Pulse discharge battery ratings aren't going to happen
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I think its the total time, 5 seconds on 30 seconds off rather than the time on load......
The problem with doing a standard for pulse discharge is that the maximum pulse discharge is primarily dependent on the length of the pulse and the recovery period (though other factors exist too). For instance, 5s is too long of a pulse if one is looking at preheat conditions of under 1s. However, the recovery period after a preheat will typically involve some variable discharge, as opposed to no discharge at all. In the end, if someone doesn't know any relevant parameters for how pulse discharge will be used, all one can do is run a massive sweep of battery tests and hope that at least one test will be relevant.
I think there's an element of wishful thinking wanting to believe in pulse ratings.
If a manufacturer produces a battery with a cdr of 30amps but which can be pulsed at 100 amps for 100 milliseconds every second with a 50% loss of longevity (less recharge cycles), he's going to tout the "100 amps" and not mention the downside.
If a manufacturer produces a battery with a cdr of 30amps but which can be pulsed at 100 amps for 100 milliseconds every second with a 50% loss of longevity (less recharge cycles), he's going to tout the "100 amps" and not mention the downside.
In practice, I agree with you. Stay within the CDR for greatest lifespan and safety. In fact, (as I always state), I use a 50% safety factor on the CDR. It just makes me happier and more confident about having that thing near my really expensive teeth.
Technically, if you stay within the specification of the pulse rating, you're fine.
But pulse rating specs vary so widely that you really need to do some highly technical research to determine that. And of course, you can't use the pulse rating at all if it was calculated using millisecond pulses. Even if they were multiple second pulses, you always have to be careful to give it the stated cool-down time--and not use it in conditions where cool-down can't happen quickly enough.
Functionally, I agree with you--repeat the In Practice section above here.
5 sec on / 35 sec total time = 0.142 duty cycle
20A * 0.142 = 2.84A equivalent continuous discharge
80 min = 1.33 hours
2.84A x 1.33 hours = 3.78Ah, just about right for a 26650.
Thanks much Brother Mooch 
and YES!
It most DEFINITELY is;
(a Spy Capture Photo from Brother Mooch's Laboratory perhaps?)
and YES!
It most DEFINITELY is;
(a Spy Capture Photo from Brother Mooch's Laboratory perhaps?)
Only down to 100mS and that's only for one of my loads. Unfortunately, it's the one that doesn't have the graphical interface so I have to set up the other to just monitor voltages...a big pain. I agree it would be interesting to see the results though. If I can ever get out of the backlog of tests that has built up, now several weeks long, I think this would be worth exploring. Perhaps by modifying my LE80 mod and just monitoring its voltages.
Thanks much Brother Mooch
and YES!
It most DEFINITELY is;
View attachment 523579
(a Spy Capture Photo from Brother Mooch's Laboratory perhaps?)
Arrgghh...who hacked my web cam!
Perhaps you could just switch a FET with a timer circuit at the required frequency then connect it to your normal continual discharge setup? Not trying to make more work for you, you do enough already!
That was about what I was going to do until I remembered that the LE80 already has the circuit in it. I don't mind modding it as it's easy to unmod it again after testing is done.
That was about what I was going to do until I remembered that the LE80 already has the circuit in it. I don't mind modding it as it's easy to unmod it again after testing is done.
No worries, I am not familiar with that mod as I am a mech guy
Having thought about it for a while though, I am not sure that you would gain much in terms of usable data running the tests. We can work out the run time from the data already collected using the frequency and duty. We already know the recommended CDR that most will use as a safety guide. I suppose cell temperature would be different depending on the duty cycle, but its not going to be higher than the temperature for the cell during the continuous test so not really a safety issue. You are going to run into the same kinds of issues as with the pulse ratings that you have already attempted. A lot of test time for no real gain in my opinion.
Keeping things simple makes mores sense to me. For some battery safety seems to be difficult enough to deal with as it is.
Thanks for what you have done so far. I am sure the information that you provide keeps a lot of people safe
Agreed. However, in a VW device it is entirely possible that while your Atty may never get 20A, your battery could be drawing that much and more.
I'm still interested in a single quantity pulse comparison. Maybe something like: "Number of Pulses Above 3v" or some such, where both run time and sag (or Capacity v Power) are cobbled together into one easily comparable number. Perhaps you could subdivide the tests into power classes by doing:
- Number of Pulses Above 3.5v
-Number of Pulses Above 3.0v
and
-Number of Pulses Above 2.5v
Where those voltage cutoffs are 'under-load' voltages and not 'standing' voltages
Actually the chip acts as a bit of a safety mechanism in two ways.
For one, assuming it's a chip with some sort of safety features built into it, it'll give a low resistance or short warning if you try to find something that exceeds the limit of the chip, which sorta has to do with the second reason.. Before you fry your batteries, you'll fry the chip.
Most PCB's for vaping are actually only rated for about 20A or 30A. At that point, the chip literally burns out, and inherently this will kill any connection that the batteries had to the atomizer. In a best case scenario, you'd hit the fire button, the device would do nothing, and you'd smell some kind of "burnt plastic" smell. In a worst case scenario, you might have a small fire in the case of your mod if the device overheats.
And then you can add to that, most devices have some sort of "crystal diode" setup where there's a diode that will disconnect the chip from the batteries if a certain amperage is met, at which point you will have to replace the diode, but not the chip or the batteries (and you won't have a catastrophic failure).
Hope that makes sense, was in a bit of a rush.
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