is a Vaporesso Switcher and the batteries are two Hohm Life 18650s. I recently wrapped 2 coils that ohm’d out at .12 (together) and when dividing the voltage output on the screen I got 21 so I believe that means I need to have 21 amps to use in my batteries. The batteries I’m using are essentially rated at 20A continuous, but there’s two of them so am I at my peak right there or is 40 my cut off and with this set up and build I’m at about 50% of what my batteries can handle in terms of amps?

Aside from that everything else seems in the clear as far as safety goes, I’m going to link to the batteries page with specs just incase there’s some other factor I’m unaware of.

HΩ LIFE (HOHM LIFE) 18650 (2 pack) INR+ 3.6V LI-NMC 3077MAH 30.2A INSANE HIGH DRAIN RECHARGEABLE LI-ION BATTERY - Hohm Tech

I appreciate you guys setting me straight. I know there’s safety features and all that with a regulated mod but, all things considered I’d like to not rely too heavily on that to keep things in one piece.

 

[Punk In Drublic]

With a regulated device, the regulated circuit separates the battery from the coil. The battery does not see the current draw at the coil, it only see’s the power in which the regulated circuit is requesting.

Lets assume you are running 100 watts with your 0.12 ohm coil.

Voltage would be
V = √PxR
Voltage =3.46 volts

Current would then be
I = V/R
Current = 29 amps

On the battery side, the regulated circuit is only requesting power. Current = Power/Battery Voltage. As your battery voltage depletes, current draw increases to meet your power demand. This is why we use the low voltage cut off of the device to determine the max current draw at the battery. We also need to know the efficiency of the device. Given we do not know this figure for many devices lets assume a 90% efficiency. So the equation would be

Power/Number of cells/Voltage cut off/Efficiency

100 watts/2 cells/3.2 volts/0.9 efficiency = 17.4 amps per cell.

Despite we are drawing close to 30 amps current at the coil, you are only drawing 17.4 amps per battery given your 100 watts setting

 

[greek mule]

Might give these a read:calculating battery current draw for a regulated mod

To answer your second question,it does not matter how batteries are connected (series or parallel) at regulated mod as we are already taking that into account when we calculate the max power for each battery.

Most regulated multi battery devices utilize series battery connection because a boost circuitry isn't needed.They just use a buck circuitry that bucks the voltage of batteries down, or a pulsed DC circuitry to achieve the desired wattage.

 

[Dr. Seuss]

Alright I have your equasions jotted down, I’m going to play around with those for a little while and try to get a better grasp on that, which also knocks out my first question.

Is there a way to tell series vs parallel with a quick visual check? I always just sort of assumed the switcher was parallel but when I went to double check I wasn’t pulling up any links that gave an actual answer. I got mainly links that explained what the two methods are but nothing relating to my specific mod even on the vaporesso website. From what I gathered they’re two different paths to reach the same point but the difference would play a role in which battery you would pick.

 

[greek mule]

I imagine stacked is pretty obvious as far as my understanding goes because they’re physically stacked. How could I tell visually if a mod is series or parallel?

They are wired in series not physically stacked.Usually placed inverted.

 

[greek mule]

From what I gathered they’re two different paths to reach the same point but the difference would play a role in which battery you would pick.

The difference is that series regulated mods have better efficiency than parallel ones.(The boost circuitry has some energy loss, so it will use a little more watts from the batteries than at a lower voltage output from the batteries).

It's vary rare to find a parallel regulated device nowadays.
One such a device is Joyetech Cuboid 150W Dual 18650

 

[Dr. Seuss]

What’s up Greek

I think I’m close to getting this, I’m just unsure where I’m getting my voltage number for the equation. Am I looking for a cut off that’s programmed into the mod, or am I looking for the square root of PxR?

It sounds like the link is saying you look for something in relation to the mod, where it cuts off. Am I reading that wrong?

I’m also confused because I checked the specs of the Switcher and it says the volt range is 0V-8.5V, but it also says it has low voltage protection, and you can’t get much lower than 0V so I don’t know what it would be protecting.

Edit: Link was a pdf, here’s a screenshot instead:


I think once I’m certain on where I’m getting my V number from I’m golden.

 

[Punk In Drublic]

What’s up Greek

I think I’m close to getting this, I’m just unsure where I’m getting my voltage number for the equation. Am I looking for a cut off that’s programmed into the mod, or am I looking for the square root of PxR?

It sounds like the link is saying you look for something in relation to the mod, where it cuts off. Am I reading that wrong?

I’m also confused because I checked the specs of the Switcher and it says the volt range is 0V-8.5V, but it also says it has low voltage protection, and you can’t get much lower than 0V so I don’t know what it would be protecting.

I’m not sure if I’m posting links right but here’s the spec sheet,
https://www.vaporesso.com/hubfs/imgs/downloads/manual/User_Manual_Switcher.pdf

I think once I’m certain on where I’m getting my V number from I’m golden.

