12S 100a Mountain Board without a BMS

In the past, I’ve made a board with a 10s battery and used a 45a BMS.

From what I have heard, using a BMS is essential for keeping your battery in good condition.

Thinking of making a mountain board with a 12s, 100a battery.

Would a BMS on a this 12s system be necessary.

Mandatory or not depends on the chemistry of the cells and how you charge and discharge them. In most cases a bms is necessary.

it’s an extra $20 for a bms that you can bypass for discharge. I highly recommend it, it will make your life a lot easier

After removing my BMS my board ran alot better. Fuck BMS. I don’t run them in any of my boards anymore. Just balance manually and check cell voltages myself every month. Very simple easy and safe if u don’t slack off.

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was it bypassed for discharge?

No they were not. But I don’t like them for charging either. They don’t balance very well. And just another thing to break. I like to know what my cells looking like by checking them manually. Don’t trust the BMS so much. So I removed them totally.

Can you link me to a 12s BMS that is $20 please… All of the bms’s I look at, are much more than that

What do you do to check the voltages manually? Do you just use a balance alarm?

Your right, you don’t need a bms as long as you manually balance charge your battery and never discharge it below 30% and never brake downhill on a full battery and never get a short and your battery’s spot welds never fail.

As for your bms degrading performance, I’m curious about what brand of bms you where using?


If you have some space in the enclosure and money left I would recommend a BMS for discharge, too (e.g Bestech). If you want a cheap one for charging only you could bypass this one in combination with a 50.V Li-ion charger:

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This is 21a, I need an extremely high discharge. I want the acceleration on this board to be out of this world

I thought you want a cheap one for charge only, that’s why I linked to this one. If you like it for discharge, too I would go with Bestech (min. order 2 pieces). Or this one from aliexpress: https://www.aliexpress.com/item/12S-120A-version-S-lipo-lithium-Polymer-BMS-PCM-PCB-battery-protection-board-for-12-Packs/32796917556.html?spm=2114.search0104.3.49.NyOsAW&ws_ab_test=searchweb0_0,searchweb201602_2_10152_10065_10151_10344_10068_10345_10342_10547_10343_10340_10341_10548_10541_10562_10084_10083_10304_10307_10302_5080011_10539_10312_10059_10313_10314_10534_10533_100031_10604_10603_10103_10594_10557_10596_10595_10142_10107,searchweb201603_14,ppcSwitch_5&btsid=c955bc1a-fb37-4b5b-a441-560cf7707aa2&algo_expid=6bb4e8ae-d093-4195-8cf6-2a4af2560f32-6&algo_pvid=6bb4e8ae-d093-4195-8cf6-2a4af2560f32&rmStoreLevelAB=1

I ordered 2 Bestech 50A BMS because of the small size and ended up with total cost of 160€/190$ including shipping and taxes. The shipping from china to europe was 1 day :laughing: