Update: One Battery to Rule Them All

[NorthernFocus]

Updated with performance report in post #7

I recently finished installing a LiFePO4 battery for my house bank. I elected to go with the IP67 rated Epoch DP12300H. The DP in the model number stands for dual purpose. The battery capable of 300A continuous draw and 1000A for 5s. This made it possible to eliminate the thruster bank and power the thrusters and windlass off of the house bank. It should also be capable of starting the engine so I installed a selector switch to allow using either the dedicated starter battery or the house bank. In spite of all I'd read about the complexities of converting to LiFePO4 the new system is actually simpler and removed a lot of weight back aft. Net cost was about $1700. Benefits are:

• 2 battery banks simpler than 3
• 2 ACRs and associated wiring eliminated(see attached pic)
• 160lbs lighter and shifted weight forward(new 80lb battery located in the "cave")
• 300Ah available for house load vs 100Ah previously(50percent of 2x100Ah flooded cells)
• much faster recharging house bank when depleted(no solar)
• phone app connects with the BMS(battery management system) to provide real time state of charge, net amp flow in/out, time remaining to full charge/discharge, etc.
• aft lazarette now available for other use

The only added complexity of this configuration is the need to install a DC/DC charger between the lead acid start battery and the LiFePO4 house bank. Which is pretty straight forward.

 

[Cutwater28GG]

did you install a alternator protector like the balmar to prevent damage to the alternator when the BMS shuts off? - or is this not needed anymore with these batteries?

if im understanding your setup

solar to house
alternator + shorepower charger to house
DC-DC to engine start?

what else?
are you using stock shorepower converter?
did you change the inverter?

 

[NorthernFocus]

did you install a alternator protector like the balmar to prevent damage to the alternator when the BMS shuts off? - or is this not needed anymore with these batteries?

if im understanding your setup

solar to house
alternator + shorepower charger to house
DC-DC to engine start?

what else?
are you using stock shorepower converter?
did you change the inverter?

No solar.

Alternator and shore power charger connect to starter bank lead acid battery.

DC/DC charger from starter battery to house bank.

No inverter.

 

[Cutwater28GG]

ah. thanks for the details.

 

[Spencer2829]

Very cool. Do you have a picture of how you installed the battery in the cave?

 

[NorthernFocus]

Very cool. Do you have a picture of how you installed the battery in the cave?

It's still just a temporary install. I'll fiddle around with it a bit. I set it as far inboard as possible. But it needs to move outboard. With all the weight gone out of the lazarrette we now have a starboard list. Plus it has a cooling plate on top and I wanted to monitor temps for a while to determine how much ventilation it needs. So far it looks like zero. With 50A max charge as I've got it set up heat appears to be a non issue.

 

[NorthernFocus]

Update: performance report

We just returned from our shakedown cruise with new battery system and new engine. Following observations:

• house bank LiFePO4 used for both single thruster operation and main engine starting with no observable voltage drop(engine starts before voltage drop shows up on digital display)
• 300ah battery comfortably provides enough capacity for 4+ days on the hook at our typical usage(no inverter/110v appliances)
• net charge rate while under way with all electronics etc functioning is +- 40A; typical overnight usage(heater, fridge, laptop, anchor light) recharges in about an hour of run time
• virtually zero temperature change noted in battery during charge/discharge

Essentially we're now running everything off of a single battery bank. The starter bank just sits there in backup mode. The one exception is that the ECM is wired directly to the starter bank. But that is somewhat moot as it only draws (measurable)power when the engine is running and the alternator is providing power.