Small Boat BMS/LFP with backup

[svsagres]

What happens when a 12.5v SLA is hooked up to that alternator, isn't it going to try and jam 100A into the battery? All the logic of disconnecting the BMS solenoid and 12->12 charger relay can be avoided with a 1-2-off switch
Sorry for butchering your nicely drawn layout. The red circles are 1-2-off switches. From LFP you can select between feeding the BMS solenoid, by passing it or isolate the battery.
Switch 2 selects if the DC panel is feed by Lynx, SLA or OFF
Orion is feed by Lynx, a switch could be inline if to turn it off.
This would eliminate all the relays, switches controlling the BMS solenoid and keep the SLA from being over charged.
View attachment 113981

Without BMS control, the Wakespeed will set its voltage out to limit to a configured value. On my boat, I have it at the default limp mode at 13.2v, but unless things go really bad, I’ll just run the lfp without the bms.

 

[rgleason]

Anarchyjet, Ideas are food, diagrams are for understanding. There are many ways to accomplish things.

As stated at several times and in several places, when the Wakespeed Regulator WS500 is operating in limp home emergency mode, it operates at a maximum voltage of 13.8vdc which is basically absorption mode, so the Alternator is not a problem.

I see what you are suggesting with regard to the two 1-off-2 switches. It may be simpler. I am going to let the others comment first about those changes. I guess I really don't think I want to change the Orion Tr wiring at this point although I remain open to it if it is really an improvement.

Its late here now so I am going to have to study your revisions further on Thursday. Thanks for posting.

 

[Goboatingnow]

I have not read the whole post and this is based off the latest diagram. In Limp Home mode, all your LFP charging sources are connected directly to your SLA bank. Orion should be hooked up to Lynx to continue charging SLA via Alt, Solar or Phoenix. SLA should be then be switched in to DC panel and disconnected from Lynx.

Why. There’s no issue using the charge sources on the SLA

The 1-2 original was elegant simple for a user to understand and safe

Personally loosing the electrical interlocking to prevent the bms reconnecting the li to the SLA is a big error and it specifically violates ISO

Since the mppt and Orion have remote shutdown you could interlock them with the same signal from the interlocking relay
I see no electrical issues leaving them connected , I think there is far better logical thinking on this forum then cruisersforum

 

[Goboatingnow]

What happens when a 12.5v SLA is hooked up to that alternator, isn't it going to try and jam 100A into the battery? All the logic of disconnecting the BMS solenoid and 12->12 charger relay can be avoided with a 1-2-off switch
Sorry for butchering your nicely drawn layout. The red circles are 1-2-off switches. From LFP you can select between feeding the BMS solenoid, by passing it or isolate the battery.
Switch 2 selects if the DC panel is feed by Lynx, SLA or OFF
Orion is feed by Lynx, a switch could be inline if to turn it off.
This would eliminate all the relays, switches controlling the BMS solenoid and keep the SLA from being over charged.
View attachment 113981

To me this wiring of the Orion is wrong. It’s rightly a consumer. Looking at the specs it’s no problem leaving it connected to the dc panel.
Again you have the paralleling of thd batteries issues plus no interlocking of the two battery selectors

 

[rgleason]

@AnarchyJet This morning after reading @Goboatingnow 's post I realize that the simpler diagram you suggest does indeed allow paralleling the LFP and SLA which must not occur by ABYC standards. Sorry about that. Its is certainly worthwhile to bring these ideas forward to be reviewed and considered.

There is one aspect of your diagram that intrigues me, and that is the idea of placing the 3 way switch between the LFP and the relay, but using the 1-Off-2 Switch pretty much as we have developed it in our diagram. First of all, I do not know if moving the switch to this position would be against ABYC requirements, but that position might have some advantages because the relay can be readily overridden for "SLA Emergency and LFP Disconnect" without reliance on an AFD and the small relay. The "Off- LFP Normal" position would be the same as before. The "LFP/BMS Bypass would also work without the AFD and relay. The dashed red SLA Emergency feed would remain as we show it. The small AFD relay would still be needed for the automatic Orion Tr turn off/on.

I would be interested in what the others ( @Goboatingnow @svsagres @wholybee ) think about this potential improvement?

 

[rgleason]

John Harries of https://www.morganscloud.com/2022/07/03/building-a-seamanlike-lithium-battery-system/#comment-304160
and Attainable Adventure Cruising https://www.morganscloud.com/ would like

I would definitely want to two busses independently controlled and I would not install a BMS that had to be shorted out to reset after a dump. I have not done detailed research into BMSs but I would bet large sums that the good BMSs from companies like Victron and Lithionics have a better way to reset.

