ABYC and ISO Li reference diagram

[newhaul]

Originally Posted by rgleason

What? please explain.

Issue with gbn being backwards. I'm saying to be able to parallel your lfp with a low fla start battery for starting. . He's saying no can't do it because it will cause damage to your lfp bank because if you need to parallel it must mean something wrong with your lfp bank.

[rgleason]

There are many points of view, here is @Goboatingnow writing:

In my case each “ battery “ consisting of 4S cells of 100Ah capacity will have battery based current protection.

If that battery current trips the BMS will shut down every battery until manual overrides can be triggered to decide what is appropriate to reconnect. This means system current is limited to individual battery max. I feel strongly this limits cascade failures.

I agree that LFP is reliable , I find some of these debates building all sorts of redundancy designs switching in SLA , bypassing this that or other rather “ amusing “ as if LFP failure which is , as you say, highly unlikely , is somehow going to happen every time the boat senses a Lee shore at night. Over protecting one unlikely failure mode while ignoring everything else is silly.

There seems to be a body of opinion that this “ new fangled “ “ Lithium thingy” is dodgy, prone to failure or burns the boat down whereas the truth , as you say it , is it’s actually more reliable.

He has helped tremendously, even though he doesn't really think that backup is needed! I really respect that.

Thanks @Goboatingnow.
I am interested in your bank idea.

[rgleason]

Revision 10-04-2022 which is probably 99% finished.
Many thanks to Goboatingnow, svsagres and wholybee for contributing your essential knowledge and experience. For me, this was a valuable learning experience.


The main thread is on Diysolarforum.com under Marine > Small Boat BMS/LFP with backup Post #402 Before this post there is a treasure trove of dialogue and information, focused on developing this diagram.

[fxykty]

Are you showing switches on the positives between the MPPT controllers and the Lynx/battery and nothing to interrupt the current between the panels and MPPT controllers? Shouldn’t there be an interrupt (fuse or circuit breaker) on the pane output and no switch on the controller output?

[s/v Jedi]

Originally Posted by fxykty

Are you showing switches on the positives between the MPPT controllers and the Lynx/battery and nothing to interrupt the current between the panels and MPPT controllers? Shouldn’t there be an interrupt (fuse or circuit breaker) on the pane output and no switch on the controller output?

Exactly, I reported that twice before. The mppt requires a fuse at the battery busbar, not at the controller. Then, for solar panels, each panel of string of panels that is parallel requires a breaker or at least a fuse.

I see yet another battery switch… that’s 3 already

[wingssail]

Originally Posted by rgleason

Revision 9/27/2022, from the main discussion thread DIYsolarForum.com thread, Small Boat BMS/LFP Backup, post #343. This post also includes a PDF that is clearer, but not under the 2mb required here. Also included in the post is a drawio zip file.

I'd kind of like to study this but the low resolution hurts my eyes. The link you referenced seems to require that I have a log in. Can you publish a little better resolution here?

[fxykty]

Originally Posted by wingssail

I'd kind of like to study this but the low resolution hurts my eyes. The link you referenced seems to require that I have a log in. Can you publish a little better resolution here?

Save the posted photo to your phone or computer, then open the photo in a viewing app that allows you to zoom in. There’s enough resolution in the posted photos that you can zoom in lots.

[goboatingnow]

Originally Posted by Baronkrak

Which is reckless and may only aggravate the fault.

I like to see admirals and other elephants that cannot differentiate a Sounder from a Speed display.



been able to remove loads and bypass safeties.







It is not appropriate to override or bypass safety devices.



It still remain that, the safest way to clear a BMS load disconnect fault, is to charge the battery, and to clear a charge disconnect fault is to discharge the battery

In you last paragraph yes BUT

But only so manually not by any automatic bms processs for safety after a major safety trip like LVE HVE , and full battery disconnect as required by ABYC and ISO, then full manual inspection should occur and then and only then charge sources or loads can be reconnected to the system , that manually initiated reconnection can be as simple or as complicated as you like.

Never have automatic BMS reconnects after any safety trip event which led to battery disconnect until an inspection had occurred to determine exact cause.

That’s the intent of ABYC and ISO and it’s a good “ safety first “ approach.

A bms doesn’t “ know “ what caused the LVE HVE etc. hence it shouldn’t act as if it did and take automatic decisions.

Hence the current total disconnect strategy in ISO and ABYC is completely sound logic. Only the bms remains connected after that disconnect.

In any electronic system controlling power on a boat YOU must have manual bypass solutions to restore partial operation after things like complete BMS failure etc. this requires and demands bypasses of safety devices. With appropriate notices and training ( and the required ABYC/ISO user manual ) there should be no issue operating such bypass systems.

This is very much the case in the RGleason reference diagram where electrical interlocks of the manual systems provide a certain degree of safety.

But the BMS contactor definitely needs a bypass as well as all batteries need mechanical master disconnects as is normal practice.

By the way people onboard with no understanding of the boats electrical system have no place anywhere near it and certainly not reconfiguring it in bypass mode.

[rgleason]

Nick,

This is discussed quite extensively in the main thread. Yes you did raise the issue. Thanks.

The main thread is on Diysolarforum.com under Marine > Small Boat BMS/LFP with backup Post #402 Before this post there is a treasure trove of dialogue and information, focused on developing this diagram.

[Baronkrak]

Originally Posted by goboatingnow

…. .

You do get very confused sometime and keep repeating things like, LVE HVE etc

A basic BMS does know why it caused a “relay" to operate. A basic BMS monitor temperature and cells voltage, values that should be readily available with Bluetooth.

Are you trying to convince people than when a Low Fuel indicator lit on a dashboard, people should pull the engine apart?

I repeat it is a bad idea to bypass safety devices. Faulty safety devices get replaced and not bypassed.

Redundancy is not in bypassing safety devices it is in having alternative safe systems.

You need to familiarize your self with lithium battery and looking at the resulting disastrous and dangerous diagram produced here. I doubt that a person will get that knowledge from a Diy Solar forum.

By the way was it the space station or the Apollo Space Program?

[goboatingnow]

Originally Posted by Baronkrak

You do get very confused sometime and keep repeating things like, LVE HVE etc



A basic BMS does know why it caused a “relay" to operate. A basic BMS monitor temperature and cells voltage, values that should be readily available with Bluetooth.



Are you trying to convince people than when a Low Fuel indicator lit on a dashboard, people should pull the engine apart?



I repeat it is a bad idea to bypass safety devices. Faulty safety devices get replaced and not bypassed.



Redundancy is not in bypassing safety devices it is in having alternative safe systems.



You need to familiarize your self with lithium battery and looking at the resulting disastrous and dangerous diagram produced here. I doubt that a person will get that knowledge from a Diy Solar forum.



By the way was it the space station or the Apollo Space Program?

LVE and HVE as I’m am concerned are not “ low fuel “ please note these terms ARE defined in the ABYC and ISO spec s.

We have to abandon the idea the LVE and HVE are normal. They are the same as your engine ecu warning light on or “ lo oil pressure. “ light. Not low fuel.

In a proper function system just like a car the LVE and HVE should NEVER normally occur.

( in the last 20 years and 6 boats I’ve never even had a low bat condition. )

A bms has no idea WHY a LVE occurred or why an HVE occurred all its know it did , it has no “ eyes “

Hence automatic charge sources and loads should never be automatically connected ( or remain connected ) following a battery bms disconnect ISO and ABYC are in complete agreement with me on this

As safety devices. IF your BMS fails you absolutely need a manual bypass around the contractor. It’s why BLUE Seas Ml have One.

Secondly as ABYC and ISO mandate you also need to provide emergency sources in the case of disconnect hence the interlocked way to bring the SLA into play.

So let’s puts these in good practice “ rules “

1) a BMS safety event as per ABYC/ISO disconnects the battery completely with an advance warning all loads and charge sources are disconnected.

2) manual inspection then confirms disconnect reasons , Ascertains battery integrity and can switch on charge sources or loads as required

3) such manual switching may have to bypass the bms in such an emergency

4) as per ABYC ISO consideration should be given to switching in alternative power sources if needed. Various system can be deployed to this end

4)mechanical or electrically interlocking should prevent inadvertent paralleling of different chemistry banks

RGleason diagram meets and exceeds these practices. I commend his effort.


I’m not really interested in to and fro on this. Put whatever you. like on your boat. Hopefully your insurers will agree with you.

And as a EE with years of design experience including battery system. Pleas don’t tell me what’s “ disastrous “ and don’t denigrate diy Solar forum. It has way more hardcore EE and tech people then a bunch of boaters on a cruising forum !!!


