Two scenarios: Alternator to LFP House Bank or Alternator to Starter battery?

[goboatingnow]

Originally Posted by AllenRbrts

I have a catamaran and opted for option 1. The starboard engine starts off the house battery and the port engine has a separate FLA battery for start. The idea is if house is dead, I can still start the port engine and then starboard engine. The alternators were converted to external regulation and are limited to 100A charging each to preserve belts and alternators. The port start battery is charged with a 30A victron DC-DC charger. It all works well but option 2 would have less invasive work (original alternators, no new regulators) but would have less charging capacity from the alternators to the house (at least for what I looked at). I also was concerned about high amp DC-DC charging with low RPMs loading up the alternators, I didn't see enough control on the DC-DC chargers that I looked at to make me happy.

good solution and efficient

[thataway41]

I have been using LiFePO4 batteries for house bank for 3 years. I used a 30 amp Sterling Battery to Battery charger run off the start battery, which is charged by the alternator. Works well.

[PaulCrawhorn]

Originally Posted by dreuge

I would never use option 1 as it could end up killing your alternator when the BMS disconnects the battery during charging unless you have an alternator protector.



...


See my blog describing how to use a simple push-pull switch and a smart (arduino) switch for controlling the ACR. https://svjohannarose.blogspot.com/2...m-w-solar.html

> Because the BMS can abruptly disconnect the battery during charging, an alternator should not be directly connected to a BMS controlled battery without additional protections. There are many solutions to protect the alternator. A safe, simple, and affordable solution is to use a tradition battery (FLA or AGM) for a START battery with the alternator connected directly to the START battery for charging. A battery combiner, such as an automatic charging relay (ACR) or DC to DC charger, can then safely combine the START and HOUSE banks for alternator charging. If during charging, the BMS disconnects the HOUSE bank, the alternator which is always connected directly to the START battery, is protected from the sudden disconnect of the HOUSE battery.

[PaulCrawhorn]

Originally Posted by mjgill1

I think this will help protect the alternator from an abrupt cut off from the BMS.



https://www.sterling-power-usa.com/a...iondevice.aspx

Not quite snake oil, but...

A solution in search of a problem.

[chris5977]

Originally Posted by jc1409

Two scenarios:


1. Alternator connected to Lithium house bank, with DC-DC charger used to charge the start batteries


2. Alternator connected to start batteries, with DC-DC charger used to charge Lithium house bank


Assuming proper setups, charge configurations, sufficient wiring, and all other things being 'equal', which is better?

There's a third option: I have a dual output alternator that always charges both the lead and lithium. Yes, it is terrible for lithium to overcharge them, but with the heavy loads on my system with refrigeration, this has never happened.

The most important thing is to NOT charge your lithium when on shorepower for long term. In this situation, I isolate my lithium and run the house DC loads off lead.

[Networker]

Originally Posted by PaulCrawhorn

Not quite snake oil, but...

A solution in search of a problem.

How’s that snake oil. I bought one just haven’t installed it yet. What I understand is that the alternator will charge this and blow it out of the battery is disconnected, which is better than having the alternator charge nothing and having it blow out

[Trvlmedic]

Just installed this charger for my system on the Cat. I left the Port engine alone to only charge its' AGM starting batt only. The Starboard engine alternator is hooked to its AGM starting batt. Then the Mastervolt Chargemaster has a 5a-40amp programmable input/output lead that will charge the house LifPo batteries from that starboard alternator/AGM. When ashore or on the Gen it will maintain the starboard AGM. Also have 680 watts of solar for the house bank. 90 amp alternators with stock regulators.

I'd love to hear your inputs of my system. Boat is still on the hard so I cannot give a functional report until I fire up the engines after splash.

Don

[URL="https://www.mastervolt.com/products/chargemaster-plus/chargemaster-plus-12-100-3-czone/"]

[PaulCrawhorn]

Originally Posted by Networker

How’s that snake oil. I bought one just haven’t installed it yet. What I understand is that the alternator will charge this and blow it out of the battery is disconnected, which is better than having the alternator charge nothing and having it blow out

I'm not saying purpose-build circuitry cannot be made to do the job, but as stated in my post immediately prior to the one you responded to and many more throughout the thread, a lead battery hardwired to the alt output will do the same thing.

Cheap, proven, simple, reliable, well understood, and if you have a Starter battery, already in place.

[CaptainRivet]

Originally Posted by jc1409

Two scenarios:


1. Alternator connected to Lithium house bank, with DC-DC charger used to charge the start batteries


2. Alternator connected to start batteries, with DC-DC charger used to charge Lithium house bank


Assuming proper setups, charge configurations, sufficient wiring, and all other things being 'equal', which is better?

