Lithium House bank/FLA start/Twins

[Dougcole]

Hi All,


I'm considering switching over to Lion for our house bank when our current bank dies (likely 12 to 24 months) and wrapping my head around what that would entail.


Current setup is 6 6V FLA in series and parallel for a house bank. Start for both motors is a single FLA group 31 start battery. Both engines feed the start battery and then the house bank via an ACR. Yanmar 4LHA-stp with OEM internally regulated Hitachi alternators. I replaced the V-Belt on the port side alternator with a serpentine belt kit last year (huge improvement).


Shore power charger is 50 amp, lithium compatible pro mariner, about 2 years old.


I am adding 200 to 400 watts of solar through an MPPT next month. I have zero expectations of this covering all of our needs, I am just trying to offset some of our fridge use and the Skylink.



My questions:


1. I think if I am going to mix and FLA start bank with a Lion house bank,I need to use a DC to DC charger, right?


2. Can I still run both alternators through the start battery and the ACR to the house bank? How would that work with twins? How would it work with a DC to DC charger?



3. I assume my alternators wouldn't work for Lion, but can I replace one of them and keep the other? I realize they are a very basic alt with some issues, but they have worked fine for our usage for 10 years. I don't really have it in the budget for two high end alternators.


Thanks and Merry Christmas,


Doug

 

[SteveK]

@Doug
1) I went DC2DC from FLA start to LFP house from the alternators. This was to avoid an ALT meltdown that was suggested by several experts?
2) The ACR is direct connection from one bat to the other may blow the ALTs as said before I used the DC2DC to protect the ALT. You will not need an ACR with a DC2DC installed.
3) forget the ALT upgrade as your current bank suggests you will not have a much larger LFP bank to justify ALTs that can be regulated for LFP.

ETA Merry Christmas

 

[vertigopilot]

Hi All,


I'm considering switching over to Lion for our house bank when our current bank dies (likely 12 to 24 months) and wrapping my head around what that would entail.


Current setup is 6 6V FLA in series and parallel for a house bank. Start for both motors is a single FLA group 31 start battery. Both engines feed the start battery and then the house bank via an ACR. Yanmar 4LHA-stp with OEM internally regulated Hitachi alternators. I replaced the V-Belt on the port side alternator with a serpentine belt kit last year (huge improvement).


Shore power charger is 50 amp, lithium compatible pro mariner, about 2 years old.


I am adding 200 to 400 watts of solar through an MPPT next month. I have zero expectations of this covering all of our needs, I am just trying to offset some of our fridge use and the Skylink.



My questions:


1. I think if I am going to mix and FLA start bank with a Lion house bank,I need to use a DC to DC charger, right?


2. Can I still run both alternators through the start battery and the ACR to the house bank? How would that work with twins? How would it work with a DC to DC charger?



3. I assume my alternators wouldn't work for Lion, but can I replace one of them and keep the other? I realize they are a very basic alt with some issues, but they have worked fine for our usage for 10 years. I don't really have it in the budget for two high end alternators.


Thanks and Merry Christmas,


Doug

Hi, Doug.


I just finished (this afternoon) replacing my house batteries (4 x 215Ah AGM) with LifePO4 (2 x 410Ah) and reconfiguring the LFP house bank to coexist with my AGM banks (1720Ah total) for Start, Stern Thrust, and Bow Thrust. The Balmar 250A alternator charges directly to the LFP house bank and is connected to the MC 618 external regulator reconfigured for LFP charging profile. I added a Balmar APM (Alternator Protection Module) as the primary protection against sudden BMS disconnect of both LFP batteries while under heavy charge.


Added a Victron Orion Smart DC-DC 30A charger between the House bus and the Start bank to provide managed charge current from the LFP bank to the AGM bank(s). When I turn my Pathmaker switch on (or leave it set for Auto), the AGM banks are all connected in parallel and the House bank supplies input current to the combined AGM banks, delivering an appropriate charge profile for the AGM batteries.


Windlass and davit loads were moved from the house bank to the Bow bank, eliminating all high-load demands from the House bank.



By keeping the main engine's alternator output connected directly to the LFP house bus, I get the benefit of rapid charging of the house bank, while the DC-DC charger provides secondary charging of the lesser loads on the AGM banks.


If I anticipate a need for heavy thruster use during docking, then I can start the 8kW genset to provide 60A charge direct to the Start & Stern Thrust AGM banks, and 30A from the two AC-DC chargers at the Stern and Bow banks.


Initial results are pleasing.

