BMS warming light and buzzer before disconnect

[ben373]

The Australian standards are calling for a warning prior to BMS disconnect.

This is to be a light and loud buzzer so would needed to be a relay output so that the light and buzzer can be remote.

Are there any BMS doing this.

Pantaneous insurance are now requiring this.

See below..

ASNZ Standards for Lithium Batteries
AS/NZS 3004.2 (2014) Lithium Battery requirements:
"2.9.3 Additional requirements for lithium ion batteries
The following additional requirements apply:
(a) Lithium ion batteries shall be installed in locations that ensure the battery manufacturer's specified operating temperature limits cannot be exceeded and are appropriate for the IP rating of the battery and its management system.
(b) Each lithium ion battery shall be provided with a battery management safety system 216.7.15784.291787 (BMS) either integrated into a battery pack or as a separate component located adjacent to the battery. The BMS shall continuously monitor the voltage and temperature of each cell in the battery.
(c) All charging sources shall be automatically disconnected by the BMS when voltage exceeds the manufacturer's recommended maximum.
(d) All connected load shall be automatically disconnected by the BMS when the voltage falls below the manufacturer's recommended minimum.
(e) The battery shall be automatically disconnected by the BMS from all connected load and all charging sources when temperature exceeds the manufacturer's specified maximum.
) The BMS shall provide an audible and visual alarm at the normal vessel operating position before a disconnection event occurs.
(g) Lithium ion battery ventilation air flows shall be in accordance with the manufacturer's requirements. If specific air flow data is not provided the requirements of Clauses 2.9.2.2 or 2.9.2.3 shall be applied. NOTE: Care must be exercised when disabling charging sources to avoid the risk of elevated voltages that may damage the equipment.

[wholybee]

Originally Posted by ben373

The Australian standards are calling for a warning prior to BMS disconnect.

This is to be a light and loud buzzer so would needed to be a relay output so that the light and buzzer can be remote.

Are there any BMS doing this.

Pantaneous insurance are now requiring this.

See below..

ASNZ Standards for Lithium Batteries
AS/NZS 3004.2 (2014) Lithium Battery requirements:
"2.9.3 Additional requirements for lithium ion batteries
The following additional requirements apply:
(a) Lithium ion batteries shall be installed in locations that ensure the battery manufacturer's specified operating temperature limits cannot be exceeded and are appropriate for the IP rating of the battery and its management system.
(b) Each lithium ion battery shall be provided with a battery management safety system 216.7.15784.291787 (BMS) either integrated into a battery pack or as a separate component located adjacent to the battery. The BMS shall continuously monitor the voltage and temperature of each cell in the battery.
(c) All charging sources shall be automatically disconnected by the BMS when voltage exceeds the manufacturer's recommended maximum.
(d) All connected load shall be automatically disconnected by the BMS when the voltage falls below the manufacturer's recommended minimum.
(e) The battery shall be automatically disconnected by the BMS from all connected load and all charging sources when temperature exceeds the manufacturer's specified maximum.
) The BMS shall provide an audible and visual alarm at the normal vessel operating position before a disconnection event occurs.
(g) Lithium ion battery ventilation air flows shall be in accordance with the manufacturer's requirements. If specific air flow data is not provided the requirements of Clauses 2.9.2.2 or 2.9.2.3 shall be applied. NOTE: Care must be exercised when disabling charging sources to avoid the risk of elevated voltages that may damage the equipment.

While I think this requirement is nonsense, I also am confused while with so much discussion about it that the feature isn't standard on every single BMS and battery produced. It's practically free to implement.

I have designed and built a battery SOC meter that will connect to an Overkill / JBD BMS via bluetooth. It can replace a Victron or other SOC meter, providing SOC%, Voltage, Current, and also individual cell voltages, as well as provide an alarm before disconnect, satisfying that requirement. I have been too lazy to make a video demonstrating it, but the project is here:

https://github.com/wholybee/esp32-smartBMSdisplay

[fxykty]

TAO BMS does this. I’m sure other external BMS in the one boat buck range do as well. In the case of the TAO, it has a remote LED panel that normally flashes a green heartbeat. It can flash or solid light and audible alarm in response to certain events (by default, shutdown due to voltage, temperature, imbalance is among those events that trigger an alarm).

