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Old 12-05-2018, 11:14 PM   #1
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Managing electricity. Generator? Batteries? Warm beer?

Hello all! Our brand spankin new to us boat is a 47’ Marine Trader Tradwinds. We have two Lehman 225’s and a Westerbeke 8kw genny. If cruising for 5 hours to an anchorage, do you run the genny? What will the engine alternators be doing for me if I shut it down?
Our fridge is 110v only! Will my beer be warm when I really need one? Will ice packs on the fridge be enough?
While on the hook we decide we don’t need heat or AC, if we shut the genny-rator down, what is the boat running on? The house batteries? How do I know how much juice I am using and how much I have left? Do the genny and mains have their own starting battery?
How do I know what percentage of the genny am I using? If I run the gen while under way with heat/AC off, am I basically just keeping the beer cold? That can’t be good for it, but a pretty damn important job.
When switching from shore to generator power, do you turn each ac off at the thermostat before switching? What about the other systems? Or do you just leave everything on and turn the switch?

Sorry for the newbie questions! Electricity doesn’t come naturally to me. I know it’s there. I kinda know where it wants to go and why. I can’t see it. It really hurts when I touch it.

Thanks everyone!
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Old 12-06-2018, 05:23 AM   #2
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Read the Calder it will be a good introductory course.

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Old 12-06-2018, 05:53 AM   #3
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You are looking for a several day course both in electric and YOUR boat...the 2 go hand in hand as we don't know how your boat is set up.

Even if you pay someone a $1000 to teach, point out items, make improvement suggestions or identify flaws...you might save that easily in preventing damage and just plain old piece of mind.
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Old 12-06-2018, 06:17 AM   #4
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As noted above it is almost impossible to give specific advice without knowing how your boat is set up. Seems that you have two choices:

Read Calder's book and spend hours going through your boat until you understand it.
or
Hire a marine electrician to spend a few hours with you on your boat and advise you how to operate it.

With that said, some generic answers:

With a 110V fridge (and are you sure it doesn't also run on 12V?) you need some source of AC all of the time either from shorepower, genset or an inverter powered by your batteries.

Boats like yours usually have three battery systems: one or two (with twins) engine starting batteries, a genset starting battery and a house battery system. It is important to keep them isolated so if you run your house battery down, you don't also run your engine starting battery down. There are lots of schemes and devices to do this and a marine electrician is probably the best way to understand them.

You probably have an AC ammeter which will tell you how much your genset is putting out. If not you need to install one.

You may want to install a battery monitor which will tell you how much you have left in your house batteries.

Turn the main AC breaker off before switching from shore to genset to shutdown all AC devices. It isn't good for a genset to suddenly hit it with lots of loads, so also turn off the big ones like the A/C first also before switching and then after a few minutes to let the genset warm up turn the A/C breaker back on.

Any more is too boat dependent.

David
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Old 12-06-2018, 06:45 AM   #5
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The best boat buck you can spend is for a really great refrigeration system.

The biggest power drain on a battery bank is the reefer setup.

If you have the room a Sunfrost would be an easy start.

But there BIG! and expensive.

Sun Frost: Energy Efficient Refrigerators, Freezers, and Sustainable ...

www.sunfrost.com/
Sun Frost: worlds most energy efficient refrigerators and sustainable living products. Including composters, solar vaccine refrigerators and composting toilets.


WE chose an RV propane unit , as it allows 3 weeks on a single bottle and requires no electric.

But some folks who do not understand propane PANIC at the thought.

The real question is use, are you an M>M (marina to marina ) cruiser or do you enjoy a week at anchor?
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Old 12-06-2018, 07:49 AM   #6
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Steve
Yes, educate yourself via Calder etc.

Three questions
- does your boat have a house bank
- is there an inverter
- do you have a smart trustworthy boating buddy that can give you some help

BTW, decades ago I had a boat with a 110 fridge only. No problem coordinating genset and dock time to keep stuff cool. You’ll figure all this stuff out, just dive in.
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Old 12-06-2018, 07:53 AM   #7
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Propane gas powered fridges need to be reasonably level to work right. That is why they are never used on sailboats.