 

[mvweebles]

My 2-cents. Put a high output Balmar on the engine with serpentine belt for LFP house bank. Keep the OEM Hitachi alternator on the other and use to charge the AGMs. No DC-DC charger needed. Run the solar charger to the LFP bank. I suppose you could put a parallel switch between the two banks for emergency use. A Balmar APM is a fairly low cost insurance policy against cooking your diodes, in my opinion, a better solution than putting AGMs in front of the LFPs.

Start/Thruster battery banks have a much, much different duty cycle than LFP/House banks. They are almost never deeply discharged but rather deliver high current for very short durations.

You could go with two high output alternators with both going to LFP/House and a DC-DC to charge the AGMs. It would provide redundancy but you'd have to decide whether it's worth the additional expense and complexity.

One thing that bit me on my unstall: make sure you use robust cables. LFP batteries have a relatively narrow band between charged and discharged. Voltage loss due to undersized cables will confound your system. Even 3% voltage loss is too much.

Finally, if you don't already have one, the Victron SmartShunt provides a ton of charge/current information and is relatively affordable (under $150).

Good luck and I look forward to updates on what you decide.

Peter

 

[Dougcole]

Hi, Doug.


I just finished (this afternoon) replacing my house batteries (4 x 215Ah AGM) with LifePO4 (2 x 410Ah) and reconfiguring the LFP house bank to coexist with my AGM banks (1720Ah total) for Start, Stern Thrust, and Bow Thrust. The Balmar 250A alternator charges directly to the LFP house bank and is connected to the MC 618 external regulator reconfigured for LFP charging profile. I added a Balmar APM (Alternator Protection Module) as the primary protection against sudden BMS disconnect of both LFP batteries while under heavy charge.


Added a Victron Orion Smart DC-DC 30A charger between the House bus and the Start bank to provide managed charge current from the LFP bank to the AGM bank(s). When I turn my Pathmaker switch on (or leave it set for Auto), the AGM banks are all connected in parallel and the House bank supplies input current to the combined AGM banks, delivering an appropriate charge profile for the AGM batteries.


Windlass and davit loads were moved from the house bank to the Bow bank, eliminating all high-load demands from the House bank.



By keeping the main engine's alternator output connected directly to the LFP house bus, I get the benefit of rapid charging of the house bank, while the DC-DC charger provides secondary charging of the lesser loads on the AGM banks.


If I anticipate a need for heavy thruster use during docking, then I can start the 8kW genset to provide 60A charge direct to the Start & Stern Thrust AGM banks, and 30A from the two AC-DC chargers at the Stern and Bow banks.


Initial results are pleasing.

Thanks for the info and that sounds like a great system.


Mine will be pretty different though as I have twin engines and no thrusters.

 

[Dougcole]

My 2-cents. Put a high output Balmar on the engine with serpentine belt for LFP house bank. Keep the OEM Hitachi alternator on the other and use to charge the AGMs. No DC-DC charger needed. Run the solar charger to the LFP bank. I suppose you could put a parallel switch between the two banks for emergency use. A Balmar APM is a fairly low cost insurance policy against cooking your diodes, in my opinion, a better solution than putting AGMs in front of the LFPs.

Start/Thruster battery banks have a much, much different duty cycle than LFP/House banks. They are almost never deeply discharged but rather deliver high current for very short durations.

You could go with two high output alternators with both going to LFP/House and a DC-DC to charge the AGMs. It would provide redundancy but you'd have to decide whether it's worth the additional expense and complexity.

One thing that bit me on my unstall: make sure you use robust cables. LFP batteries have a relatively narrow band between charged and discharged. Voltage loss due to undersized cables will confound your system. Even 3% voltage loss is too much.

Finally, if you don't already have one, the Victron SmartShunt provides a ton of charge/current information and is relatively affordable (under $150).

Good luck and I look forward to updates on what you decide.

Peter

Thanks Peter.


I was thinking of that as well. Use one engine to charge the house bank and one the start bank.


I would likely keep the serp belt on the hitachi alt and get a new alt with its own serp belt for the other engine. I had to change out the pulleys on the engine that currently has a serp belt on it, they are specific to the hitachi alt. The 4LHA is notorious for eating belts, I switched it out to reduce dust and constant tightening. My plan was to test it on one side to see if I liked it then change the second one. But if I am going to upgrade the alt on the second motor I will do the belt at the same time.


I already have a victron smart shunt on my house bank. I really like it.

 

[z1nonlyone]

Hi, Doug.


I just finished (this afternoon) replacing my house batteries (4 x 215Ah AGM) with LifePO4 (2 x 410Ah) and reconfiguring the LFP house bank to coexist with my AGM banks (1720Ah total) for Start, Stern Thrust, and Bow Thrust. The Balmar 250A alternator charges directly to the LFP house bank and is connected to the MC 618 external regulator reconfigured for LFP charging profile. I added a Balmar APM (Alternator Protection Module) as the primary protection against sudden BMS disconnect of both LFP batteries while under heavy charge.


