Friday, May 6, 2011

PIC-Based Battery Monitor

My friends, as usual, drove me to craziness again and led me to design, fabricate and test a smart battery monitor... The usual blinking lights and so on... This prototype is using an 18-pins PIC but for the real runs, an 8-pins PIC is more than sufficient... I happen to have the 18-pins PIC in my junk box... yeah, it's a very big junk box... :)

video

Tuesday, April 26, 2011

Battery Monitor - Revisited

After my initial try with the battery monitor, I wasn't too happy as it wasn't simple enough to use. The original circuit need to be switched on and off in order to avoid draining the battery.

Here comes version 2. The LED will only come on when the voltage drops below the set threshold. While connected to the battery in the 'LED OFF' state, the circuit will draw less than 1mA which is likely to be much lower than the LiPo self-discharging current... As such, the circuit can be connected to the battery indefinitely... the LED will only comes on if the voltage drops below the set threshold. The photo above show the old circuit and the new one (which is SMD).

Monday, April 4, 2011

Rechargeable batteries... I'm not a salesman...

In today's modern age, one cannot run away from buying and buying and buying batteries for all the nice gadgets we have... I've been on that route... Since last 1 year, I've been using the Sanyo Eneloop Rechargeable NiMH battery for my camera's flash and I'm very pleased with it so I'd like to share that knowledge with my friend...

Eneloop battery are regular NiMH battery but can retain it charge for a much longer time compared to standard NiMH batteries... After 1 year, it is supposed to retain about 85% of it charge! No more 'oops, forgot to charge the batteries excuses'... Of course, it's a bit more expensive though... :)

Read a detailed review and test of the battery here for more details...

p/s: I'm not a Sanyo staff :-)

Monday, March 28, 2011

Simple Variable Voltage Power Supply...

To set the threshold voltage for unit below, a variable power supply is needed... Below is a simple one based on the industry workhorse, LM317... Click image to go to source site...


LM317 is a very versatile component... Download the datasheet here to see other applications using the same component...

Thursday, March 24, 2011

[Updated] New Hobby... New Tinkering... Lipo Battery Monitor...

I recently started playing RC helicopters... nothing fancy... just beginner models...

As anyone in RC knows, LiPo battery is very sensitive to charging and discharging activities... Charging needs to be accurately monitored and discharging should not be all the way to zero capacity... There are various voltage versus capacity chart on the 'net and plenty of ready of-the-shelf LiPo battery monitor on the market... Me being me again, I wanted a simple LiPo voltage monitor for my RC usage (and friends using LiPo to replace obsolete battery on their amateur radio handies)...

The following circuit was found on the 'net... It can be wired point to point or a small PCB could be made for it... I'm yet to test it out (waiting for parts) but if it proves practical, I'll probably go with SMD route to make it as small as possible... I'll replace R1 and R2 with trimmer so that the unit can be made universal to monitor any batteries... btw, the estimated parts cost is around RM1.00 :) ... so stay tune...


[Update]... Parts arrived already...
Here the photo of the unit I made over the weekend to show the size next to a 7.4V 850mAH LiPo battery... Trigger voltage is adjustable using the trimmer... As set, the unit takes about 10mA when LED is on (voltage is at or above the set threshold)...

Wednesday, May 26, 2010

Aahhh... it's that time again... thinking time...

Found this video while surfing the 'net.
Got me thinking... We all, in fact everything in the universe and beyond, are nothing but nothing...
Watch the movie, ponder about it, reflect on it and chart your destiny...

video

Thursday, April 1, 2010

LHC is alive... and so are we...

The large Hadron Collider (LHC) has successfully managed to perform what it was supposed to do... a 7TeV proton collision... (no no, not the Wira, Perdana, or the likes)...


Yet, we are still here... the earth hasn't been swallowed by black hole (yet?)... anyhow, more news on the net.. one of it is here ...