power use

E

Ed604

Active member
Joined
Dec 1, 2022
Messages
41
Fluid Motion Model
R-25 (Outboard)
Vessel Name
Misty-may
Hello there,

I am an owner of a 2019 c-302 northwest edition and have a question that I have been trying to research which is, power consumption and battery bank duration. I have not done overnight trips where I am not at a marina connected to power. My wife and I are planning a trip up to desolation this summer and we will be looking for off grid spots to set the hook.

When at anchorage in these more remote areas without power but, assuming summer sun from the solar panel. How long can I expect to get out of the standard bank of batteries? I have been searching for things like "power use" and "Battery use" but I am not finding the answer. I am sure I am using the wrong terms for the search bar. Is 2 - 3 days something that I can use as a base without needing to re charge?

I am not asking for the load calculations of all possible power use here. Rather, I am asking in a general sense how many days of normal use can I get before needing to recharge. Normal use would be lets say, 2 people using lights at night, watching a movie or two, using the fridge as normal and microwave a couple of times a day and all the flushing of the power toilet that one does each day.

I am trying to figure out if I need to pick up an inverter generator for my trip.

Thanks for any advice or experience shared.

kind regards,
Ed604
 
Hi Ed,

I am certain you’re well aware of the many variables, but do appreciate your desire for a simple answer. So, here goes my best: (I have a R31 with 4 group 31 house batteries that are about 4 years old and the numbers are from when I had the original panel: 140 W. I have since increased to 375 W panel but have not had much experience in the sun with it yet.

I consume about 1% per hour using:
1 main refrigerator
Normal lights (interior and masthead light while anchoring overnight
Normal use of water pump for toilet and sinks.

Using the Webasto and the inverter does take a noticeable bite. E.g. when I used the inverter to make a pot of drip coffee I lost 4% points. I switched to using a French press and boiled water on the propane stove.

Last month I anchored at Gig Harbor with intermittent sun for about 40 hours before hitting the 52% mark. The webasto shuts down at around 52%. I think my batteries might be getting a little old.

Good luck!
 
Suggest you watch this video from Ranger Tugs on power management.
https://youtu.be/Uj_am-ecSt4

I’m going to make a lot of assumptions to answer your question. If these assumptions are incorrect then the correct answer could be significantly different.
I’m assuming you have four AGM 110 AmpHr batteries in your house bank. I’m assuming you have the stock 140 watt solar panel with the Morningstar SunSaver Duo controller.
Assuming your power usage on the hook is reasonably conservative you probably use up 50 to 65 AmpHrs of power a day. The solar panel adds back in 20 to 30 AmpHrs a day on average. Let’s assume you use 65 AmpHrs and get 20 AmpHrs from solar for the calculations.
Also assume your house batteries are all in great condition and draw down in a linear manner. From full going down to 60 percent of full gives you approximately 176 AmpHrs of usable capacity starting from fully charged (440 x 0.4 = 176). After 48 hours at anchor you have used 130 AmHrs and added 40 AmpHrs from solar. You are down to 86 AmpHrs of usable power remaining. At 72 hours you are down to 39 usable AmpHrs. Your house batteries would be below 60 percent of full by 96 hours without recharging the batteries.
Important note: Using the inverter will suck up HUGE amounts of your house battery capacity. If there is anyway you can live without the microwave or any other D/C appliance (e.g. coffee maker) I’d highly recommend that. You could literally use up all your house battery capacity in under 24 hours by running the inverter constantly.
This numbers are all just ballpark to give you a rough idea. Watching your house battery voltage will give you a much better idea of your actual net power consumption. Here’s a chart in this article that compares voltage to remaining capacity.
https://marinehowto.com/under-load-batt ... ge-vs-soc/

PS: A lot of the great anchorages in DS are really pretty close to one another. Don’t assume you will be running the engine long enough to fully recharge the batteries from say 60 percent of full when going from one place to the next.
 
I would recommend a battery monitor. I installed a Victron smart shunt. There are several brands that will work. You will be able see power consumption in real time and better manage your batteries.

Britt
 
Wow! Two fantastic answers that I find most helpful.
Thank you Both! I would offer that all assumptions made here are along the lines of my question and I appreciate the suggestion to make coffee with a press. Great idea to not drive power use! I have to start the day with a cup or two!

