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HPR3816: Post Apocalyptic 4s5 Battery Pack

Hosted by Mechatroniac on 2023-03-20 00:00:00
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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

  1. 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

  2. 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)

  3. wrap in cardboard and tape as per pictures

  4. add the cd/dvd drive lids(if you taped well you won't short anything and burn your house down

  5. 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
Battery Schematic
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Cut through tape to reveal battery
Cut through tape to reveal battery
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Flat metal holds cells together
Flat metal holds cells together
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Detail of 4.2v
Detail of 4.2v
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Only have to desolder one side
Only have to desolder one side
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New cells in
New cells in
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Make sure there is thick tape covering battery
Make sure there is thick tape covering battery
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DVD drive case for stability
DVD drive case for stability
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Tape the DVE case to battery
Tape the DVE case to battery
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Charge board with Molex connector
Charge board with Molex connector
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Outdoors 1
Outdoors 1
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Outdoors 2
Outdoors 2
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Comments


Reto says: The podcast

Re: hpr3816::2023-03-20 Post Apocalyptic 4s5 Battery Pack by Mechatroniac from the series Hobby Electronics
00:07:59 Listen in ogg, spx, or mp3 format.


Hi Mechatroniac,

Having accus on hand with different voltage sounds good.

Almost like Ken, I don`t think soldering destroys the accu as long as you have a large soldering iron, why not building a DIY Spot Welding Machine?
I watched some videos in the past like:

With parts of an old Microwave: https://youtu.be/vStYS6eoscU?t=184

or a bit more risky, just a battery. Risky as it has no on/off switch. https://www.youtube.com/watch?v=yYivIldvS6o

Cheers
Reto


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