LiFePO4 reference diagram, Alternator version

[s/v Jedi]

Originally Posted by rossdv8

Just got to the end of this interesting post, (so fat) and one thing stood out.
A number of references to 'Blue Blobs' and to whether things were in parallel or series.


I have a question that should be obvious, but has been bugging me.


Shouldn't a 'Reference Diagram' be read in conjunction with a 'Circuit Schematic'?


A Circuit Schematic alone is confusing as hell for many non-electrical and non-electronics trained people.
But add a Reference Diagram and it all begins to make sense.
Annotate the Reference Diagram with Component Names and suddenly it all makes a LOT of sense.


The added bonus 'might' be no name calling, less derogatory comments about relative qualifications and skills, and a more constructive discussion.

My diagrams require a (basic) level of understanding of these components and installations as they are not complete. Most of the negative conductors are missing completely.

The thing is that when these diagrams are too difficult to understand for someone, then it isn’t meant for that person to use. I got to realize that people want to take this diagram and build it without knowing how an alternator works, let alone a regulator for it, or a BMS etc. This is not for them so there’s no need for further labels.

[newhaul]

Originally Posted by goboatingnow

I think ISO has far less producer influences by nature of how it makes up its technical groups

Interestingly I met a person recently who was involved in an iso tech working group. He opined that ABYC were aligning with iso and not the other way around. But who knows

Bet it's far more producer influenced. Graft always follows government regulations .

[goboatingnow]

Originally Posted by newhaul

Bet it's far more producer influenced. Graft always follows government regulations .

Technical working group 48 which formulated the lSO lithium is a big group with heavyweights like BSI , ANSI, DIN. These groupings if anything tend to look down their noses at Mere “ industrialists “ so unlike ABYC which is nothing more then a representative body. I doubt your claim

ISO isn’t government controlled anyway

The EU does get lobbied in respect of the RCD but not that much in respect of ISO

anyway given the whinging that occurs from boat builders over tHE RCD and ISO clearly they feel their not having much influence to begin with. ! ! !

[Dr.No]

I am going to jump into the fray and announce that Jedi in particular, as well as others like FxyKty have been incredibly instructive in writing enough quality knowledge to allow me to design a 400 amp hour @24 volt Winston cell battery for my French aluminum sloop that is undergoing a multi year refit. That’s a long sentence. Thank you, Jedi for continuing to fight the good fight. The 24 volt addition came about by adding a 24V Vetus bow thruster, Andersen 72 electric winches, and a new 24V Lofrans windlass. This allowed for a completely new system compatible with Lithium ion cells. There is no fancy Bluetooth equipment. The battery is in a custom welded aluminum box. The details are extensive: 4/0 cables to 400 amp T fuses (positive and negative - Nigel Calder personally said to use both in case of a lightening strike), then 600 amp negative mechanical, and positive RBS cutoff switches (positive part of the LVC relay from the TAO BMS), then 2 sets of 3/0 cables to Load Bus A and Load Bus B (dual Mastershunts as Slave and Master so the load is not limited by the 300 amp continuous maximum ). That is perhaps the first 10% of the system details. My system is drawn on a huge sheet of paper - have just started looking at Lucidchart. My point is that every overall electrical diagram is going to leave out an incredible amount of detail simply because it will become unreadable if you put Everything in. Secondly, there is more than one way to do this properly and safely. I’m using both Mastervolt and Victron, as well as a new Balmar smart regulator. I might go all Victron and a WS500 regulator, if starting fresh. Just got the battery and BMS connected, and nothing blew up. Cheers!

[Dirk01]

Originally Posted by s/v Jedi

“Before the current reaches the fuse”

Yes, maybe put it a little funny. My English is not as good as yours.

I meant it like this (knowing that as an EE you can surely understand what I mean):
A cable, like a consumer, is also just a consumer. If the cable is now divided into many very small resistors, a little power loss occurs at each resistor. At the same time, the voltage decreases inch by inch. The power loss produced also decreases step by step (P=U^2 / R). The power loss can also be described as heat loss. Heat increases resistance and amplifies this effect.
You can also describe the power loss as P=I^2 x R, but that doesn't explain the relationship that well.
So my statement "Before the current reaches the fuse" can be misinterpreted. Thanks for the hint.

As said before, a well sized wire (and as I know you a bit over time, IT IS well sized in your DIY system) would not burn out the wire before the fuse acts. Especially with a dead short. So you can do it, but I think it's good practice to place the fuse where the juice enters the wire, not where it exits (to stay on point and not ramble on about things that weren't asked by you.).

