How do you figure the actual amp draw on a Cana

[Agamer]

Sorry for another question about these batteries but I have one here goes.

I am using a Cana mod with a 1.9 ohm kayfun and typically vape it at 12 watts now the question is what numbers do I use to determine the amp draw on the battery.

Do I use the readout on the screen of 4.8 volts and the resistance of 1.9 totaling 2.526 amps
or
Do I use the ohm rating of 1.9 and a voltage of 4.2 (fully charged battery) totaling 2.210 amps

I know this seems like splitting hairs but knowing what one to use will determine if it is mandatory to use a sony vtc4 or ok to use a Panasonic ncr18650b

In this example it gives two drastically different numbers at max usage

calculating max watt draw using battery voltage 1.9/4.2 =2.210 amps
calculating 30 watts using screen readout 1.9/7.549=3.973 amps

Both are within the most common amp limit I have seen for the Panasonic ncr18650b (green one) of 6.8 amps
And well within the 30 amp limit of the sony battery

So the question is what numbers do you use to determine the amp draw? Or am I missing something really obvious

 

[AzPlumber]

You should be using a high drain IMR battery.

The circuit on a protected ICR cell doesn't play well with a regulated mod and an ICR cell is much more violent when the vent.

 

[anumber1]

As the battery voltage drops in use, the chip is going to draw more amperage to maintain the wattage setting.

The ohms law equation becomes a moving target as battery voltage drops, wattage remains constant, amperage drawn goes up.

In no case is the 6.8A max, not high drain Panasonic NCR18650B battery a good choice.

It is just not the right battery for the aplication.

You need a high drain battery capable of at least 12a max draw.

 

[Papa Lazarou]

You always lose a bit in the voltage conversion as well. No chip is 100% efficient. Samsung and LG both have relatively high capacity batteries (2500mah) which are available and can easily provide sufficient current.

 

[Agamer]

As the battery voltage drops in use, the chip is going to draw more amperage to maintain the wattage setting.

The ohms law equation becomes a moving target as battery voltage drops, wattage remains constant, amperage drawn goes up.

I have only used a vtc4 in the cana (and after your answers have no plans to do something other than that) but It made me think about how this is calculated when I came across the old ncr18650b that I used to use when I used the same 1.9 ohm kayfun on a mech and it made me curious.

But I do have a question about the quoted part of your post in more of a theroycrafting direction and in an effort to understand more.

How does it draw more amperage does it simulate a lower resistance therefore pulling current out of the battery or does it just make the chip work harder to boost the power near the end of the batteries life. Again this results in two different components being stressed based on the answer.

In the case of the chip working harder to boost the current within itself the chip is stressed and in the case of the battery having more drawn from it quickly the battery is stressed.

Again thank you for the answers it is more of a for curiosity sake now vs can I use this battery in this application since the answer seems to be a no

 

[anumber1]

It is not really stressing anything to do what it does.

The Evolv and it's clone the Cana chip operate like an amplifier circuit basically. It is a high frequency, low voltage amplifier at heart, capable of delivering high current.

 

[Agamer]

So the chip is where the magic happens then. It does bring me back to my original question though what numbers do you use to determine amp draw the screen readout or the actual battery voltage?

 

[anumber1]

So the chip is where the magic happens then. It does bring me back to my original question though what numbers do you use to determine amp draw the screen readout or the actual battery voltage?

Actual battery voltage is used for the amp draw calculations. Then, add 15 to 20% for circuit loss of the amplifier. I have not been able to find a schematic of the circuit. I imagine Evolv has kept that close to their vest but that should be a ballpark loss figure.

 

[anumber1]

Ten characters

 

[AzPlumber]

You can use the battery drain module of Steam Engine to calculate the current draw on your battery. Just input your parameters and it will tell you the amp draw at the coil and battery. You can also change the regulator's efficiency percentage to simulate whatever.

Battery drain | Steam Engine | free vaping calculators

 

[Agamer]

You can use the battery drain module of Steam Engine to calculate the current draw on your battery. Just input your parameters and it will tell you the amp draw at the coil and battery. You can also change the regulator's efficiency percentage to simulate whatever.

Battery drain | Steam Engine | free vaping calculators

OK that calculator is neat thank you

 

[anumber1]

Cool calculator. Thanks!

 

[Ryedan]

You can use the battery drain module of Steam Engine to calculate the current draw on your battery. Just input your parameters and it will tell you the amp draw at the coil and battery. You can also change the regulator's efficiency percentage to simulate whatever.

Battery drain | Steam Engine | free vaping calculators

You know, I've been using the Steam Engine calulators for Ohm's law and coil building for a while now and never saw this one. Thank you AzPlumber!

The way to manually calculate battery draw for a regulated mod is to plug the watts and battery voltage into a Ohm's law calculator, then add a percentage to the amps given for regulator inefficiency. This calculator makes it so much easier . The battery list is also a very nice feature.

 

[Agamer]

Thank you all very much for your input patience and knowledge. I have learned a new way to calculate battery usage using a regulated mod.

That's why I love this place odds are if you have a genuine question some one will have the answer and you can learn whatever you are looking for.

A gamer

 

[KenD]

The way to manually calculate battery draw for a regulated mod is to plug the watts and battery voltage into a Ohm's law calculator, then add a percentage to the amps given for regulator inefficiency. This calculator makes it so much easier . The battery list is also a very nice feature.

But, shouldn't it be more complicated than that though? As the voltage of the battery drops, and the wattage remains the same, the resistance doesn't drop. With a 0.5 ohm coil, what's the amp draw at 30 watts on a 4.2v charge vs a 3.4v charge? It should be higher at 3.7v, or am I wrong?

EDIT: sorry, I hadn't actually used steam engine before. Great to see that you can actually calculate the real amp draw on a regulated device. Would love to see the formula of how to calculate though.