And if I’m wrong about that, then it makes my backup design detailed above that much more necessary since it will keep everything going, including charging the lead-acid backup, for as long as it takes to get the lithium back on line.

This link to his diagram may not work:

https://etugri87v3i.exactdn.com/wp-content/uploads/2022/07/Lithium-Backup.pdf?_gl=1*w7nboh*_ga*NjQxNDI1MTgzLjE2NjM5NTcxNTQ.*_ga_9M7X2VRKRH*MTY2NDQ1MDYyMC4xOC4xLjE2NjQ0NTI2MDUuMC4wLjA.&_ga=2.87253720.1385959397.1664287435-641425183.1663957154

Do any of you know if such a BMS exists? I wonder what Lithionics or Victron offers in the way of features.

 

[Goboatingnow]

John Harries of https://www.morganscloud.com/2022/07/03/building-a-seamanlike-lithium-battery-system/#comment-304160
and Attainable Adventure Cruising https://www.morganscloud.com/ would like


This link to his diagram may not work:

https://etugri87v3i.exactdn.com/wp-content/uploads/2022/07/Lithium-Backup.pdf?_gl=1*w7nboh*_ga*NjQxNDI1MTgzLjE2NjM5NTcxNTQ.*_ga_9M7X2VRKRH*MTY2NDQ1MDYyMC4xOC4xLjE2NjQ0NTI2MDUuMC4wLjA.&_ga=2.87253720.1385959397.1664287435-641425183.1663957154

Do any of you know if such a BMS exists? I wonder what Lithionics or Victron offers in the way of features.

That diagram is fine and with a 1-2 switch does not parallel the SLA with the li

There are two faults with it.

Since the assumption is the bms in integral in the battery. There’s
(A) no manual emergency override of the bms. Personally I would want that.

(B) if you add an external bms and its cutoff you are back to your original two manual switch option and and you have the issue that you can now inadvertently parallel the batteries.

c nomeans of charging the SLA.

Your original interlocked diagram is far superior.

1. Emergency use of li or SLA with no paralleling risk.

2. Interlocking To prevent operator error and inadvertent bms relay operation Protection when in “ SLA “ mode

3 charge sources get connected to the SLA which is good.

You are being distracted by people fix using or the Orion. At a minimum the Orion lockout voltage settings can be set so that the SLA won’t charge itself. ( as the Li terminal voltage is better )

Or implement the simple relay lockout.

 

[AnarchyJet]

I did miss the possibility of manually paralleling the 2 chemistries. Could be fixed with a mechanic interlock between the 2 switches but I don't know if something like that is commercially available. Something like this but for DC battery switches


Original design is good but complex. My initial thought was to simplify it, if possible. My experience (sailboats) is you don't see relays because they are not reliable enough. Having a complex multi contact battery switch could be hard to source if it fails. While the level of options to combat a failure are excellent, the complexity to make it all work could be the cause of the failure. For a long time our back up to connect the house bank to starter was a set of jumper cables on board. Used it once due to a failed ground cable.

I still have issue with LFP chargers connected to SLA, voltage is too high and potential to charge at a too high amp rate. Alt will be ok i see, but not solar. That why having the DC->DC come from that bus and stay connected would be desirable while isolating it from solar.
Eliminating the option to bypass the BMS solenoid could simplify things a lot. If it did fail you could always break out the jumper cables

 

[svsagres]

I did miss the possibility of manually paralleling the 2 chemistries. Could be fixed with a mechanic interlock between the 2 switches but I don't know if something like that is commercially available. Something like this but for DC battery switches
View attachment 114116

Original design is good but complex. My initial thought was to simplify it, if possible. My experience (sailboats) is you don't see relays because they are not reliable enough. Having a complex multi contact battery switch could be hard to source if it fails. While the level of options to combat a failure are excellent, the complexity to make it all work could be the cause of the failure. For a long time our back up to connect the house bank to starter was a set of jumper cables on board. Used it once due to a failed ground cable.

I still have issue with LFP chargers connected to SLA, voltage is too high and potential to charge at a too high amp rate. Alt will be ok i see, but not solar. That why having the DC->DC come from that bus and stay connected would be desirable while isolating it from solar.
Eliminating the option to bypass the BMS solenoid could simplify things a lot. If it did fail you could always break out the jumper cables

In regards to the solar, it’s all managed by the Cerbo GX. So the MPPTs themselves can be programmed for lead acid. This will be overridden when they’re connected to the cerbo and being remote controlled. (The Cerbo takes in the voltage/current limits and measurements from the BMS, and translates them to the MPPTs. Without the remote control, the MPPTs will revert to their internally measured voltage set points.

