Gone in 0.5 Seconds (BMS - Protection Measures Delay)

1

Dear friends,

BMS circuits are useful for protecting the battery packs. In case of voltage, current, temp, balance… anomalies, they cut power in a very short time. So, here comes the question;

What if a new design is introduced to have a number of advantages over current ones, but, there is a disadvantage on the “Protection measures delay”…

So, instead of (rephrased);
Anomaly is detected -----> x microseconds delay ------> Protection measures taken

This one is offered;
Anomaly is detected -----> 0.5 seconds delay ------> Protection measures taken

*** So, what is your opinion on having a 0.5 second “Protection measures” delay in battery protection function ? Would it be problematic ? (Keeping in mind that there are a number of advantages coming in with the new design)

P.S. There is no schematic yet and the most important question now is the delay.
@mmaner @longhairedboy @Mainflow @mishrasubhransu @b264 @Psychotiller (All opinions will be welcomed, these are the guys I recalled about this issue at this instant)

Thanks for your time

2

How about adding a warning tone with the delay before cutting the power? That would make sense.

6 Likes
3

That is possible, good one… :+1: The question actually was about the safety concerns on battery protection function.

4

Why did you recall me about that issue?
Imo for the safety of the rider I would say, that the bms should cut the power immidiately to prevent electronics damage and fire, but for the rider’s safety I would prefer the .5 seconds cutoff delay, so that the rider can prepare himself for that.

2 Likes
5

Hard to keep something in mind if we don’t know what it is. At the moment you want to compromise a working function so that your board can shoot laser lights out the front and sing kumbaya when it detects a camp fire.

Details or no point offering it really. This is a DIY forum, if you’re planning to protect your features for business reasons that’s understandable but you’re asking in the wrong place without full details.

5 Likes
6

I prefer not to have the power cut at all. If something’s gonna melt down I want to give myself brakes for as long as possible. Basically, I value myself over the battery.

Need to understand that “power is cut” sounds like you’re saving stuff, but if I’m in traffic carrying my dog that also can mean “brakes are cut” and that’s a no-no at any time. I’d rather the board catch fire…as long as I got two more seconds of brakes while it burnt.

10 Likes
7

I totally agree with you, sorry, let me correct myself… Considering a not-on-the-road situation or while charging, A +0.5 sec delay, critical or not ?

8

Anomaly detected --> Make a loud, annoying beeping noise --> Never cut power :slight_smile:

7 Likes
9

I think for small toy boards used at low speeds it is fine – more safety means a longer lasting toy.

In other words: if it is a charge only BMS, it’s okay :slight_smile:

2 Likes
10

Yeah @rusins that’s the thing, I agree. For a 10A discharge / 10A charge BMS where we will route the ESC directly to the battery, and either nothing or just some lights on the BMS discharge, this setup described at the top is perfectly great.

If you’re talking about discharging the ESC through the BMS then it’s not.

I’d also love to see an ESC where it has an input for the BMS P- wire, but it doesn’t pull power from it. It just senses if the BMS cuts power… and then can cut throttle… but leave the rest alone

5 Likes
11

Ooh that would be cool! I guess it might be possible with an arduino and some vesc firmware reprogramming.

12

Thanks that was a helpful tip :+1:

2 Likes
13

I think with a few resistors and zener diodes, you could run it directly into a VESC MCU’s unused I/O pin…

2 Likes
14

okey :slight_smile: :+1:

15

If the discharge is low like 10A then cutting power is good because it’ll turn off lights and whatnot the way I wire it. But running the ESC through it, no way.

So we’d need more details like @Brenternet said.

1 Like
16

That plan is even better, yes details are on the way :+1:

17

Seems like an appropriate order of events from an engineering standpoint would be to first have the BMS ignite the battery and then begin to sing kumbaya. By the time the BMS melts and can no longer sing, the crowd would have already picked up the tune.

8 Likes
18

FYI, traces aren’t terminated or broken out with vias (which get sealed with mask). You want a header (unpopulated) or a test point if you don’t want through hole. Vias are intended for layer to layer connections, not external.

2 Likes
19

Anomaly detected —> THIS IS NOT EVEN MY FINAL FORM —> catapult the burning BMS out of the enclosure --> less weight for more speed…no?

2 Likes
20

Yeah, lets forget the secs or anoma - pro mea somethings, drink some beer and enjoy the ride… Totally understood the spirit :+1:

1 Like