LiFePo House Battery 330 Express

[isurus22]

I am thinking of adding a Lithium Iron Phosphate battery 200-300Ah to my 330 Express to run all the house electrical system. I will leave the 4 existing Lead Batteries as my starting batteries but will place the Lithium battery on top of the water tank area (where the newer 330s have their batteries). I am doing this because when I fish I am running my livewell and all my electronics and my batteries get low after a couple hours (which is damaging the batteries, and makes me nervous). If I run the generator it still only puts 10 amps of charging into the system which takes a long time to charge. I like the stealth of not running the generator as well. Here is my plan:
-The Lithium battery will connect to the Lead bank #1 via a DC to DC charger which only will charge with Lithium battery only when the engines are running.
-The lithium battery will connect to a switch which can, in an emergency, allow me to switch to the lead batteries to run the house. The switch is LA or Lithium only, and they cannot accidentally connect to each other.
-The lithium can also be charged via the AC system by a smart 25 A charging system.
-I was not planning on adding an inverter because I do have a Fischer panda generator, although if my generator ever dies I think a couple of these batteries could easily power the AC system.
-Safety. The LiFePo4 batteries are different chemistries than the Lithium Ion batteries and are much safer.
Anyone done anything like this?

 

[everwhom]

What electronics are you running? How recently have you replaced you Lead Acid batteries? I run my livewell, 2 MFDs, radar, 1kW sonar, fridge all day and night without running down the house bank (though with the starboard motor running). I'm wondering if your house bank batteries are still good?

 

[isurus22]

The boat is new to me but the batteries are several years old. I have run checks on them and they are ok but I am sure they are on their way out. I think if I replace all the lead batteries I will have good results. In the end though any time you draw more than 20% off the lead you are damaging them. Ideally replacing the lead and adding the lithium would give me a much longer life span for my batteries.

 

[Hookup1]

I had problems with low voltage warnings after for a few hours. I run all electronics all the time and typically have a livewell and a bait tank running pumps. Pumps may be running all night while at the dock on the charger.

4 Duracell AGM batteries. Group 34M for each engine, Group 27M for large house battery and Group 34M for bait tank, bow thruster and windlass. I installed a second charging shunt on my Yamaha F150. Each engine charges its starting battery and a house battery. The Yamaha alternators produce a lot of power even at idle or trolling speeds. I have a ProMariner 3-bank smart charger and a Noco single for the 4th battery for at the dock. My motors are always running and my low voltage problems are gone.

 

[seasick]

Regarding the OPs statement about the batteries getting low and damaging them, note that the house batteries should be designed for deep discharge and therefore using starting batteries for long discharge cycles can damage those batteries or at a minimum reduce their life.
There may also be an issue with the concept of a DC to DC charger arrangement if current is drawn from the starting batteries (motors not running) if that is your plan.
I would have a load test done on you batteries to determine their actual condition and capacity. It may just be that you need new ones and those would cost a lot less than lithium cells, compatible dc-dc converters, battery state monitor and shore power/generator Li battery charger.

 

[everwhom]

You might try buying or borrowing a DC clamp ampmeter and measuring how many amps are flowing into your house battery bank from the motors when idling and also how many amps your electronics are consuming. With the F300's (assume these are the 4.2L 4-strokes?) I'd be surprised if the difference was that large. Knowing how much current your batteries are being asked to supply will be helpful in figuring out what you need.

 

[seasick]

Good suggestion.

 

[everwhom]

Regarding the OPs statement about the batteries getting low and damaging them, note that the house batteries should be designed for deep discharge and therefore using starting batteries for long discharge cycles can damage those batteries or at a minimum reduce their life.

Great point. That reminds me that when I replaced my house / starboard battery bank a couple of years ago, I used dual-purpose batteries which are supposed to handle deeper discharges better than normal starting batteries. These are still flooded cell lead acid because apparently my 2003 OEM Guest chargers doesn't handle AGM.

 

[everwhom]

OP: I think if I were going to go to LiFePo house bank, I'd probably drop to single lead acid or AGM starting battery for each motor (instead of the factory bank of 2 each) and then wire 2 Victron Orion DC-DC chargers from each battery to a 100 AH LiFePo, mounted in the same location as the port-most lead acid battery. This would also allow you to wire the bow thruster (if you have one) to the LiFePo. So you'd go from 4 lead acid batteries to 2 lead acid and 1 lithium and still have space to add another lithium if you wanted to. I think you'd need another battery switch, however, since the house loads are wired together with the starboard motor.

As I understand it, the Victron Orions only draw current if the lead acid battery is fully charged and if the alternator is still putting out excess current. They look pretty cool!

As mentioned elsewhere, i replaced my OEM Fischer Panda with a 2000w inverter setup, but opted to go lead acid batteries, leaving the original setup intact. I may have been too conservative, but I still feel the lithium batteries are a generation or two behind where I'd like them to be.