 

[rgleason]

In regards to the solar, it’s all managed by the Cerbo GX. So the MPPTs themselves can be programmed for lead acid. This will be overridden when they’re connected to the cerbo and being remote controlled. (The Cerbo takes in the voltage/current limits and measurements from the BMS, and translates them to the MPPTs. Without the remote control, the MPPTs will revert to their internally measured voltage set points.

Thanks @svsagres That is very useful to know.

@AnarchyJet We are using a small relay to repurpose a standard 1-Off-2 with AFD switch which is mechanically disconnected when on OFF. What we need is a purpose built switch that inverses that operation. Mechanically it may be a relatively simple matter of making a new conducting contact plate. Earlier, before idea to use a relay occurred, I was trying to encourage Blueseas to consider making a purpose built switch like the 1-Off-2 with AFD but the inverse. They had no interest and really were no help, even with regard to replacing the contact plate for the AFD. So the next practical step is to inspect and perhaps buy one and see if the contact plate can be changed appropriately. At this point I don't even know if we can take it apart. It would be really helpful if we could repurpose the 11001. I think you would find that a simpler solution if it can be done and that would be a very fruitful improvement.

 

[rgleason]

In reading more about the REC BMS I found an interesting idea to save some energy use from the main contactor.
controlling CERBO GX with REC BMS hibernate switch?

I'm running things the way you describe right now. The 'parasitic' load from the BMS/CERBO GX and relays is only 500mA or 6W so the 160W solar array is keeping up, even with the boat on the hard with a plastic cover over it!! If I leave the Victron Multiplus on, that adds another 50W so I turn that off when I leave the boat.

In a Victron system with a VE.Bus BMS, you power it through the 'load enable' output of the VE.Bus BMS. So power is provided when the BMS is turned ON and it's cut-off in the event that the battery becomes depleted.

The way my REC-BMS system is configured now, when the main battery switch is OFF, the BMS can be ON but the main contactor (150mA) and the CERBO GX (500 mA) are not energized to limit the parasitic load on the 560AH LFP battery. Now that I know what the CERBO GX can do, I view it as a critical part of the BMS and I'd like to move the CERBO GX to be powered by the BMS. I believe I can configure RELAY DCH output as 'load enable' to provide REC BMS controlled power to CERBO GX when main battery switch in the OFF position (disconnect when battery is depleted). Does that sound right?

Rick-Admin wrote afterwards:

Got the drawing. Nice work!

I like your idea of using the the second relay as your interlock to power your mission critical low power loads like the Cerbo direct from the battery pack. By default it should be set up to disconnect loads on a low voltage so it is likely already configured to work for your application. And if you set it to trip around 2.9 volts it will give you low voltage cutout protection for those loads as well.

Please let us know how this works out for you.

 

[Goboatingnow]

Thanks @svsagres That is very useful to know.

@AnarchyJet We are using a small relay to repurpose a standard 1-Off-2 with AFD switch which is mechanically disconnected when on OFF. What we need is a purpose built switch that inverses that operation. Mechanically it may be a relatively simple matter of making a new conducting contact plate. Earlier, before idea to use a relay occurred, I was trying to encourage Blueseas to consider making a purpose built switch like the 1-Off-2 with AFD but the inverse. They had no interest and really were no help, even with regard to replacing the contact plate for the AFD. So the next practical step is to inspect and perhaps buy one and see if the contact plate can be changed appropriately. At this point I don't even know if we can take it apart. It would be really helpful if we could repurpose the 11001. I think you would find that a simpler solution if it can be done and that would be a very fruitful improvement.

The AFD terminals can be used to drive a simple signal relay , that relay , or even more then one can be used to do all sorts of things , (a) interlock the BMS contactor , (b) signal off the mppt and Orion , all these victron units have a simple remote on of line , (c) drive indicators and alarms , lights etc to alert the user that these manual override modes have been selected

It make no sense to seek a custom AFD when a simple relay can easily invert the logic

Secondly it’s much easier to wire and configure the DC bus arrangement for the “ normal “ 99% functionality that’s what good engineering does. You focus on the “ normal “. The “ abnormal “ situation is therefore less optimally engineered

Hence I would leave the mppt and Orion wired as originally proposed , with optional electrical interlocks to prevent them being activated , equally the Cerbo can reconfigure these controllers.

