LFP FLA hybrid

[ramblinrod]

Originally Posted by Dockhead

Yes, we are all well aware of these issues, which is one of the main design challenges of any lithium power system.


It's easy to solve with a hybrid bank if you connect the loads and the main charging sources to the lead bank. But that's not the only way to solve it, by any means.


Here is one way to deal with the alternator:


https://sterling-power.com/products/...-70f-ald-17500

Who's this "we"?

Everyone who may read this thread?

How do we (you and I) know that we (everyone on the planet who may read this) are all aware?

I have been reading accounts of folks trashing banks, nav electronics, and equipment, due to this very cause.

FWIW, in contradiction to another post in this thread, and for others who may not be aware...

When a high current source is suddenly connected or disconnected via a contactor, it can impose a significant transient voltage spike in the circuit.

Anything susceptible to damage by transient voltage spikes may be hurt.

A quick disconnect of low current circuits does not usually generate high voltage transients, there is generally enough in circuit capacitance to filter it.

This is true of all electrical circuits and not just associated with LFP marine circuits.

This is why we can't just let an LFP HVD or LVC event occur on house circuits without some means to "filter" the transients.

I am not an "expert" on LFP marine applications.

In my opinion there are only a handful on the planet. The folks at Calb, Winston, Ocean Planet, etc. are definitely experts IMHO, and only a few of them are experts on the needs of marine house bank applications.

However, I do have a significant electrical / electronic background in a variety of fields, and consult, configure, sell, install, troubleshoot, repair, and warrant all types of marine electrical equipment and systems.

I have yet to install LFP, as I am still learning all of the pitfalls to avoid, so I don't repeat the expensive mistakes made by others that we can all learn from if we keep our eyes and ears open and promote/engage healthy, helpful communication.

[CatNewBee]

Is true for all kind of inductive loads.

They should have some protection around (e.g. by protection diodes, as done on relays etc.)

However, this is not a LFP only issue, but applies to every installation that has circuit breakers, switches or relays on pumps, winches, windlasses etc.

LVP and OVP are considered smart fuses, they do not switch in regular operation at all.
They only switch if something really goes wrong. It is he exact same problem as with a
normal fuse in high current applications regardless of chemistry.

So why this scaremongering?

[Dockhead]

Originally Posted by ramblinrod

Who's this "we"?

Everyone who may read this thread?

How do we (you and I) know that we (everyone on the planet who may read this) are all aware?

I have been reading accounts of folks trashing banks, nav electronics, and equipment, due to this very cause.

FWIW, in contradiction to another post in this thread, and for others who may not be aware...

When a high current source is suddenly connected or disconnected via a contactor, it can impose a significant transient voltage spike in the circuit.

Anything susceptible to damage by transient voltage spikes may be hurt.

A quick disconnect of low current circuits does not usually generate high voltage transients, there is generally enough in circuit capacitance to filter it.

This is true of all electrical circuits and not just associated with LFP marine circuits.

This is why we can't just let an LFP HVD or LVC event occur on house circuits without some means to "filter" the transients.

I am not an "expert" on LFP marine applications.

In my opinion there are only a handful on the planet. The folks at Calb, Winston, Ocean Planet, etc. are definitely experts IMHO, and only a few of them are experts on the needs of marine house bank applications.

However, I do have a significant electrical / electronic background in a variety of fields, and consult, configure, sell, install, troubleshoot, repair, and warrant all types of marine electrical equipment and systems.

I have yet to install LFP, as I am still learning all of the pitfalls to avoid, so I don't repeat the expensive mistakes made by others that we can all learn from if we keep our eyes and ears open and promote/engage healthy, helpful communication.

If you read the rest of the thread, you will see that ALL of the participants, even me (the least knowledgeable in this company for sure) have knowledge more than sufficient to cover issues of transient spikes, and have dealt with (even me!) issues of transient spikes in other practical electrical projects we've actually carried out with our own hands.


And John's remark about current vs. voltage with regard to HVC operation of a BMS was correct.




By the way, it is not correct to speak of current as the source of high voltage transients. In this case, it is reactance, specifically, induction which does it. Without electric motors and relay coils connected in the system, there is little issue.


For any hypothetical person reading this thread who is NOT familiar with these concepts, here's a great resource:


http://www.nhu.edu.tw/~chun/BE-Ch14-...Transients.pdf

[Dockhead]

Originally Posted by CatNewBee

Is true for all kind of inductive loads.

They should have some protection around (e.g. by protection diodes, as done on relays etc.)

However, this is not a LFP only issue, but applies to every installation that has circuit breakers, switches or relays on pumps, winches, windlasses etc.

LVP and OVP are considered smart fuses, they do not switch in regular operation at all.
They only switch if something really goes wrong. It is he exact same problem as with a
normal fuse in high current applications regardless of chemistry.

So why this scaremongering?

Absolutely right, and I think everyone who is bothering to read this thread knows this stuff.


I'm only a lawyer, with no formal EE education, but on the other hand I am an Extra Class radio amateur who has spent some time in the vineyards with electricity and electronics theory.


I even know the formula for Faraday's Law, which is the basis of this problem! Ha, ha. Didn't forget quite everything I had to learn for the radio exam, as it turns out

[Delfin]

Originally Posted by Dockhead

Thanks to both of you for all this great information. It's cool to see all the sheer brainpower which has been invested into this technology by users.


Lithium is surely not yet ready for accountants or for weekend boaters who are not smart or knowledgeable enough to dive deeply into the technology -- as I think everyone agrees. But that doesn't mean that there aren't people smart enough to reach an adequate understanding!

I'm sure you're right about the accountants/weekend boaters, but could we add lawyers to that list?

IMO, Lithium probably makes no sense unless you spend a lot of time away from the dock. It sounds like RR's clients tend towards those who sail on a lake (even if a very, very big lake) and don't spend days away from a power post, so LA makes perfect sense. But if you do spend a lot of time away from a dock, then you are probably used to managing the boat's systems. You can bugger up a diesel quite easily if you pay no attention to oil levels or clean fuel and you can bugger up a lithium bank if you ignore that. To me, if you have the wits to anchor out a couple hundred days a year, then you have the wits for Lithium and in that sense it is technology that is ready to go and be used quite satisfactorily.

[ramblinrod]

Originally Posted by Dockhead

If you read the rest of the thread, you will see that ALL of the participants, even me (the least knowledgeable in this company for sure) have knowledge more than sufficient to cover issues of transient spikes, and have dealt with (even me!) issues of transient spikes in other practical electrical projects we've actually carried out with our own hands.

Possibly, but there may be others reading this with little or no prior knowledge, who are thinking, "Wow, I can drop in an LFP battery and all is well."

And John's remark about current vs. voltage with regard to HVC operation of a BMS was correct.

I disagree.

12 vdc nominal is relatively low voltage.

An HVC or LVD event can cause a high voltage transient (50- 100 volts or more).

This will be far more likely to occur when switching high current.

When switching high voltage (low current) voltage transients are not usually an issue at all.

It seems I do have something of value to contribute to the higher learning of participants in this thread.

[ramblinrod]

Originally Posted by Delfin

I'm sure you're right about the accountants/weekend boaters, but could we add lawyers to that list?

IMO, Lithium probably makes no sense unless you spend a lot of time away from the dock. It sounds like RR's clients tend towards those who sail on a lake (even if a very, very big lake) and don't spend days away from a power post, so LA makes perfect sense. But if you do spend a lot of time away from a dock, then you are probably used to managing the boat's systems. You can bugger up a diesel quite easily if you pay no attention to oil levels or clean fuel and you can bugger up a lithium bank if you ignore that. To me, if you have the wits to anchor out a couple hundred days a year, then you have the wits for Lithium and in that sense it is technology that is ready to go and be used quite satisfactorily.

This is not a LFP vs FLA thread.

In my experience, which includes serving Caribbean and world cruisers, there are a lot of folks cruising and anchoring out who are not very electrical system savvy, let alone know anything about LFP batteries.

Meanwhile, some unscrupulous manufacturers and distributors are promoting LFP "drop-ins" with integrated BMS.

Just look at UMA and Abandon Comfort on YouTube.

Creating electric propulsion systems with 14.4 kWh banks to be recharged with a few hundred Watts of solar.

It can't be both ways.

We can't say LFP is becoming mainstream in one breath, and then that it is only suited to the best of the Electronic and Electrical Engineers in the next.

What's more, not every EE is created equal and I have more direct and extensive (and expensive) experience with this than I care to recount.

[Dockhead]

Originally Posted by ramblinrod

. . . I disagree.

12 vdc nominal is relatively low voltage.

An HVC or LVD event can cause a high voltage transient (50- 100 volts or more).

This will be far more likely to occur when switching high current.

When switching high voltage (low current) voltage transients are not usually an issue at all.

It seems I do have something of value to contribute to the higher learning of participants in this thread.

I'm sure you have plenty to contribute, especially what concerns practical experience, but do you actually understand how high voltage transients are produced? Reading this makes me doubt it. Hint: It is not current, but rate of change of current, which figures in the formula. The other parameter is inductance in the circuit. That is why a very low current device like a relay coil can produce a dangerous voltage spike requiring a snubber or a flyback diode.


This is also why a very high current resistive load like a calorifier coil or an electric heater, causes zero problem with high voltage transients, despite the high current.

[tanglewood]

Regarding shutting off high power chargers......