However, people like Turk who think some software can handle things flawlessly for ever may not (or just can't) follow me. They just look at a spreadsheet, regardless of other circumstances or takes what anyone has written down. But to understand the whole thing, you have to read to the end. Only my 5 cts and I'm aware of getting hit by him now.

A well designed DIY system outstands every mass production. Mass products has to compete with other manufacturers in the same field. They are always designed for the lowest requirements. (Again my 5 cts).

Cheers
Dirk

[s/v Jedi]

Originally Posted by Dirk01

Yes, maybe put it a little funny. My English is not as good as yours.

I meant it like this (knowing that as an EE you can surely understand what I mean):
A cable, like a consumer, is also just a consumer. If the cable is now divided into many very small resistors, a little power loss occurs at each resistor. At the same time, the voltage decreases inch by inch. The power loss produced also decreases step by step (P=U^2 / R). The power loss can also be described as heat loss. Heat increases resistance and amplifies this effect.
You can also describe the power loss as P=I^2 x R, but that doesn't explain the relationship that well.
So my statement "Before the current reaches the fuse" can be misinterpreted. Thanks for the hint.

As said before, a well sized wire (and as I know you a bit over time, IT IS well sized in your DIY system) would not burn out the wire before the fuse acts. Especially with a dead short. So you can do it, but I think it's good practice to place the fuse where the juice enters the wire, not where it exits (to stay on point and not ramble on about things that weren't asked by you.).

However, people like Turk who think some software can handle things flawlessly for ever may not (or just can't) follow me. They just look at a spreadsheet, regardless of other circumstances or takes what anyone has written down. But to understand the whole thing, you have to read to the end. Only my 5 cts and I'm aware of getting hit by him now.

A well designed DIY system outstands every mass production. Mass products has to compete with other manufacturers in the same field. They are always designed for the lowest requirements. (Again my 5 cts).

Cheers
Dirk

Yes, you are completely correct. I feared you meant that the current decreases along the wire but it’s 100% clear now. Yes, this is why the fuse needs to be as close to the power source as possible and why the terminal-mounted fuses are so great as they aren’t just as close as possible, but also eliminate a cable between the power source and the fuse

[Dirk01]

Originally Posted by s/v Jedi

Yes, you are completely correct. I feared you meant that the current decreases along the wire but it’s 100% clear now. Yes, this is why the fuse needs to be as close to the power source as possible and why the terminal-mounted fuses are so great as they aren’t just as close as possible, but also eliminate a cable between the power source and the fuse

Current cannot decrease. It is always constant. It doesn't matter wether you measure at the beginning or at the end of the cable. It will show you always the same number. If you measure different numbers you have a major problem with stray current. (I deleted the "may", because you definitively have then a major problem )

This post is not really for you. It is a statement for somebody who might struggle in this field.

Ahmm - not to forget - nice diagram. I'll copy parts of it. Thanks for your posts.

Cheers
Dirk

[s/v Jedi]

I believe my thread is back to normal again, so let me try starting it back up;

I want to explain how to chose the right type of battery for an application. My diagram is showing Odyssey PC2100 batteries in the start bank, not LiFePO4 even though I am a big supporter of lfp batteries for boats and this is the lfp forum!

In another thread I tried to explain the different aspects of component selection during the design phase. I will use the start batteries as an example for this:

1. Define tasks.

Primary task here is starting diesel motors for the main engine and possibly a generator set. This is a high power but low energy (it takes a very short time) task.

A secondary task I identified is acting as an energy buffer for a dc-dc converter running off the house bank, which can be a higher voltage, powering 12V devices. A dc-dc converter may get overloaded during peak loads, and the start batteries provide backup for it. Examples are a windlass, electric sheet or halyard winch, autopilot drive etc. These tasks are the same as starting a motor: high power, short duration.

Another secondary task is backup for when the dc-dc converter(s) fail. This one is different, because it requires capacity to last as long as possible before another charge source is required to recharge the batteries, which would be the alternator.

2. Typical state in which component operates.
For a battery this is about cycles, charging, discharging etc. It is clear that we want to see these batteries fully charged for most of the time, ready to start motors and ready to backup the dc-dc converter(s). It’s two apparent charge sources are the alternator and the dc-dc converter. For either charge source, they would typically be in float charge, supplying any loads of the bank with energy, only charging the battery initially and after a high power consumer overwhelmed the alternator and/or dc-dc converter capacity, which was assisted by the batteries.

