Late reply. Sorry for the delay.
Replaced Gas Geyser batteries with wired connection 5v 1A charger + 2 meter long USB cable for limiting current. Also added switch board near Geyser for convenience and for safely turning off supply.
When Gas Geyser connected to 18 watt fast charging high speed USB cable used for mobile devices. Sparking was too fast and loud so used normal USB cable 2 meter long. Now everything works fine.
So no D size battery needed and no converter needed now.
I purchased this Power Bank Case from banggood last year.
Tried batteries from old laptop battery mentioned here. It's working great.
C16-PD-QI Removable 16-section Power Bank Shell Mobile Power Bank Assembly Kit Diy18650 Battery Box Wireless&Quick Charging Version - Black
Earlier I faced problem with this power bank as it was showing incorrect percentage. But eventually I learnt that, after inserting batteries you need to completely discharge and charge powerbank once for to see exact percentage.
So, I purchased 20 nos. Samsung INR18650-35E at ₹442.6 (including taxes) from "IndiaMart" to India. As I couldn't find any website which ships to India and shipping cost is too high.
I want to know are these genuine or fake. As I am getting 1800-1900 mAh capacity from battery. Cut-off voltage 3.11 volts as power banks shows 0% and shut down.
I measured capacity using AccuBattery and Battery Guru apps from Google Play store.
Charged power bank to 100% (16*3500 mAh approx = 56000 mAh) then discharged power bank by charging 3 mobiles with these apps installed and measured capacity of total 16 batteries. Result was 29737 mAh Battery Guru app and 30594 mAh on AccuBattery app. So calculated that each battery have around 1800-1900 mAh.
Please check attached images.
Attached Images:
