LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[Highland Fling]

Originally Posted by Highland Fling

We have available 800AH. I have 200AH sitting in a 4P not in use/in circuit configuration. 200AH is normally switched out of circuit, so we are using 400AH for everything including cooking induction hob/Microwave/Instant Pot/Rice Cooker. I have 800AH because I could have that very cheaply AND at that stage I still had LA thinking. Now having some sort of experience of LIFePO4 batteries I UNDERSTAND the totally different thinking needed when you move from LA to LIFePO4 batteries. For sure I am a happy bunny LIFePO4 beats Duracell

The last time I had a look at them which is around ten days ago (apart from 'noticing' the house bank voltage and AH used which is a few times daily) the cells were all sitting at a voltage difference of 0.001 volts.

As an engineer I found / find that simply amazing but then these batteries are, when compared to LA and remember we had 14 year old gel cells that were doing ok UNTIL we started asking them to support heavy loads to cook with.

Then the voltage went downhill like Niagra falls with the inverter complaining loudly until it said enough of this nonsense and switched off.

[mbartosch]

After reading all of this thread, digesting a lot of insight and information and doing my own research and design I have finished most of the installation on our boat Entropy just recently.

In order to give something back to this great community I have documented my design on our cruising blog in the Engineering section. It's not yet finished, I would like to add posts about the physical installation of the system, but the schematics are all there already.

Find the overview on the Engineering Articles here:
Engineering - Entropy

Direct link to the design documents:
Designing a LiFePO4 Battery System Part 3 - System Design - Entropy
Designing a LiFePO4 Battery System Part 2 - Battery Management System Module - Entropy

I hope this helps other cruisers with their design.

Cheers

Martin

[OceanSeaSpray]

Originally Posted by mbartosch

After reading all of this thread, digesting a lot of insight and information and doing my own research and design I have finished most of the installation on our boat Entropy just recently.

In order to give something back to this great community I have documented my design on our cruising blog in the Engineering section. It's not yet finished, I would like to add posts about the physical installation of the system, but the schematics are all there already.

Find the overview on the Engineering Articles here:
Engineering - Entropy

Direct link to the design documents:
Designing a LiFePO4 Battery System Part 3 - System Design - Entropy
Designing a LiFePO4 Battery System Part 2 - Battery Management System Module - Entropy

I hope this helps other cruisers with their design.

Cheers

Martin

First design ever that I see using a HPBMS while actually addressing some of its worst shortcomings.
Fair amount of complications and high standby power consumption, but nice to follow the diagrams and thought process.

[Journeyman]

Mbart,
Great write up. Did you look at baseing the battery design on a pair of MasterVolt 12V/2500W Li-Ion batteries? If so, what was your conclusion?
Thank you,
Journeyman

[mbartosch]

Originally Posted by Journeyman

Mbart,
Great write up. Did you look at baseing the battery design on a pair of MasterVolt 12V/2500W Li-Ion batteries? If so, what was your conclusion?

It's like comparing apples and oranges. The Mastervolt Lithium batteries (and counterparts from other companies such as Victron) are all-in-one solutions which combine the lithium cells, BMS and protection circuits. They aim at being "drop in replacements" for existing lead acid batteries.

There are lots of reasons for me not to pick these ready-built packages, ranging from simple physical issues (they are too high for my battery compartment), over economical, to technical ones (BMS is built in, no chance to extend the system e. g. for properly cutting off the alternator) etc.

[exMaggieDrum]

Originally Posted by mbartosch

After reading all of this thread, digesting a lot of insight and information and doing my own research and design I have finished most of the installation on our boat Entropy just recently.

In order to give something back to this great community I have documented my design on our cruising blog in the Engineering section. It's not yet finished, I would like to add posts about the physical installation of the system, but the schematics are all there already.

Direct link to the design documents:
Designing a LiFePO4 Battery System Part 3 - System Design - Entropy
Designing a LiFePO4 Battery System Part 2 - Battery Management System Module - Entropy

Martin

Martin,
This is truly a remarkable set of diagrams and documentation of your battery system. I, honestly, believe it is the very best I have seen related to boats. Much better than the several noted authors of the standard boating technical books. Of course this is very specific to just one subject. This will be very helpful in the design of my system. Thank you for taking the time to produce this and sharing it with us.
Joe

[Maine Sail]

Originally Posted by mbartosch

After reading all of this thread, digesting a lot of insight and information and doing my own research and design I have finished most of the installation on our boat Entropy just recently.

In order to give something back to this great community I have documented my design on our cruising blog in the Engineering section. It's not yet finished, I would like to add posts about the physical installation of the system, but the schematics are all there already.