3. Disqualifying candidates.
Two of the three identified tasks including the primary task, disqualify deep cycle batteries. That said, from candidates left, having some deep cycle ability is an advantage over others as long as the high cranking amps requirement is met as well.
For state we see that the battery is typically fully charged. We know that lead acid batteries need to be fully charged on a regular basis, while lfp does not like a full charge at all and this reduces it’s lifespan considerably.

4. Identifying qualifying candidates.
Clearly dual purpose batteries dominate the candidates, followed by large capacity start batteries. Flooded lead acid, maintenance-free lead acid and AGM lead acid are right there, but they are old technology, so let’s see if there is something newer. I have identified LTO, Litium Titanate Oxide batteries as suitable but it’s lack of capacity is a negative. For pure starting, side thruster and windlass boost, LTO is a winner but here it’s held back by it’s low Ah rating.
Another candidate are the lead carbon AGM batteries. I don’t have much experience with these but know they handle not being fully charged better and they have a history of manufacturing and quality trouble. Compared to regular AGM they seem better suited for house batteries.

5. Other considerations.
Time to put candidates in order of suitability and look at other factors like price, availability etc.:

- Odyssey TPPL group 31M (Thin Plate Pure Lead) AGM battery. Pro: the best, approved for military use. Con: price, the most expensive. Looking at other AGM options in the 100Ah range, about $100 per battery can be saved but always at a cost like lower cranking amps. In my view it isn’t worth loosing performance for $200 savings on an electrical system as expensive as we have.

- Duracell Marine & RV deep cycle group 31M. Looking at specs it still has 1,000 cranking amps and it is half the price of the Odyssey. This is the budget option.

So there you have it. I have a lot of experience with these Odyssey batteries and think they are well worth the extra cost, making a battery like the Duracell a better budget choice than cheaper AGM batteries. There will be $500+ between the two choices, which is significant and although I never used them myself, from hearing others who do use them, I think the Duracells will perform well.

I hope the above explains how for component selection you first try to find candidates that fit the application best. Putting a battery that hates float charge in this position makes bad engineering even if that battery has perfect specs otherwise. A battery like the Battleborn LFP is 4x as expensive as the Duracell and is cutting edge technology, but for this application is clearly beaten by the old tech Duracell, with the Odyssey overlooking the competition like Julius Ceasar looked over his armies winning the battle

[fxykty]

Originally Posted by s/v Jedi

I believe my thread is back to normal again, so let me try starting it back up;



I want to explain how to chose the right type of battery for an application. My diagram is showing Odyssey PC2100 batteries in the start bank, not LiFePO4 even though I am a big supporter of lfp batteries for boats and this is the lfp forum!



In another thread I tried to explain the different aspects of component selection during the design phase. I will use the start batteries as an example for this:



1. Define tasks.



Primary task here is starting diesel motors for the main engine and possibly a generator set. This is a high power but low energy (it takes a very short time) task.



A secondary task I identified is acting as an energy buffer for a dc-dc converter running off the house bank, which can be a higher voltage, powering 12V devices. A dc-dc converter may get overloaded during peak loads, and the start batteries provide backup for it. Examples are a windlass, electric sheet or halyard winch, autopilot drive etc. These tasks are the same as starting a motor: high power, short duration.



Another secondary task is backup for when the dc-dc converter(s) fail. This one is different, because it requires capacity to last as long as possible before another charge source is required to recharge the batteries, which would be the alternator.

…

The primary task of an engine start battery is to start the engine, so the battery profile needs to support that in the first instance. High enough CCA to comfortably start the engine, including when repeated extended cranking is required. Generally it will be recharged while the engine is running; either directly via its alternator or indirectly from the house bank.

I would suggest that in an LFP house bank situation that the secondary task for the start battery is to provide a backup power supply when the LFP house battery goes offline. The battery should have sufficient capacity to enable all critical navigation and other systems to run for at least several hours at a time - the start battery should not require continuous running of the engine for recharging.

Now, if you’re running a 24V house battery and 12V start battery, then supporting the provision of 12V power becomes part of the second task. Provision of 24V power could be done via a normally offline 12-24V converter, but that starts adding complexity and hopefully none of the 24V consumers (windlass, thruster, electric winch(es), inverter, etc) are critical systems that need to be provisioned when the house battery is offline.

I do agree that an LFP start battery is the most expensive way to provision these tasks, but if space and/or weight is an issue a completely independent LFP battery could work. It would require a compatible charger and it would not provide alternator cut off protection, if that is how your system is designed. Lead acid is a more conservative and appropriate choice generally for engine start if there are secondary tasks for the battery.

