Tag Archives | trawler

Merry Christmas 2025

By on December 14, 2025 in The Pearl
It’s that time of year again when we like to reach out and tell all our friends and family hello and Merry Christmas. We had another great year splitting our time between Texas, New York and our wonderful little home in Lewisburg, PA. We didn’t do any large trips this year, just relaxing weeks on the lake in NY and a week in the Adirondacks in September.  

It’s hard to believe we are getting so old…the thing that makes it the most evident is looking at our grandchildren. All five are excelling in school and becoming interesting and entertaining young people. Our oldest turned 13 this year and our youngest is six.

I hope that all of you have a wonderful holiday season. We look forward to another year and hopefully we are able to cross paths with a few of you soon.

Merry Christmas 2025

By on December 14, 2025 in The Pearl
It’s that time of year again when we like to reach out and tell all our friends and family hello and Merry Christmas. We had another great year splitting our time between Texas, New York and our wonderful little home in Lewisburg, PA. We didn’t do any large trips this year, just relaxing weeks on the lake in NY and a week in the Adirondacks in September.  

It’s hard to believe we are getting so old…the thing that makes it the most evident is looking at our grandchildren. All five are excelling in school and becoming interesting and entertaining young people. Our oldest turned 13 this year and our youngest is six.

I hope that all of you have a wonderful holiday season. We look forward to another year and hopefully we are able to cross paths with a few of you soon.

Keith’s Perspective on Baltimore and DC Museums and Memorials/Le point de vue de Keith sur les musées et les mémoriaux de Baltimore et Washington DC

By on December 14, 2025 in Kosmos

This week has been fun. On Saturday, we went to the marina pool.  Cette semaine était amusante. Samedi nous sommes allés à la aupiscine de marina.  On Sunday, we went to Washington DC by car just for the day. We … Continue reading →

Monitoring Battery Activity – Part 2 – The Charge Cycle

By on December 13, 2025 in M/V Alpenglow

The “yang” to the discharge cycle’s “yin”, is the charge cycle. We have three ways to restore the batteries after they have been depleted.

Shore Power – We have a Victron Multiplus 24 3000/70 inverter/charger that when provided AC power can recharge the battery.  While our boat is wired to accept 240V-50A, for simplicity, we only connect to shore power via 120V-30A

Alternator – We have two alternators on our Lugger 1066T diesel engine, one for the start battery and the other for the house bank battery. The house bank alternator, a Leece-Neville 4740JB (24V-200A), is regulated by a Balmar MC-624.

Generator – We have a Northern Lights OM773LW2 – 9KW generator. This provides AC power to the Multiplus Inverter/Charger but, in addition, we have a Victron Skylla-I 24/100 charger attached to the output of the generator.

The “State of Charge” (aka SoC) is often the metric used to determine the status of the battery.  It runs from 1 (or 100%), when the battery is “full” to 0 (or 0%), when there is no power available.  For our battery bank, each 1% change in the SoC is about 5 Ah.  With a 24V battery bank, that 5Ah of energy would power the base load of our boat (8-9 A) for about 35 minutes.

For this analysis, I wanted to see the charging characteristics all the way until battery full and so I eliminated cycles that didn’t go to at least 99% SoC.  I wasn’t quite as concerned about the starting level of the discharge, though.  I ended up with 219 charge cycles that went to completion, 7 for shore power, 27 for generator and 185 for engine.  The small number of shore power charging is not surprising since upon arriving at a dock, in most circumstances, would already be full.

The chart below shows the aggregate charging profile for each method of charging. While the monitoring system collects data continuously, it only preserves the data for the long term once every six minutes (one-tenth of an hour), taking an average of the values since that last time increment.  To allow the comparison of charge cycles with different durations and different battery depletions, I used the charge cycle’s end point as a reference.  At any given time point, I averaged SoC for those charge cycles that extended to it. 

