Feeling the Power

By the Capt.

Our cruising plans are to throw off the lines in the fall and live off the grid most of the time.  It is the only way to maintain our budget.  It will mean living more simply but we will still need to stay connected and power is a key to running the equipment that maintains and facilitates that connection.  Even if that connection is to read a book, listen to music or watch an old movie.  All of it takes power. 
 
The Caliber 40 can come with a house battery bank made up of 3 4D AGM 200 AH batteries.  That is a total capacity of 600 AH.  Because that rating is generally expected to be delivered over a 20 hour period then theoretically these batteries should be able to deliver 30 amps for 20 hours to go from 100% charge to 0% charge.  It is not recommended to discharge the batteries more than 50% as permanent loss of capacity can result.  The open circuit voltages listed below approximates the various States of Charge (SOC).

DOD (%)	1 hr. Rate	8 hr. Rate	20 hr. Rate	120 hr. Rate
10	12.23	12.62	12.65	12.79
20	12.16	12.51	12.55	12.69
30	12.07	12.39	12.42	12.55
40	11.96	12.25	12.28	12.40
50	11.83	12.11	12.13	12.22
60	11.70	11.96	11.98	12.08
70	11.55	11.79	11.81	11.90
80	11.38	11.59	11.61	11.70
90	11.15	11.32	11.34	11.43
100	10.50	10.50	10.50	10.50

Please note that these voltages are averages and will vary slightly temperature and from battery type or manufacturer to battery type or manufacturer even of the same rating. They are, however, a good indicator of state of charge for an AGM battery.  An older battery will measure a lower voltage for a given DOD.

We have four (4)  power sources to charge the batteries and supply power to all the gizmos we can't seem to live without.

1. The shore power battery charger.
2. The engine alternator
3. Solar panels
4. Wind turbine generator.

Once we are away from the dock the 1st one will not be of much use.  In fact the shore power charger is also an inverter and will become an additional load if we need 120 VAC power for anything such as charging computers, cel phones, watching a movie or running a power tool such as a drill.

 

The engine alternator is the 2nd item and is the standard 80 amp alternator.  It is not meant to be a regular charging solution as the efficiency of running a 50 HP engine to produce, at best, 1/2 HP of electrical output from the alternator.  This method of charging was not something I planned on making a regular practice unless we are steaming somewhere which I hope is normally only about 10% to 15% of the time. 

 

The solar panels on the other hand should be very efficient.  I have installed two (2) 140 watt Kyrocera polycrystalline solar panels over the cockpit awning. I got them from altEstore.  The folks their were very helpful and seemed to know a great deal more about marine applications than I expected.   The most common solar panel sizes are in the 220 to 260 watt size but their physical size (approximately 60"L X 39"W) would only allow me to mount one (1) panel.  It also would present a large surface area to wind and waves and stress whatever mounting they were secured to in rough weather.  Short story is a bit of research went into the panel selection.  The panels are electrically connected in series meaning their output voltages are additive.  Their total open circuit voltage in direct sunlight is about 44 VDC.  The panels were  connected this way to decrease the wire size required between the solar panels and the charge controller.  I would expect to get about 240 watts or 20 charging amps for about 5 hours each fully sunny day.  The panels are fix mounted so their output will quickly fall off as the sun travels away from being directly overhead.  The solar panels are strictly dependent on direct sunlight and cloud cover will cut their output to 10% to 15% of their maximum output.  I have installed a Blue Sky 3024il MPPT charger (also from altEstore) that boosts the recoverable power from a solar panel for battery charging by typically 30%.  I won't go into how the MPPT charger does this because the explanation is lengthy but I will explain why it is necessary.  12 VDC solar cells or photo voltaic cells (PV) are neat things. Unfortunately, they are not very smart. Neither are batteries - in fact batteries are downright stupid. Most PV panels are built to put out a nominal 12 VDC.  The catch is what "nominal" can mean. In fact, almost all "12 VDC" solar panels are designed to put out from 16 to 18 volts. The problem is that a nominal 12 volt battery is pretty close to an actual 12 volts - 10.5 to 12.7 volts, depending on state of charge. Under charge, most batteries want from around 13.2 to 14.4 volts to fully charge - quite a bit different than what most panels are designed to put out.  OK, so now we have this neat 140 watt solar panel. The primary problem is that the panel is rated at 140 watts at a particular voltage and current. The Kyocera KC-140 is rated at 7.9 amps at 17.7 volts. (7.9 amps times 17.7 volts = 140 watts).  If you hook the solar panels to a regular  battery charger (a rectifier) the PV voltage will drop to the battery voltage (12.7 VDC) at the same current (7.9 amp) which equals 100 watts of transferred power to the battery.  The MPPT charger tracks the maximum power point of the solar cells.  In other words the MPPT chargers will accept the 17.7 VDC @ 7.9 amps at its input and convert that power internally so it can output to the battery 12.7 VDC @ 11.2 amp. 
Specifications for the Blue Sky 3024il charge controller

