BATTERY DIY MODELS
Before you get started take a few minutes to learn about batteries. It very well could stop your newly made pride and joy from exploding in your face.
Just decided to build my own device...
Slim and simple EVOD tank, eGo Twist 1100 mAh battery. DruidPriest
I so wish I could understand how to do this~! I have to see it being done to 'get it'.
I saw the coolest flashlights that would make a sweet looking mod, but I just can't do it myself![]()
are all 18650 batteries high drain? do they all have the same c rating? I am getting a dna 30 board and one of evolvs usb chargers would that work to recharge an 18650? would an 18650 be an appropriate long lasting battery to power a dna 30 pumping 30 watts through a 1.5 ohm dripper with dual coils?
The laptop battery pack I stripped only contained 18350, but one of those lasts me all day. The shunt regulator charger I built gets pretty much the full 500mA from a USB wall-ward when the battery is fully discharged, this just about fully charges it in 24h.
For original equipment batteries (about 200mAh) you can get away with a TL431 shunt regulator - it can only handle 100mA so that is the most the dropping resistor should supply at a terminal voltage of 4.2V, at that point the TL431 is bypassing all the current.
I'll leave it as an exercise for the student how to get more than 100mA shunt current.
I think that the evolv usb charging board doe 500 mah but I might be wrong
I ended up getting 2 Sony US18650VTC4 2100mAh Li-Ion Rechargeable High Drain Battery 30A. I was hoping to get a flat cell but couldn't decide which one to get. maybe I will strip it down later and change the battery if I find a good one.
USB chargers conforming to the 500mA spec are cheap and readily available, but you can sometimes find regulated 5V wall-warts from routers that are capable of in the region of 1.2A.
It would be unwise to try mating this up to the end of charge chip from an original e-cig battery unit - it could fail short circuit and fry the battery.
Currently I'm using a shunt regulator with a standard spec USB wall-wart, it does what I need so I've no immediate plans to modify it further - but it would be easy to upgrade for faster charging.
This is what the datasheet for the dna 30 says I cannot find a datasheet for the usb charging board. Does that sound like it would work?
I'm not sure I will have to do further research.....
The Vapourlites charger is little more than a 15R current limiting resistor - the important bit is the end of charge disconnect chip in the battery unit.
In my earlier experiments I tried reducing the resistance to increase the current, but the disconnect chip got noticeably warm - it just wasn't worth the risk of the chip failing S/C and flaming the battery, so I developed a shunt regulator that bypasses 100% of the charge current when the battery is full.
these are the specs for the battery but perhaps I should look into a safety backup...
or maybe design for removal and charging in wall unit
Maximum Continuous Discharging Current: 15A
Maximum Rated Discharging Current: 30A
Maximum Pulse Discharging Current: 60A
Maximum Continuous Charging Current: 6.5A
Nominal Voltage: 3.8V
Maximum Charge Voltage: 4.2V
All you really need is a shunt regulator set so it bypasses 100% of the charge current at exactly the maximum charge voltage.
With a simple current limiting resistor, the charge current at minimum cell voltage will only be a little bit more than the maximum current the shunt regulator can bypass.
You could also sense cell temperature and use a comparator to operate an emergency shutdown relay - but I think the safe/jet of flame margin is quite narrow.
well I will admit you are talking over my head but I love to learn and I just bought some stuff because I decided I want to learn electronics sooo.... google read try is the next course of action for methanks for the idea!!!
BTW this is my very first mod I built it last night in a few hours. I was bored+Broken flashlight+broken 1100mah twist+wire+led+resistor+switch+time = practice for putting together my dna mod lol. supposed to be here tomorrow.