YO3BN - Lightweight Portable Li-Ion Pack 16V 3.4Ah

Posted at - 31st May 2017
Last edited - 7th Jun 2017

Li-Ion Pack for Portable Applications

I have built this battery pack out of four Li-Ion accumulators because I want to replace my bulky and heavy lead-acid accumulator used for portable applications. The nominal voltage of four Li-Ion cells in series is 14.4V. I used 3400mAh cells, meaning a power of 14.4 * 3.4 = 49Wh and it weighs only 250g, unlike lead-acid battery which is rated with 12V at 7Ah meaning 84Wh @ 2.0Kg. Therefore, there is a massive improvement of Li-Ion over lead-acid regarding the power over weight ratio.

The Li-Ion battery gives 49Wh @ 0.25Kg, while the lead acid gives 84Wh @ 2.0Kg, so Li-Ion gives more than a half of power at a weight eight times smaller than lead-acid.

Li-Ion type:

Full charged voltage: 16.8V
Discharged voltage: 12V
Current: 3.4Ah
Weight: 0.25Kg

Lead-Acid type:

Full charged voltage: 12.8V
Discharged voltage: 10.8V
Current: 7Ah
Weight: 2.0Kg

The voltage - 16.8V - supplied by Li-Ion pack can damage or stress some transceivers, so there can be several things to do:

Using diodes or linear voltage regulators in order to drop several volts, but this method waste energy
Using switching voltage regulators to maintain a constant voltage, wasting less energy but can introduce noise
Using under-charged Li-Ion pack, the most power efficient method, prolonging cell life, but will reduce total capacity

73 de YO3BN