You keep using this “ disasterious “ term around the provision of a BMS contactor override . Are you suggest a perfectly fine battery with a failed BMS should then be left disconnected in an emergency. !!

That’s high nonsense in my opinion. ( and the bms contactor bypass is the only bypass in the RLeason diagram

[Baronkrak]

You did not get it did you?

Originally Posted by goboatingnow

LVE and HVE as I’m am concerned are not “ low fuel “

A basic BMS monitor temperature and cells voltage and yes a low cell voltage is low fuel.

Originally Posted by goboatingnow

We have to abandon the idea the LVE and HVE are normal. They are the same as your engine ecu warning light on or “ lo oil pressure. “ light. Not low fuel.

Are you trying to convince people than when a Low oil pressure indicator lit on a dashboard, people should pull the engine apart?
Normally after a low oil pressure people assert that there is oil in the engine (same than checking the cells voltage) then replace the oil pressure switch.

A bad idea to bypass it.

Set as a warning a low cell voltage is a good indication that the cell needs charging.
A bad idea to bypass the load disconnect relay. Let the BMS clear the fault.

Originally Posted by goboatingnow

Hence automatic charge sources and loads should never be automatically connected ( or remain connected ) following a battery bms disconnect ISO and ABYC are in complete agreement with me on this.

You got that one mixed up.

Originally Posted by goboatingnow

As safety devices. IF your BMS fails you absolutely need a manual bypass around the contractor. It’s why BLUE Seas Ml have One.

If the BMS fail the battery is without protection and should not be used at all, in my case, be discarded.

Originally Posted by goboatingnow

Secondly as ABYC and ISO mandate you also need to provide emergency sources in the case of disconnect hence the interlocked way to bring the SLA into play.

200Ah at 24V of SVLA provides a good backup.

Originally Posted by goboatingnow

1) a BMS safety event as per ABYC/ISO disconnects the battery completely with an advance warning all loads and charge sources are disconnected.

I doubt that ABYC/ISO requires that all loads and charge sources be disconnected.

Originally Posted by goboatingnow

3) such manual switching may have to bypass the bms in such an emergency.

I doubt that ABYC/ISO would allow of the bypassing of a major safety device.

Originally Posted by goboatingnow

( in the last 20 years and 6 boats I’ve never even had a low bat condition. )

Obviously as an EE with years of design experience, you never tested a low cell voltage disconnect or a high cell voltage disconnect.

[goboatingnow]

Originally Posted by Baronkrak

You did not get it did you?







A basic BMS monitor temperature and cells voltage and yes a low cell voltage is low fuel.







Are you trying to convince people than when a Low oil pressure indicator lit on a dashboard, people should pull the engine apart?

Normally after a low oil pressure people assert that there is oil in the engine (same than checking the cells voltage) then replace the oil pressure switch.



A bad idea to bypass it.



Set as a warning a low cell voltage is a good indication that the cell needs charging.

A bad idea to bypass the load disconnect relay. Let the BMS clear the fault.







You got that one mixed up.







If the BMS fail the battery is without protection and should not be used at all, in my case, be discarded.







200Ah at 24V of SVLA provides a good backup.





I doubt that ABYC/ISO requires that all loads and charge sources be disconnected.







I doubt that ABYC/ISO would allow of the bypassing of a major safety device.







Obviously as an EE with years of design experience, you never tested a low cell voltage disconnect or a high cell voltage disconnect.

Give up the personal slagging mate will ya , you are entitled to have different ideas that’s fine. What’s not acceptable is denigrating good alternative designs.

I DO NOT accept you’re basic premise. I fully “ get “ what your saying , I simply think, professionally , it’s wrong that’s all.

LVE is NOT “ low fuel “. LVE is defined by ABYC and ISO as the lowest allowable voltage by the cell manufacturer. In normal usage you should NEVER get near this level.

Secondly ABYC and ISO require all connections except the BMS to be disconnected or BMS trigger.

Low battery is not a fault and your ordinary battery monitoring systems present today on a boat will warn you of lower SOC , none of this triggers LVE.

ABYC and ISO are very nebulous of failed systems , but I would contend that a mechanism for bypassing the BMS must exist in extremis. Lightning can easily take out a bms

Emergency use of the battery can then continue even using a DMM regularly to monitor cell voltage.