A characteristic of LFP batteries is that they accept high levels of charging current until nearly complete.  My observation is that the charging is nearly constant, limited by what the charging source can provide, until about 98% SoC.  At that point, the current acceptance rate decreases rapidly.  At 99% SoC, the battery monitor, a Victron BMV-712 in our case, may say it is “close enough” and report a 100% SoC. 

On the chart, I’ve had Excel compute the linear regression line for each category with the Y-intercept being set to a 100% SoC. The X- coefficient in the equation represents the slope of the charging curve. An average hourly charge rate can be computed from the coefficient by multiplying it first by 500 (the number of Ah in our full battery bank) and then again by 60 (the number of minutes in an hour).  For shore power that calculation suggests a 48 amps per hour charge rate. For the engine it is 96 amps per hour and for the generator 129 amps per hour.  These charge rates are lower than the actual output of charging source because they are net of the charging source’s output and whatever DC loads the boat’s system requires.

 

Monitoring Battery Activity – Part 2 – The Charge Cycle

By on December 13, 2025 in M/V Alpenglow

The “yang” to the discharge cycle’s “yin”, is the charge cycle. We have three ways to restore the batteries after they have been depleted.

Shore Power – We have a Victron Multiplus 24 3000/70 inverter/charger that when provided AC power can recharge the battery.  While our boat is wired to accept 240V-50A, for simplicity, we only connect to shore power via 120V-30A

Alternator – We have two alternators on our Lugger 1066T diesel engine, one for the start battery and the other for the house bank battery. The house bank alternator, a Leece-Neville 4740JB (24V-200A), is regulated by a Balmar MC-624.

Generator – We have a Northern Lights OM773LW2 – 9KW generator. This provides AC power to the Multiplus Inverter/Charger but, in addition, we have a Victron Skylla-I 24/100 charger attached to the output of the generator.

The “State of Charge” (aka SoC) is often the metric used to determine the status of the battery.  It runs from 1 (or 100%), when the battery is “full” to 0 (or 0%), when there is no power available.  For our battery bank, each 1% change in the SoC is about 5 Ah.  With a 24V battery bank, that 5Ah of energy would power the base load of our boat (8-9 A) for about 35 minutes.

For this analysis, I wanted to see the charging characteristics all the way until battery full and so I eliminated cycles that didn’t go to at least 99% SoC.  I wasn’t quite as concerned about the starting level of the discharge, though.  I ended up with 219 charge cycles that went to completion, 7 for shore power, 27 for generator and 185 for engine.  The small number of shore power charging is not surprising since upon arriving at a dock, in most circumstances, would already be full.

The chart below shows the aggregate charging profile for each method of charging. While the monitoring system collects data continuously, it only preserves the data for the long term once every six minutes (one-tenth of an hour), taking an average of the values since that last time increment.  To allow the comparison of charge cycles with different durations and different battery depletions, I used the charge cycle’s end point as a reference.  At any given time point, I averaged SoC for those charge cycles that extended to it. 

A characteristic of LFP batteries is that they accept high levels of charging current until nearly complete.  My observation is that the charging is nearly constant, limited by what the charging source can provide, until about 98% SoC.  At that point, the current acceptance rate decreases rapidly.  At 99% SoC, the battery monitor, a Victron BMV-712 in our case, may say it is “close enough” and report a 100% SoC. 

On the chart, I’ve had Excel compute the linear regression line for each category with the Y-intercept being set to a 100% SoC. The X- coefficient in the equation represents the slope of the charging curve. An average hourly charge rate can be computed from the coefficient by multiplying it first by 500 (the number of Ah in our full battery bank) and then again by 60 (the number of minutes in an hour).  For shore power that calculation suggests a 48 amps per hour charge rate. For the engine it is 96 amps per hour and for the generator 129 amps per hour.  These charge rates are lower than the actual output of charging source because they are net of the charging source’s output and whatever DC loads the boat’s system requires.