The other is is that the termination voltage of Li is typically <3.6 per cell , often 3.4 , the voltages x4 are no issues being applied to a starter battery.

The debate particularly on cruisersforum gets sterile fast, you have people “ that have always done it this way or that “
What’s much better is to examine each aspect or change With good “ product “ engineering decision:

(A) the reason for the change or feature
(B) the demand for the change or feature , will it be very occasionally used or common
(C) the performance of the feature
(D) the effect of the remaining system
(E) the cost and the return on that cost

Arguing about 130mA hold current fail safe over 13mA latching for example on a system with literally 100s of AH is absolute nonsense in my view

 

[Goboatingnow]

In reading more about the REC BMS I found an interesting idea to save some energy use from the main contactor.
controlling CERBO GX with REC BMS hibernate switch?



Rick-Admin wrote afterwards:

I fail to see the point of this argument. Why would you want your Cerbo powered up when the BMS is off or the LFP battery is in hibernate mode. Why not just leave the battery system normally on. The loads that won’t be running , won’t be running anyway

 

[rgleason]

Thanks @Goboatingnow for your response and keeping this on track.

I asked Peter Kennedy of PKYS to take a look at the diagram and he was helpful, but of course, since it is not a Victron BMS and battery he had some points about that. I am going to post his comments below and I hope @svsagres will also be able to comment. My father was an inventer, and could prototype a device in no time. I had tremendous respect for him. So the word "tinkerer" is a very positive word to me.

I can only give you some general comments on this because the basis of the system is a battery and BMS combo that we don't sell.

Here are a few things I noted on your drawing:

You have an unusually low value for your main fuse. 160 amps is the rated output of your alternator. Its quite possible for it to put out more than its rated output for a brief period and that alone would blow the main fuse. You also have lots of other things connected which could contribute to this situation. If the main fuse blows the alternator will be toast.

Your system has a BMS designed to stop charging if any cell gets too high a voltage and stop loads if any cell gets too low a voltage. The BMS is just a simple processor, it has to act on the system to be effective. How does it disconnect your DC loads in the event of a low cell? There doesn't seem to be any way for it to achieve this.

I have to question how the BMS acts for the other load and charge devices too. Perhaps it can communicate with the Cerbo to achieve this electronically with connected devices using DVCC but you would have to verify that the integration works. Your Cerbo does not have its own way of measuring current or voltage, you would have to establish that the BMS is communicating that information to the Cerbo.

ABYC standards call for the system monitoring equipment to stay active in the event of a BMS shutdown. Have you taken care of this in your system?

There isn't much support for this kind of system. Neither Victron nor I will support this, you have put yourself in the hands of the tinkerers. Official support extends to the individual Victron devices themselves, not for integration with third party products. Support for this will have to be from other tinkerers and you will find lots on the Victron Community Forum

I think his first point is interesting, because I never intend to run the regulator at 160a, as it will be "belt managed" or field current limited to 100a. I had sized the wire for 160a in an engine compartment. If I increase the fuse to 200a I will then have to increase the wire sizes to 2/0 AWG for 12' (total adding both ways) 75deg C insulation when in an engine compartment. If blowing the main fuse will indeed blow my alternator, I want to be careful about this.

How does it disconnect your DC loads in the event of a low cell? There doesn't seem to be any way for it to achieve this.

It should disconnect the DC loads by way of the relay. I am puzzled by this statement. Perhaps the group could respond to his other questions?
Thanks.

 

[Goboatingnow]

Thanks @Goboatingnow for your response and keeping this on track.

I asked Peter Kennedy of PKYS to take a look at the diagram and he was helpful, but of course, since it is not a Victron BMS and battery he had some points about that. I am going to post his comments below and I hope @svsagres will also be able to comment. My father was an inventer, and could prototype a device in no time. I had tremendous respect for him. So the word "tinkerer" is a very positive word to me.



I think his first point is interesting, because I never intend to run the regulator at 160a, as it will be "belt managed" or field current limited to 100a. I had sized the wire for 160a in an engine compartment. If I increase the fuse to 200a I will then have to increase the wire sizes to 2/0 AWG for 12' (total adding both ways) 75deg C insulation when in an engine compartment. If blowing the main fuse will indeed blow my alternator, I want to be careful about this.


It should disconnect the DC loads by way of the relay. I am puzzled by this statement. Perhaps the group could respond to his other questions?
Thanks.

 

[Goboatingnow]

I can only give you some general comments on this because the basis of the system is a battery and BMS combo that we don't sell.

