Amperage

[Mden89]

So I have these sony VTC4 batteries with a CDR of 30amps. If I build a .15 coil on a mechanical mod, at full charge id be pushing 28amps. Technically I wouldn't be pushing the battery over its limits, but 2 amps is pretty close.

My question is: How will this effect the battery? Will the battery wear faster? Is this safe?

 

[IMFire3605]

So I have these sony VTC4 batteries with a CDR of 30amps. If I build a .15 coil on a mechanical mod, at full charge id be pushing 28amps. Technically I wouldn't be pushing the battery over its limits, but 2 amps is pretty close.

My question is: How will this effect the battery? Will the battery wear faster? Is this safe?

Yes, any time you heat the battery up by reaching its maximum or close to maximum output, changes its chemical make up, decreases is life cycle. Reaching max output also drains the charge fast, thus requiring more recharging cycles, Li-Ion batteries are generally only rated a life expectancy of 200 to 500 duty (charge - discharge) cycles depending on model and brand, average 250 to 300 cycles.

 

[Mden89]

Yes, any time you heat the battery up by reaching its maximum or close to maximum output, changes its chemical make up, decreases is life cycle. Reaching max output also drains the charge fast, thus requiring more recharging cycles, Li-Ion batteries are generally only rated a life expectancy of 200 to 500 duty (charge - discharge) cycles depending on model and brand, average 250 to 300 cycles.

Excellent thank you. Just wanted to double check

 

[ian-field]

If you go under 2Ω and over 10w you'll shoot your eye out.

0.15R isn't far short of a short circuit, and lithium batteries can react badly to being shorted - they can vent with flaming gas!

My setup is a basic single cell 3.6V unit and I usually wind coils for 10x that resistance, the batteries are safe at that loading, but they're not going to last a *HUGE* length of time even at that current draw.

 

[K_Tech]

If you go under 2Ω and over 10w you'll shoot your eye out.

Thanks? I don't appreciate your condescending comment. I come here to get advice from people with more experience. If you don't have anything to contribute then kindly see your way to another thread.

"We" can collectively be a bunch of smart alecs, I wouldn't sweat it. Your question is one that is often asked, and one that can often lead to "you're gonna die!!" comments. Don't take it personally if someone chimes in from the peanut gallery, we're just trying to get ahead of the doomsayers, lol.

That being said, I'd be careful, depending on what you're using to check your resistance. I know the accuracy (or inaccuracy, rather) of my el-cheapo atomizer ohm reader is, and I know that if mine read 0.15, I'd be over the amp limit for my Sonys because it reads 0.03 high. That's just me. If you're gonna build that low, pay very close attention to what your battery is telling you. Heat is the enemy, and can make bad things happen. Don't want to tell you what to do, but do go into it with your eyes and ears open, please.

Yes, any time you heat the battery up by reaching its maximum or close to maximum output, changes its chemical make up, decreases is life cycle. Reaching max output also drains the charge fast, thus requiring more recharging cycles, Li-Ion batteries are generally only rated a life expectancy of 200 to 500 duty (charge - discharge) cycles depending on model and brand, average 250 to 300 cycles.

Well said. For lack of a better term, I'll call it "microdamage". It's cumulative, and it will decrease a battery's performance, capacity, and lifespan. All things being equal, a battery discharged at high current and recharged from low voltage will expire faster than one discharged at moderate current and recharged at 50% capacity remaining.

 

[Susan~S]

I try to never exceed 50% of the CDR (continuous discharge rating) of a fully charged battery (4.2v). So with a 30A battery, that would be 15A. This Ohm's Law Calculator tells me that a .28 ohm build is as low as I would want to use.

The reason that I place a 50% limit is because as a battery ages the mAh of the battery degrades, as the mAh degrades so does the batteries c rating (amp limit). So down the road, a 30A battery may only be a 15A battery."

 

[ian-field]

"We" can collectively be a bunch of smart alecs, I wouldn't sweat it. Your question is one that is often asked, and one that can often lead to "you're gonna die!!" comments. Don't take it personally if someone chimes in from the peanut gallery, we're just trying to get ahead of the doomsayers, lol.

That being said, I'd be careful, depending on what you're using to check your resistance. I know the accuracy (or inaccuracy, rather) of my el-cheapo atomizer ohm reader is, and I know that if mine read 0.15, I'd be over the amp limit for my Sonys because it reads 0.03 high. That's just me. If you're gonna build that low, pay very close attention to what your battery is telling you. Heat is the enemy, and can make bad things happen. Don't want to tell you what to do, but do go into it with your eyes and ears open, please.
.

The digital multimeter I use for checking coils has no provision for nulling out the resistance of the test leads which adds in series with that of the coil - the meter is getting on a bit and the contact resistance of the plugs on the front of the meter can vary a bit too, so I not only have to take that into account each time - I have to check it each time as well.