But with any BMS (or BMV-712 monitor, or whatever you use to control your LFP battery) that has relay outputs, it would be relatively simple to create a relay-controlled alarm circuit with light and buzzer that is triggered when certain events take place. The only caveat is that the warning should be triggered by the same component that will be doing the subsequent disconnection.

[wholybee]

Originally Posted by fxykty

TAO BMS does this. I’m sure other external BMS in the one boat buck range do as well. In the case of the TAO, it has a remote LED panel that normally flashes a green heartbeat. It can flash or solid light and audible alarm in response to certain events (by default, shutdown due to voltage, temperature, imbalance is among those events that trigger an alarm).

But with any BMS (or BMV-712 monitor, or whatever you use to control your LFP battery) that has relay outputs, it would be relatively simple to create a relay-controlled alarm circuit with light and buzzer that is triggered when certain events take place. The only caveat is that the warning should be triggered by the same component that will be doing the subsequent disconnection.

One boat buck is ridiculously expensive for a BMS. Every BMS in that price range will do it. You can buy 300Ah of drop-ins with built-in BMS for a boat buck. And that one feature would cost nothing for them to add to those cheap batteries. I am at a loss at to why it isn't a common feature.

[SaylorMade]

"The BMS shall provide an audible and visual alarm at the normal vessel operating position before a disconnection event occurs."


I don't understand how this a good requirement.

1 It does not state how much in advance, so if it is 1 second before the shutdown, you are in compliance, and yet it does nothing useful for you?

2. If an overvoltage or especially over-discharge-current!! event occurs, I would like my BMS to shutdown right now and then when that event occurs!! Not hang around to sound a buzzer for a period of time and THEN shut down.
It could be very dangerous to let the BMS run for even a fraction of a second more if it's an over-discharge-current event.



Can someone shed some light on why this requirement is there, and why it is there for LFP batteries in particular? (Other battery types can shutdown too, a connection can fail, a breaker can trip etc etc etc)

[lmxr]

Originally Posted by SaylorMade

"The BMS shall provide an audible and visual alarm at the normal vessel operating position before a disconnection event occurs."


I don't understand how this a good requirement.

1 It does not state how much in advance, so if it is 1 second before the shutdown, you are in compliance, and yet it does nothing useful for you?

Agreed. It also does not specify loudness or much else. That said, even with this ridiculously low requirement, that has now been known for several years in this or similar forms (i.e. ABYC TE-13), many so-called 'marine' BMS's still lack this basic feature ...

Makes me question how serious these 'market leading' companies are about bringing a halfway decent product to the market, if they can't even manage to let their 'high-tech' device make a buzzing sound?

2. If an overvoltage or especially over-discharge-current!! event occurs, I would like my BMS to shutdown right now and then when that event occurs!! Not hang around to sound a buzzer for a period of time and THEN shut down.
It could be very dangerous to let the BMS run for even a fraction of a second more if it's an over-discharge-current event.

Overcurrent protection should be handled by mechanical fuses. The BMS can add additional protection if desired, but should not be the sole protection.

There is little reason to shut down immediately on overvoltage. LFP batteries have no problem at all accepting a few tenths of volts over their maximum rating for a few seconds.

Can someone shed some light on why this requirement is there, and why it is there for LFP batteries in particular? (Other battery types can shutdown too, a connection can fail, a breaker can trip etc etc etc)

An LA battery can run empty but that's a more continuous process and as a crew you know it's empty when the lights start dimming etc. Even with the lights dimmed, the VHF will still function. However, with LFP it's all or nothing, and therefore some measure that notifies the crew of the LFP running empty add to the crew's situational awareness.

While it's true that anything can fail, there are differences in probability. On a somewhat decent electrical install, the probability of the main fuse tripping due to a serious short somewhere, or the probability of a connection getting loose, is far lower than that of a tired crew accidentally overdraining the battery, leading to a low-voltage disconnect.