That’s fine but it doesn’t mean alternatives are worse they could easily be better

Here are a few things I noted on your drawing:

You have an unusually low value for your main fuse. 160 amps is the rated output of your alternator. Its quite possible for it to put out more than its rated output for a brief period and that alone would blow the main fuse. You also have lots of other things connected which could contribute to this situation. If the main fuse blows the alternator will be toast.

Well it’s a call. If there is a serious risk of that type of current. Then the fuses needs to be upped. If your design calculations are due less then that then the fuse is there to protect the cable. If ( and it’s an if ) it goes the alternator may not survive. Either you up the cable massively and not fuse or fuse and evaluate the risks.

Your system has a BMS designed to stop charging if any cell gets too high a voltage and stop loads if any cell gets too low a voltage. The BMS is just a simple processor, it has to act on the system to be effective. How does it disconnect your DC loads in the event of a low cell? There doesn't seem to be any way for it to achieve this.

Bms as defined by ABYC and ISO is not required to disconnect loads selectively. It’s required to shutdown the battery in the event of LVE HVE , overtemp over over current. That’s it.
Most boats have no comprehensive battery low protection this is not LVE LVE should be set at the lowest manufacturers cell voltage of SOC. battery Soc disconnects are separate and if fitted shoujd trigger above LVE.

I have to question how the BMS acts for the other load and charge devices too. Perhaps it can communicate with the Cerbo to achieve this electronically with connected devices using DVCC but you would have to verify that the integration works.

It can communicate or you can have seperafe “ battery saver “ disconnects. Your diagram has neither

Your Cerbo does not have its own way of measuring current or voltage, you would have to establish that the BMS is communicating that information to the Cerbo.

Again this is a claim. The REC can relay current and voltage to the Cerbo.

ABYC standards call for the system monitoring equipment to stay active in the event of a BMS shutdown. Have you taken care of this in your system?

No such statement exists in TE-13 to my knowledge.

There isn't much support for this kind of system. Neither Victron nor I will support this, you have put yourself in the hands of the tinkerers. Official support extends to the individual Victron devices themselves, not for integration with third party products. Support for this will have to be from other tinkerers and you will find lots on the Victron Community Forum

That’s an unjust claim. Victron supports all normal use cases. The Victron community is there to support you.

The tinkers comment is unwarranted. Every lithium install on a boat is a “ tinkering “ cause nobody has all the components of a fully interconnected system with all charge sources controller and loads managed.

The last paragraph makes me question his whole answer.

 

[rgleason]

Either you up the cable massively and not fuse or fuse and evaluate the risks.

Perhaps I should increase all the Alternator to Battery cables to 2/0 AWG and change the Alternator Lynx fuse to 200a and increase the LFP Battery fuse to 200a mrbf (this size fuse is just 2a more than the ampacity). I understand that the T-fuse has an extremely fast short circuit response and is the type of fuse we need on the battery, of course that fast characteristic jeopardizes the Alternator but protects the system.

John Harries suggests sizing the alternator fuse at 120% of the rated capacity and then sizing the wire for that.
160A x 120% = 192A so 200A should be ok.

Most boats have no comprehensive battery low protection, this is not LVE. LVE should be set at the lowest manufacturers cell voltage of SOC. Battery Soc disconnects are separate and if fitted shoud trigger above LVE.

I believe @svsagres uses a Victron Smart Battery Protect 65 in the bus to the DC Panel Loads with an automatic disconnect at some voltage greater than the LVE disconnect voltage. Is this a device that I should have on the feed from the Lynx to the DC Panel ? I understand this is a system separate from the BMS for "comprehensive battery low voltage protection".

Peter Kennedy wrote:

I have to question how the BMS acts for the other load and charge devices too. Perhaps it can communicate with the Cerbo to achieve this electronically with connected devices using DVCC but you would have to verify that the integration works.

@Goboatingnow wrote:

It can communicate or you can have separate “ battery saver “ disconnects. Your diagram has neither

I thought that @svagres had all Victron devices like Solar MPPT and Phoenix 120vac charger connected to the CerboGX and via VE.direct so that the CerboGX would control them appropriately. I have shown these VE.direct cable connections in the diagram as 1,2 & 3 (inside a small circle). Won't the CerboGX control these devices so that they don't overcharge and shut off, and charge when the LFP is low?
LATER: Refer to @Goboatingnow Post #280

You can run DVCC on the Cerbo Gx and Control all Mppt and alternator charge sources , allowing central control What would be nice would to add the ability in the Cerbo to instruct the REC to reconnect the battery , this would even allow remote ( via victron VRM ) ability to reengage charge sources etc. I must study the Ve.can integration of the REC to see what it’s possibilities are.

