# To use Power banks and DC-DC step up Converter to make Electric Bicycle battery Pack

Summary of the whole project

I have a small project in mind, just want to find out is this a possible way to make a useful power pack rather then use this normal way [![enter image description here][2]][2]

to make a traditional E-bike power pack

situation

1. I will use twelve QC 3.0 capable power banks to constantly supply 20V with around 0.9A, then I parallel them by joining 12 outputs into a thick copper wire.

2. Because the DC-DC step up converter can only handle 15 Ampere max input (10 Ampere if no cooling, so I choose limit to 10 amp )

3. step on converter specification: It can take in 16-60 Volt as input ( with max Current 15 Amp ) output voltage is 18-80 Volt with max current 10 Amp

4. If need more power, I might make another step up converter group or groups, later join both (or all 3) step up converters output before BMS ( battery management system )

[![enter image description here][3]][3]

1. 500W motor will get electrical power from BMS :)

ok, now come some questions

1. How do I ground the circuit? Do I need to ground the circuit? Is it necessary??
2. If I use 2-3 step up converter groups, how should I deal with the grounding circuit problem?
3. Do I need to put diode ? Especially just outside output of each power banks . If No need Diode , then I can save more energy :)
4. Do I need to put diode outside the step up converter ? I means in between steps up converter groups and BMS

5. Any other points that might stop the project from working ?

• was trying to upload more picture, failed Jun 29 '16 at 16:28
• Please be aware that if your 20V battery buss is limited to 10 amps, your TOTAL power (including converter inefficiency) is 200 W max. So call your motor power on the order of 160 to 180 watts, or 1/3 of your expected power. Is this acceptable? Jun 29 '16 at 16:33
• @WhatRoughBeast that is why I am thinking to use 3 groups of converter let me try, I am still new to this site :) Jun 29 '16 at 16:37
• imgur.com/a/YGZJD these are the link to the photos that I suppose to upload, one is sample photo of a traditional battery another photo is the way I am intend to add more converter group thanks @Passerby Jun 29 '16 at 16:43