 

Monitoring Battery Activity – Part 3 – The Aging Process

By on December 13, 2025 in M/V Alpenglow

Batteries are such a solid (often made primarily of lead, after all), quiet and passive object, that their “wearing out” seems hard to believe. Underneath their cases of rubber and plastic, however, is a cauldron of electro-chemical processes that can turn motors, power lights, heat water and make life more comfortable. After doing that, providing the batteries with appropriate electricity power can reverse those electro-chemical processes so that the cycle can be repeated.

Our current lithium ferro phosphate (LFP) batteries are the third set of batteries we’ve used. The previous two battery banks were both made up of AGM lead acid batteries. For AGM batteries, typical lifespan is 500-1,000 cycles and four to eight years. Our two AGM battery banks lasted about six years. One of the claims of LFP batteries is greater longevity. Our Battleborn Batteries are rated at 3,000 to 5,000 discharge cycles so we are hoping they will last the rest of our ownership of Alpenglow. Ignoring the small discharge cycles accompanying the transition between shore power and engine alternator, we have had 261 discharge cycles of more than 50 Ah in years 2023 through 2025. Assuming our first full year, 2022, with the new batteries was similar, I estimate that we’ve had fewer than 400 significant discharge cycles so far.

While batteries can fail suddenly, normal “wear and tear” usually shows up as reduced capacity. Our LFP battery bank is rated at 500 amp-hours (Ah), but we have never intentionally consumed that much energy (more about an unintentional discharge later) before recharging. Searching the Internet for methods to determine a batteries capacity usually give solutions that are impractical for “working” batteries because they require they usually require the such the isolation of some or all the batteries from loads for a period of time followed by monitoring the battery while under a constant modest load.

The method I am using to assess the battery bank is monitoring the bank’s voltage over the course of many discharge cycles. While each discharge cycle will be of different duration, depth of discharge, and rate of discharge, I am hoping the aggregation of data will reveal patterns and trends.

In my dataset, for the cruising seasons 2023, 2024 and 2025, I identified 201 discharge cycles that started from a nearly full battery (<2 Ah of discharge) and resulted in a discharge of more than 50 Ah. I had 37,758 measurements of the battery during those discharge cycles. Each measurement included the battery bank’s voltage, state of charge, amp-hours discharged and rate of discharge. These measurements were the average of instantaneous values during the previous six minutes (five minutes in the case of the 2023 cruise year). The discharge cycle ended when the next charge cycle began. In most cases, the charge cycle was the main engine starting, but it could have been the generator starting or even the shore power breaker being switched on if I was purposely cycling the battery bank while at a dock.

Besides the aggregated data from three cruising seasons, I also have one case of the total discharge of the battery bank. This unfortunate and unintentional “test” occurred over about 4-1/2 days during the New Year’s holiday of 2023/2024. The shorepower to the boat was turned off and the battery bank depleted until the battery management system (BMS) incorporated in the individual batteries shut things down to prevent any further depletion. The boat sat for over 3 weeks with dead batteries until I returned to the boat near the end of January for my regular mid-winter visit. I restored shore power and the inverter-charger then recharged the battery. In a call to the battery manufacturer’s technical support, they told us that the accidental complete depletion ought not have any long-term impact on the battery.

Below is the graph of the house bank battery voltage versus the amp-hours discharged for that unfortunate incident. We had most things shut down so the typical discharge was only a little over 4 amps. The discharge curve is relatively flat, although it steepened at about 150 Ah discharged until about 180 Ah whereupon it flattened again, creating a slight “S” shape. A few bumps in the curve are when the diesel furnace came on to heat the boat (we keep the thermostats at 45°) and increased the discharge rate, The discharge curve steepened again at about 350 Ah discharged, then plummeted after about 470 Ah. The BMS turned off the batteries at 509 Ah after 4-1/2 days.

The next graph shows the aggregated discharge curves for the 201 discharge cycles in the cruising seasons of 2023, 2024, and 2025. The scales are different because the range of voltages and amp-hours is more constrained. I have also included the relevant portion of the 2023 total battery discharge as a reference curve since its low, steady discharge rate is closer to what a bench test might be.

