Difference between nominal voltage and displayed voltage

[meph1]

Hey Guys!
So im using an efest 20A continous discharge battery.

My question is: It reads 4.14V on 35W,with a 0.5 (0.49) R.
If memory serves, thats 8.4A continous discharge for chain vaping.
BUT! The battery reads a nominal voltage of 3.7V. Does it has anything to do with the voltage on the display? Am I safe? Or is it the voltage level i should charge the battery on/to

Thank you!

 

[bombastinator]

The VV mods generally use boost/buck circuits to alter voltage.
Buck–boost converter - Wikipedia

 

[bwh79]

"Nominal" voltage is used, because as a cell discharges, its actual voltage varies from moment to moment. The cells we use go up to about 4.2v at full charge, and down to around 3.2 when they need to be recharged. "Nominal" voltage is just halfway between those two extremes. It's what we "call" the voltage ("nominal" just means "what it's named"), just so that we can assign it a specific number instead of a range of values.

The voltage displayed on your device's screen is likely the output voltage. This doesn't have anything to do with your battery's charge state, this is the voltage delivered to the atomizer by the computer chip inside of the device. But, the whole point of having that chip in the first place is to "regulate" the voltage i.e. change it from what it is at the battery, to something else. You don't say what device you're using, but many of them have some button combination that will display the battery voltage, but it's not usually shown in the main info screen.

 

[Topwater Elvis]

The battery itself has a nominal voltage of 3.7, full charged 4.2.

The batteries supply power to the 'chip' / regulator / buck boost circuitry / magic gizmo board, it supplies power to the delivery device.
The readings on the display are output to the delivery device.

I'd ditch the efest & get quality name brand cells.

 

[meph1]

"Nominal" voltage is used, because as a cell discharges, its actual voltage varies from moment to moment. The cells we use go up to about 4.2v at full charge, and down to around 3.2 when they need to be recharged. "Nominal" voltage is just halfway between those two extremes. It's what we "call" the voltage ("nominal" just means "what it's named"), just so that we can assign it a specific number instead of a range of values.

The voltage displayed on your device's screen is likely the output voltage. This doesn't have anything to do with your battery's charge state, this is the voltage delivered to the atomizer by the computer chip inside of the device. But, the whole point of having that chip in the first place is to "regulate" the voltage i.e. change it from what it is at the battery, to something else. You don't say what device you're using, but many of them have some button combination that will display the battery voltage, but it's not usually shown in the main info screen.

Ah, thank you! I use an eleaf istick pico though. So after all, im safe at 4.2 or so voltages?

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[meph1]

The battery itself has a nominal voltage of 3.7, full charged 4.2.

The batteries supply power to the 'chip' / regulator / buck boost circuitry / magic gizmo board, it supplies power to the delivery device.
The readings on the display are output to the delivery device.

I'd ditch the efest & get quality name brand cells.

What do you say would be cool? I used a Sony VTC5 before.

 

[Topwater Elvis]

Sony vtc5A must be 'A' would allow you to use the full power range of the Pico safely.

 

[bwh79]

Ah, thank you! I use an eleaf istick pico though.

On the pico, you can turn it off (5x clicks of the fire button), then hold the fire and minus buttons for a few seconds to display the battery voltage (charge state.) Or, if you put it in "bypass" mode (3x clicks of the fire button while turned on to enter the menu, select "Bypass," press fire to confirm selection) it will show charge state as well. Be aware that in bypass mode, it does not regulate voltage, instead it behaves much like a mech mod and delivers raw battery power.

So after all, im safe at 4.2 or so voltages?

Yes the battery should read 4.2v at full charge. The output voltage on a regulated device doesn't really factor in. Amp draw is determined by the battery voltage (charge state) and watts setting. On a mech/unregulated device, it's voltage and atomizer resistance (ohms) that make the call. In this case, "voltage" refers to both the battery and output voltages, because the voltage is not regulated; what goes in equals what comes out.

using an efest 20A continous discharge battery.

Efests aren't really the "cream of the crop" when it comes to battery brands (they're not really a brand, they buy cheap "b-bin" cells from other brands and put their own labels on) but presuming it is what it says it is and has a true 20A discharge capability, then it should be safe up to about 60 watts in wattage mode, or down to 0.21 ohms on a mech mod or unregulated device. Note that these values will put you right at the 20A discharge rate, so there will be no margin for error. Most people keep a bit shy of these ranges, for that reason. Battery life will suck at that level, anyway.

That looks safe to me. 35w is just over half of the maximum safe wattage for a 20A battery. You should have plenty of room to play around.

I agree with Topwater Elvis, though, about getting a new battery. The one you have should be "pretty safe" but a VTC5A would be even better. Right now they're 5.99 on illumn.com. Get a pair (or two) and an external charger (~$20) so you can use one while the other(s) is/are charging. You won't regret it.

(Oh, I just realized you might not be in the US. So you probably don't want to buy from Illumn, even if you could. @Mooch's charts have a list of trusted vendors both for US and UK customers, perhaps you can buy from one of those?)

 

[meph1]

since this post “happened”, some things just went by:
i got to known mooch, im buying 2xVTC5(~9USD here), xtar chargers(like 5 bucks here) and a case for my mod and one for the unused, secondary battery.
and im kinda affraid to vape now since i read a lot of stories about how ....ty efest batteries were, but they are not that bad now, still i mind losing half of my face. i can only go to a store next week, so uh thanks guys [emoji1]


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[meph1]

On the pico, you can turn it off (5x clicks of the fire button), then hold the fire and minus buttons for a few seconds to display the battery voltage (charge state.) Or, if you put it in "bypass" mode (3x clicks of the fire button while turned on to enter the menu, select "Bypass," press fire to confirm selection) it will show charge state as well. Be aware that in bypass mode, it does not regulate voltage, instead it behaves much like a mech mod and delivers raw battery power.


