Lithium house battery 1997 Yamaha 2 Strokers

Germanmattlanta

Active Member
Joined
Jun 17, 2025
Messages
34
Reaction score
5
Points
8
Age
46
Model
Gulfstream
Hello Everyone,

I have a 1994 232G and I am thinking about replacing my lead acid house battery (starboard) with a Life Po4 battery. I was thinking something in the 200 Amp hour range.

I have read that it is best to use a 12/12/30 amp DC/DC charger to equalize charging voltage from the stator. I would keep the lead acid starting battery on the port side. My system has two battery switches with 1, 2, ALL, and OFF positions. Below is a list of electronics. My main goal is to be able to use the boat on the battery when at a sandbar or anchored for say 5 to 6 hours. I doubt it would every be that long but I'd rather have extra capacity. What are some of the things I am missing or should think of? Any of you that have done this, what problems did you run into?

Garmin 943xsv
B75M Trans
Garmin VH215
Fusion RA670
1 Amp @ 1100 Watts RMS (4 speakers, 1 sub)
1 Amp @2200 Watt RMS (4 speakers, 1 sub)
Would like to add a Inverter at some point for small TV

Standard 232G equipment:
Washdown & Livewell pumps
Macerator
Lights (not upgraded yet)
 
Not that it's bad to do this, but maybe there's an easier solution.

With my last boat, a cruiser, I had ONE group 27 LA deep cycle battery as the house battery. As a test, I once went 3 days/nights using only that battery - and only ran the engine on two days - once for about 30 minutes, once for about 45 minutes. I was using the stereo every so often... the Vacuflush head, the fridge ran non-stop and I used various lights at night along with the all-around light all night. Still had plenty of juice to start the engine on the last day.

I think your draw is going to be similar or maybe less?

Obviously the macerator doesn't come into play since you can't use that given the areas you're talking about.

Small TV's are often actually 12V powered to begin with - if you see a "brick" in the cord, cut it off and wire a 12V plug - that will use less amperage than an inverter.
 
Last edited:
I have done a few LiFePO4 installs in boats. 200AH lithium is a lot of battery storage. Lithium AH's are about 90% usable when compared to LA batteries AH only 50% usable. With 200 AH LiFePO4 you will be able to crank those amps out and still have power to spare. The charging source will be Lead acid battery attached to a DC to DC charger. The DC to DC will keep the motor charging output separated from the LiFePO4. You did not say what motor you have and what the max charging output of the motor is. The rule of thumb is the maximum DC to DC charger output should be no more than half of the motor/alternator max output. Example: If the Motor has a stator driven charging system with a voltage regulator that has a max charging capacity of 40amps. The largest DC to DC charger I would install would be a 12V/12V/20A. This will help maintain the longevity of the regulator/rectifier. I use Victron 12v/12V/18A in my small alternator 60A or less installs. If you install a LiFePO4 make sure to read the battery owners manual when installing in a boat. I also recommend reading the ABYC installation recommendations. LiFePO4 batteries have low internal resistance and can produce a lot of amps if shorted. It is mandatory that a T-class fuse be used at the battery+ terminal or within 7" of it. LiFePO4 batteries are advertised as drop in batteries. IMO they are not drop in batteries.

For what you are trying to do I would keep it simple. Install an ACR to isolate your engine battery from the house battery and purchase a good AGM group 31 110 AH battery . That will give you 55AH of usable AH's. Purchase a 12V TV that is much more efficient way to power a TV. Compared to using an inverter. Most small TV's are low voltage with a 120V external brick-style transformer that converts this high voltage down to 12-24 volts DC to power the TV. Purchase a 12V and use less AH.

Good luck with you project.
Brian
 
If I understand your loads correctly, you have 3300 watts RMS draw for the stereo alone. That doesn't sound right to me.

Your 200 amp LiPo battery at 12 volts has a capacity of 2400 watt hours that will be depleted in just under 45 minutes. Something seems off.
 
  • Like
Reactions: Sardinia306Canyon
I wrote a tread about how i changed house battery from AGM to LiFePo on my 306 Canyon, most applies to your boat, some not.
https://www.greatgrady.com/threads/...ry-on-gw-2-1-battery-setup.39344/#post-281622
I have a LiTime 140Ah LiFePO as i can't install a bigger one and i never depleted it lower than 70% running hours all electronics and stereo.
I don't use the live well nor the macerator pump, the live well pump matters, the macerator pump not as it run for a short time.
Inverter and TV would matter too, however a 12V RV Vehicle TV do not use a lot of power and would be the better choise than a 110V one.
For the above i also believe that 200Ah is too much, but the cost diference is not that much and if a 200Ah fit the space, why not.

From what i uderstand you have one outboard, one starter battery for it and a house battery?
In this case use a Victron Orion XS connected to the cranking battery who charge the LiFePo
Outboard --> Crankling Battery --> Orion XS --> LiFePo
The Orion XS will power off when engine is off and separate the two batteries, if set correctly.
Chris
 
Based on the title of the post, I assumed two engines. In that case, the existing battery arrangement info is needed to make suggestions.