Battery Amp Limits and Real World Implications?

[mscott]

With all these 20amp batteries that are being sold as 35amp continuous, I see people (even popular reviewers) using them as actual 35amp batteries. My question is, has anyone vented a battery pushing the 20amp limit to 35? If it was as dangerous as some suggest, wouldn't we hear about it more often? I was using the 35amp purple efest before I discovered that they are not as advertised and never had issues.

I know what people will say..its not safe, you are gambling with your face, etc. but what I'm trying to figure out is where on the continuum of danger is it? Like running around the swimming pool (scraped knee), exceeding the speed limit (crash), or playing russian roulette (blow your face off). I've seen all of these responses from people here and I'm just curious if anyone has any knowledge beyond speculation.

I don't know if it's pulsing or voltage drop that allows vapers to push the limits below .1ohm but I'm just trying to learn what the actual limits are before erecting walls of ignorance around my behavior as I was doing before (i.e. diacetyl). I'd be grateful for any kind of fact-based explanation before I put my mechs away and move on to regulated devices. It would do a lot for my mind to know exactly where the cliff is so I don't build false barriers or go tumbling over.

Cheers.

 

[tj99959]

My question is, has anyone vented a battery pushing the 20amp limit to 35?

A few have vented, but there is no way to tell how far they were pushing the amperage after the fact.

For "real world experience":
The problem, as I see it, is that after a battery has a few miles on it the mAh begins to drop off, as the mAh decreases so does the c rating, and the battery isn't even a 20 amp battery anymore.
For that reason I try to never exceed 50% of a batteries CDR. There are more than enough ways to get a great vape at 10 amps or less. (0.4 ohms on a fresh battery)
For example, my Kayfun is pulling a whopping 2.5 amps.

 

[WattWick]

There seems to be a misconception that either a battery vents instantly - or everything is perfectly OK. The fact that the battery didn't vent does not mean you can safely push it even harder the next time. The damage is gradual. A high drain battery repeatedly pushed past its limits will not remain a high drain battery for very long.

To fit the 'cliff analogy' - picture the cliff crumbling away. How far you can walk before falling off is not a constant. Put more weight on it and it crumbles quicker.

 

[skoony]

the truth is just because it can be done doesn't mean it should be.
sub ohming is an extreme carry over from the R/C and flashlight
modders communities whom make abusing batteries part of the hobby.
the first thing these hobbyist learn is how to overcharge their batteries
and adjust there gear to get the maximum amount of current out of
them. the second thing they learn is battery safety.
a battery with a twenty amp max current draw is for a time
no greater than 1 minute(the longest time i have seen actually in a spec.)
before the battery will destroy itself. running at max current also affects
the batteries normal usable life cycle. the spec itself is not a safe spec
to design your circuits for. its given for designers to know that in critical
situations if needed this is what it will do and for how long. its also
important to note that the batteries themselves are actually made to
a higher spec than listed on the battery as a built in extra safety margin.
this is perhaps why some claim there are batteries that will pull 35 amps.
in the end its all about being safe. learn about the batteries and battery
safety first,then max the begeebers out of them.

regards
mike

 

[Thrasher]

The well know batteries that we use are extremly safe if used within their limits
as for pulse ratings I have seen some say 4 to 6 seconds some say 5 to 7.

But even then why some people choose to take a battery to the extreme limits of its output I will never understand.
as far as venting- this actually is the safety feature as long as the mod has vent holes and can release the gas as fast as its made there should be no explosion. The explosions will happen when a mod contains the gas causing pressure to rise.
before vents eere added batteries did actually explode from gas build up.

Every mod I own I try to blow air through from bottom, top, button, etc and check for air flow.

If you pay attention, adhere to common sense, and dont try to drive the battery to its extremes all the time the chance of a popular well known brand failing is very small.

It does happen, but you can see videos on youtube where even when forced into a shorted situation many of the better batteries simply wont vent. So with that in mind it makes me wonder how hard people with problems are really driving these batteries.

