Electric systems on our boat (solar, batteries, bow thruster, etc.)

I have probably touched on this a time or two in my other posts, but here is a more specific discussion of the electric systems on our boat. Also options I am considering and reasons that I am considering some of these changes.

There is a lot of information here, as this is a place for me to put all my notes on what I am thinking about.

Batteries (3 banks as follows):

1 Type 27, AGM 100 AH battery start for Engine

1 Type 27, AGM 100 AH battery start for Generator

6 Type 31XT AGM 125 AH, total 750 AH battery bank for house, windlass, and bow thruster

6 Battleborn LiFePO4 100 AH, total 600 AH battery bank for house, windlass and bow thruster. Replaced December 2020

Sources of power

2 30 amp shore power connections

8 KW generator

470 watts solar via an Outback FLEXmax 60 controller (two 235 watt panels) (more on this later)

1,100 watts solar via 2 100/50 Victron Energy smart chargers. Replaced June 2022

100 amp alternator on the engine

15 amp alternator on the generator

Battery chargers:

110 amp charger/2000 watt inverter (house bank only), (I previously believed this was a 2500 watt inverter, I have checked model numbers and verified that it is a 2000 watt inverter).

60 amp charger (house and engine start battery only)

AC system:

There are four sources of AC power on this boat.

1. Shore power Line 1, powers bus “A”, outlets (more on this later), water heater (which is also heated by the cooling water in the engine) both battery chargers, and the beverage cooler (which is AC/DC powered). Limit on this is 30 amps, not an issue unless we are powering both “A” and “B” buses.

2 Shore power Line 2, power bus “B”, (this bus can be powered from bus “A”) Air Conditioning, washer/dryer and water maker. Limit is 30 amps, the water maker does not get run in port, so not on shore power, only on the generator.

3. Generator, can be aligned to only bus “A” or both buses.

1. Limit on the generator is 80 amps, which means we can power everything at once and still have no concerns about overloading it.

4 Inverter, only powers the outlets. This is seamless and requires only turning on the inverter to power the outlets, completely automatic.

Three DC systems, easiest first:

1. Generator start battery is charged by the alternator on the generator. The only loads on this system are the generator.

2. Engine start battery is charged by the alternator on the engine, and the 60 amp charger, both of these use a smart controller to send power to the house bank or the engine start battery. Loads on this system are associated with the engine.

3. House bank is charged by the 110 amp charger, the 60 amp charger, the 110 amp alternator on the engine, and the solar panels. Loads are a bit more complicated:

1. house loads, refrigeration (freezer, refrigerator, and drink cooler) lights, radios and instruments, inverter, head pumps, water pumps etc.

2. Bow Thruster, this is a 6 horse power 12 volt motor in the front of the boat. This means that it takes 350-400 amps to make it work. The copper in the cable is about the diameter of a penny, and with the insulation about the size of a nickel.

3. Anchor windlass a large motor that uses gears to haul the anchor and chain back on board. Pretty big wire for that as well.

4. Three electric wenches, two for the jib sheets, and one for the main sheet.

 

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Concerns with this system, in no particular order:

1. There is no breaker, or switch between the battery and the bow thruster, only a huge fuse.

2. The house bank is 750 ah, but it is a lead acid battery (AGM) so in reality, we are limited to no more than 50% of that capacity or 375 ah.

1. On a typical night, we use about 35% of battery capacity to run the anchor light and the refrigeration, (we have a lot of refrigeration for a boat). If we watch a movie, add another 5%. If we use the microwave, figure 1% per minute.(Yeah it really is that much).

2. Charging a lead acid battery takes a long time. Even though we have two battery chargers (110 + 60 amps) we can’t put that much into the batteries. So, if we have a cloudy day, we can expect to run the generator for about 3 hours a day to bring it back to fully charged.

3. The house bank is about 6 years old, and typically an AGM battery is only good for about 7 or 8 years. Sometimes, a bit longer.

3. Age in general of all components. No particular issues (yet), but some parts of this system are getting old.

Thoughts on changes.

1. A breaker/switch will be installed in the circuit for the bow thruster.

2. Solar panel options

LG makes panels that are about the same size as our current panels that are 375 watts each, ours are 235. Swapping them out would take us from 470 watts of solar to 750 watts. This is within the limits of our current controller  (750 watts).

https://www.lg.com/us/business/solar-panels/lg-lg375q1c-v5

LG375Q1C-V5

375W High Efficiency LG NeON® R Solar Panel with 60 Cells(6 x 10), Module Efficiency: 20.8%, Connector Type: MC4

Module Dimensions (L x W x H)

1,700mm x 1,016mm x 40m

66 59/64” x  40” (These are 1” wider and about 1 inch longer than what we have now, 39” x 65.4”).

Solar 2 panels, 235 watts each, total 470 Watts, Controller: Outback FLEXmax 60, input voltage is approximately 57 volts. 