I have a friend who uses one on his CHB 45' trawler and it works well. I don't think one would work well during a rolly passage though.

David
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Old 12-06-2018, 08:50 AM   #8
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I too have a 120Vac fridge and it is powered by a 1000W inverter when under way, so I don't need to run the gennie for fridge. Works well. Gennie gets run for hot water and AC, otherwise stays shut down. Fridge and little AC loads (laptop, phone chargers, shavers, hair dryer (on low), coffee pot, etc) can run off the inverter powered by main engine alternator. Fridge can also run overnight with main engine off drawing off the house batt.

As others have posted, you really need to pick through your system and map out how it is set up and operated.
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Old 12-06-2018, 09:09 AM   #9
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Quote:
Originally Posted by Steve91T View Post
If cruising for 5 hours to an anchorage, do you run the genny?
I don't. What do you need to run? I would if I wanted to run heat or AC while I was underway.

Quote:
Originally Posted by Steve91T View Post
What will the engine alternators be doing for me if I shut it down?
More than likely charging the starting battery. Hopefully, it is also powering the 12v panel and your 12v devices.

Quote:
Originally Posted by Steve91T View Post
Our fridge is 110v only! Will my beer be warm when I really need one? Will ice packs on the fridge be enough?
This is like asking "how long is a piece of string". Ice packs will allow the fridge to hold temperature. It will depend on ambient temp. of the space and how long the fridge is shut down.

Get a dual voltage fridge. Also, beer in the fridge? There isn't enough room in our fridge. We use the fridge for food and a cooler for beer.

Quote:
Originally Posted by Steve91T View Post
While on the hook we decide we don’t need heat or AC, if we shut the genny-rator down, what is the boat running on? The house batteries?
12v is running on Batteries. 120V is running on nothing, unless you have an inverter installed. Then what is running on the inverter @ 120v is also running on your batteries.

Quote:
Originally Posted by Steve91T View Post
How do I know how much juice I am using and how much I have left?
Battery Monitor or intuition.

Quote:
Originally Posted by Steve91T View Post
Do the genny and mains have their own starting battery?
They should. This is not always the case. A trip to the bilge will answer this question.

Quote:
Originally Posted by Steve91T View Post
How do I know what percentage of the genny am I using?
Turn on the genny, then start turning things on. Listen as the genny steps up. Continue until everything is one. now start slowly powering things down and listen to the genny step down. After time, you will be able to guesstimate by ear.

Quote:
Originally Posted by Steve91T View Post
If I run the gen while under way with heat/AC off, am I basically just keeping the beer cold? That can’t be good for it, but a pretty damn important job.
Get a dual-voltage fridge or get a cooler and keep the beer in a cooler.

Quote:
Originally Posted by Steve91T View Post
When switching from shore to generator power, do you turn each ac off at the thermostat before switching? What about the other systems? Or do you just leave everything on and turn the switch?
In order to switch between shore power and generator, you need to first turn the main breaker of one system off before turning the main breaker of the other system on. If you look at your panel, there should be lockouts from shore power and generator breakers so that both systems cannot be on at the same time.

I turn all of the A/C units by the control module, then turn off all AC breakers, then turn off the main breakers, then switch the main breakers between Shore power and generator, then turn the AC breakers back on again. Since I never run with the generator running, this is never an issue as the AC panel is offline whenever the engine is running.
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Old 12-06-2018, 09:13 AM   #10
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In rebuilding our boat I did a complete rewire of all electrical systems. I read Calder and various online resources (including this forum) and eventually made a rough layman’s sketch of how I thought all the systems/components should be laid out for functionality, safety and efficiency. Then I sent a copy of the sketch (along with some money) to Pacific Yacht Systems in Vancouver, BC and had a couple of EXTREMELY helpful telephone conversations with the folks at PYS to discuss and tweak my plans. It was a tremendous amount of fun, and my systems are all safe and functional as a result.
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Old 12-06-2018, 09:49 AM   #11
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Thanks guys! Yeah I know it was a pretty generic question but your answers definitely helped.