SPECIFICATIONS	Solar Boost 3024iL
Output Current Rating	30 Amp @ 24 Volts / 40 Amp @ 12 Volts
Nominal Battery Voltage	12 / 24VDC
PV Input Voltage	57VDC maximum
Power Consumption	0.35W Typical standby • 1.0W Typical charge on
Charge Algorithm	3-stage Bulk/Acceptance/Float Plus Equalize
Acceptance Voltage	14.4VDC (range 14.0 – 14.8VDC, 10.0 – 40.0VDC)
Float Voltage	13.4VDC (range 13.2 – 13.8VDC, 10.0 – 40.0VDC)
Equalization Voltage	15.2VDC (range 10.0 – 40.0VDC) • automatic or manual operation
Auxiliary Output Function	Single output field configurable as either: 20 Amp load controller –or– 2 Amp auxiliary battery charger
Aux. Battery Charge Load Control Dusk to Dawn Control	2 Amp typical, same charge voltage as primary battery 20 Amp maximum; ON @ =12.6VDC / OFF @ =11.5VDC (Range 10.0 – 40.0VDC, or net battery amp-hours) Variable Post-Dusk and Pre-Dawn timers, Range 0.5 - 20.0 Hours
Temperature Compensation	Optional temperature sensor adjusts charge voltage setpoints based on measured battery temperature, -5.00 mV/°C/cell correction factor (Range -0.00 – -8.00 mV/°C/cell) • sensor range -60 – +80°C
Power Conversion Efficiency	97% @ 28 Volt 24 Amp Output
Cabinet Dimensions	6 7/8”H x 6 5/8”W x 3 3/8”D (17.4cm x 16.8cm x 8.59cm)
Analog Input Accuracy Range	Battery & Aux. Battery voltmeters, 40.0VDC ±0.50% FS • PV voltmeter, 60.0VDC ±0.50% FS 42.0A +/- 0.50% FS
Communication	Blue Sky Energy’s proprietary IPN Network interface
Environmental	-40 – +40°C, 10 – 90% RH non-condensing
Approvals	ETL Listed to UL STD. 1741, Certified to CAN/CSA STD. E335-1/2E, CE labeled, FCC part 15 certified

This Blue Sky MPPT charger has several standard configurations and one that supports 24 VDC solar panels that are charging a 12 VDC battery system.  The charge also supplies a 2 amp charge current for charging the engine battery once the house bank is mostly charged.  This is a bonus for an engine battery that does not get exercised that often.  I have not hook this function up yet but it is on the list.

Pictured above is the solar panel MPPT charge controller and as seen in the evening with over cast  grey skies the charge output is pretty much nothing but earlier that day this charger was putting out 11 amps of charging current.  They have only been install for about 5 days and they already have a thin coating of dust on them.  I am hoping once we are away from land this will become less of an issue.  Even a thin film of dust will decrease their output as will partial shading.  Partial shading can be a real problem for solar panels.  These Kyrocera panel come standard with diodes that prevent a shaded panel from accepting current from a non shaded panel when wired in parallel with it.  Wiring these panels in parallel would be a acceptable however I would need to increase the wire size to do so.

 

 

The last item to be covered in this post is the wind enerator.  We purchase a SunForce 600 WATT Wind Turbine Generator with MPPT controller. 

Again I did a lot of research and can't say if I have ultimately made the right choice but so far I am not disappointed.  In the marina here at Bayland there are 3 types of wind generators are represented.  The owners of each swear by their selections and only the AirBreeze owner ridicules all the other type of wind generators however his ridicule readd exactly like the sales brochures sent with the AirBreeze units.  I actually bought the same kind of wind generator as Eric the Viking       (I called him Eric the Viking because I am terrible with name and could not remember his last name) but I did not know it at the time.  Actually Eric was the most modest about his wind generator.  He said it worked pretty good and the price was reasonable.  Oddly enough that was what I found after my research.  The highest rated wind generator by far was the German made SuperWind but I just could not bring myself to shell out $2400 for the unit.  At the price I paid for the Sunforce I can replace it 3 time for the price of the SuperWind. 

The owner of the SuperWind are a great Cruising couple (Bud and Jill from SV Earendil) we met and they are quick to admit it is a pricy unit but they have no complaints after 4 years and it is pretty quiet. They have a really nice Norsemen 447 about 60 ft away at the marina.  We really enjoy when they visit.  They have given the first mate and I so much cruising advise that their is no way to repay them for it.

Anyway the installation mast and stabilizer kit was also available from SunForce however I was unable to buy directly from SunForce and had to buy it thru the evil empire (West Marine)  They had 2 in stock and eventually were able to locate one and ship it to Texas.  My good friend John Jacobs and his wife Victoria came down to help install it on Kooky Dance. It was a really good visit and very much appreciated.  I believe these friends will come to visit us in far and distant lands and I can say without hesitation that I look forward to it. 












The SunForce came with the MPPT charger.  The winds in the area we are at are generally light and variable and the wind generator needs about 20 to 25 knots to output its maximum power of 450 watts. 

The unit comes with a manual dynamic brake that electrically shorts the 3 phase turbine windings together and stops the wind turbine from turning.  It works by making the current generated by rotating the turbine and directing back into the turbine windings and creating a counter emf that drives the turbine in the opposite direction.  The harder the wind tries to the turn the turbine the harder the counter emf resists that force.  The charge controller also employ the same dynamic brake when it detects the batteries are fully charge.  I got to test the unit last weekend and when the winds gusted to 25 knots the wind generator often stopped charging by braking the turbines rotation.  It was good to see it working as advertised.