Two things strike me about the curves. First, the steepening of the discharge curve (the “S” bend) at about 150 Ah is consistent across all discharge cycles and not an artifact of a particular cycle (e.g., the discharge rate increased because of a device being turned on). It must be inherent in the battery, either something to do with the BMS or the batteries construction (e.g., as the discharge continues additional/different internal portions of the battery are called into action). The second observation is that as the battery is aging, the discharge curve is lowering (i.e., the battery voltage is less for the same level of amp-hours discharged). In the flatter portions of the curve, we are only dealing with 10 millivolts (mV) or less. In the steeper portions of the “S” bend, it is much easier to see because it is closer to a 50 mV difference between the 2025 curve and the 2023 curve. The aggregate data at higher amp-hour discharge is noiser because I have fewer discharges going that deep and therefore the varying loads (e.g., furnace, inverter, Starlink) that come on or drop off can swing the voltage.

We are still very happy with the LFP battery bank we installed in 2021 and have no regrets. They make cruising more pleasant in not having to worry about managing loads or charging schedules. Compared to our previous AGM batteries they charge dramatically faster and reduce the time we must run the generator when we are spending multiple days at anchor. As to their longevity, from our previous experience with AGM batteries, I believe I would be noticing far more reduction in capacity in the AGM batteries at this point, four cruising seasons, than I’ve detected in the LFP batteries.

All of the measurements I’ve used in the analysis, battery voltage, state of charge, amp-hours discharged and rate discharge were obtained from our battery monitor, a Victron BMV-712 installed in 2021 as part of the LFP battery installation. The BMV-712 directly measures the battery voltage. The current going into or out of the battery bank is computed by the BMV-712 via measuring the tiny voltage drop across a 500A shunt (a known resistance) and applying Ohm’s Law. The BMV-712 computes the other values from tracking the current flows over time. At the time of installation, the BMV-712 was configured with the appropriate values for our battery bank.

Monitoring Battery Activity – Part 3 – The Aging Process

By on December 13, 2025 in M/V Alpenglow

Batteries are such a solid (often made primarily of lead, after all), quiet and passive object, that their “wearing out” seems hard to believe. Underneath their cases of rubber and plastic, however, is a cauldron of electro-chemical processes that can turn motors, power lights, heat water and make life more comfortable. After doing that, providing the batteries with appropriate electricity power can reverse those electro-chemical processes so that the cycle can be repeated.

Our current lithium ferro phosphate (LFP) batteries are the third set of batteries we’ve used. The previous two battery banks were both made up of AGM lead acid batteries. For AGM batteries, typical lifespan is 500-1,000 cycles and four to eight years. Our two AGM battery banks lasted about six years. One of the claims of LFP batteries is greater longevity. Our Battleborn Batteries are rated at 3,000 to 5,000 discharge cycles so we are hoping they will last the rest of our ownership of Alpenglow. Ignoring the small discharge cycles accompanying the transition between shore power and engine alternator, we have had 261 discharge cycles of more than 50 Ah in years 2023 through 2025. Assuming our first full year, 2022, with the new batteries was similar, I estimate that we’ve had fewer than 400 significant discharge cycles so far.

While batteries can fail suddenly, normal “wear and tear” usually shows up as reduced capacity. Our LFP battery bank is rated at 500 amp-hours (Ah), but we have never intentionally consumed that much energy (more about an unintentional discharge later) before recharging. Searching the Internet for methods to determine a batteries capacity usually give solutions that are impractical for “working” batteries because they require they usually require the such the isolation of some or all the batteries from loads for a period of time followed by monitoring the battery while under a constant modest load.

The method I am using to assess the battery bank is monitoring the bank’s voltage over the course of many discharge cycles. While each discharge cycle will be of different duration, depth of discharge, and rate of discharge, I am hoping the aggregation of data will reveal patterns and trends.