Yes, we have the original bank of 4-AGM batteries and the stock panel.
I will watch the suggested video too. I like those series of videos, I have not seen that one yet.

I wonder how long the alternators on the twin Yamaha's would take to re- charge the batteries that are drained down to 60% level?

Great stuff, I have been planning the trip with some Marina visits mixed in to fully recharge the bank and pick up needed supplies. Hmmm, maybe I won't need a generator with these windows (48hours) being, in my mind, viable times between moving and or being docked and at power.
cheers,
Elton
 
We have a 2019 C30 inboard and I would agree with the observations here. With modest power management we get 2 days at anchor with no problem, and could probably stretch OK to 3 days with high solar boost.

That works fine for us because we're always ready to move (and recharge the hot water, which is engine-warmed), provision, refill water, etc, after a couple of days.

Running the engine for a while at anchor is a backup option, not great to do often but possible.
 
The three main marinas with shore power in DS are Gorge Harbor, Refuge Cove and Toba Wilderness Marina. I’m sure there are a few more outside DS and the Discovery Islands proper, I’m just haven’t used them up there
Unlike those of us with diesel inboards, you won’t have hot water for more than a day or two between shore power recharges. Heating hot water with the inverter is impractical while at anchor from a conservative power management standpoint.
I know in the RT seminal they used 67 AmpHrs a day as a rule of thumb by using only the DC powered things. We have a portable freezer in the cockpit that uses close to 50 AmpHrs a day of DC power just by itself so we are chewing up 110 to 115 AmpHrs a day in total energy consumption. That’s why we went to a 335 watt solar system with a V/E MPPT controller that puts back in 85 AmpHrs a day. We get 2-3 days at anchor with out needing to recharge the batteries with the freezer running. Adding a third house battery would give us several more days between recharging. Without the freezer we are currently almost energy self sufficient.
The V/P D4 diesel charges the batteries at about 110 AmpHrs at higher RPMs. I know the Yamaha 300 charges at about 70 AmpHrs an hour at higher RPMs. Don’t know the underway charging numbers for the C-302.
 
I will answer this from what my experience was when I had my C26 Cutwater with (3) North Star group 27 90 amp hour batteries used for the house bank. On the hook charging was done only by the engine Volvo D3 that had an advertised max charging capacity at 80% throttle of 180 amps. At 1500 rpm estimate about half of that. I always figured 60 amp charge. My main power usage was the LED cabin lights, the factory installed refrigerator, the electric head, electric water pump, a 12V receptacle for my C-pap used while sleeping, 12V receptacle for charging our cell phones, LED anchor light, a portable 12V freezer ( uses about 5amp per hour) and the big user was the 2k inverter. If I dropped the hook at 4 pm and had the bank at full 100% charge by 6 am the next morning I had used between 40% to 50% of my battery capacity. 270 AH @ 50% = 135AH that is 14 hours of battery use. My battery use average was 8 amps =112 AH over night. 40% usage = 108 AH. Now I have a bank of batteries that need to be charged to at least 90% charge throughout the day. I need to replenish the batteries if I plan another night on the hook at this location. Solar (150W panel) may give enough power to keep all 12V users running for 8 hours but will not replenish the batteries to a charge capacity to 90% or higher. My choice was to run the engine for an hour at 1200 rpm in the morning and an hour in the evening to try to charge the batteries for another night on the hook. The more I thought about this. It was not smart! I'm running a diesel engine 2 hours a day to maintain my batteries. I had two choices add more solar or add a portable generator. Adding a portable generator was the cheapest choice. The one item I had to change was the battery charger. My C26 came with a 20 amp Promariner. I would have to run the generator for 5 hours to charge the bank. A 50 amp charger was needed. We purchased a 2200 w Honda generator with a CO auto shut off. I installed two extra CO detectors one in the cockpit under the gunnel and one in the V-berth area. and had the factory installed Co in the cave. The generator was used in the morning for breakfast, coffee, Microwave, and stove+ battery charger. We used power management using one item 120V + battery charger at a time. Once breakfast was done we would turn the hot water heater on to replenish hot water for the day. The generator was used for about an hour and a half in the morning and we repeated this in the evening at dinner time. This changed our ability to stay on the hook and give the batteries a chance. I learned the hard way after destroying batteries because they never were recharged properly.

