The Transition
In the beginning, I always recommended using either three AA or AAA batteries to power my circuits. That combination provides a good 4.5 volts which was as close as I could get to 5 volts. The reasoning was that if anyone uses my circuits during a show and runs out of batteries, they can be easily replaced. A lot of stores do sell AA or AAA batteries nowadays. At that time, I was introduced to the Lithium Polymers (LiPo) but for me, it was still too early since the prices were, unfortunately, quite high.
Eventually, when the Mobile Phone Power Banks starts appearing on the shelves, it was time to jump in. Early capacities were 5,000mAh which, in some tests, could run for an average of five hours or so. It was also the time where I started to heavily depend on PWM programming, which, in theory further reduces the power consumption to the point that most modern power banks actually shuts down after 30 seconds. A function which I later discovered in most power management circuits (or chips) to conserve battery. So, yeah, I had to re-design my circuits to use at least 50mA and not below that threshold. By the time I have ironed out these issues, 5v and USB Power Banks (no, not USB from the PC, mind you) became the new solution. I was encouraging everyone I know, to use Power Banks as they last longer than the AA (or AAA) batteries.
I loved this Brand and my very first was a 5,000mAh which at that time, was literally the top of the line. The slim unit even has a torchlight. Unfortunately, if I am not mistaken, they have stopped manufacturing in Malaysia.
(Courtesy of Pineng.com.my)
The Freedom of Portability
Indirectly, that was my entry into rechargeable lithium-ions outside of mobile phones. The next step was to integrate them into the actual model or prop. I can design around them to either use Lithium Ions (aka Li-Ion) which has a few standard sizes such as the most common 18650 (18mm in diameter by 65.0 mm in length). Or, I can use the Lithium Polymer aka LiPo which comes in various sizes and capacities imaginable. This time, most of my circuits are meant to be ‘carried around’ and although they can utilise the power Banks, I opted to use LiPo which has a discharge voltage of 3.7volts.
I am not going to discuss about the pros and cons between the two bat here is a good link for you.
Both Lithium types are rechargeable and so, the next issue would be to look into chargers. The Solutions can be in the form or either commercial chargers or, modules, with both of them connecting to (non-PC) USB ports. There is another option which is to design my own charging system but looking at the manufacturing costs, ultimately, it was much cheaper to purchase and adapt those ready-made modules.
This revelation then made it possible for Props to be displayed for a longer period. And charged via a USB Wall Adaptor. However, this is only for small single piece of Lithium. You’d still need a dedicated charger if you’re using a pack of 4 or more 18650’s. And this kind of configuration means heavy usage of an amplifier or, 12 LED strips.
The MH-CD42 Charger/Discharger Module
The only reason I had this module was because it had a 4-LED battery indicator. The module is quite handy if you need to display Scale Models or some electronics in a show. After going through their Datasheet, the module uses the IP5306 Power Management IC. The chip is great if you want to make a basic mobile phone power Bank as it has an automatic shutdown after 30 seconds if the current flow is less than 50mA. What’s more, the IC can also be triggered to shutdown either either LOW level signal to Pin #5 or via the I2C command.