Option 3: your lifepo4 is starter and house, if your BMS can handle the extra current=Scenario alternator LI capable charges it and simplify your life. Its more reliable then AGM and LFA if setup correctly. A good BMS can even switch all unnecessary loads of if its below eg 30% SOC so it will be full enough to start engine at any time...

and if you want add a backup starter with a 1 or 2 +combine switch that's charged
A) via small 50-90W solar Panel, eg flexible one
B) or via Dc-DC charger from LI.

If you have a cat one hull lifepo4 starter+house, other hull 40-80AH LTO starter/backup charge with alt LI setting for house +top up charge to 18V with small 50-90w solar+mppt.
100% you always have enough amps to start engines

[CaptainRivet]

Originally Posted by Trvlmedic

Just installed this charger for my system on the Cat. I left the Port engine alone to only charge its' AGM starting batt only. The Starboard engine alternator is hooked to its AGM starting batt. Then the Mastervolt Chargemaster has a 5a-40amp programmable input/output lead that will charge the house LifPo batteries from that starboard alternator/AGM. When ashore or on the Gen it will maintain the starboard AGM. Also have 680 watts of solar for the house bank. 90 amp alternators with stock regulators.

I'd love to hear your inputs of my system. Boat is still on the hard so I cannot give a functional report until I fire up the engines after splash.

Don

[URL="https://www.mastervolt.com/products/chargemaster-plus/chargemaster-plus-12-100-3-czone/"]

Suggest to put a Victron cytrix battery combiner in that connects both AGM starter together when a charge is applied. so when either of the engines runs it charges both AGM starters and also the LI via Dc-DC charger. Otherwise you can't charge the house with port engine and you will need that one day for sure...

That's the simple standard way mass production cats setup from factory, especially the smaller and cheaper one eg FP Mahe 36.

[CaptainRivet]

Originally Posted by chris5977

There's a third option: I have a dual output alternator that always charges both the lead and lithium. Yes, it is terrible for lithium to overcharge them, but with the heavy loads on my system with refrigeration, this has never happened.

The most important thing is to NOT charge your lithium when on shorepower for long term. In this situation, I isolate my lithium and run the house DC loads off lead.

Really bad system design, it will happen one day and this will be a very bad day for you...
Charge both with LI profil and choose an LFA with a high float voltage, then directly charge the lead additional with a small solar panel to top it up and get it to float voltage.

You should charge your house via shorepower BUT the shorepower charger settings should be adjusted for storage mode so the LifePo4 isn't charged above 65%SOC,better 60 and discharged to max 30%. That guarantees it never get fully discharged and dead...

[CaptainRivet]

Sailors a starter battery needs charges around 1-5A if below 150AH battery as the AH taken out by starting is minimum.
If you have a LFA or AGM starter connect a 50W flexible solar panel (you can fit that on a any boat) with a controller and your starter will be always full and life maxed.
Connect your DC to DC for the lifepo4, configure only via trigger so they charge only when engine is running and all is good. If you configure via voltage sensing the solar tricks it out and it will charge without engine running.

[CaptainRivet]

Double post

[CaptainRivet]

Originally Posted by AllenRbrts

I have a catamaran and opted for option 1. The starboard engine starts off the house battery and the port engine has a separate FLA battery for start. The idea is if house is dead, I can still start the port engine and then starboard engine. The alternators were converted to external regulation and are limited to 100A charging each to preserve belts and alternators. The port start battery is charged with a 30A victron DC-DC charger. It all works well but option 2 would have less invasive work (original alternators, no new regulators) but would have less charging capacity from the alternators to the house (at least for what I looked at). I also was concerned about high amp DC-DC charging with low RPMs loading up the alternators, I didn't see enough control on the DC-DC chargers that I looked at to make me happy.

Very good and effective setup. Just one change:
Highly recommend 6S LTO 40AH Linglong (no BMS needed) instead of your LFA starter.... That 1000% always starts your engine, works - 50 till 120 Celsius, 10C=400A permanent discharge, 30000 cycles, 100% no maintenance, no significant self discharge, can be 100% discharged and charged again.
Buy it once, drop in and forget. It will live longer then your boat...
If this LFA, now LTO is your backup in case of BMS shutdown, you could get 6 extra cell and make a 80AH 2P6S battery.

[peanpe]

Hello S/VJedi,

Sorry if I interrupt here, but I can't find the function in the Victron Connect app for the Smartsolar to activate the external contact if it can supply power/charge.

Maybe I'm thinking too complicated or am operationally blind.

Please give me a tip how you realized that.



Greetings from Germany from the island of Rügen.


Claus,


SV PEANPE