Find the overview on the Engineering Articles here:
Engineering - Entropy

Direct link to the design documents:
Designing a LiFePO4 Battery System Part 3 - System Design - Entropy
Designing a LiFePO4 Battery System Part 2 - Battery Management System Module - Entropy

I hope this helps other cruisers with their design.

Cheers

Martin

Martin,

That is exactly how the HPBMS is meant to be wired. The only two things I would do a bit different would be to sense alt voltage and Victron voltage closer to the battery bank, but that may not be clear in the diagram.

The designer of the MC-614 (the actual electrical engineer who designed it not Balmar) prefers to see an HVC cut on the 12V B+ to the regulator not the ignition. Both will work but he insists the 12V B+ is what should be used.

Question: What did you program the Duo charge cut in/ON voltage and cut out/OFF voltages for or is that what the manual switches are for?

[mbartosch]

Originally Posted by Maine Sail

The only two things I would do a bit different would be to sense alt voltage and Victron voltage closer to the battery bank, but that may not be clear in the diagram.

Voltage sense of the Victron is directly attached to the battery.

After lots of consideration I decided to attach alternator regulator voltage sense and alternator B+ behind the Main Contactor, not directly attached to the battery. I know I am taking a risk of destroying the alternator diodes if the Main Contactor drops for some reason while the alternator is charging the battery.
The reason I did this is that I wanted to be sure that the main contactor really isolates the battery bank.

The designer of the MC-614 (the actual electrical engineer who designed it not Balmar) prefers to see an HVC cut on the 12V B+ to the regulator not the ignition. Both will work but he insists the 12V B+ is what should be used.

Thanks, I did not know this. From the Balmar manual it looked like they advocate the ignition input. Luckily this can be easily changed.

Question: What did you program the Duo charge cut in/ON voltage and cut out/OFF voltages for or is that what the manual switches are for?

You are referring to the overview schematics? There are two Digital Duos there. One is charging the starter bank and is controlled by a timer relay (triggered by state of charge and ignition).

The other is "a spare Digital Duo put to some useful purpose". I use it to recharge my portable battery bank. Hence the manual switch to activate it explicitly.

I did not program any cut in/cut out voltages - not needed in my design, as the "logic" for controlling the Digital Duo charging the starter battery is working very well without it.

[offpist]

I just want to throw in that the KILOVAC EV200 relay can be ordered with an "Optional auxiliary contact", prefect for connection the "REG ON" to the regulator. Same relay can then disconnect battery and turn off alternator at the same time.

Optional auxiliary contact can only take 2A current so its not for Field current.

[exMaggieDrum]

Originally Posted by offpist

I just want to throw in that the KILOVAC EV200 relay can be ordered with an "Optional auxiliary contact", prefect for connection the "REG ON" to the regulator. Same relay can then disconnect battery and turn off alternator at the same time.

Optional auxiliary contact can only take 2A current so its not for Field current.

I looked at the Kilovac website in particular and it had the two different types, one with and one without an "auxilliary contact". They didn't really explain what that was or what it would be used for. I intended to contact them (no pun intended) to ask. Thanks for clearing that up. One question though, is the auxililary contact electrically isolated from the main contact? I would think it would be if it acts as a DPDT switch.

[mbartosch]

Originally Posted by offpist

I just want to throw in that the KILOVAC EV200 relay can be ordered with an "Optional auxiliary contact", prefect for connection the "REG ON" to the regulator. Same relay can then disconnect battery and turn off alternator at the same time.

Optional auxiliary contact can only take 2A current so its not for Field current.

Right, but there's a problem: the magnetic field in the alternator does not collapse immediately. If you cut the field coil supply and at the same time cut the B+ output, the alternator diodes can still be damaged simply because there is enough residual field energy to sustain power generation of the alternator.
Shutting down the alternator properly requires a (short) delay between field shutdown and load dump.

[offpist]

Originally Posted by exMaggieDrum

I looked at the Kilovac website in particular and it had the two different types, one with and one without an "auxilliary contact". They didn't really explain what that was or what it would be used for. I intended to contact them (no pun intended) to ask. Thanks for clearing that up. One question though, is the auxililary contact electrically isolated from the main contact? I would think it would be if it acts as a DPDT switch.

Yes its isolated from the main contact, and has two separate cables.
Having two relay`s on one just makes more sense.
Less complex and saves power. (only 1,7W holding)

I also included an "pre charge resistor".
Meaning it will "charge" the load circut for about 3 seconds before turning on the contact. This allows the capacitors of the inverter etc to fill, meaning lower inrush current and longer contator life.