There are typically other ways to shut them off in a graceful way, and I think these approaches are preferred, where possible. The key is having a BMS that provides a "stop charging" signal, which most do. The Stop Charging signal gets activated as a warning, and occurs well before BMS does an abrupt disconnect. If charging continues after the Stop Charging signal is asserted, you will risk a disconnect, and that's to be avoided if possible.


Here are some examples of soft shutdowns that I'm aware of.



- Some Victron chargers have an input signal that can be configured to stop charging.


- Some Victron chargers can be told to stop charging via Canbus or Modbus.

- Some Victron Inverter/chargers have an input signal that can be configured to stop charging.


- Some Victron inverter/chargers can be told to stop charging via Canbus or Modbus.


- Other brand inverter/chargers can be configured for external on/off of charging.


- Balmar alternator controllers can be shut down by disconnecting the Ignition wire (preferred according to Balmar), or the field wire.


- Other external regulators can be stopped via similar methods.


- Internal regulators can be stopped by breaking the power connection to the regulator which is similar to turning off the key switch for the engine.


- I haven't looked carefully at solar controllers, but some have control inputs like inverters an chargers. Others can be controlled via canbus or modbus.


- In a pinch, you could install a relay to break the solar input side of the solar controller.


- In a pinch you could install a relay to cut AC input power to a charger to stop it from charging.


There are probably plenty of others that I haven't seen. The bottom line is that with an appropriate BMS, there are lots of graceful ways to shut down charge sourced without spikes, without attached LA batteries, and without a total battery disconnect.

[Dockhead]

Originally Posted by Delfin

. . . IMO, Lithium probably makes no sense unless you spend a lot of time away from the dock. It sounds like RR's clients tend towards those who sail on a lake (even if a very, very big lake) and don't spend days away from a power post, so LA makes perfect sense. But if you do spend a lot of time away from a dock, then you are probably used to managing the boat's systems. You can bugger up a diesel quite easily if you pay no attention to oil levels or clean fuel and you can bugger up a lithium bank if you ignore that. To me, if you have the wits to anchor out a couple hundred days a year, then you have the wits for Lithium and in that sense it is technology that is ready to go and be used quite satisfactorily.

Yes, I'm coming around to this view. The more I study it, the more straightforward the issues seem to me.



Moreover, it's not like managing a lead bank for off grid use requires no thought or care. Far from it! How much time have I spent in my cruising life worrying about finishing charges, looking for shore power because I haven't had a good charge in a few days, equalizing and worrying about overdoing it, bla bla bla. A lead acid battery bank is NOT a low maintenance system on a cruising boat -- far from it.


Lithium does require some knowledge to design and install, but probably requires less knowledge to actually manage the finished and working system, than lead does -- just, it's different knowledge, and what you know about lead doesn't help you, so you have to start over from zero.



I guess a well-executed lithium power system will greatly reduce the work load on the cruiser, flowing from the power system. Lithium is somewhat complex to implement, but once you have it, it's like a fuel tank -- don't have enough power, pour some in. Have some power? Take it out. Much simpler than lead. Equalization? Finishing charge? Sulfation? What's that?

[ramblinrod]

Originally Posted by CatNewBee

Is true for all kind of inductive loads.

They should have some protection around (e.g. by protection diodes, as done on relays etc.)

However, this is not a LFP only issue, but applies to every installation that has circuit breakers, switches or relays on pumps, winches, windlasses etc.

LVP and OVP are considered smart fuses, they do not switch in regular operation at all.
They only switch if something really goes wrong. It is he exact same problem as with a
normal fuse in high current applications regardless of chemistry.

So why this scaremongering?

This is not scaremongering.

It is a fact that "we" (boaters considering LFP install) all need to be aware of.

If the BMS disconnects the LFP bank for any reason, and it takes out all of the electronics and alternator on the boat, because nobody did anything (like have an FLA battery always connected) "we" are going to be pretty upset.

[Dockhead]

Originally Posted by tanglewood

Regarding shutting off high power chargers......


There are typically other ways to shut them off in a graceful way, and I think these approaches are preferred, where possible. The key is having a BMS that provides a "stop charging" signal, which most do. The Stop Charging signal gets activated as a warning, and occurs well before BMS does an abrupt disconnect. If charging continues after the Stop Charging signal is asserted, you will risk a disconnect, and that's to be avoided if possible.


Here are some examples of soft shutdowns that I'm aware of.



- Some Victron chargers have an input signal that can be configured to stop charging.


- Some Victron chargers can be told to stop charging via Canbus or Modbus.

- Some Victron Inverter/chargers have an input signal that can be configured to stop charging.


- Some Victron inverter/chargers can be told to stop charging via Canbus or Modbus.


- Other brand inverter/chargers can be configured for external on/off of charging.