Also by adding a Victron Smart Battery Protect 65 in front of the DC Panel loads we wouldn't we then have a better battery protection?

First see Post #86

2. Smart disconnect. If u intend to use this as a disconnect device it must be next to the battery. No other devices except the bms must remain connected and provision must be contained within the bms to not discharge the li completely either. Hence as it is the smart switch is not compliant with ABYC or ISO.

In reviewing the past posts in the thread we have had a number of discussions about having a Smart Battery Disconnect 65. I believe that Goboatingnow does not recommend having one of these devices for several reasons.

The remaining device to consider is then the Alternator and Regulator (Wakespeed) which has an Balmar APD (to perhaps help) and the regulator is interlinked via Canbus to the REC Active BMS and VE.canbus to the CerboGX and is then controlled by the CerboGX to shutdown in advance of a BMS HVD or HVE (High voltage event)?

Post #361 svsagres - nice.

Without BMS control, the Wakespeed will set its voltage out to limit to a configured value. On my boat, I have it at the default limp mode at 13.2v, but unless things go really bad, I’ll just run the lfp without the bms.

Also I believe that the Wakespeed has its own high voltage setting which stops the alternator from charging which would be set at a lower voltage than HVDisconnect or HVEvent setting. In addition, I think the CerboGX will control other charge devices like the Solar MPPT?

Post #369 svsagres -nice!

In regards to the solar, it’s all managed by the Cerbo GX. So the MPPTs themselves can be programmed for lead acid. This will be overridden when they’re connected to the cerbo and being remote controlled. (The Cerbo takes in the voltage/current limits and measurements from the BMS, and translates them to the MPPTs. Without the remote control, the MPPTs will revert to their internally measured voltage set points.

Alternator protection when switching
Should the Alternator brown or the field wire be run through the 1-off-2 switch AFD to protect the alternator when switching, or should we just shut the engine down before touching the switch? --NO
LATER: No that isn't going to work,

• When switch is at OFF "Normal LFP" we want the alternator to be able to charge.
• When we switch to "LFP Disconnect & SLA Emergency Feed", if the engine is running, hopefully the alternator/regulator will adjust to the "limp home" setting (13.8-13.2v).
• When we switch to LFP Override, if the engine is running, then we may want the alternator to be charging or may not depending on the state of the battery!
• Does this need further attention? - No, not going to do.

LATER: Regarding PK question about keeping the BMS powered after shutdown.
Post #184

BMS draws its power from the sense leads connected to the (LFP) battery, so it will always be powered.

Additionally, the CerboGX is powered from the SLA battery so it will continue to function with Victron equipment (MPPT, Orion-Tr) and with the Wakespeed, and the BMS since it continues to be powered from the LFP.

Svsagres wrote:

For me, if I’m not aboard, I put the boat into hibernation mode. That drops my load to 20W or so (Cerbo, Instrumentation, AIS, and LTE left on). With my battery that gives me about 20 days to respond to something gone wrong with charging.

If I’m just leaving the boat for an afternoon, I really don’t care, since I’m fully operational mode (refrigeration, devices, laptops, etc…) I still have about 4 or 5 days until I really need a charge.

 

[rgleason]

Post #93 Summary ABYC and Major Requirements

Post #247

The key point both under ABYC and ISO is the presence of a BMS , a complete disconnection of the Battery from both loads and charge sources , and advance warning of such an action

Post #280

I do not think dual bus systems , ie CH and DCH buses , despite was Bruce Swarb suggested , will appear In ABYC or the more prescriptive ISO standards simple because both are focused on battery safety first not overall system design. As you easily retrofitted. With you components , ie. REC BMS , you have very fine control over charging limits , especially as you can run DVCC on the Cerbo Gx and Control all Mppt and alternator charge sources , allowing central control What would be nice would to add the ability in the Cerbo to instruct the REC to reconnect the battery , this would even allow remote ( via victron VRM ) ability to reengage charge sources etc. I must study the Ve.can integration of the REC to see what it’s possibilities are

See Post #383 John Harries checked, a response to Bruce Schwab's...

13.7.2.1A BMS shall respond to any conditions outside the SOE by activating the output disconnect device.