Voltage cut off is unknown with many devices unless specified or measured. 3.2 volts is the approx. average for a regulated device. Should the voltage be higher than 3.2 volts, the current draw will be lower. But you can safely allow for a variance between 2.8 to 3.5 volts. Drawing just a few amps above your recommended CDR at the devices cut off voltage is not going to make a huge difference. The cell is operating at that voltage for an extremely short duration. It is when you are operating above your recommended CDR for the full duration of the cells operation do you pose a higher risk.

0 to 8.5 volts is the applied voltage at the coil. Although 0 volts means it is not firing (kinda strange!). The voltage at the coil will be different than the voltage at the battery. If the battery does not provide the acceptable voltage, the device will cease to function and give an error.

 

[Dr. Seuss]

Word, so that equation you gave me is always going to stay consistent (with that mod), except for watts and the answer?

 

[HigherStateD]

I think you're over thinking it.

Quite simply, no matter what, mech, series, parallel, regulated; the wattage shouldn't exceed three times the amp limit.

Now, different configurations, like series vs parallel MECHS will require slightly different math o figure that out, BUT, the end result is the same. Watts = Volts * Amps.

In a regulated device, such as yours, the Watts are what you set, the Volts used for the maths is the minimum voltage cutoff, usually 3.2~, and a little head room, so roud to 3, which also makes the math easier!

So, max wattage = min voltage * max amp rating.

120=3v* 20A * 2(2batteries)


MECHS are where series and parallel matters most, as series doubles voltage, but not amp limit. Parallel does the opposite, almost.

 

[greek mule]

Yes you are looking for the cut off that’s programmed into the mod.

I have checked this manual too,to find the devices cut off voltage but I found nothing.Use 3.2 for your calculations and you are good to go.In worst scenario your cut off voltage might be 3 Volts.
In this case the max wattage you can set without stressing batteries,can be calculated using this formula:
P=V cut off x CDR x number of cells x0.9 (chip efficiency).
So with the batteries you have it will be:
3 x 20 x 2 x 0.9 =108 watt

 

[Punk In Drublic]

Word, so that equation you gave me is always going to stay consistent (with that mod), except for watts and the answer?

The equation was to demonstrate that coil resistance has no bearing on current draw with a regulated device. Power does. Every device will have its own inconsistencies in terms of reading resistance, applied voltage, efficiency and voltage cut off. So although the equation reflects how a regulated device works, it is not a true representation for all devices. But it is one that can be used to evaluate what we are drawing at the battery.

 

[HigherStateD]

I just did a little research. I can't be sure, but I'd be surprised if a mod with TC curve and memory modes, as well as a real time clock, doesn't have a voltage display for battery charge. You should be able to see what the battery voltage is when it won't allow you to fire the coil. That should give you peace of mind that you're using the correct number for the math.

 

[Punk In Drublic]

I just did a little research. I can't be sure, but I'd be surprised if a mod with TC curve and memory modes, as well as a real time clock, doesn't have a voltage display for battery charge. You should be able to see what the battery voltage is when it won't allow you to fire the coil. That should give you peace of mind that you're using the correct number for the math.

I am sure there are others, but only device that I have seen perform such function is a DNA and you have to specify that within its settings – it is not turned on by default. Every chip has is min voltage operation. Should you not meet that requirement, the chip will give a low voltage error.

 

[Dr. Seuss]

Hallelujah we made it folks! I understand it

Miracles do happen. Thanks guys.

 

[HigherStateD]

I am sure there are others, but only device that I have seen perform such function is a DNA and you have to specify that within its settings – it is not turned on by default. Every chip has is min voltage operation. Should you not meet that requirement, the chip will give a low voltage error.

It's that uncommon to have a numeric voltage readout?

 

[Punk In Drublic]

It's that uncommon to have a numeric voltage readout?

Apparently. Guess designers feel there is no value in having such reading.

It is also uncommon to show and or display the final live resistance when using a TC coil. Something I feel has way more value than a voltage reading at the battery. But lets save that for another conversation

 

[Dr. Seuss]

@ Higher, it doesn’t display it on the mod when charging (that I’m aware of) but the Nitecore charger I use does display where it’s at, like the first bit of the battery bar on the mod that disappears does it at 4v, so I can run the battery down and find out. I’ve just never run them down that low before, I try to get the batteries on the charger asap after the battery bar hits halfway. So now that you mention that, I’ll run them down and see where I’m at.

 

[greek mule]

Read the articles in here to get an idea [url=https://www.e-cigarette-forum.com/blogs/baditude.88498/]Baditude's Blog[/URL]

 

[HigherStateD]

@ Higher, it doesn’t display it on the mod when charging (that I’m aware of) but the Nitecore charger I use does display where it’s at, like the first bit of the battery bar on the mod that disappears does it at 4v, so I can run the battery down and find out. I’ve just never run them down that low before, I try to get the batteries on the charger asap after the battery bar hits halfway. So now that you mention that, I’ll run them down and see where I’m at.

Ahh, a nitecore with a screen. Excellent. That should give you an accurate read.

@Punk In Drublic that really is a shame. Both things the topside does, but yet no stealth mode or brightness control. Go figure.