Thursday, October 3, 2013

Portable Charger with Battery Bank Revisited

5 months ago, when I first posted my project, the portable charger with battery bank, I wrote that I am still waiting for the arrival of  4 pcs lithium ion batteries and will be looking for a transparent enclosure so that the battery charge indicator will be exposed. Unfortunately, my batteries did not arrived and had to cancel my order and could not find a nice trasnparent enclosure.

3 weeks ago, I tried to find a similar battery but I also failed so I settled for 4 pcs 900mAH 1.2V lithium ion rechargeable AA batteries. This is way below the original specs but the price is also cheap because each battery cost Php60 only. I will use this batteries just to offset the waiting period for the arrival of my newly ordered  high capacity batteries. I also plan to upgrade my exisitng DC-DC Step up module from 500mAmp output to 1.5mAmp output.

I had been playing with it for a week now and surprisingly all of my tests yielded unexpected results. The current specs is as follows:
1) 5V 1Amp Input derrived from the USB Charging module
2) Battery Bank capacity is 3600mAH. 2pcs connected in series and resulting in 2 pcs of 1800mAH 2.4V and connected them in parallel.
3) 5V 500mAmp output.

I don't expect much juice from that configuration since it's a low-voltage configuration which translates to a much lower mAH in reality.

 Here is the resulting device:

I used electrical tape to hold all 3 pcs together(the batteries, charging module and dc-dc usb step up module) and to hide all the wires in between.

Here are some results of my experiments:
1. Charging time is at least 4hours. 4.2V can never be achieved since the battery bank is only 2.4V as a result the red led in the mini usd charging module will never light up. The red led will light up if a 3.7V battery is fully charged at 4.2V.

2. When fully charged, it can be a temporary power source of an Ipad mini or any Android Tablet for 30 to 45 minutes but could not charge it. This surpassed my expectation since the output is only 500mAmps while the Ipad Mini requires at least 1Amp.

3. It can power up a 12V 0.15Amp dc brushless motor for 30 minutes. I used the 5W DC DC 5-12V Step Module.