Yes the battery should read 4.2v at full charge. The output voltage on a regulated device doesn't really factor in. Amp draw is determined by the battery voltage (charge state) and watts setting. On a mech/unregulated device, it's voltage and atomizer resistance (ohms) that make the call. In this case, "voltage" refers to both the battery and output voltages, because the voltage is not regulated; what goes in equals what comes out.


Efests aren't really the "cream of the crop" when it comes to battery brands (they're not really a brand, they buy cheap "b-bin" cells from other brands and put their own labels on) but presuming it is what it says it is and has a true 20A discharge capability, then it should be safe up to about 60 watts in wattage mode, or down to 0.21 ohms on a mech mod or unregulated device. Note that these values will put you right at the 20A discharge rate, so there will be no margin for error. Most people keep a bit shy of these ranges, for that reason. Battery life will suck at that level, anyway.


That looks safe to me. 35w is just over half of the maximum safe wattage for a 20A battery. You should have plenty of room to play around.

I agree with Topwater Elvis, though, about getting a new battery. The one you have should be "pretty safe" but a VTC5A would be even better. Right now they're 5.99 on illumn.com. Get a pair (or two) and an external charger (~$20) so you can use one while the other(s) is/are charging. You won't regret it.

(Oh, I just realized you might not be in the US. So you probably don't want to buy from Illumn, even if you could. @Mooch's charts have a list of trusted vendors both for US and UK customers, perhaps you can buy from one of those?)

thank you, well i know how to use the pico ( i own the second one since september, killed first one so.. ) but the first came with a VTC5, which is sitting there for months, so im nkt really into using it again, im buying a new one instead and find a recycling plant to get rid of the old VTC and this Efest


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[Ionori]

A few months shouldn't have a significant impact on a battery's performance, provided it hasn't dipped significantly below 3 volts, I would recommend popping it into the mod, and if it powers on using it for a few discharge cycles to check if you like the performance before disposing of it.

 

[meph1]

Guys! One more question: Im using the bypass mode to check the voltage of the battery, trying to recharge it when it gets near between 3.6-3.4 (well today only had chance to do this at 3.28..).
So what do you recommend, how much should i charge it? Go up until 4.20 or stop a bit below?

 

[untar]

In wattage mode the voltage display just shows what the mod will be firing at. It has next to nothing to do with your battery, there is a regulator board between your battery and the atomizer and the displayed voltage is meaningless for what happens with the battery.
All that matters is what power setting and which mod (more importantly its low battery voltage cutoff) you use, from there you can calculate what the CDR of your battery should be.
For your single battery pico

35.0W/3.2V = 10.94A (3.2V being the voltage at which the pico will tell you the battery is empty)

so the batteries you're using should have at least 11A CDR rating, if you're using one with a higher rating there's no problem. Mooch's blog is a good place to inform yourself about the measured/real CDR in contrast to the label CDR which are sometimes exaggerated.
Mooch's blog | E-Cigarette Forum

 

[Topwater Elvis]

Guys! One more question: Im using the bypass mode to check the voltage of the battery, trying to recharge it when it gets near between 3.6-3.4 (well today only had chance to do this at 3.28..).
So what do you recommend, how much should i charge it? Go up until 4.20 or stop a bit below?

Why?
I'd let the Pico's low voltage cut off determine when to charge & I'd always fully charge / 4.2v.

Not letting it discharge to the Pico's low voltage cut off and discontinuing charge before 4.2v might add a few recharge cycles to the cells life span.
If it is safety you're concerned about that's why regulated power devices have built in safety features such as low voltage cut off / over discharge & over charge protections.

 

[Eskie]

Guys! One more question: Im using the bypass mode to check the voltage of the battery, trying to recharge it when it gets near between 3.6-3.4 (well today only had chance to do this at 3.28..).
So what do you recommend, how much should i charge it? Go up until 4.20 or stop a bit below?

There's really no need to go to bypass mode just to check the voltage........

Oh well, no point finishing this post as @Topwater Elvis just sniped me. What Topwater just wrote

 

[meph1]

There's really no need to go to bypass mode just to check the voltage........

Oh well, no point finishing this post as @Topwater Elvis just sniped me. What Topwater just wrote

I just like to be sure...

Why?
I'd let the Pico's low voltage cut off determine when to charge & I'd always fully charge / 4.2v.

Not letting it discharge to the Pico's low voltage cut off and discontinuing charge before 4.2v might add a few recharge cycles to the cells life span.
If it is safety you're concerned about that's why regulated power devices have built in safety features such as low voltage cut off / over discharge & over charge protections.

Ok, i can see that now

In wattage mode the voltage display just shows what the mod will be firing at. It has next to nothing to do with your battery, there is a regulator board between your battery and the atomizer and the displayed voltage is meaningless for what happens with the battery.
All that matters is what power setting and which mod (more importantly its low battery voltage cutoff) you use, from there you can calculate what the CDR of your battery should be.
For your single battery pico

35.0W/3.2V = 10.94A (3.2V being the voltage at which the pico will tell you the battery is empty)

so the batteries you're using should have at least 11A CDR rating, if you're using one with a higher rating there's no problem. Mooch's blog is a good place to inform yourself about the measured/real CDR in contrast to the label CDR which are sometimes exaggerated.
Mooch's blog | E-Cigarette Forum

Thank you, im aware of the math, but im still a beginner (has literally no more vapers around me, so..), so thanks for the breakdown for later use.

Thanks everyone, you guys were fast & helpful as always. <3