LiFePO4 (Redodo or Eco-worthy)

[CaptainRivet]

Originally Posted by Wandering1

You say you have mixed lead and LiFePo as a hybrid. Maybe you need to show your wiring or explain how you are a hybrid but don't mix chemistries

Hybrid means is use one pure lifepo4 bank as starter as well as a house bank. Means the engine starter is connected to house.
Thats always called a hybrid battery which you can use to start and deep cycle in one, independent from battery chemistry.

I don't mean to connect lead and lifepo4 to make a hybrid house bank of 2 differrnt battery chemistry like Emily and Clark did, thats what they made up as hybrid but totally misleading.

No i didn't mix lead and lifepo4, never ever...i try to get rid of lead wherever possible.

I have and advise to use a pure Lifepo4 bank as house and starter and use a seperate buffer battery (which was your starter before) that should be LTO or Lifepo4 but can be also lead, best AGM. I also described that buffer is charged/connected by an isolated DC2DC converter so you isolate galvanically the buffer and nav electronics from the house to protect them from spikes and distortions.

[s/v Jedi]

Qualification doesn’t just mean that one has done something and lived to tell… for technical, electrotechnical innovations to be created, one must understand all the underlying principles and for this at least relevant university studies are required. This is what defines the engineering profession.

Of course there have been many innovations by people who were not educated in the field at all. One can have a vision and pursue that. But for things like designing electrical systems for boats this doesn’t work like it does for inventing a new type of umbrella.

I have posted many of my “reference diagrams” on CF and for most members when they study them, they barely scratch the surface of why things are done that way. Even for me, the diagrams I started with have been adapted over the 20 years of live aboard cruising as you need to have that experience as well as the technical knowledge.

And yet, again and again people post their own diagram and ask me what I think. What can I say… no, it doesn’t look like my reference diagram at all. Because explaining the reasons would include all the years of university study, the apprenticeships and 20 years of using these systems… impossible to explain to the person.

[Wandering1]

Originally Posted by Pete7

I can do no better than copy this from another forum:

I think I should address the oft stated 'commandment' "Thou shalt no mix chemistries because to do so is an abomination"
In the past I have taken the stance that this is true except in the case of LiFePO4 and lead acid where the lithium sits within the profile of the lead acid quite happily and they live a loving symbiotic life together.

I have however now decided to approach it from a different perspective and argue that you are in fact not mixing chemistries. If you think about it, using the old definition, then when you charge your phone on the boat you are mixing chemistries because the lead acid boat battery is connected to the phone but it is via a charger and a BMS in the phone. Now look at the Lithium / Lead acid hybrid. You are connecting the lead acid to the lithium but not directly, one of the most fundamental things is that you do so via a BMS which does exactly what the BMS in your phone does and protects the battery.

In the case of the phone the input is 5v and it charges a battery to a max of 4.2v. In a boat system you don't need the actual 12v-5v converter because the lithium charge requirements sit within those of the lead acid. This gives another layer of safety to the system because a BMS failure will not expose the lithium to any excess / dangerous voltage. Ironically if the phone BMS dies then the phone battery can explode and if the 12-5v converter fails it can fry the phone and the phone uses a flammable battery technology.
Maybe that is a better way of looking at that commandment and saying that it actually doesn't apply!

Acknowledgement: Phil Brooke-Little

I am not here to argue about the benefits of a hybrid system. Just pointing out that the ISO says no.
When somebody says they are ISO compliant but has a hybrid system I wonder how?

[CaptainRivet]

Originally Posted by Wandering1

I am not here to argue about the benefits of a hybrid system. Just pointing out that the ISO says no.
When somebody says they are ISO compliant but has a hybrid system I wonder how?

Hybrid in technical electric terms means that a battery of the same chemistry is/can be used for start applications as well as deep cycle applications means each of the two or both simultaneously.

Mixing different chemistries into one bank is NOT hybrid!!!! in electrical terms and usage. In electrical terms thats called creating a desaster...

[CaptainRivet]

Originally Posted by s/v Jedi

Qualification doesn’t just mean that one has done something and lived to tell… for technical, electrotechnical innovations to be created, one must understand all the underlying principles and for this at least relevant university studies are required. This is what defines the engineering profession.

Of course there have been many innovations by people who were not educated in the field at all. One can have a vision and pursue that. But for things like designing electrical systems for boats this doesn’t work like it does for inventing a new type of umbrella.

I have posted many of my “reference diagrams” on CF and for most members when they study them, they barely scratch the surface of why things are done that way. Even for me, the diagrams I started with have been adapted over the 20 years of live aboard cruising as you need to have that experience as well as the technical knowledge.

And yet, again and again people post their own diagram and ask me what I think. What can I say… no, it doesn’t look like my reference diagram at all. Because explaining the reasons would include all the years of university study, the apprenticeships and 20 years of using these systems… impossible to explain to the person.

Fully agree.
Would love to have your comments and insides with the other thread " regarding do we really need a dedicated starter with lifepo4 "...
With technolgy changed here i think its time to adapt that old concept. I mean not replace it but have a better one that makes use of the advantge of lithium.
With more and more electronics we rely on, its time that 2nd battery we have onboard is better used then sitting around waiting to be used to start the engine (and then find out its dead and cannot be used).