If you have room for Solar install it! When I sold the Cutwater I purchased a 34 Mainship pilot that has a large area on the pilot house roof that is perfect for panels. I have 3 200 watt panels. I also have enough room for 640 AH batteries. I have tried using old school flood batteries. This has worked great. I have fully charged batteries by 1:00pm every day while on the hook and all 12Volt users are powered by the solar after the batteries are charged. I still use the Honda in the morning for cooking and Hot water. If I install lithium batteries the Honda will no longer be needed.

To answer the question Ed604 that you posted. I would recommend getting the Honda. My reason is stated above.
 
Fantastic feedback, thanks everyone!
I wonder if the 70 amp charging is doubled where you have twin 300 engines? Does anyone know if that is the case?

I was thinking that I might be able to get away without the gen set but hearing Brian's power use overnight makes me think that I should bring one even if its just back up. I really don't like to listen to them but I would rather not be forced to put hours on the mains for Battery charging. Again, Brian, good point.

I watched that power management video yesterday and that was really helpful. If anyone finds this thread in the future it is a great resource for sure. I too would recommend it to anyone interested in power use. Thanks again for the suggestion to look into that.

warm regards,
Ed604
 
If you’re only staying a day or two between anchorages, travel at least 45 minutes or so between anchorages, stay on shore power every few days, don’t use your inverter and use your DC powered devices in a conservative manner I don’t think you will need the generator. But that’s a lot of ifs.
I have a Honda 2000 generator that I thought I might need with a R-25 Classic that had absolutely no solar. Installing a solar system from scratch was much easier than carrying around the generator in the cockpit.
If you’re still worried I’d consider upgrading your solar system down the road.
You have a lot more house battery capacity than Brian had in his C-26. And with reasonable consumption habits you should be able to cut his 112 AmpHr overnight draw down to 40 to 45 AmpHrs. In about 120 nights of anchoring I’ve never used more than 70 AmpHrs in a 24 hour period (as measured by voltage under load) without our portable freezer running.
Besides, no one wants to be anchored next to a boat that’s running a loud generator for hours on end. I’ll move if I end up next to one of those guys!
 
your biggest issue with AGM and lead acid batteries isn't increasing the alternator capacity but giving batteries nearing 80-100% SOC the time to absorb the rest of the charge.

AGMs and lead acid have 3 stages of charging: bulk, absorption (and float)

the absorption stage is about charging the last 20% and this takes a long time. you cant just dump power (amps) into the batteries at this stage of charging. (this is different to lithium). so the only way to get to 100% SOC is a long charge time. Solar does this well. but running the engine at idle for hours is incredibly inefficient and not great for the engines.

Not doing the last 20% charge basically means you only get 30% of your battery capacity to use. if you have 200Ah capacity batteries thats only 60Ah of usable power before you need to start recharging or you degrade battery life!

this is why lithium is so good. you can pour the power in fast up to 100% SOC. and you can use power below the 50% SOC down to 10-20% SOC.

if you have AGM's I strongly suggest upgrading your solar configuration if you plan to spend a few days at anchor.
 
We have a 2019 R-29, so the same battery setup as the OP. We've done minimal anchoring since our first year when we had brand new batteries. Those experiences worked well. The batteries would dip down, but never below 12.2 volts, the solar panel would bring the batteries back up during the day. We ran the refers (2), some lights, the radio. One morning we ran our Nespresso, but it struggled. 5 years in, we're getting all new batteries this weekend.

We now have an EcoFlow Delta 2 as a backup power source. We can run the Nespresso, the missus can run her hair dryer, and we can plug it into the shore power input on the boat to supplement our new 220W solar panel for topping off the batteries. It can store 1 kwH and can put out up to 1800 watts. It has its own 220W solar panel for recharging, we set that up on the bow of the boat. It's a bi-facial panel so it not only gets solar from the front of the panel, but also from the light reflecting off the white fiberglass onto the back of the panel.
 
Thanks to all who have replied. I have been thinking about this and I am leaning to the idea of trying to upgrade the existing panel to a higher watt panel. If possible I would like to keep the existing wiring and simply put a new panel in place of the old. I have a solar expert coming to look at the boat and help me determine if the existing equipment can handle the higher load. I am trying to find the parts list as I think I remember seeing one for the 302.