[offpist]

Originally Posted by mbartosch

Right, but there's a problem: the magnetic field in the alternator does not collapse immediately. If you cut the field coil supply and at the same time cut the B+ output, the alternator diodes can still be damaged simply because there is enough residual field energy to sustain power generation of the alternator.
Shutting down the alternator properly requires a (short) delay between field shutdown and load dump.

The alternator is connected thru an battery isolator, so the current will simply go to the start battery (also Lifepo4) for the split second it takes for the regulator to turn off.

I have run high voltage cut of simulation under motor a few times already and no problems or voltage spikes.

[missourisailor]

Hi All,
Just to give another perspective on a LiFePo setup, here is a simplified diagram on one of my boats.
What I have that is different than other systems that have been discussed here, is the Time Delay circuit in the OV (over voltage) disconnect system.
This is put here solely to protect the alternator system.

What happens is when initial power is applied, the alt reg power is delayed for 5sec after the command to close the OV solenoid is initiated. This ensures that the batteries are connected before the field is energized.

On a OV event, the OV solenoid is held closed for 5secs after the open command is issued. This gives the alt.'s magnetic field time to collapse. Thus saving not only the diodes but also lessening the effects of a sudden disconnect on the reg..

The time delay circuit is all SS (solid state) and is about the size of your thumbnail. It is rated at 5amps.

Just another way to do it.

Okay, for some reason the image is not coming through.. so here is a link.
http://www.midwestsailing.com/CF/LiFePo-simplified.pdf
http://www.midwestsailing.com/CF/LiFePo-simplified.pdf

[Highland Fling]

Nice design and write up of a rather complex complicated LIFePO4 system.

I see KISS was thrown out of the window in fact it looks like it was thrown out of a window on the top floor of the Burj Khalifia.

As an electrical and electronics engineer I love the design, write up and the diagrams BUT for sure most of this I see as unneccessary for MY BOAT.

LIFePO4 just like LA does not like Over or Under charging.......seems to me that the need for these systems has not been 'seen as neccessary' for LA batteries as to why we need to install all that complex circuitry for LIFePO4 batteries well I just don't get that or agree that is is neccessary never mind wanted on a cruising boat certainly not on mine.

Just another simpler way of doing things.....KISS. Also I am NOT Looking for an argument here. as to which system is 'best'

THIS IS My System you can design yours to meet your wants desires needs.

NO changes to the alternator it is a Delco Remy 10SI with external sensing.

I still have the Diode splitter for the house and engine start batteries and I do have in a cupboard somewhere a Sterling no loss battery splitter (never fitted)

I have Four 200A seperate house batteries WTS 200A cells in a 4S configuration

Each 200A battery has a BMS and Cell boards from EV-POWER

BMS

A much nicer (marine) solution that the House power one IMHO.

The engine start battery is still LA, an AGM 8D and the biggerst change I have made is to ramp up the switch off voltage on my two Blue Sky Solar Boost 2000i controllers to cut off the charging just under the BMS OVC voltage.

IF or when the AGN battery dies I will use a LIFePO4 battery and I 'may' put another diode in the circuit so it can never experiece an OVC unless a cell went bad. So that IF all three or four of my 200A batteries simultaneously went off line while the alternator was charging that would not kill the alternator......

However read my previous posts despite the alternator main feed wire breaking AND also on a seperate event the diode bock inside the alternator coming loose (both when charging) the alternator survived these events with absolutely no damage......

So while theoritically it should have blown the diodes as every one will tell you 'must happen' that was not the case.

For sure that lovely complex complicated system and lovely write up and diagrams is only going to convince the undecided masses that LIFePO4 is not for me.

There seems to be a lot of wrong headed thinking here about what is 'needed' for a sucessful LIFePO4 installation. After all it is 'just a battery' one that offers a lot of benefits to cruisers but is surroded by mistique and rules that you must follow.

I have no issues with the complex solution it just does not fit in with my mindset. A year down the line I am very happy with my LIFePO4 house bank so happy that we 'now' only use 400AH regularly, 200A is stilling happy out of circuit for a year now in a 4P configuration at 3.25V and the other 200A is avaiable at the flick of a switch and is also sitting at 3,3V per cell 13.2V I have no cell balance issues whatsoever.

Almost any decent electrician who understands boat wiring would not be overawed by my system...that said the few that have looked at my installation don't understand the ins and out of cell boards and BMS's......asking one of these guys to look at that complex system......would be an interesting exercise and IF or ONCE you sell the boat ....... is that sort of LIFePO4 system going to attract buyers or scare them off.


Nice system nice write up and diagrams on a nice boat but there are for sure more than one way to skin this particulat cat......saying that LIFePO4 is a great battery system for a Cat.....the sailing kind.