It is known while a battery may say 20 amps, constant strain of actually running that hard, does damage and degrade the chemical structure, meaning in 6 months (or whatever) it may very well be the battery can no longer sustain maximum output like it used to.

example of this is I have some batteries here I drove pretty hard for a while. They no longer hold charges as long as they used to and the voltage sag under heavy load is terrible now.

Just know your limits, know your batteries and just be mindful of what we actually do.

People seem to not realize 15 amps is a heck of a lot of current from a tiny tube. And that is a lot of stress. This is Enough to knock down a human and send them to the hospital no problem

But look how many devices use li ion products. Phones, laptops, rc toys, rechargable flashlight cordless tools,etc.
and very few have problems in most cases a bad charger or short causes the issue.

Even with thst in mind many who fear mods with replacable batteries and keep using ego'sego's and other sealed mods seem to forget they are still holding the exact same type of battery in their hand and we dont actually know how well those are made either, cause we cant get them out.lol

 

[Elektrey]

It's a question of what the pulse rating means. Most of the definitions I have seen are more than 5 seconds for definition and the ones that are small are usually something crazy like 120A.

Another thing to consider is that when people say design 35A coils, they are designing them for 4.2V, when in reality you have voltage drop from the mod and atty and also have voltage drop due to the battery under load. So while they design for 35A who knows they might be pushing 25 or 30A.

Battery load ratings also degrade over time and is another thing to take into account.

just my 0.02 from what I've read

 

[edyle]

With all these 20amp batteries that are being sold as 35amp continuous, I see people (even popular reviewers) using them as actual 35amp batteries. My question is, has anyone vented a battery pushing the 20amp limit to 35? If it was as dangerous as some suggest, wouldn't we hear about it more often? I was using the 35amp purple efest before I discovered that they are not as advertised and never had issues.

I know what people will say..its not safe, you are gambling with your face, etc. but what I'm trying to figure out is where on the continuum of danger is it? Like running around the swimming pool (scraped knee), exceeding the speed limit (crash), or playing russian roulette (blow your face off). I've seen all of these responses from people here and I'm just curious if anyone has any knowledge beyond speculation.

I don't know if it's pulsing or voltage drop that allows vapers to push the limits below .1ohm but I'm just trying to learn what the actual limits are before erecting walls of ignorance around my behavior as I was doing before (i.e. diacetyl). I'd be grateful for any kind of fact-based explanation before I put my mechs away and move on to regulated devices. It would do a lot for my mind to know exactly where the cliff is so I don't build false barriers or go tumbling over.

Cheers.

I doubt you will see any 20 amp continuous battery being sold as "35 amp continuous" (except by sayso/hearsay/rumour).

A 2000maH battery x 4 volts = 8000 milliwatthours: say 8 watthours of energy.
If you run a 4 volt battery at 20 amps that's 80 watts.
80 watts x 0.1 hours = 8 watthours.

Continuous amps:
Basically you should be able to run a 2000maH 20ampcontinuous battery at 20 amps continuous for 0.1 hours which is 6 minutes.
After that the battery doesn't have much energy left.

Pulse rating:
The problem with pulse ratings is what definition is being used for a pulse.
For starting a car engine, you get a high initial pulse to crank the engine, then immediately after, the faster the starter motor turns the higher the impedence and back emf, and the current soon goes to almost zero. The initial high amp pulse might just be milliseconds.

This is one of the important applications of amp pulse rating- for electric motors.

In the vaping world, our 'pulse' is a 10 second pulse!! not a millisecond pulse!
Some batteries will report a pulse rating in excess for 100 amps, but that's a millisecond pulse for applications in electric motors on remote controlled vehicle applications.


Now for the 35amp efest, if you left your bottom switch mod on vertically or if there were a short in the mech, but you only have a 0.2 ohm load, the battery should run down in about 5 minutes without a total catastrophic meltdown.

But if you had a 0.12 ohm coil, the battery would have a problem.

Meanwhile, on a 0.12 ohm coil, drawing 35 amps, a 5 or 10 second at a time drain on the battery with breaks in between, isn't going to be as bad and a button stuck for 5 minutes.