That said, an alarm five seconds before the disconnect is not that useful, I think. On our boat we have 30 s before a disconnect, we have a reliable SoC gauge and also look at the voltage (if it's going below 13.0 V, we consider recharging using the engine).

[SaylorMade]

Originally Posted by lmxr

Agreed. It also does not specify loudness or much else. That said, even with this ridiculously low requirement, that has now been known for several years in this or similar forms (i.e. ABYC TE-13), many so-called 'marine' BMS's still lack this basic feature ...

Makes me question how serious these 'market leading' companies are about bringing a halfway decent product to the market, if they can't even manage to let their 'high-tech' device make a buzzing sound?

Overcurrent protection should be handled by mechanical fuses. The BMS can add additional protection if desired, but should not be the sole protection.

There is little reason to shut down immediately on overvoltage. LFP batteries have no problem at all accepting a few tenths of volts over their maximum rating for a few seconds.

An LA battery can run empty but that's a more continuous process and as a crew you know it's empty when the lights start dimming etc. Even with the lights dimmed, the VHF will still function. However, with LFP it's all or nothing, and therefore some measure that notifies the crew of the LFP running empty add to the crew's situational awareness.

While it's true that anything can fail, there are differences in probability. On a somewhat decent electrical install, the probability of the main fuse tripping due to a serious short somewhere, or the probability of a connection getting loose, is far lower than that of a tired crew accidentally overdraining the battery, leading to a low-voltage disconnect.

That said, an alarm five seconds before the disconnect is not that useful, I think. On our boat we have 30 s before a disconnect, we have a reliable SoC gauge and also look at the voltage (if it's going below 13.0 V, we consider recharging using the engine).

While I agree that mechanical fuses should be first line of defense, I do not agree that means that it is ok to amputate the second line (the BMS).
Note that I am not talking about overvoltage here, but over current protection.
And if that occurs on my boat, I demand that the BMS shuts of pronto and not sitting around to let a buzzer sound for a while before shutting down. I can tell you that if my house battery starts pumping out more than 100A, something is shorted, not caught by the first line of defence.

This seems very strange to me. Well the rule does not apply to me, I was just curios if there were any sound arguments for this requirement.

[lmxr]

Originally Posted by SaylorMade

While I agree that mechanical fuses should be first line of defense, I do not agree that means that it is ok to amputate the second line (the BMS).
Note that I am not talking about overvoltage here, but over current protection.
And if that occurs on my boat, I demand that the BMS shuts of pronto and not sitting around to let a buzzer sound for a while before shutting down. I can tell you that if my house battery starts pumping out more than 100A, something is shorted, not caught by the first line of defence.[...]

Correctly installed quality fuses tend to be extremely reliable, so I doubt that a BMS overcurrent protection would add much, and rather make the system more unreliable without getting much additional safety in return.

A well-implemented overcurrent protection in the BMS won't hurt too much I guess, and indeed in that situation a long warning duration does not make any sense.

[wholybee]

Originally Posted by SaylorMade

"The BMS shall provide an audible and visual alarm at the normal vessel operating position before a disconnection event occurs."


I don't understand how this a good requirement.

1 It does not state how much in advance, so if it is 1 second before the shutdown, you are in compliance, and yet it does nothing useful for you?

2. If an overvoltage or especially over-discharge-current!! event occurs, I would like my BMS to shutdown right now and then when that event occurs!! Not hang around to sound a buzzer for a period of time and THEN shut down.
It could be very dangerous to let the BMS run for even a fraction of a second more if it's an over-discharge-current event.



Can someone shed some light on why this requirement is there, and why it is there for LFP batteries in particular? (Other battery types can shutdown too, a connection can fail, a breaker can trip etc etc etc)

I agree with you, it is a nonsense requirement. From what I understand of the history, it goes something like this.

