LFP FLA hybrid

[evm1024]

John, Thanks to the reminder to follow the links. I'll read through that one soon. It does appear to be just what I was thinking.

Attached is a very basic block diagram of such a system. All of the disconnects, fuses, shunts etc are there just left out to see the basics.

As noted when charging is needed the black box joins the Start (AGM?) and House (LiFePO4) batteries. The charge voltage drops to match the SOC of the LiFePO4. And starts rising as the LiFePO4 bank SOC increases. At a set point where the LiFePO4 bank reaches end of charge voltage the black box opens.

The house bank is now isolated from the charge source and goes about its merry way while the "bulk" of the charge voltage goes into the start battery and follows an AGM start battery curve.

So bear with me while I develop this further step-wise. Also let me know if this is the wrong thread for this....

Like many of you I've worn many hats over the years. One of those hats was as a real time control programmer. As such I don't leave any gray areas in the code I used to write.

I called the combining relay a black box because I can see many more state transitions in joining and breaking the tie than just a few. Plus there are other modes - Manual join, tell me what you would do but do not do it and who knows what else.

Brainstorming, yes. That is how I come to understand what the operating envelope is. Over thinking too but one can dial back the complexity.

[newhaul]

Originally Posted by john61ct

See Cpt Pat's logic, link #251 that resurrected this thread. Paraphrasing, feel free anyone to refine if too rough.

Assume charge sources are "lead side" A. LFP circuit B, combiner between.

No nitpicking over V setpoints, adjust to suit your taste, assume delay / hysteresis to avoid chatter.

State 1 no charging, low volts say under 13.5V, A and B are isolated.

State 2 charging A side circuit, when it gets up to 13.55V combiner closes, LFP starts charging.

Voltage keeps climbing, when it gets to 13.85V that's State 3, LFP is Full (enough), only lead bank(s) on A circuit keep charging.

When charge source stops, return to State 1.

over complicating the issue .

[Q Xopa]

Originally Posted by evm1024

John, Thanks to the reminder to follow the links. I'll read through that one soon. It does appear to be just what I was thinking.

Attached is a very basic block diagram of such a system. All of the disconnects, fuses, shunts etc are there just left out to see the basics.

As noted when charging is needed the black box joins the Start (AGM?) and House (LiFePO4) batteries. The charge voltage drops to match the SOC of the LiFePO4. And starts rising as the LiFePO4 bank SOC increases. At a set point where the LiFePO4 bank reaches end of charge voltage the black box opens.

The house bank is now isolated from the charge source and goes about its merry way while the "bulk" of the charge voltage goes into the start battery and follows an AGM start battery curve.

So bear with me while I develop this further step-wise. Also let me know if this is the wrong thread for this....

Like many of you I've worn many hats over the years. One of those hats was as a real time control programmer. As such I don't leave any gray areas in the code I used to write.

I called the combining relay a black box because I can see many more state transitions in joining and breaking the tie than just a few. Plus there are other modes - Manual join, tell me what you would do but do not do it and who knows what else.

Brainstorming, yes. That is how I come to understand what the operating envelope is. Over thinking too but one can dial back the complexity.

The Sterling 'Pro connect' CVSRs look like they would work well for this ACR application? Anyone using them?
https://sterling-power.com/products/...-fine-adjust-1

[john61ct]

Needlessly convoluted. Are the setpoints even adjustable?

[john61ct]

Originally Posted by evm1024

Attached is a very basic block diagram of such a system.

Looks good. I would have the A circuit be a Reserve deep cycle bank in lead, see no use in carting around a Starter type.

Yes the Alt is A circuit hardwired to the lead bank,, but the starter motor and all other propulsion / Essentials **loads** could be directed to either bank via an A/B switch.

As with the House (non Essential) loads circuit.

Just give a bit more flexibility, easy handling of any unexpected failures, but no risk of load-dumping the Alt diodes.

[Q Xopa]

Originally Posted by john61ct

Needlessly convoluted. Are the setpoints even adjustable?

Yes Set points apparently are adjustable. As you say has many different features, which can be used or not.

[cuffy]

Originally Posted by evm1024

John, Thanks to the reminder to follow the links. I'll read through that one soon. It does appear to be just what I was thinking.

Attached is a very basic block diagram of such a system. All of the disconnects, fuses, shunts etc are there just left out to see the basics.

As noted when charging is needed the black box joins the Start (AGM?) and House (LiFePO4) batteries. The charge voltage drops to match the SOC of the LiFePO4. And starts rising as the LiFePO4 bank SOC increases. At a set point where the LiFePO4 bank reaches end of charge voltage the black box opens.

The house bank is now isolated from the charge source and goes about its merry way while the "bulk" of the charge voltage goes into the start battery and follows an AGM start battery curve.

So bear with me while I develop this further step-wise. Also let me know if this is the wrong thread for this....

