I know some of you are probably gonna think I'm being a bit too cautious here, but I'm serious about this battery safety stuff and have been doing a hell of a lot of searching and reading these past few days. I've discovered some new information about how regulated mods work that has really changed how I'm going to pick my box mod. And I want to post this here, even if only so people new to this stuff can learn something (so please correct me if I get anything wrong! I'm not posting this to try and be a smartass - only to educate myself and others).
So basically, doing a straight "Ohms law" calculation is suitable for unregulated/mechanical mods, but not for regulated mods (infact, the coil resistance doesn't really matter for regulated mods). So in my previous post where I said "even if I ran the full 75W output of the Pico through a 0.5 ohm coil, the current would be 12.25 amps." - I was totally wrong (the current would actually be about 26.9A!).
The way to figure out the current/amp draw for a regulated mod is to divide power (Watts) by the voltage. When doing this, you need to also account for the power efficiency of the mod and battery sag (or so I read), so I add an extra 15% onto the wattage to try and be safe (it helps to know the exact power efficiency rating of the device for this calculation).
The other
really important thing to know is the low voltage protection/cut-off point of the device you're using. For a lot of devices this seems to be 3.2v (some are lower - so check!).
So for example: If you have a battery rated for a 20A continuous draw, you should be safe using it on a regulated mod with output power up to about 50W (factoring in an extra 15% to watts for safety, and assuming the mod has a 3.2 low voltage protection/cut-off point).
Calculation: (50W + 15% =) 57.5W / 3.2v (low voltage cut-off point) = 17.9A (leavs a nice 2A approximate headroom for a 20A battery).
Here's a post on Reddit explaining in more detail (it also links to another post about it):
https://www.reddit.com/r/electronic...nt_draw_on_regulated/?st=isy1hg0p&sh=b4e52980
Now based on all I've read these past few days, I want to get either LG HG2 (probably these for their higher capacity) or Samsung 25R batteries. Both are rated for 20A continuous draw. I could use one of these batteries with a single 18650 battery mod like the istick pico (75W) and just make sure I don't run it above approximately 50W, sure. But I like setting things up for worst case scenario to be safe, and I know safety is paramount on these vaping forums... right?
So if that Pico accidentally fired on the full 75W setting, it would be very dangerous for my 20A battery. Now I can totally see why Eleaf recommend a battery above 25A! They certainly are playing it safe, and so am I.
So... I figure I have two choices here. I can get something like the iStick TC100W dual battery regulated mod which should not exceed the amperage draw of two of these batteries, even if fired at 100W (according to my calcs). But then I'd have to deal with rotating batteries after each charge, and I would prefer not to need to bother with that. Or, I can get a single battery regulated mod with a limit of 50W (or one where you can set your own Wattage limit).
Do you guys have any suggestions for a good 50W regulated mod which takes a single, replaceable 18650 battery?
And please - do go ahead and correct me if I've gotten anything wrong. Again, this is just about safety and education for myself and others. That's all. Thanks Apes
.