When ABYC was early in meetings/discussions on requirements, there was concern that a boat with electric propulsion could unexpectedly loose propulsion and cause a collision leading to a death. So, the requirement was included in the draft proposal. However, it was later downgraded to a recommendation in the final.

It does at least make some sense to have a warning before you loose propulsion. But loosing lights and radio/navigation, while a serious problem, is much less so on a sailboat than loosing your engine as well. And, of course a fuse might blow or breaker trip leaving no warning at all.

But following the draft proposal, now many individuals, and apparently other standards organizations, are following suit.

In any case, not immediately disconnecting on an overcurrent event is stupid. Awesome, your radio works, but your boat is on fire. Just dumb. At most, I would suggest an alarm before a low voltage cutoff, and nothing else.

Pretty much every BMS made already has the hardware for this, perhaps a 2 cent FET would need to be added for a GPO output to trigger an external alarm. The firmware change is basically free. Even the bottom barrel $20 BMSs sold on amazon and ebay should include this. I don't understand why anyone should pay $1000 for just this one feature (assuming they didn't want/need the $1000 BMS for other features it might have).

[ben373]

I certainly agree this is a strange requirement.

Nonetheless this is what insurance want to see.

I can't find a BMS that had that feature.

[SaylorMade]

Originally Posted by wholybee

Pretty much every BMS made already has the hardware for this, perhaps a 2 cent FET would need to be added for a GPO output to trigger an external alarm. The firmware change is basically free. Even the bottom barrel $20 BMSs sold on amazon and ebay should include this. I don't understand why anyone should pay $1000 for just this one feature (assuming they didn't want/need the $1000 BMS for other features it might have).

I don't think you will find any mainstream BMS with this feature, because it makes zero sense, so no demand for it.

The requirement in RS would be like: "When an event occurs that should shut down the BMS, keep the BMS on for x seconds anyway but output a signal in the meantime, that can be used for an audible alarm."

Never going to pass any QA review in any company.

I don't understand why this should be applied to boats with electric propulsion in particular. I mean, if your diesel pump dies on your diesel propelled vessel, the pump is not going to output a signal and then keep going for another x seconds. (Or any other sudden fossil engine event)

Very odd this.

[Simi 60]

Originally Posted by ben373

The Australian standards are calling for a warning prior to BMS disconnect.

This is to be a light and loud buzzer so would needed to be a relay output so that the light and buzzer can be remote.
.

You have lithium Ion batteries on your boat?
These are in your mobile phone, tablet, camera, battery tools laptop right?
Do any of those have an alarmed BMS?

Your house batteries surely aren't lithium ion.

Pantaneous insurance are now requiring this.

I'm surprised anyone still uses them in Oz.
But that's another discussion.

[SaylorMade]

Originally Posted by Simi 60

You have lithium Ion batteries on your boat?
These are in your mobile phone, tablet, camera, battery tools laptop right?
Do any of those have an alarmed BMS?

Your house batteries surely aren't lithium ion.


I'm surprised anyone still uses them in Oz.
But that's another discussion.

Right, when I read the text again, it also struck me that it says "Lithium batteries" or "Lithium ion" batteries, which is a generic description, that covers a wide variety of chemistries, with very different properties and individual concerns.

It is surprising that something like this can come from an "official body"

[wholybee]

Originally Posted by SaylorMade

I don't think you will find any mainstream BMS with this feature, because it makes zero sense, so no demand for it.

The requirement in RS would be like: "When an event occurs that should shut down the BMS, keep the BMS on for x seconds anyway but output a signal in the meantime, that can be used for an audible alarm."

Never going to pass any QA review in any company.

I don't understand why this should be applied to boats with electric propulsion in particular. I mean, if your diesel pump dies on your diesel propelled vessel, the pump is not going to output a signal and then keep going for another x seconds. (Or any other sudden fossil engine event)

Very odd this.

I agree. The requirement is nonsense. The only reason for it is to satisfy whatever governing body, and then you should disable it.

[fxykty]

Originally Posted by ben373

…

I can't find a BMS that had that feature.

You need to look harder - there are several commercial BMS that do this (alarm prior to disconnect).