bank manager system BBMS plus

[Goboatingnow]

I just looked at the video re the BBMS system

First thoughts

Hmm. Ok for big lead and small li. Not good as a solution where the only lead is a starter battery.

Not ISO compatible so that’s Out for European Boats. ( that’s ok cause he doesn’t ship )

My own view is a system that actively manages the two banks only connecting them when it’s safe to do so is not fail safe especially with latching contactors. A failure of the BBMS leaves you exposed to large current flows between batteries.

By the way anyone charging Li only using voltage set points doesn’t know what they are doing , all charging should measure tail currents.

It’s expensive for what it does. It’s conceptually very simple.

If you really want similar sizes lead and Li the simplest way is to isolate each bank using big diodes. This prevents any inter battery flow.

You either then charge each bank separately or charge one back and dc dc charge the other.

That concept is safer. At no point are batteries electrically paralleled as they are in the BBMS , which is forbidden by ISO lithium specs on a boat anyway.

Both lead and lithium should be separately fused.

 

[rgleason]

Where is this video? Just trying to get up to speed on what the system is.

 

[jdege]

Why you need a BankManagerPlus for an off-grid ststem

 

[Goboatingnow]

It’s a funny concept , really , because you need a big domestic lead Acid system I’m not sure why people would do that as most lithium are replacement systems not additions

 

[rgleason]

It is clever and is thoughtful, and it does address some safety concerns about connecting LFP and FLA by only connecting when battery voltages are within some small range (not stated in the video), however this system would not qualify as being ABYC compliant.

 

[Goboatingnow]

It is clever and is thoughtful, and it does address some safety concerns about connecting LFP and FLA by only connecting when battery voltages are within some small range (not stated in the video), however this system would not qualify as being ABYC compliant.

Well that’s the end of that neither ABYC or ISO compliant

 

[Volts and Amps]

I just looked at the video re the BBMS system

First thoughts

Hmm. Ok for big lead and small li. Not good as a solution where the only lead is a starter battery.

Not ISO compatible so that’s Out for European Boats. ( that’s ok cause he doesn’t ship )

My own view is a system that actively manages the two banks only connecting them when it’s safe to do so is not fail safe especially with latching contactors. A failure of the BBMS leaves you exposed to large current flows between batteries.

By the way anyone charging Li only using voltage set points doesn’t know what they are doing , all charging should measure tail currents.

It’s expensive for what it does. It’s conceptually very simple.

If you really want similar sizes lead and Li the simplest way is to isolate each bank using big diodes. This prevents any inter battery flow.

You either then charge each bank separately or charge one back and dc dc charge the other.

That concept is safer. At no point are batteries electrically paralleled as they are in the BBMS , which is forbidden by ISO lithium specs on a boat anyway.

Both lead and lithium should be separately fused.

What specific ISO standard is it you are referring to? Why not Big Li and small lead? That would for sure save your alternator if the BMS shuts the Li down.
Just looked at the system and why the hall effect sensor if only voltage setpoints are used for the charging of Li? (agree with your view in general about only using voltage setpoints.)
How could there be a current surge that is dangerous if the BBMS only connects at the same voltage in the two banks? A failure where the BBMS should connect with a voltage difference I can understand but then the BMS in the Li part would shut the Li down. And regarding fail-safe or safe-fail two different approaches used in the airline industry it for sure is easy enough to make the system safe fail with a simple fuse between the Li and connecting relay, which would actually give safe fail with redundancy!
My take is that the system the way I understand it actually is brilliant and I am for sure researching it to fully understand it since I am interested in it for my own sailing yacht.
I really want to keep my big lead AGM bank that is used in the bow for Bowthruster, Windlass , and furling system and at the same time have a Li bank for the "house" needs. For sure I do not want to have to change my 5k USD MasterVolt charger or the Solar charge controller if this device can be used instead!
Really interested in a deeper understanding of what your concerns are!

 

[svsagres]

What specific ISO standard is it you are referring to? Why not Big Li and small lead? That would for sure save your alternator if the BMS shuts the Li down.
Just looked at the system and why the hall effect sensor if only voltage setpoints are used for the charging of Li? (agree with your view in general about only using voltage setpoints.)
How could there be a current surge that is dangerous if the BBMS only connects at the same voltage in the two banks? A failure where the BBMS should connect with a voltage difference I can understand but then the BMS in the Li part would shut the Li down. And regarding fail-safe or safe-fail two different approaches used in the airline industry it for sure is easy enough to make the system safe fail with a simple fuse between the Li and connecting relay, which would actually give safe fail with redundancy!
My take is that the system the way I understand it actually is brilliant and I am for sure researching it to fully understand it since I am interested in it for my own sailing yacht.
I really want to keep my big lead AGM bank that is used in the bow for Bowthruster, Windlass , and furling system and at the same time have a Li bank for the "house" needs. For sure I do not want to have to change my 5k USD MasterVolt charger or the Solar charge controller if this device can be used instead!
Really interested in a deeper understanding of what your concerns are!

So ABYC TE.13 is the technical standard that was recently released that covers Lithium power systems on boats. The IEC standard closely mirrors it, with a few differences.

One of the things that both standards do is prohibit the paralleling of batteries of different chemistries. They can exist in a system, but they need to be separated by something like a DC:DC charger.

But the whole concern over a system disconnect hurting an alternator is largely moot in a compliant system anyhow. Aside from the fact that you should never be putting your system into a situation where you will have a disconnect, in a properly designed system it won't cause problems with your alternator. You also should be doing this as at least a minimally integrated system.

The ABYC standards require that the BMS have a pre-warning of an impending disconnect so that the user can take appropriate actions. In an alternator connected system, you use this signal to de-energize the alternator. If the disconnect actually comes, no harm, no foul. All you need is a normally open relay controlling your field wire.

On my own system, I've gone for deep integration, so my alternator is connected to my BMS (via an advanced regulator and CANBus) and takes its directions from the BMS. If the BMS starts getting into trouble, it will signal that it wants zero power from the alternator so the regulator will stop the alternator from producing any power.

 

[wholybee]

Lets ignore compliance for a moment. If you parallel the batteries, you give up many of the advantages of lithium. Just stick with lead. You either want 5he advantage of lithium, or not.
If you really want to experience what lithium can do, stick with all lithium. Because you can discharge it so much deeper, it doesn't have psoc issues, and charges in less time, you can usually use a smaller lithium battery.
Lithium is a better battery for high load applications, and also better if it must be installed at the bow because its 1/3 the weight for the same usable capacity. But even if you keep an AGM there, there is zero reason to parallel it, a dcdc charger is more than adequate.
Another consideration, LFP is a higher voltage, and experience lag sag while under load. So not the need to keep it close to a windlass or thruster. Even with a voltage drop from a long wire run, it will match the voltage of a heavily loaded lead acid at the bow.
None of that considers the ABYC and IEC issues. Considering those issues as well, its foolish to consider something like the bbms.
I might understand something like the bbms in a large stationary solar application, where there exists a very large lead acid bank, and you want to add capacity with lfp. Boat on a boat? Nope.