HR000000000

H Hybrid: Denotes some prepurchased or hard to find components

R Robotics: suitable for robots

buy: 4s 40A BMS

https://www.aliexpress.com/item/4000025857655.html

(can't specifically vouch for this vendor, just chose the first that

came up)

make sure to choose 4s and balance

find or buy materials: duct or gorilla tape, trashed computer dvd

or cd drive, 20 18650 cells, molex connectors(you can also use barrel

jacks or whatever you want to transfer power), wire and maybe 'tab wire'

https://nl.aliexpress.com/item/32650006768.html

solder everything together as per schematic and pictures (there

is theoretically a danger in soldering cells, but I have never had a

problem. Have a pair of pliers and a nearby window handy to throw them

out of if anything goes wrong)

wrap in cardboard and tape as per pictures

add the cd/dvd drive lids(if you taped well you won't short

anything and burn your house down

tape dvd lids to battery

Getting into the battery for maintenance just requires a utility

knife.

Watt Hour does a great job describing the 3s BMS, which is very

similar to the 4s used in my case: https://yewtu.be/watch?v=QNENyu97w2A

Battery Schematic

Click the

thumbnail to see the full-sized image

Cut through tape to reveal battery

Click the thumbnail to see the full-sized

image

Flat metal holds cells together

Click the thumbnail to see the full-sized

image

Detail of 4.2v

Click the thumbnail

to see the full-sized image

Only have to desolder one side

Click

the thumbnail to see the full-sized image

New cells in

Click the thumbnail to

see the full-sized image

Make sure there is thick tape covering battery