With my trip coming this might be the most simple way to help without making it into a larger project/problem. I think that adding a much higher watt system will be a long term goal that looks to hit 600 - 900w. I really do hate listening to the generator run... so I like the idea of solar.

The fellow has suggested the possibility of using a 300w panel in place of the older unit. I may need to change the controller to allow that, I am not sure about the conductor size of the wires? This is the first item to determine.

I will explore this and share what comes out of it.

still looking,
Ed604
 
Upgrading to a larger solar panel is a good first step in getting more energy out of your solar system.
As a rule of thumb, on a good sunny summer day you will get about 1/4 in AmpHrs of the solar panels rated wattage with a MPPT solar controller. So a 320 watt solar panel should, on average, give you about 80 AmpHrs of charge per sunny summer day. If your average usage out of the house bank is 75 AmpHrs per day the larger panel would give you energy independence. Surprisingly, you still get a lot of charging from the solar even on cloudy or rainy days.
The big killer of solar output happens when the panel is shaded. I have a cargo box on my sports rack and made sure the panel didn’t cross over the boats centerline to minimize shading from the cargo box. A 335 watt panel was the biggest I could physically fit into the space I had available on the port side of the sports rack.
The Morningstar SunSaver Duo controller is of the PWM type and is not as efficient as a MPPT controller. So you may only get 1/5 to 1/6 times panel wattage to AmpHrs compared to 1/4 average for a MPPT controller. Lots of variables here so, again, this is just a rule of thumb estimate. Also, the Morningstar caps out at 25 amps of charge so you may not get all the energy the panel puts out through the Morningstar into the house batteries.
The existing wiring from the solar panel is probably large enough to handle a 300 to 400 watt panel without any modifications but you would want to double check just to be sure.
 
One thing I have learned is that it is very important to keep the solar panel clean. During the height of pollen season here in New Jersey my panel output dropped to almost zero.

I did an incremental upgrade over the winter to a 200 watt panel. I tested it at the dock. Unplugged from shore power and just used the boat as I would if at anchor. After three days I was down to 60% on my AGM's. Refrigerator ran 24/7, made coffee and meals, all of that. I think that's good. I had one day of mostly cloudy overcast skies.

It's important to do the math, but real world testing is important too. Everyone's use varies.

A small panel works for me as I have a generator also.

-martin610
 
It boils down to what comfort level you want to have if you are anchored out. It also boils down to battery capacity when choosing solar panel size. The bottom line with Lead acid batteries is when discharged 70% ,60%, or 50% the batteries should be recharged to full capacity in a cycle. If this is not done the longevity of the battery is decreased. Many purchase expensive name brand AGM batteries thinking the life span will be much greater than an inexpensive flooded lead acid battery. This may be true if the AGM battery is cycled each time it is discharged 100% to 50% to 100%. If the charge cycle is always on bulk and the battery never reaches its full 100% charge while cruising the battery will quickly have a reduction in capacity. It will still work but may be working with a less than 90% capacity.

Martin610":3q14qglf said:
After three days I was down to 60% on my AGM's. Refrigerator ran 24/7, made coffee and meals, all of that.
Click to expand...
Remember you are not talking about one battery at 60%. It is the bank. If your statement means that the three days that you were using only solar for charging and 12V use and your batteries were at 60% discharge Max. Then you are not doing you batteries any favors. If your statement is after three days the batteries were fully charged each day to 100% while using all 12volt accessories coffee pot, cooking and refrigerator then depleted to 60% at night and the third day when starting your day the battery bank was at 60% you are doing real good with 200AH of solar. Remember the solar is charging the batteries only if no 12V users are on. If 12 volt users are on in most cases all the solar input is used to power the user what is left is used to charge the battery. In many cases the user is using more than the solar can generate so the battery is actually loosing charge when the solar panel is at full output. At 100% output a 100W panel will make 8 amps at 12V. In my experience from the time the sun hits the panel and the energy is produced the output to the solar controller charging the batteries best case is 70% of the panel capacity max. You may see 80% in perfect conditions. The highest output I have seen with 600W panels using a Victron solar controller 100Volt/50 amp is 36 amp output from the Victron. The theoretic output based on the panel size is 48 amps. There is never a sun shadow on my panels mounted to a pilot house roof of 9'X12'. Based on nine months of continual use the best observed output was in May while tied to a city wall on the Erie Canal for two days. 34 amps output from solar, 8 amps was used to maintain the 12volt users 26 amps was used to charge my battery bank. The average battery capacity I have left in the morning is 70% of theoretic 640AH battery bank. My battery monitor is using this number as a base line. This equates to 192 AH used ( It is not that much) It is closer to 150 AH used from the time the solar output no longer generates enough power to compensate for my 12 volt use and battery storage is used to the time the solar starts to take over in the morning. I estimate based on my personal experience during summer sun I average 20 amps charge going to my battery bank from 9am to 4 pm and 8 amp average maintaining all my 12 volt users. Meaning I average 28 amp output from my 600 Watt panels in a 7 hour period. From 4 to 6 pm there is still output enough to maintain the 12 volt users and 8am to 9 am about the same. When the solar controller goes on Float which is in mid afternoon We turn the Icemaker on and make ice for a few hours so that we are not wasting solar energy. This puts the solar controller back to bulk charge. The Victron controller is smart!! It works well with the alternator charging and the 120 Volt battery charger. I keep the on all the time for solar back up when at shore power. I have Flooded lead acid batteries. In 9 months of cruising I have added less than 16 oz of water to 4 group 31 batteries (East Penn) and one 4D (East Penn) battery. These batteries have been charged using a 30 Promariner (original equipment to my 20 year old Mainship Pilot) Two alternators ( original alternators 4LHA STP Yanmar engines and the Victron 100/50 solar charger.