See Post #383 John Harries wrote: All that said, if it were me I would consider installing an all Victron or Lithionics system with duel busses and then hide behind:

13.6.1.2 No electrical connections shall be made directly to a battery that would bypass a BMS or any battery protection circuits. EXCEPTION: Connections made specifically per the battery manufacturer’s instructions.

Post #261

At the end of the day Li is just a battery doing the same thing in a boat as the lead acid did. All we have added is a safety system that acts in “ last moment “ events to protect the battery. Arguably we should have had some of it in LA systems.
Hence I ( and ABYC) don’t require anything else , no complex charge and load bus separation etc.

Offgridsolutions Post #10 Benv Comments

ISO 13297 9.3: Remote controlled battery disconnect switches, if used, shall also permit safe manual operation.

1. If never paralleled than all is ok.
As I mention I didn't read all the details.

2. With 2 relays there is also a complete disconnect!!!
They rules don't say it need to be one contactor. It only says disconnect completely, when needed thats done with 2 contactors!!
Off course it is good to have in the ""user manual"" a comment about this. That the system has 2 contactors..
Name the contactor like main contactor, 1/2 and 2/2 as example and labeled like that.

Dont forget this part from the rules.
ISO 13297 9.3 says:
""Remote controlled battery disconnect switches, if used, shall also permit safe manual operation.""

The contactor in your system can be seeing as a remotely controlled contactor?.
This means there need a manual control from the contactors also!!!
This means if there is a faulty BMS, you can still operated the system.
ONLY in case off a fault in equipment, and NEVER for normally use!!!. It should labeled as this also!!

This seams contradiction with other rules, BUT I see this as a extra safety if lightning damage a processor in the BMS. You can have long discussions with technician about this which rules overrules another rule or not!!

3. What is the exact discretion from BMS?
Battery Management System.
In your setup the REC AND the CERBO together are the battery management system.
I interpreted the Rules like that.

Yes the REC has the name, BMS, the Cerbo, is named different. BUT only together the have the function from a complete battery management system.

What they like to say, in my personal interpretation, as example, don't connect any other equipment like chargers, mppt direct to the battery without discontactor.

About settings: Every device has settings, not that difficult, but if you are new in this, it is lot off reading.

I hope this info will help you. Ben

Post #256

Not suggesting that people don’t do this , what I saying is that fron a basic safety perspective , compliant to ABYC or ISO , there’s no point in dual disconnects( load and charge ) and complex manual overrides and so forth.

Sure fit them , knock yourself out. But again a simple all load and charge source disconnect and a man with a pair of jump leads is all you really need in extremis .

Post #390 Goboatingnow

Again yes if you want a CH and a DCH bus great use two contactors but the bms should kill both in lve and hve

Post #242 Panbo identification of ABYC E-13 items:

E-13.7 requires a BMS on all lithium batteries installed on boats.
E-13.8.1 Battery Manufacturer will provide a manual that provides information...
Notes at the end E-13.7 (serve as recommendations but don’t carry the same requirements as items in the main body of the standard).
Note 1 recommends alternative power sources for critical systems (engine starting, propulsion, navigation lights, etc) . It’s worth noting, another lithium battery is acceptable as a redundant power source.
Note 2 BMS should give an audible or visual signal when a disconnect condition is approaching.
Note 3 A BMS may suddenly and unexpectedly disconnect a battery from charge and load sources.

Also the standard says that dissimilar batteries should not be paralleled.

Post CF #65

ISO says
4.9 In normal operation, different battery chemistries should not be connected in parallel or in series.
Interesting while Broadly similar ABYC te-13 omits that sentence.
Bit the oft repeated issues of connecting LFP to SLA means safety is best served by preventing paralleling. It’s been standard practice in most designs to use dc dc to separate the batteries.
Neither ABYC or ISO support operation of the batteries outside manufacturers reccomendations
So can you point to a LFP battery manu that supports direct paralleling. I have not seen one .

Post #349 and Post #340

ABYC 13.5.3 Consideration should be given to providing alternative power for critical systems (e.g., engine starting,
navigation lights, etc) if a BMS shuts down the battery.

CF Post #48
Originally Posted by s/v Jedi View Post

I held the diagram against ABYC recommendations and it appears that the manual switch violates 13.7.7
13.7.7 No electrical connections should be made directly to a lithium ion battery that would bypass a BMS or the protection relays.
The switch clearly bypasses the protection relays.