- Balmar alternator controllers can be shut down by disconnecting the Ignition wire (preferred according to Balmar), or the field wire.


- Other external regulators can be stopped via similar methods.


- Internal regulators can be stopped by breaking the power connection to the regulator which is similar to turning off the key switch for the engine.


- I haven't looked carefully at solar controllers, but some have control inputs like inverters an chargers. Others can be controlled via canbus or modbus.


- In a pinch, you could install a relay to break the solar input side of the solar controller.


- In a pinch you could install a relay to cut AC input power to a charger to stop it from charging.


There are probably plenty of others that I haven't seen. The bottom line is that with an appropriate BMS, there are lots of graceful ways to shut down charge sourced without spikes, without attached LA batteries, and without a total battery disconnect.

Thanks for this, and I believe you, but I guess that we need to think one step further than just a normal shutdown of the charge source (easy on my system with Victron and Balmar), and make sure that even an emergency cutoff will not wreck anything with an inductive voltage spike.



This requires some engineering, but I'm sure it can be done. I believe Charlie Sterling's "alternator linearizer" will deal entirely with all the alternator issues. I don't know about the Victron charger, but the place to find out will be from Victron, who give awesome technical support.


Then I guess we need to think about the LVC and the loads, if there is much inductance in the system, which there is in my case. How did you deal with this, on your system?

[ramblinrod]

Originally Posted by Dockhead

Yes, I'm coming around to this view. The more I study it, the more straightforward the issues seem to me.



Moreover, it's not like managing a lead bank for off grid use requires no thought or care. Far from it! How much time have I spent in my cruising life worrying about finishing charges, looking for shore power because I haven't had a good charge in a few days, equalizing and worrying about overdoing it, bla bla bla. A lead acid battery bank is NOT a low maintenance system on a cruising boat -- far from it.


Lithium does require some knowledge to design and install, but probably requires less knowledge to actually manage the finished and working system, than lead does -- just, it's different knowledge, and what you know about lead doesn't help you, so you have to start over from zero.



I guess a well-executed lithium power system will greatly reduce the work load on the cruiser, flowing from the power system. Lithium is somewhat complex to implement, but once you have it, it's like a fuel tank -- don't have enough power, pour some in. Have some power? Take it out. Much simpler than lead. Equalization? Finishing charge? Sulfation? What's that?

OK, this is not supposed to be a FLA vs LFP thread, but I have to comment on this falsehood.

With appropriate charge sources an FLA bank is pretty idiot proof.

If the resting voltage before sunrise will be 12.2 Vdc or greater, and the days forecast is full sun and wind, nothing to do.

If lower than 12.2 Vdc start the ICE charger (rare, maybe once per week).

If 12.2 Vdc or greater, and insufficient sun or wind likely, start the ICE charger (rare, maybe once per week).

If non VRLA, check/refill the water once per month.

Researching, designing, installing, operating a LFP bank; more complicated, plain and simple.

You are looking at this solely from the perspective of one who will not consider anything other than ICE charging.

In my opinion, this is unusual for a cruising sailor intending to spend most time on the hook, who would prefer alternate solutions to ICE charging.

Your personal view is not necessarily the consensus.

My view is based on reviewing/consulting/advising hundreds of boaters.

OK, enough FLA vs LFP.

This is a hybrid thread and how to combine FLA and LFP.

[john61ct]

Originally Posted by Delfin

No John, that is not correct. It may be correct with LA, but not with LFP.

No Delfin, I stand by what I wrote, and many if those whose posts I respect on the topic agree.

> When the acceptance rate of an LFP battery drops to near zero, it is full, regardless of the voltage you are charging the battery at.

That's just crazy talk. Allowing the bank to go above 14V for any length of time will cut longevity dramatically.

If you slavishly follow the industry specs, you will fail to get the much greater longevity possible from avoiding the shoulders.

In daily use there is no reason to Absorb at all.

If precision is required, then endAmps at .03C is fine, but I only do so at 13.8.

Going to some crazy high voltage like 14.6V **and** forcing current until it drops to an even lower point is just silly, you might squeeze another few AH in, but if habitual, losing many hundreds, maybe thousands of lifetime cycles.

And if you are never going that high, why would you include it within your definition of 0-100%?

> In any case, as Maine Sail has pointed out, 14.2 volts for 5 minutes has a very different effect on an LFP battery than 14.2 volts for 4 hours.

Yes, and just stopping at 13.8V with zero Absorb is very different for longevity than going to 14.2 at all.

You don't gain **anything** at all by doing so.

For storage of your banks, do whatever you like, we also disagree on that, but not arguing that here.

[rgleason]

Please substitute LFP in place of LA in this post. Sorry I don't know what I was thinking. Its FLA and LFP. Sorry for the confusion.