Most of the time my set up works without the use of a generator. I want batteries charged full cycle each time they are used. This pays off with longer life batteries. I want to be comfortable when at anchor and use all the amenities of the boat. The 600 watt almost does this. If I had lithium batteries it would. My main use of the Honda generator is the hot water heater for a warm shower every night and making breakfast in the morning. Even the days on the wall on the Erie Canal I used the generator in the morning for breakfast and hot water. The generator ran for about an hour along with the rest of the boats on the wall 9 in total. Most of the other boats ran their generators all of the time while we were tied up. There were only two boats that had sufficient solar to keep things running. My boat and a older 32' Bayliner Motor Yacht.

9 months on the water and 60 nights at anchor. I have put less than 20 hours of run time on the 2200W Honda. I base the hours on fuel used. I have filled my outboard 3 gallon fuel tank 3 times. This gas is used for the 6 hp Suzuki dingy motor and the Honda. When I use the Honda it is used for high amp use. Microwave, cook stove or hot water heater. It burns about .3 gph. 3 hours a gallon I estimate half the 9 gallons of gas used has been for the generator. My point ,I don't use it much but I would not leave home without it. 34' is a small boat to live on I want to be comfortable!
 
I am planning to upgrade this fall with the help of my brother in law. Plan to follow this thread as I know nothing at this point but doing the research. Interested in what people find out about existing wiring and the capacity to handle 300W.
 
Hello Brian,

I had a quick question for you. When you are using the generator are you plugging the shore power cord into the generator or, are you connecting the generator directly to the battery bank and using the 12v feature of the gen set?

if you are using the 12v feature, do you just use jumper cables or did you splice up some eyes and alligator clips for the cable to connect it? I am thinking that going direct to the bank will get the most efficient use of the gen set?
I have purchased a larger panel and am going to test it out to see how it goes on my trip. I am also going to bring the gen set as I do have the room. I just hope not to have to use it!

thanks,
Ed604
 
I just got back to the dock yesterday afternoon. Fully charged batteries 2021, C30. I forgot to plug in and returned to the boat at noon. Portable chest freezer tripped out because the 12v was to low. Part of the problem was having the paddle boards blocking the solar panel. Only items that were on was house batteries, both refrigerators, the portable freezer.

Point is. You can test your boat at the dock intentionally/unintentionally. That way you don't run out of juice while on the hook. Just leave the things you think you will use plugged in. And remember that overcast sky's or hot weather will change the math significantly.
 
Real world example:
335 Watts solar MPPT system, 100-120 Amp Hrs of draw from house bank each day, on average panel producing 1,150 Watt Hrs per day (80-90 Amp Hrs), and running engine at 1400-1600 rpm 1-2 hrs per day between anchorages. Not on shore power past 8 days - no need. Lowest house bank battery reading in last 8 days was 12.43 volts under load or about 75-80 SOC.
I’m a happy camper. Sent from Refuge Cove, Desolation Sound.
 
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