Like many of you I've worn many hats over the years. One of those hats was as a real time control programmer. As such I don't leave any gray areas in the code I used to write.

I called the combining relay a black box because I can see many more state transitions in joining and breaking the tie than just a few. Plus there are other modes - Manual join, tell me what you would do but do not do it and who knows what else.

Brainstorming, yes. That is how I come to understand what the operating envelope is. Over thinking too but one can dial back the complexity.

I have just purchased my Lfp bank (260ah)and have a 123 bms the GWL dual relay. This will constitute the OV and LV disconnect. My system is very
similar but the black box in your diagram is a Sterling B2B charger in my case. This will be controlled by my BMV 700?? via the ignition switch function. All of the legacy shore chargers, solar and Honda will be used unchanged. Although the 60a OP of the sterling B2B is quite low it protects my alternators from overheating and I am hoping for most charge via 400w solar already fitted.

[john61ct]

Originally Posted by Q Xopa

Yes Set points apparently are adjustable. As you say has many different features, which can be used or not.

Yes but the other ones you're paying lots of extra money for, are IMO solutions in search of an actual problem.

But adjustable setpoints are indeed very rare in any OTS VSR suited for marine use, so if Charles did build that in (really?) then that would be worth paying for.

[john61ct]

Originally Posted by cuffy

the black box in your diagram is a Sterling B2B charger in my case.
…
Although the 60a OP of the sterling B2B is quite low it protects my alternators from overheating and I am hoping for most charge via 400w solar already fitted.

Yes the Sterling BB fronting all charge inputs is a great approach, that's the only regulator touches the bank, all upstream sources can be left legacy, cheap, stupid, old, fragile, doesn't matter.

And the Sterlings can be stacked if you need 120 or 180A.

If an ICE-only setup, the BB can even be reversed to top up the lead Reserve bank's long tail to 100% Full from the LFP, as if the latter were solar panels,

as needed when the ICE isn't running long enough for other purposes

[evm1024]

Originally Posted by john61ct

Looks good. I would have the A circuit be a Reserve deep cycle bank in lead, see no use in carting around a Starter type.

Yes the Alt is A circuit hardwired to the lead bank,, but the starter motor and all other propulsion / Essentials **loads** could be directed to either bank via an A/B switch.

As with the House (non Essential) loads circuit.

Just give a bit more flexibility, easy handling of any unexpected failures, but no risk of load-dumping the Alt diodes.

In the Full(er) diagram that I am working on there are a bunch of LVC,HVC disconnects, Switches to isolate batteries and in general reconfigure to ones heart content.

Having the Starter switchable is a thought that I'll look into. It can be done with the existing switches in the full diagram.

I'm using a single AGM start battery because that is what I have on my boat.... For no other reason.

One mode of operation that comes to mind would be to configure so that the LiFePO4 bank is out of circuit when charging sources are producing current greater than the load (and of course the LiFePO4 bank is above the "full" setting).

[Q Xopa]

Originally Posted by john61ct

Yes but the other ones you're paying lots of extra money for, are IMO solutions in search of an actual problem.

But adjustable setpoints are indeed very rare in any OTS VSR suited for marine use, so if Charles did build that in (really?) then that would be worth paying for.

Yes maybe, but they also sound like these 'solutions waiting for a problems' sound similar to the issues being dicussed here about the best ways to get a Hybrid LFP - FLA system to work together.

For example, as you mentioned programable set points.

Also the ability to normally direct yhe charge source to the house bank but for example other times bi directionally to charge a FLA long tail charge.

Just some spit balling, trying to match square in square holes.

[rgleason]

It seems to me that some applications with large loads on the House side, such as winches, windlass, watermaker etc would need this Sterling Pro CVSR current sensing relay to avoid damage to the relay. At least that is what the documentation indicates. Is there some other way to handle this condition?


Since we would want the relay open normally, so it fails that way, and that is when the LiFePo4 Bank is not being charged, so we don't need to worry about a latching relay. The relay will just use some power to close while it is charging the LiFePo4 Bank and while the alternator is running.


How does this situation affect a low power charge source like SolarPV? You wouldn't want to use that power to keep the relay closed to charge the LFePo4 would you?i

[newhaul]

Originally Posted by rgleason

How does this situation affect a low power charge source like SolarPV? You wouldn't want to use that power to keep the relay closed to charge the LFePo4 would you?i

that's where you set your voltage charge profile to stop at a predetermined voltage point.
For me that point is 13.8v on my 400 watts.

[john61ct]

At this point those wanting to get into the details and pro vs cons of those unique Sterling CVSRs, ProSplitRs and ProCon IFs, should IMO start a new thread appropriately titled to attract more & better responses.

[rgleason]

The basic question is what do you do about high current loads that should be disconnected when the LFP are low that will damage the relay.