Solar Panels Kyocera KD235GX-LPB 39” x 65.4”

The manual for the controller says that the maximum wattage of solar panels for this controller is 750 watts, I have 470, which leaves 280 watts more before I would HAVE to get a new controller. If we can design a system that would give significantly more power than 750 watts, I would be willing to consider getting a new controller. 

I would also be willing to just get a new controller to go with the new panels to add to the mix, as in 470 watts on the existing system and 450 (+/-) on the new system. 

3. I am considering replacing the house bank batteries with Lithium, specifically a LiFEPO4 battery. I have been looking at a battery that is 1000 ah, they have a smaller version at 700 ah.

1. There is a table below with a comparison of 3 kinds/sizes of Lithium batteries and the Lifeline type 31 XT AGM’s that we have.

2. Some important notes about these comparisons, typically the AGM’s are good for about 5,000 cycles (discharged to 50% and recharged), the Lithium batteries are good for about 20,000 cycles (discharge to 80% of capacity then recharged). The 700 ah and 1000 ah batteries are actually individual cells, it takes 4 of them to get 12 volts (nominal), the Battleborn Lithium batteries are “drop in” replacements for a standard 12 volt battery, so the right shape, and 100 ah each. Note that the Battleborn batteries would be as much money ($5,700) for 600 ah (480 ah useable) as the 1,000 ah (800 ah useable) of the other batteries. The cycle difference, means that instead of about 8 years life for the batteries, it would be closer to 30 years. Way beyond where we would care. Also, if we owned the boat 16 years after we changed the batteries over, the cost would be less to go with Lithium.

3. Initial cost for the Lithium batteries is pretty high, but when you consider the advantages, it is really not that expensive. Consider that we would go from 375 ah useable to 800 ah useable. Consider that the Lithium batteries take full charging current until they are fully charged. So, if we had a regular night at anchor and watched a movie, we would have used 35% of 750 ah (~250 ah),  and had a cloudy day the next day, we would have to run the generator about 4 hours to recharge the battery. With the Lithium we can charge at a higher rate of charge (maybe 200 amps, and at a flat rate for the full charge). So about an hour. Also, considering that the batteries would have 800 ah available, if we used 250 ah we could go three days like that before we would have to charge the batteries.

4. Negatives to changing to the Lithium, we would almost certainly have to change the 110 amp/2000 watt inverter, and the 60 amp chargers. So, more money.

5. Having just completed measurements of the two battery compartments, there is a table below for that as well. What it shows is that there will need to be some modifications to allow either the 700 or 1000 ah battery options.

1. For the 1000 ah battery, the compartment behind the seat is not big enough, nor tall enough. There is room to modify, as the compartment measurements are the bottom and this compartment has the hull as the outside wall, which tapers outward as it gets taller, so if we raised the floor a couple of inches, we would get the width, but we also need the height, so, it would take room out of the space above, probably most of the compartment. Not a real good option.

2. For the 700 ah battery, the compartment behind the seat would probably work. The fore/aft measurement was an approximation, there are wires and other things at the end, so it would be tight length wise. It might also be possible to get the engine and generator start batteries in the same compartment behind the seat, thereby freeing up the battery compartment under the seat for storage. This would also be a reduction of 259 pounds from the port side of the boat. 560 ah vs 375 ah (useable) is about a 50% increase. Cost would be about $1500 more than just replacing the batteries, plus the cost of changing chargers.

6. I have more investigation to do concerning battery options, and sizes. I have only really started looking into this.

		MM	IN	KG	LBS	*4 inches	*4 lbs	Price with S/H	Price per rated AH	useable	Price per useable A/H
WB-LYP700AHA	Height	305	12					$3,968		560
	Width	67	2.6			10.56
	length	627	24.7
	weight			21	46.3		185		$5.67		$7.09
WB-LYP1000AHC(A)	Height	356	14					$5,672		800
	Width	130	5.1			20.5
	length	560	22
	weight			41	90.4		362		$5.67		$7.09
						*6 (2*3)	*6	Price W/O S/H
LifeLine XT31	Height	241.5	9.51					$420 each		375
	Width	171.3	6.75			20.25		$2,520.00
	length	328.5	12.93			25.86
	weight			34	74		444		$3.36		$6.72
												$0.37
												$3,152.00
												$1,448.00
Pirce of Lifeline batteries vs LifePO4 batteries. The lifelines are at 750 AH rated, which is what we have, the LifePO4 are at 700 AH or 1000 AH. For the 700 AH https://everspring.net/?page_id=180 for the 1000 AH https://everspring.net/?page_id=174 March 21, 2020
		MM	IN	KG	LBS	2×3 inches	*6 lbs	Price with S/H	Price per rated AH	useable	Price per useable A/H
Battleborn 100 AH	Height		9					$5,700		480
	Width		6.875			20.625
	length		12.75			25.5
	weight				31		186		$9.50		$11.88

Battery compartment measurements
	wide (inches)	high (inches)
Access behind seat	16	9.25
Access down into battery compartment	15.5	16
	fore to aft	side to side	high
Battery compartment	24	17	13.5
Under seat
Access	15.75	9.75
Battery compartment	28	24.5	11