In my dataset, for the cruising seasons 2023, 2024 and 2025, I identified 201 discharge cycles that started from a nearly full battery (<2 Ah of discharge) and resulted in a discharge of more than 50 Ah. I had 37,758 measurements of the battery during those discharge cycles. Each measurement included the battery bank’s voltage, state of charge, amp-hours discharged and rate of discharge. These measurements were the average of instantaneous values during the previous six minutes (five minutes in the case of the 2023 cruise year). The discharge cycle ended when the next charge cycle began. In most cases, the charge cycle was the main engine starting, but it could have been the generator starting or even the shore power breaker being switched on if I was purposely cycling the battery bank while at a dock.

Besides the aggregated data from three cruising seasons, I also have one case of the total discharge of the battery bank. This unfortunate and unintentional “test” occurred over about 4-1/2 days during the New Year’s holiday of 2023/2024. The shorepower to the boat was turned off and the battery bank depleted until the battery management system (BMS) incorporated in the individual batteries shut things down to prevent any further depletion. The boat sat for over 3 weeks with dead batteries until I returned to the boat near the end of January for my regular mid-winter visit. I restored shore power and the inverter-charger then recharged the battery. In a call to the battery manufacturer’s technical support, they told us that the accidental complete depletion ought not have any long-term impact on the battery.

Below is the graph of the house bank battery voltage versus the amp-hours discharged for that unfortunate incident. We had most things shut down so the typical discharge was only a little over 4 amps. The discharge curve is relatively flat, although it steepened at about 150 Ah discharged until about 180 Ah whereupon it flattened again, creating a slight “S” shape. A few bumps in the curve are when the diesel furnace came on to heat the boat (we keep the thermostats at 45°) and increased the discharge rate, The discharge curve steepened again at about 350 Ah discharged, then plummeted after about 470 Ah. The BMS turned off the batteries at 509 Ah after 4-1/2 days.

The next graph shows the aggregated discharge curves for the 201 discharge cycles in the cruising seasons of 2023, 2024, and 2025. The scales are different because the range of voltages and amp-hours is more constrained. I have also included the relevant portion of the 2023 total battery discharge as a reference curve since its low, steady discharge rate is closer to what a bench test might be.

Two things strike me about the curves. First, the steepening of the discharge curve (the “S” bend) at about 150 Ah is consistent across all discharge cycles and not an artifact of a particular cycle (e.g., the discharge rate increased because of a device being turned on). It must be inherent in the battery, either something to do with the BMS or the batteries construction (e.g., as the discharge continues additional/different internal portions of the battery are called into action). The second observation is that as the battery is aging, the discharge curve is lowering (i.e., the battery voltage is less for the same level of amp-hours discharged). In the flatter portions of the curve, we are only dealing with 10 millivolts (mV) or less. In the steeper portions of the “S” bend, it is much easier to see because it is closer to a 50 mV difference between the 2025 curve and the 2023 curve. The aggregate data at higher amp-hour discharge is noiser because I have fewer discharges going that deep and therefore the varying loads (e.g., furnace, inverter, Starlink) that come on or drop off can swing the voltage.

We are still very happy with the LFP battery bank we installed in 2021 and have no regrets. They make cruising more pleasant in not having to worry about managing loads or charging schedules. Compared to our previous AGM batteries they charge dramatically faster and reduce the time we must run the generator when we are spending multiple days at anchor. As to their longevity, from our previous experience with AGM batteries, I believe I would be noticing far more reduction in capacity in the AGM batteries at this point, four cruising seasons, than I’ve detected in the LFP batteries.

All of the measurements I’ve used in the analysis, battery voltage, state of charge, amp-hours discharged and rate discharge were obtained from our battery monitor, a Victron BMV-712 installed in 2021 as part of the LFP battery installation. The BMV-712 directly measures the battery voltage. The current going into or out of the battery bank is computed by the BMV-712 via measuring the tiny voltage drop across a 500A shunt (a known resistance) and applying Ohm’s Law. The BMV-712 computes the other values from tracking the current flows over time. At the time of installation, the BMV-712 was configured with the appropriate values for our battery bank.

