# To BMS or not to BMS?
**URL:** https://foil.zone/t/to-bms-or-not-to-bms/7036
**Category:** Electronics (ESC, remote, batteries)
**Created:** [March 7, 2020, 1:06am UTC](https://foil.zone/t/to-bms-or-not-to-bms/7036 "2020-03-07T01:06:53Z")
**Posts on this page:** 5
**Page:** 2
### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [October 13, 2022, 8:53am UTC](https://foil.zone/t/to-bms-or-not-to-bms/7036/21 "2022-10-13T08:53:10Z")
Some words of caution: If BMS fails it is often failed shorted which means that it no longer will stop overcharge or discharge. Therefore BMS is not intended to be used as a normal charge control, it should basically only cut power during emergency events. If you build a charger with PSUs then make sure that max voltage out is the correct for your battery. 12s=12\*4.2=50.4V max, no higher.
On the bms/no bms question:
Unfortunately the wear and ageing of cells is an unstable process. The weakest cell get loaded harder, it ages a bit more and becomes even weaker etc so even a perfectly built pack will eventually get out of balance without BMS or cycles on a balancing charger. I have done battery builds both with and without BMS and unfortunately i have killed some batteries without BMS… It’s good practice to use them (but get a better quality one)
I agree with pacificmeisters post that a BMS cutout while far away from home can be dangerous. I ride in the winter and so far -12 deg C in the air and zero in the water is my coldest. It’s better to damage your battery than yourself in a situation like that, therefore i can bypass my bms circuit without tools if i need to. My controller low voltage cutoff is also really low, at 2.5V, after this there’s very little energy left in the battery so i would gain more distance by paddling for a few minutes extra than to set it lower and kill the battery completely.
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### Author:  [@pablo\_foil](https://foil.zone/u/pablo_foil)
#### Post date: [October 13, 2022, 12:51pm UTC](https://foil.zone/t/to-bms-or-not-to-bms/7036/22 "2022-10-13T12:51:52Z")
What about using a smart charger and monitor the cell voltage befor charging starts? A dying cell should warn you by having low initial voltage.
At least thats my plan for my next build…
I know that means i still have to leave 10%-20% as safety, but anyway id leave it to extend battery life
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### Author:  [@Larsb](https://foil.zone/u/Larsb)
#### Post date: [October 14, 2022, 12:58pm UTC](https://foil.zone/t/to-bms-or-not-to-bms/7036/23 "2022-10-14T12:58:43Z")
Sure, any way to continuously monitor your pack will be great, either a balancing charger or a smart BMS. Next build i’ll do i’m planning to get me something like the skyrc pc1500 charger [https://www.skyrc.com/pc1500](https://www.skyrc.com/pc1500) and a 50Ah 14S battery, no BMS. With this huge battery i hope to stay away from the limits even on a longer trip.
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### Author:  [@thuffam](https://foil.zone/u/thuffam)
#### Post date: [March 15, 2024, 5:47am UTC](https://foil.zone/t/to-bms-or-not-to-bms/7036/24 "2024-03-15T05:47:02Z")
Just chiming in on this old thread… looking into battery design and to/not-to BMS…
Does anyone use a non-BMS battery with an under-board design (FD #2 style)? I’m thinking of doing this - and using an RC plane low voltage alarm - I’ve used them on planes before, and as others have mentioned, setting the warning level a bit above the danger zone gives you a reserve tank to get home.
I’m not planning on having any above-deck components - other than remote - not sure if that can show voltage - be awesome if it could (Maytech) - hence the alarm idea.
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### Author:  [@windego](https://foil.zone/u/windego)
#### Post date: [March 15, 2024, 12:34pm UTC](https://foil.zone/t/to-bms-or-not-to-bms/7036/25 "2024-03-15T12:34:08Z")
Not sure what esc you will use but the flipsky vesc you can set voltage limits to shutdown where you want. Also the vx3 remote has a voltage display.
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