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Why is voltage drop unsafe?
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ghh3rd Offline
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Post: #1
Why is voltage drop unsafe?
How do you know when it's time to recharge or swap out your battery on an unregulated mechanical mod?

I was researching possible safety issues with building a mechanical mod, and am confused. 

I read about watching that battery voltage doesn't drop too low... or it gets unsafe.  But:

If I have a battery at 4.0 volts with a .5 ohm coil, I should be drawing 8.0 amps.
If I have a battery at 3.0 volts with a .5 ohm coil, I should be drawing 6.0 amps.

I thought that the only reason not to draw down the volts too low was to keep from ruining the battery.  Why is voltage drop on a mech mod unsafe?

Thanks,

Randy
09-05-2015 04:40 AM
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Michael Offline
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Post: #2
RE: Why is voltage drop unsafe?
Just to clarify, the term "volt drop" refers to the drop in voltage due to the internal resistance of the mod, not the same thing as letting the battery drain. Volt drop isn't unsafe, it just means that a particular mod isn't as efficient and thus won't produce quite as big of clouds. 

Letting the voltage drain too low isn't necessarily unsafe. It will put more strain on the cell, which isn't usually unsafe unless you're at low resistance where the cell already has a fair amount of stress to begin with. 

I could be wrong though, hopefully one of the battery experts will come along and help out. I really don't think that it's really unsafe, just unwise because you'll kill your cells much faster than if you just charge them when they need it instead of running them down super low. 

As far as knowing when to charge, it's just trial and error really. You might want to measure the voltage every now and then to get an idea for how long it takes to drain, and after a while you'll just know. I can usually tell when my cells are getting low just by the way it's performing. Mech mods will put out less power and therefore less vapor as the cells drain, so you can tell pretty easily when it's time to charge just by how much vapor it's creating and how long it takes to heat the coils. 
09-05-2015 06:31 AM
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ghh3rd Offline
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Post: #3
RE: Why is voltage drop unsafe?
Thanks for the answer...
09-05-2015 02:28 PM
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Don Online
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Post: #4
RE: Why is voltage drop unsafe?
On a regulated mod, letting the voltage go too low could easily get into unsafe territory if it wasn't that they will all cut out when the cell voltage gets too low.

TVF tested battery info to be found here

http://www.preventsuicideapp.com

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10-05-2015 10:29 AM
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Nihilum Offline
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Post: #5
RE: Why is voltage drop unsafe?
On an unregulated box...the easiest way to tell is when the ramp up time starts to get longer.  I vape on 2 unregulated mods...a triple 26650 parallel and a double 26650 series.  Both act the same when it's time to charge the batteries....the ramp up time starts to get longer.  At that point I throw them on the charger and they're usually sitting at 3.6.  If you're using a Lithium-ion battery 3.6 is as low as you want to take them.  With IMR batteries they're fine til you hit 3.4.

If you don't usually pay attention to ramp up time, your clouds will start to decrease as well.

Voltage drop is the amount of power lost between the batteries and the atty.

Battery sag is a measure of stress on the battery while under load.
11-05-2015 09:10 AM
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Almost Jaded Offline
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Post: #6
RE: Why is voltage drop unsafe?
Don - PUNCTUATION, MAN!  Holy shit was that hard to sort through, lol.

What Don was saying is, regulated mods will shut off before allowing the batteries to get to an unsafe level.

Remind one liberal per day, that laws affect only the law-abiding.
(This post was last modified: 12-05-2015 04:07 AM by Almost Jaded.)
12-05-2015 04:06 AM
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Don Online
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Post: #7
RE: Why is voltage drop unsafe?
You aren't used to the sort of writing I see often. The sentences are longer than my paragraphs. Tongue

I used to type stuff for a disabled academic philosopher. His paragraphs routinely spanned several pages. And I could know the meaning of every word in one of his 30 line sentences without having the faintest idea what he was talking about.

TVF tested battery info to be found here

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13-05-2015 10:12 AM
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Almost Jaded Offline
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Post: #8
RE: Why is voltage drop unsafe?
I read a lot of Donaldson, Stephenson, and Pynchon.  I can usually hang, lol.

Remind one liberal per day, that laws affect only the law-abiding.
15-05-2015 01:23 AM
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Cman Offline
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Post: #9
RE: Why is voltage drop unsafe?
(09-05-2015 06:31 AM)Michael Wrote:  Just to clarify, the term "volt drop" refers to the drop in voltage due to the internal resistance of the mod, not the same thing as letting the battery drain. Volt drop isn't unsafe, it just means that a particular mod isn't as efficient and thus won't produce quite as big of clouds. 

Letting the voltage drain too low isn't necessarily unsafe. It will put more strain on the cell, which isn't usually unsafe unless you're at low resistance where the cell already has a fair amount of stress to begin with. 

I could be wrong though, hopefully one of the battery experts will come along and help out. I really don't think that it's really unsafe, just unwise because you'll kill your cells much faster than if you just charge them when they need it instead of running them down super low. 

As far as knowing when to charge, it's just trial and error really. You might want to measure the voltage every now and then to get an idea for how long it takes to drain, and after a while you'll just know. I can usually tell when my cells are getting low just by the way it's performing. Mech mods will put out less power and therefore less vapor as the cells drain, so you can tell pretty easily when it's time to charge just by how much vapor it's creating and how long it takes to heat the coils. 


I agree 100% .   Mike is also correct about not allowing these types of cells to drain lower than absolutely needed , it will definitely decrease the batteries lifespan, especially if you do it regularly.
15-05-2015 04:06 AM
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JohnnyMac Offline
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Post: #10
RE: Why is voltage drop unsafe?
You will definitely know when the cell needs a recharge if you pay the slightest attention to your vape. Like others have said heat up time will be longer and performance will not be what it was.
17-05-2015 08:27 PM
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