Battery dischargers [SRO]

How-Tos & Esk8 mechanics
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#1

Ok folks, anyone that’s got a battery discharger, let’s show how you do it.

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This is referring to physical devices, for procedures, check out this thread

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How to discharge battery
Noob question thread! 2020_Summer
#2

I’ll start

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#3

This is my new one​

20200712_125649
20200712_1256494656×2328 3.34 MB

and the construction

20200708_193741
20200708_1937414656×2328 3.68 MB

20200708_195811
20200708_1958114656×2328 3.58 MB

20200709_024301
20200709_0243014656×2328 3.27 MB

20200709_110134
20200709_1101344656×2328 3.39 MB

20200710_105812
20200710_1058124656×2328 3.2 MB

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#4

I use this: https://www.digikey.se/product-detail/en/b&k-precision/8600/BK8600-ND/5154634?utm_adgroup=Equipment%20-%20Specialty&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Test%20and%20Measurement&utm_term=&productid=5154634&gclid=Cj0KCQjwhb36BRCfARIsAKcXh6HkRqWP1pLCNf2nTGRiEZnfvojL0NCofLOTpeE0y7dAsgXHMPuBuEAaAgoiEALw_wcB

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#5

Nice !
You’ve got a link for this one ?

#6

I just do not disconnect my 2018 anti spark switch :stuck_out_tongue_winking_eye::joy:

Seriously, I use my balance charger to discharge packs to storage charge. Didn’t have had a need to fully discharge cells/pack to dispose them yet. Might be possible to get the imaxb6 charger to do that work (1-6s only).
Don’t remember if that’s possible with the stock fw thou.

#7

Just sayin… Metr pro
That could be done with vesc tool too, you’d just have to keep eye on the temps…

10 Likes
#8

This one has everything you’ll ever want. Most importantly you can set a low voltage cutoff to stop at. Bluetooth logging to plot discharge curves. Love it.

US $38.51 21%OFF | DL24/P Color 2.4" APP DC USB tester electronic load 18650 battery capacity monitor discharge charge power meter supply checker

1 Like
#9

It’s this resistor

https://www.digikey.com/product-detail/en/stackpole-electronics-inc/KAL50FB1K00/KAL50FB1K00ND/1646209

That will work probably up to around 16S-ish

If you’re sticking to 12S or less maybe you can go 750 ohms for faster discharge

#10

I really need something to discharge my battery. It’s at 100% and I have a surgery next week which will not allow any ride for at least 6 weeks.

My battery (12S4P P42A, classic barrel charge port) can’t be used in a build yet, someone have any product that I can get in EU quickly ? I have no way to discharge it currently…

#11

Take @b264’s idea and buy some resistors. Easy to find, quick to buy, easiest to solder and better than nothing

#12

Or just ride the board :crazy_face:

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#13

Found that resistor, looks like it will work.
https://fr.rs-online.com/web/p/resistances-de-puissance/1754119/

Unfortunately.

#14

Don’t discharge too far :slight_smile:

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#15

I will monitor with a voltmeter, what volts value should I aim for if you don’t mind ?

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#16

Storage charge I would aim for 3.60 V/cell

Anywhere 3.4V to 3.6V is good though

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#17

Picture of my resistor and voltage monitor. Thanks @b264 for all the advice!

a52112c3d1bcb21aacd52b88569eba1818eb3e1b_2_666x500 cfac6f484c15923bb6a272efcd77a26a5515d366_2_666x500

1 Like
#18

VESC do a open loop

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#19

750Ohms ??
That makes a 0,067A discharge… Pretty slow, no ?

I’d go with a 30 Ohms 100W resistor for near 2A discharge.
Not good ?

#20

Try it and let us know how hot the resistor gets.

I made one that cooked itself to death, that’s why I slowed it down a little.