The Exhibition Hall in the Capitol, Washington DC – Part 3

By on December 13, 2025 in Kosmos

continued… The next exhibit was about more general early US government history. It started by explaining that the fledgling nation’s founding framework was the Articles of Confederation, enacted in 1781. And it explained why they were replaced in 1789 with … Continue reading →

Monitoring Battery Activity – Part 1 – The Discharge Cycle

By on December 12, 2025 in M/V Alpenglow

We installed our Lithium Ferro Phosphate (LFP) battery bank in August 2021 (Out with the Old, in with the New).  It consists of 10 Battleborn GC2 12V-100 Ah batteries arranged as two serial banks of five paralleled batteries giving us 500 Ah at 24V.  We also installed a Victron Cerbo to help control and monitor our Victron equipment (chargers and battery monitor).  I subsequently installed a Raspberry Pi single board computer running Signal K to record and display data being generated on board (Boat Data).

I’ve now been collecting the data for three years and I haven’t been doing much more than displaying real time data while on board.  As a winter project, I’ve tried to organize and analyze it more carefully.

While at the dock and connected to shorepower, the batteries are not doing very much. The AC needs of the boat (e.g., water heater, toaster oven) are supplied directly from the shore (mediated through the isolation transformer and inverter/charger). The DC needs (e,g, refrigerator, lights) are handled by batteries working with the DC charger half of the inverter/charger.  While actively cruising and underway, the alternator driven by the propulsion engine provides the current for DC loads while the AC loads are taken care of by inverter part of the inverter/charger powered through the alternator.

It is only while at anchor (or occasionally at a dock), with no shore power connection, that the batteries must do work and discharge some of their stored power.  In the three cruising seasons for which I have data (2023, 2024 and 2025), I identified 247 depletions of significance.  I ignored the small discharges that occur when transitioning from shore power to engine power when leaving the dock, and the reverse situation, engine power to shore power, when arriving at a dock. I also ignored short duration discharges associated with events where the engine is off and you aren’t on shore power (e.g., visiting a fuel dock, waiting in a temporary anchorage for currents to subside).

The first chart shows the distribution by duration of the 247 discharge cycles.  Our cruising style is one of motion and we only spend multiple nights at anchor in one spot a dozen or so times a year.  When we do, we run our generator daily to recharge the battery banks. A lot of the 20+ hour discharge cycles are probably associated with multiple nights at one site. Being a slow boat, cruising around 6-1/2 to 7 knots, we tend to put in long days to cover the same distance that faster boats do. The short duration discharge cycles often represent a 7 PM arrival at a destination followed by a 5 AM departure the next morning.

DistributionByDuration

The next chart shows depth of discharge (as measured in amp-hours, Ah) distribution for those same 247 discharge cycles. The same comments as above about deeper discharges being associated with multiple nights at anchor and smaller discharges representing longer days underway apply to the distribution.

DistributionByAmount

The last chart shows the power consumed by hour of the day. There are certain items on board that once they are turned on are rarely turned off.  The big examples are refrigerators and freezers (we have two of each) and all our monitoring equipment (e.g., the NMEA2000 bus). 

The data show that we consume 8-9 amps as a baseline. Because we are primarily operating on DC, while at anchor, we tend to turn on the AC inverter part of the Inverter/Charger only when we need it (e.g., using the Starlink antenna). Turning on the inverter tends to increase our usage by an additional 4 amps (we rarely use the inverter to run a large AC load like a toaster oven or electric kettle).

The last major DC load is the Kabola furnace.  On cold mornings, we often heat the boat up with the Kabola.  It will easily use 8 amps as the pumps and blowers kick on but after things warm up, the load usually drops to around 4 amps. There is a temperature dependence to our usage.  Cold weather will result in longer and more frequent operation of the Kabola while hot weather causes higher duty cycles in our refrigerators and freezers. The highest usage is in the early evening when we would have AC power on in order to watch streaming TV via the Starlink antenna and set the Kabola thermostat up to keep the boat comfortable.