It came up in another thread about a set up with Ohms and current readout can give crazy readings if crud builds up on the contacts between the battery and head.

 

[Mden89]

"We" can collectively be a bunch of smart alecs, I wouldn't sweat it. Your question is one that is often asked, and one that can often lead to "you're gonna die!!" comments. Don't take it personally if someone chimes in from the peanut gallery, we're just trying to get ahead of the doomsayers, lol.

That being said, I'd be careful, depending on what you're using to check your resistance. I know the accuracy (or inaccuracy, rather) of my el-cheapo atomizer ohm reader is, and I know that if mine read 0.15, I'd be over the amp limit for my Sonys because it reads 0.03 high. That's just me. If you're gonna build that low, pay very close attention to what your battery is telling you. Heat is the enemy, and can make bad things happen. Don't want to tell you what to do, but do go into it with your eyes and ears open, please.



Well said. For lack of a better term, I'll call it "microdamage". It's cumulative, and it will decrease a battery's performance, capacity, and lifespan. All things being equal, a battery discharged at high current and recharged from low voltage will expire faster than one discharged at moderate current and recharged at 50% capacity remaining.

im using a Drok ohm tester. It reads .18 ( I was using .15 as a low deviation number as I know the builds and readings can vary +-.2 ohms). Is this a cheap tester? The device is firing fine and im within my amperage limitations. I don't mind the batteries draining faster. I have two of these sony vtc4 batteries I dedicate specifically for mechanical mods. I kind of assumed they would die out faster

 

[K_Tech]

im using a Drok ohm tester. It reads .18 ( I was using .15 as a low deviation number as I know the builds and readings can vary +-.2 ohms). Is this a cheap tester? The device is firing fine and im within my amperage limitations. I don't mind the batteries draining faster. I have two of these sony vtc4 batteries I dedicate specifically for mechanical mods. I kind of assumed they would die out faster

The only information I could find on those testers did not specify its accuracy. However, both models I saw with the DROK logo are very similar to all the other mass-produced Chinese ohm readers. I can say they're inexpensive, but I can't say if they're cheap or not.
For the most part, the accuracy of these testers are usually stated as a percentage or an actual ohm value, sometimes both. Since I can't find any specs on the DROK, I wouldn't feel comfortable pushing really low resistance without being able to double check.
As a quick check, turn your meter on and stick a paper clip (or some wire) into the 510 connection to short it out. That will show you the internal resistance of the meter. If it jumps from zero to some value (let's say it jumps from zero to 0.03) use the higher number to subtract from what it's reading when your atomizer is attached, and that should be pretty close to its actual resistance.
I'm part geek, so I checked mine against a high-dollar, calibrated micro ohm meter, even though I'm rarely below 0.3 ohms.

 

[Mden89]

The only information I could find on those testers did not specify its accuracy. However, both models I saw with the DROK logo are very similar to all the other mass-produced Chinese ohm readers. I can say they're inexpensive, but I can't say if they're cheap or not.
For the most part, the accuracy of these testers are usually stated as a percentage or an actual ohm value, sometimes both. Since I can't find any specs on the DROK, I wouldn't feel comfortable pushing really low resistance without being able to double check.
As a quick check, turn your meter on and stick a paper clip (or some wire) into the 510 connection to short it out. That will show you the internal resistance of the meter. If it jumps from zero to some value (let's say it jumps from zero to 0.03) use the higher number to subtract from what it's reading when your atomizer is attached, and that should be pretty close to its actual resistance.
I'm part geek, so I checked mine against a high-dollar, calibrated micro ohm meter, even though I'm rarely below 0.3 ohms.

I couldn't get your paper clip trick to work, however when I test the atty out 10 times in a row, it will read either .16 or .18 (.18 seven times and .16 three times). Both of these resistances are within the limitations of the fully charged battery

 

[ian-field]

The only information I could find on those testers did not specify its accuracy. However, both models I saw with the DROK logo are very similar to all the other mass-produced Chinese ohm readers. I can say they're inexpensive, but I can't say if they're cheap or not.
For the most part, the accuracy of these testers are usually stated as a percentage or an actual ohm value, sometimes both. Since I can't find any specs on the DROK, I wouldn't feel comfortable pushing really low resistance without being able to double check.
As a quick check, turn your meter on and stick a paper clip (or some wire) into the 510 connection to short it out. That will show you the internal resistance of the meter. If it jumps from zero to some value (let's say it jumps from zero to 0.03) use the higher number to subtract from what it's reading when your atomizer is attached, and that should be pretty close to its actual resistance.
I'm part geek, so I checked mine against a high-dollar, calibrated micro ohm meter, even though I'm rarely below 0.3 ohms.

The industry standard method for measuring very low resistances, is to start with a calibrated current source. Pass a known current through the resistance and measure what voltage is developed - knowing the current and voltage; you can use Ohm's law to calculate the exact resistance.

