Why is voltage drop unsafe?

[ghh3rd]

How do you know when it's time to recharge or swap out your battery on a mechanical mod?

I was researching possible safety issues with 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

 

[edyle]

How do you know when it's time to recharge or swap out your battery on a mechanical mod?

I was researching possible safety issues with 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

when people talk about 'voltage drop' on a mech mod, they are referring to lost voltage due to for example contact resistance.

So if you have a battery which measures out at 4.2 volts but when you actauly fire it on a low ohm coil, the voltage is 3.9 volts, that means you are getting a voltage drop of 0.3 volts on that coil.

 

[Train2]

Yeah, there's some terminology confusion.
"Voltage drop" is a term that refers to the loss of voltage between the battery and atomizer. It's a measurement of how INEFFICIENT your mod is. If there's a HUGE voltage drop, I guess that indicates something's wrong - but usually it's just something you want to minimize.

Now running a battery really low isn't good - but that's just draining a battery, not "voltage drop".

 

[roxynoodle]

What Edyle said

The question you're actually asking is about knowing when to change your battery. I don't let mine get below 3.5, but generally on a mech, I'm swapping out a little sooner (3.6-3.7) because that's when the quality of my vape falls off.

 

[Robert Cromwell]

Voltage drop can generate heat at the loss point and cause problems. Depends on how much drop there is. If it at the end of the battery and gets the battery too hot then is is a bad thing.

 

[93gc40]

Voltage drop in and of itself is not unsafe, quit the opposite is true. The Cause of Voltage drops Can be unsafe, when they are due to bad connections and shorts.

 

[Nomoreash]

Along with many other variables, most of which has already been mentioned it can also be a sign of the batteries condition. Batteries that have seen a lot of use and went through many recharging cycles will have a larger drop under load than a new battery.

 

[Baditude]

Lithium batteries should not be drained below 3.0 volts. Draining them past 2.5 volts could be detrimental to the life of the battery so that it can not be recharged --> dead battery.

The thing that can be most dangerous when sub-ohm vaping with a mechanical mod is to build so low that the coil will pull more amps from the battery than it has to give, overtaxing it and forcing it into thermal runaway.

For instance, 0.5 ohms will pull 8.4 amps from the battery -- fine for a 10 amp battery. 0.4 ohms will pull 10.5 amps, which is over the 10 amp battery's limit. Pulling more amps than the battery has to give can cause it to go into thermal runaway, which is death to the battery and potentially dangerous to you and others.

1.0 ohm = 4.2 amp draw
0.9 ohm = 4.6 amp draw
0.8 ohm = 5.2 amp draw
0.7 ohms = 6 amp draw
0.6 ohms = 7 amp draw
0.5 ohms = 8.4 amp draw
0.4 ohms = 10.5 amp draw
0.3 ohms = 14.0 amp draw
0.2 ohms = 21.0 amp draw
0.1 ohms = 42.0 amp draw
0.0 ohms = dead short = battery goes into thermal runaway

Explain It To the Noob: Ohms Law Calculations

Battery Basics for Mods <-- list of high drain batteries and amp limits

Deeper Understanding of Mod Batteries

 

[93gc40]

Voltage drop can generate heat at the loss point and cause problems. Depends on how much drop there is. If it at the end of the battery and gets the battery too hot then is is a bad thing.

your NOT describing a voltage drop.. You are discribing a short and or bad connection.. The voltage drop is just a symptom that MIGHT accompany the underlining issues.

 

[Robert Cromwell]

your NOT describing a voltage drop.. You are discribing a short and or bad connection.. The voltage drop is just a symptom that MIGHT accompany the underlining issues.

True, voltage drop is due to either internal battery resistance or wiring resistance or a bad connection. Few connections are perfect though. Atomizer connection and each end of the battery plus the switch connections.