TimeOfDayUsage

When comparing our amp or amp-hour numbers, remember that we are operating at 24v DC.  The equivalent numbers for a 12v DC system would be double.

 

Monitoring Battery Activity – Part 1 – The Discharge Cycle

By on December 12, 2025 in M/V Alpenglow

We installed our Lithium Ferro Phosphate (LFP) battery bank in August 2021 (Out with the Old, in with the New).  It consists of 10 Battleborn GC2 12V-100 Ah batteries arranged as two serial banks of five paralleled batteries giving us 500 Ah at 24V.  We also installed a Victron Cerbo to help control and monitor our Victron equipment (chargers and battery monitor).  I subsequently installed a Raspberry Pi single board computer running Signal K to record and display data being generated on board (Boat Data).

I’ve now been collecting the data for three years and I haven’t been doing much more than displaying real time data while on board.  As a winter project, I’ve tried to organize and analyze it more carefully.

While at the dock and connected to shorepower, the batteries are not doing very much. The AC needs of the boat (e.g., water heater, toaster oven) are supplied directly from the shore (mediated through the isolation transformer and inverter/charger). The DC needs (e,g, refrigerator, lights) are handled by batteries working with the DC charger half of the inverter/charger.  While actively cruising and underway, the alternator driven by the propulsion engine provides the current for DC loads while the AC loads are taken care of by inverter part of the inverter/charger powered through the alternator.

It is only while at anchor (or occasionally at a dock), with no shore power connection, that the batteries must do work and discharge some of their stored power.  In the three cruising seasons for which I have data (2023, 2024 and 2025), I identified 247 depletions of significance.  I ignored the small discharges that occur when transitioning from shore power to engine power when leaving the dock, and the reverse situation, engine power to shore power, when arriving at a dock. I also ignored short duration discharges associated with events where the engine is off and you aren’t on shore power (e.g., visiting a fuel dock, waiting in a temporary anchorage for currents to subside).

The first chart shows the distribution by duration of the 247 discharge cycles.  Our cruising style is one of motion and we only spend multiple nights at anchor in one spot a dozen or so times a year.  When we do, we run our generator daily to recharge the battery banks. A lot of the 20+ hour discharge cycles are probably associated with multiple nights at one site. Being a slow boat, cruising around 6-1/2 to 7 knots, we tend to put in long days to cover the same distance that faster boats do. The short duration discharge cycles often represent a 7 PM arrival at a destination followed by a 5 AM departure the next morning.

DistributionByDuration

The next chart shows depth of discharge (as measured in amp-hours, Ah) distribution for those same 247 discharge cycles. The same comments as above about deeper discharges being associated with multiple nights at anchor and smaller discharges representing longer days underway apply to the distribution.

DistributionByAmount

The last chart shows the power consumed by hour of the day. There are certain items on board that once they are turned on are rarely turned off.  The big examples are refrigerators and freezers (we have two of each) and all our monitoring equipment (e.g., the NMEA2000 bus). 

The data show that we consume 8-9 amps as a baseline. Because we are primarily operating on DC, while at anchor, we tend to turn on the AC inverter part of the Inverter/Charger only when we need it (e.g., using the Starlink antenna). Turning on the inverter tends to increase our usage by an additional 4 amps (we rarely use the inverter to run a large AC load like a toaster oven or electric kettle).

The last major DC load is the Kabola furnace.  On cold mornings, we often heat the boat up with the Kabola.  It will easily use 8 amps as the pumps and blowers kick on but after things warm up, the load usually drops to around 4 amps. There is a temperature dependence to our usage.  Cold weather will result in longer and more frequent operation of the Kabola while hot weather causes higher duty cycles in our refrigerators and freezers. The highest usage is in the early evening when we would have AC power on in order to watch streaming TV via the Starlink antenna and set the Kabola thermostat up to keep the boat comfortable.

TimeOfDayUsage

When comparing our amp or amp-hour numbers, remember that we are operating at 24v DC.  The equivalent numbers for a 12v DC system would be double.