The means are at my disposal to do this, but it hasn't so far seemed *ALL THAT* important.

At a guess, a low power LED drive module runs on the constant current principle - as long as it produces the *SAME* current every time, all you need do is pass it through a known accurate resistor in the same ball-park as the coils you're going to wind so you can calculate that current from the voltage it develops. Once you know the current value, its used in all future calculations to find resistance.

 

[lovemytank]

We do not CDR when vaping, only momentary discharges. Get some 25+ amp CDR batteries and you should be fine unless you are going below .2ohms or above 80w. Thats what I do all day and my batteries never even get warm. I am using a sig 150w though.

 

[ian-field]

We do not CDR when vaping, only momentary discharges. Get some 25+ amp CDR batteries and you should be fine unless you are going below .2ohms or above 80w. Thats what I do all day and my batteries never even get warm. I am using a sig 150w though.

Its probably worth mentioning in passing; lithium emergency start booster packs for cars have started turning up on the market - they basically have to supply the cranking voltage for a few seconds, I was astonished by how small they actually are!

 

[VHRB2014]

IDK, How long does a hi-po motor last when pushed to its limits until it goes up in pieces?
(Asw: no one knows, until it goes!)

It IS recommended that you leave at least 30% headroom for safety.

 

[Mden89]

We do not CDR when vaping, only momentary discharges. Get some 25+ amp CDR batteries and you should be fine unless you are going below .2ohms or above 80w. Thats what I do all day and my batteries never even get warm. I am using a sig 150w though.

Your thumbnail pic is sweet! Im using 30A sony VTC4 batteries.

 

[lovemytank]

According to the US NEC, code gov for electricians, amps are rated 100% for momentary and 125% for continuous motors. We are allowed to upsize circuit breakers if a ramp up amperage to too great to start said sizing. Lots of wiggle room. If a solid 50A 18650 came out I would buy it, but for know I am completely comfortable with my 25rs.

 

[beckdg]

I try to never exceed 50% of the CDR (continuous discharge rating) of a fully charged battery (4.2v). So with a 30A battery, that would be 15A. This Ohm's Law Calculator tells me that a .28 ohm build is as low as I would want to use.

The reason that I place a 50% limit is because as a battery ages the mAh of the battery degrades, as the mAh degrades so does the batteries c rating (amp limit). So down the road, a 30A battery may only be a 15A battery."

Not a bad practice.

But far from a hard rule.

As the energy density decreases so does the potential for danger and the cells ability to deliver that energy (by any means) greatly decrease.

As the current decreases so does the potential for danger and the cells ability to deliver that energy (by any means) greatly decrease.

As the charge current decreases so does the potential for danger and the cells likelyhood to release violently that energy greatly decrease.

By the time you've lost more than probably 10% of the capacity of a battery that's being pushed a little, the performance will likely suffer to the point the user wishes to discard and replace it anyway.

Remember, the greatest potential for danger or catastrophic failure exists when the energy density and pathway for release are greatest and least restricted, respectively.

This means when the cell is at or near full capacity and new or fairly new/healthy.

Tapatyped

 

[StonyArtichoke]

When below .8 ohms I put my batteries on low current (300 ma) when they reach around 3.7 volts as to not stress them. Also if you chain vape you may notice your gear warming up. It could be heat transfer from your hand, your atomizer transferring heat and not necessarily the battery causing the warmth. Even then once I notice the warmth I let the mod and battery cool separately and vape on something else for a bit.

 

[beckdg]

According to the US NEC, code gov for electricians, amps are rated 100% for momentary and 125% for continuous motors. We are allowed to upsize circuit breakers if a ramp up amperage to too great to start said sizing. Lots of wiggle room. If a solid 50A 18650 came out I would buy it, but for know I am completely comfortable with my 25rs.

Electrical and Electronic engineers are different as are electricians and their regulations.

Motors and batteries work different.

There is no standard that defines peak or momentary for lithium battery specs.

The time frame alone may vary from nanoseconds to 10 or more seconds from one mfr to the next.

There also could be extreme laboratory cooling methods deployed to determine these standards.

Furthermore, these cells aren't mfr'd in the US and don't adhere to US standards in general.

Even continuous ratings are ambiguous as to their true interpretation and by what means they were determined.

Tapatyped

 

[WharfRat1976]

So I have these sony VTC4 batteries with a CDR of 30amps. If I build a .15 coil on a mechanical mod, at full charge id be pushing 28amps. Technically I wouldn't be pushing the battery over its limits, but 2 amps is pretty close.

My question is: How will this effect the battery? Will the battery wear faster? Is this safe?

Here is what I think about. If your coils for some reason drop to 0.75 ohms your amp draw increases to 58 amps. Let me know how that works out. Be safe out there.