In this posting I will describe how I built a cheap DIY 18650 Lithium-Ion battery pack for my Yaesu FT-817. I decided to go the cheap route by salvaging 3 x Laptop battery packs that was in my junk box. I tested each cell and discarded dead or bad cells. These cells were all Li-Ion batteries. The cell voltage of the batteries I used was in the 4.18v range.. So that gave me 12,6V on a 3S pack which is in the specs of most standard amateur radio transceivers.
I used a simple tester to test each individual battery. However this is not the way to do it but I had it on hand and thus far it has worked for me. (More information on the tester can be found later in this posting) I charged each cell separately using a one cell charger as shown in the photo. Once all three batteries were charged to within specs I used a 18650 holder instead of solder directly to the batteries which is not a good idea. There after I soldered the wires to the connectors and wires as shown in the images and schematic diagram. I did not use a Battery Management System (BMS) as I own a balancing charger. I only added a power lead for charging and a balancing lead.
The charger is depicted in the photos below. I decided to build this battery pack as simple as possible with very little bells and whistles. Thus far it works flawlessly with the FT817. This pack can also be used for a variety of other power sources. You can either add a power up converter or a down converter for the voltage that you need.
I decided to build a lightweight, low cost and KISS power pack for the FT817 but also to be used in other projects. I still have several 18650 batteries in the junk box and will construct a larger capacity battery bank for the FT817 in future.
The total cost of the project did not exceed +- R60.00 having used salvaged batteries, junk wire and balancer lead from the junk box. The items that made up the total cost was the heatshrink, XT60 connector and the 18650 case.
Finally: When using the battery pack with the Yaesu FT817 I will add the Lithium Battery Low Voltage Alarm
Indicator to the balancing lead to monitor the full (All) battery voltage and also individual No 1-3 cell voltages. Update to follow in a future post once the pack is tested fully.
(Click on images for larger view)
Above: Single cell 18650 USB Li-ion Battery Charger
Above: Battery Tester 2S-6S RC Lipo Li-ion Lithium Battery Low Voltage Alarm Indicator Meter Checker Tester Red LED Digital Display 2-6S Voltage Tester.
Specification:
Used for 2S-6S(7.4V~22.2V)Li-Po /Li-ion/LiMn/Li-Fe Battery
Voltage detection precision:±0.01V
Unit voltage display range: 0.5V-4.5V
Total voltage display range:0.5-27V
Pins distance: 2.54mm
0.36 inches digital display
Voltage Display unit is \”v\”
Display \”NO.1/2/3/4/5/6\” is the number of battery cell
Display \”ALL\” this is total battery voltage.
The use of programmable memory for calibration of the voltage measurement accuracy
Test the working state of lithium battery.
Compatible for 2-6S Lipo/ Li-ion/ LiMn/ Li-Fe battery
Color: red
Size:4.8×1.8×0.8cm
Net weight:7g