Goboatingnow wrote:

Firstly an open switch is not connected to the battery. That’s in plain sight.
Secondly both iso and ABYC recognise the need for overrides
“13.5.3 Consideration should be given to providing alternative power for critical systems (e.g., engine starting,
navigation lights, etc) if a BMS shuts down the battery.“
Thirdly the RBS ML has a integrated override that in theory violates your pedantry

Post #339

ABYC 13.7.7 No electrical connections should be made directly to a lithium ion battery that would bypass a BMS or the protection relays.

Post #160

ABYC TE-13 and ISO 23625 you cannot have anything remaining connected after safety LVC disconnect except the BMS , nothing must be wired on the battery side of round the safety disconnect breaker . On disconnect EVERYTHING must be disconnected

Post #92

Iso and ABYC standards require that a safety LI disconnect disconnects all devices from the battery bus including charge sources , nothing should remain powered by the bus expect the BMS. provision should be then made to reconnect the charge sources but only if the Li has not discharged completely.

Post #141

just to be clear ABYC does not require fail safe operation AFAIK, in other words if the BMS dies, the system is unprotected

 

[Goboatingnow]

Post 141

ABYC doesnt really address component failure or bypass systems TE-13 is far too vague on what happens as systems fail.

Hence we are on our own in this regard.

I think the manual override approach is good. But I would not bother protecting the alternator from the consequences of inappropriate manual switching

 

[rgleason]

Diagram Changes to make:

1. Add a note to the manual Switch Diagram SK-2, "Engine (Alternator) must be "Off" when switching" or if there is a separate alternator field disconnect switch, it should be off. -Done
2. Increase all the Alternator to LFP Battery cables to 2/0 AWG and change the Alternator Lynx fuse to 200a and increase the LFP Battery fuse to 200a mrbf (this size fuse is just 2a more than the ampacity).
   1. John Harries suggested Alternator output 160a x 120% = 192a fuse, then size the wire. He also says that if this fuse blows then the alternator diodes are probably damaged, so a 250a fuse might be better than 200a. - Done 250a and 2/0 AWG
3. at Starter Battery
   1. Main disconnect switch needed (Benv) -Is this really needed? Where between SLA and bus bar? Could a 250mbta suffice?
   2. Fuse needed marinehowto about starter fuse sizing #1AWG, 10' 250mbta
   3. Size for ample capacity wire, and ABYC does not require a fuse for the starter motor (Goboatingnow). -Done Increased to 1 AWG, no fuse
4. Add a note somewhere to disconnect the Solar panels at the M4 connectors before disconnecting from the batteries.
5. Add "SLA Emergency Feed (LFP Disconnected)" to the red dashed wire because people don't get the operation and are confused. -Done
6. New Victron documentation for Wakespeed WS500 (svsagres wrote below)
   1. Separate current shunt in the Alternator black - cable to the Lynx bus for current sensors. -Done
   2. Pick parameter "current sensors at Alt" (to be done)
   3. Temp sensor on alternator - Done
   4. Show sense + at the 1-off-2 switch and sense - at the shunt. -Done
   5. Change WS500 to cerboGX from VE-bus to VE-CAN. (Benv & svsagres) -Done
   6. Change REC to WS500 BMS can, to VE-CAN (Victon has BMS-CAN and VE-CAN, you need to use VE-CAN). (Benv & svsagres) -Done
   7. WS500 can share a shunt, but you need to set CerboGX to "SVS" shared voltage sense. Read the CerboGX manual. -not doing that.
   8. 13. Wakespeed WS500 support www.victronenergy.com
7. https://www.offgridsoftwaresolution...nd-wakespeed-on-bms-can-on-cerbo/#postid-1061
   1. VenusOS firmware v2.90 or higher installed on your GX device
   2. Wakespeed WS500 firmware 2.5.0 or higher installed on the WS500 controller
   3. The WS500 must connect to the VE.Can port of the GX device. It is not possible to monitor the WS500 when connected to the BMS-Can port of a Cerbo GX.

Just Considering these changes:

I think perhaps I should consider powering a few of the essential and low power loads from the SLA in the rare event a BMS/LFP shutdown occurs:

1. Nav lights (masthead) - separate dedicated switches located on the DC panel
2. Bilge pumps - separate small panel for fuse and switches
3. Cabin lights - currently uses DC circuit breaker
4. Instruments - currently uses DC circuit breaker (also part of nmea2k and nav system)

#1 & #2 could be easily done by connecting to a small 6 fuse panel powered from the SLA.
#3 & #4 are somewhat problematical because the Cabin lights need a switch, and the instruments are really part of the nav system.
Perhaps moving the Cabin lights to SLA are a priority.

See Goboatingnow comment below. Not going to make any changes about this, to complicated.