Added a Victron Orion Smart DC-DC 30A charger between the House bus and the Start bank to provide managed charge current from the LFP bank to the AGM bank(s). When I turn my Pathmaker switch on (or leave it set for Auto), the AGM banks are all connected in parallel and the House bank supplies input current to the combined AGM banks, delivering an appropriate charge profile for the AGM batteries.


Windlass and davit loads were moved from the house bank to the Bow bank, eliminating all high-load demands from the House bank.



By keeping the main engine's alternator output connected directly to the LFP house bus, I get the benefit of rapid charging of the house bank, while the DC-DC charger provides secondary charging of the lesser loads on the AGM banks.


If I anticipate a need for heavy thruster use during docking, then I can start the 8kW genset to provide 60A charge direct to the Start & Stern Thrust AGM banks, and 30A from the two AC-DC chargers at the Stern and Bow banks.


Initial results are pleasing.

Hey Peter,

Do you feel confident that the Balmar Protection Module will protect the diodes in the alternator in case of a BMS shutoff?? This has been an issue that has kept me from charging the house bank directly from the alternator. I read about it and I am not convinced that it is failsafe. Almost seems to good to be true,,,,and you know what they say!!

Chris

 

[mvweebles]

I too use of Balmar APM (I may be the "Peter" you're referencing?). Is it failsafe? Who knows - I hear more rumor of BMS disconnect than actual occurances. I've never heard of an instance where a BMS blew diodes that should have been protected by an APM. But I run my alternator derated a bit and have a generally conservative charging profile. In the end, if needed, diodes are not that expensive to have replaced (so I'm told).

To my thinking, running a FLA inline is meteorite insurance. And then you get to live with a greatly sub-optimal charging setup with an undersized DC-DC charger which means why bother with a large LFP bank that can be charged in a few hours with a hi-output alternator?

My energy budget is running about 300ah (12v - 3.5kwh) per day. Solar provides about 70% on a good day, 20% or less on a bad day. If I front-ended my LFP with a FLA and a 30a DC-DC charger, would take a solid 10+ hours to charge. With my 200a Balmar de-rated to around 150A, I can top off in under 3 hours. And I also have plenty of energy to run appliances, a small AC if I want, water maker, etc., none of which is possible with a 30a DC-DC charger.

At least that's my thinking. Someday if/when something goes wonky, I'll reassess.

Peter

 

[SteveK]

Peter. You reference a 30A DC2DC. What output is the alternator 40A? That would make it 75% of max output for safe continuous operation.

 

[woodsea]

Here was my entry on a similar question…
We have a similar approach as you have diagrammed. We use a Balmar Alternator Protect on each alternator. We have 3 Victron 30 amp dc/dc chargers that draw from the 800 AH LFP house bank and charge the start batteries and thruster/windlass batteries. Our 2000 W Magnum inverter/charger charging the house bank. We also have a Magnum trickle charger to charge the gen battery. We have solar panels that charge the house bank thru a Victron MPPT charge controller. We used 4 Discover Blue 200 AH batteries (L16 form factor) all wired with equal length to positive and negative buss bars. We have Balmar MC614 external regulators on 140 amp OEM alternators with internal regulators removed. They are programmed to limit their output and each alternator has a temp sensor that can limit output. The system works pretty well. The dual engine/alternator control is a work in progress but that’s another story won’t effect you.

 

[motion30]

I can only tell you what has worked for me. I replace my lead acid golf cart batteries with 900 amp hours of lithium had to read cable and install busbars in order to get all equal length cables. I have two group 31 starters that are totally isolated from the house Bank except for the DC to DC charger. The alternator is hooked to the starter batteries. The DC to DC charger sends 40 amps to the lithium batteries. So far I have had no alternator overheating problems. I have 1740 amps of solar that charge the lithium batteries. There is a dedicated charger run by the generator that will charge their starter batteries but rarely needed. The biggest benefit I see so far is how quick the solar can charge the lithium batteries

 

[tiltrider1]

Several different approaches listed here. All work. Different approaches have different advantages so it’s really hard to say which is best. My approach is a little different but I am considering some changes as I change the way I use the boat. How one uses the boat dictates which method is best. What equipment one starts with also affects the method.

While in the past I tended to use DC to DC chargers to share all charging sources with all banks. Now, I am moving away from that process. I am separating banks and not sharing charging systems. This works well for me but is not going to work well for everyone.