[s/v Jedi]

Originally Posted by fxykty

The primary task of an engine start battery is to start the engine, so the battery profile needs to support that in the first instance. High enough CCA to comfortably start the engine, including when repeated extended cranking is required. Generally it will be recharged while the engine is running; either directly via its alternator or indirectly from the house bank.

I would suggest that in an LFP house bank situation that the secondary task for the start battery is to provide a backup power supply when the LFP house battery goes offline. The battery should have sufficient capacity to enable all critical navigation and other systems to run for at least several hours at a time - the start battery should not require continuous running of the engine for recharging.

Now, if you’re running a 24V house battery and 12V start battery, then supporting the provision of 12V power becomes part of the second task. Provision of 24V power could be done via a normally offline 12-24V converter, but that starts adding complexity and hopefully none of the 24V consumers (windlass, thruster, electric winch(es), inverter, etc) are critical systems that need to be provisioned when the house battery is offline.

I do agree that an LFP start battery is the most expensive way to provision these tasks, but if space and/or weight is an issue a completely independent LFP battery could work. It would require a compatible charger and it would not provide alternator cut off protection, if that is how your system is designed. Lead acid is a more conservative and appropriate choice generally for engine start if there are secondary tasks for the battery.

I think you’re mostly repeating me. Did you read the OP with the diagram to put the post you’re replying to in context?

[fxykty]

Originally Posted by s/v Jedi

I think you’re mostly repeating me. Did you read the OP with the diagram to put the post you’re replying to in context?

Sorry if you feel that I repeated you - that wasn’t my intention as I wanted to raise the issue of having an alternate power source when LFP battery is disconnected, which I thought you had missed.

I have read the OP and looked at the diagram closely, as I am about to double the size of my LPF battery. That’s why I posted my system diagram to this thread as well.

Thanks very much for your work!

[s/v Jedi]

Originally Posted by fxykty

Sorry if you feel that I repeated you - that wasn’t my intention as I wanted to raise the issue of having an alternate power source when LFP battery is disconnected, which I thought you had missed.

I have read the OP and looked at the diagram closely, as I am about to double the size of my LPF battery. That’s why I posted my system diagram to this thread as well.

Thanks very much for your work!

No problem, I guess I was confused. This thread had posts deleted so it’s a bit messed up.

There are several backups for the house bank. First is that there are two house batteries, after that it gets interesting. In the diagram there is a dc-dc converter from start bank to house bank. I actually have two running in parallel. These are programmed to charge a lfp battery and only charge when the alternator is running. That programming would need to be altered to stay always on and operate in power supply mode rather than charger.

Also, I’m not sure how the mppt controllers work when there is no battery but there’s voltage from the dc-dc converters. I did not test that before installing and now I don’t have another mppt controller to test with

[fxykty]

Originally Posted by s/v Jedi

No problem, I guess I was confused. This thread had posts deleted so it’s a bit messed up.



There are several backups for the house bank. First is that there are two house batteries, after that it gets interesting. In the diagram there is a dc-dc converter from start bank to house bank. I actually have two running in parallel. These are programmed to charge a lfp battery and only charge when the alternator is running. That programming would need to be altered to stay always on and operate in power supply mode rather than charger.



Also, I’m not sure how the mppt controllers work when there is no battery but there’s voltage from the dc-dc converters. I did not test that before installing and now I don’t have another mppt controller to test with

Good question regarding the MPPT controllers. Before the disconnect they’ll get a stop charge instruction to their remote on/off terminal. But of course still connected to the house battery, as their instructions say. So if there is an LFP battery disconnect then I guess the MPPT controllers may get damaged as their solar panel input will still be present.

If you have a circuit breaker on the panel output before the controller then if that can be controlled by a relay to cut the circuit when a battery disconnect takes place then that will protect the controller.

Of course, a BMS-initiated battery disconnect event is likely very rare so perhaps not worth worrying about. But it is something to remember before turning the battery isolation switch manually.

[goboatingnow]

Good quality mppt will survive battery disconnection. Certainly my Victron do survive. However the overvoltage protection is not functional with the battery disconnected

[s/v Jedi]

I have made sure to buy mppt controllers with dedicated remote on/off terminals in addition to the ve-direct interface, so I can control them remotely. I recently discovered that the 150/45 I used has been replaced with a model that doesn’t have this and you now need at least a 150/60 to get it.

Maybe they can operate in power supply mode too?