Suggesting you carry 200Αh of SLA on the off chance once in 10 years is nonsense. Sheer nonsense.

Suggesting a 500aj lithium bank should be discarded on a failed BMS is nonsense. Sheer nonsense. A bms is a monitor that’s all. The Li battery could be perfectly fine , anyone with a DMM can manually verify LI operation.

By the way read TE-13 cover to cover and ISO 26235 as well rather then “ assuming “ things.

Given I designed a number of industrial batteries systems all possible fault scenarios were tested to verify the design just as I will do so on my next BMS project.

With modern SOC metering there’s zero reason to ever allow any battery to reach LVE. Loads should either selectively disable themselves ( most of my modern high current stuff does) , charge sources if available should be programmed to begin charging as soon as they are available. Depth of Discharge should be kept as low as practical.

Hence a good Li will never generate LVE or HVE , certainly never overtemp and never overcurrent

These are all “ faults “ and like your modern car you take it to be inspected or fixed.

Hence a bms bypass is entirely optional. It’s a decision for the designer. In this case RGleason wants to ensure the Li bank can be accessed if the BMS dies. Similarly the Blueseas ML has a similar manual override. Also useful if the contactor itself malfunctions.

In my case i don’t bother with integrated bypass switching I carry a big 3m set of jump leads. Been useful now and again.

[Baronkrak]

Originally Posted by goboatingnow

my next BMS project.

Good luck.

[newhaul]

Originally Posted by goboatingnow

Give up the personal slagging mate will ya , you are entitled to have different ideas that’s fine. What’s not acceptable is denigrating good alternative designs.

I DO NOT accept you’re basic premise. I fully “ get “ what your saying , I simply think, professionally , it’s wrong that’s all.

LVE is NOT “ low fuel “. LVE is defined by ABYC and ISO as the lowest allowable voltage by the cell manufacturer. In normal usage you should NEVER get near this level.

Secondly ABYC and ISO require all connections except the BMS to be disconnected or BMS trigger.

Low battery is not a fault and your ordinary battery monitoring systems present today on a boat will warn you of lower SOC , none of this triggers LVE.

ABYC and ISO are very nebulous of failed systems , but I would contend that a mechanism for bypassing the BMS must exist in extremis. Lightning can easily take out a bms

Emergency use of the battery can then continue even using a DMM regularly to monitor cell voltage.

Suggesting you carry 200Αh of SLA on the off chance once in 10 years is nonsense. Sheer nonsense.

Suggesting a 500aj lithium bank should be discarded on a failed BMS is nonsense. Sheer nonsense. A bms is a monitor that’s all. The Li battery could be perfectly fine , anyone with a DMM can manually verify LI operation.

By the way read TE-13 cover to cover and ISO 26235 as well rather then “ assuming “ things.

Given I designed a number of industrial batteries systems all possible fault scenarios were tested to verify the design just as I will do so on my next BMS project.

With modern SOC metering there’s zero reason to ever allow any battery to reach LVE. Loads should either selectively disable themselves ( most of my modern high current stuff does) , charge sources if available should be programmed to begin charging as soon as they are available. Depth of Discharge should be kept as low as practical.

Hence a good Li will never generate LVE or HVE , certainly never overtemp and never overcurrent

These are all “ faults “ and like your modern car you take it to be inspected or fixed.

Hence a bms bypass is entirely optional. It’s a decision for the designer. In this case RGleason wants to ensure the Li bank can be accessed if the BMS dies. Similarly the Blueseas ML has a similar manual override. Also useful if the contactor itself malfunctions.

In my case i don’t bother with integrated bypass switching I carry a big 3m set of jump leads. Been useful now and again.

My biggest issue with you is your misrepresentating the ABYC and ISO . none of which are governing bodies nothing they say is a requirement . don't make it more than it is . now as to you . a while back you were on begging for info and sources . now you try to pass yourself off as some kind of an expert on the subject of LIFEPO4 banks .
You have even told me that you can't parallel Fla and lip but won't say why that is except your opinion . many do it all the time on here there is even a thread just for fla/ lfp hybrid systems. Heck even the ABYC and ISO recomend having Fla in the setup as a backup to automatically take the load when the rare event of some kind of lfp failure happens .
If you have something constructive to contribute please do just stop the badgering of others on here that may actually know more than either of us on the subject.