The PO had just installed a brand new fridge so it’s stayung. The 1000w inverter is a great idea. I’ll have to see if I have one already. If not I’ll add one.

The boat stays at a marina and we commute to it about twice a month. We then will either overnight on the hook somewhere for a night or two to play or we’ll be cruising all day to our next anchorage as we move the boat towards the keys from St Pete. During the summer the genny will probably be running to keep an AC going so the cabin doesn’t get too hot. It that’s obviously not really needed right now and I’d hate to keep the gen runnning just to keep the fridge cold. And once in the hook it’d be nice to enjoy the time in the hook without the gen if we don’t need it.

Next time I’m at the boat I’ll spend some time with the electrical system.

The mechanic I’m using is a really nice guy. I’m sure he won’t mind spending a few minutes to run through the system with me.

Thanks guys!
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Old 12-06-2018, 11:55 AM   #12
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One thing to do once you understand the AC and DC set up , house ah, is to create a DC load chart so you can begin to understand electrons in and out over 24 hr period ...then go from there.
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Old 12-06-2018, 01:15 PM   #13
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All great advice here. Do the load chart as suggested above before buying an inverter (or doing anything else). A 1000W inverter may work for you, or it may not. We have a 3500W inverter, and it’s perfect for our power needs, especially early in the morning - the Admiral sleeps later than I do, so the genny doesn’t come on first thing in the AM.
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Old 12-06-2018, 02:41 PM   #14
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With a good inverter and dedicated bank, you can run your generator less and won't need it when the mains are running.

Except for bilge pumps, nav lights and electronics, my boat is 120/240v. I have a Magnum MS-PAE inverter and a large battery bank using 48v. It will run everything on the boat, but rarely use it for water heaters. One of my mains has an 48v alternator that keeps up with battery use when running the mains and my inverter battery bank is big enough to go a few days w/o running a generator. When I do run a generator, I make water, do laundry and if necessary heat water. When running the mains I never have to run a generator, saving 1-2 gph. And I don't notice any difference in the Detroit mains fuel economy. I have 2 chest freezers and a large reefer. I also have a lot of extra insulation around things I want to keep hot or cold. I stay in usually cold climates, so don't use much AC.
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Old 12-06-2018, 05:29 PM   #15
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Steve,

I would offer than you need to do an energy audit of your new boat, determining what items are drawing power and how much power are they drawing.

I think this is the first step before you make any upgrades to the boat. Knowing your energy consumption you could then properly determine the invertor size (still need to determine modified sine or pure sine) and maybe upgrade the battery bank to fit your needs. Also, it would be a good time to determine if maybe adding any solar might also be worthwhile.

Jim
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Old 12-07-2018, 05:49 AM   #16
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( inverter)" If not I’ll add one"

IF the main use for the inverter is the fridge on some weekends , a vacuum at times and a radar oven for reheating goodies a truck stop 1500W , about $150 will work just fine.

A SOC meter installed would be great as a battery "gas gauge" to help not harm the house set from the fridge draw..
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Old 12-07-2018, 06:52 AM   #17
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Next time I’m at the boat I’ll spend some time with the electrical system.

The mechanic I’m using is a really nice guy. I’m sure he won’t mind spending a few minutes to run through the system with me.
As someone who is slightly ahead of you, it will take more than a few minutes. I have had electricians onboard 3 times and am still asking questions. Write everything down. Everything. Make really bad drawings while he is explaining. Quality doesn't matter at that point. Write everything down. Is the PO or broker available at all? PO was a big help on ours. Write everything down. Another mistake I made was not labeling things as they were found or pointed out. Take the time to do so. Use your camera.

Did I mention writing everything down?

I believe the Calder book being mentioned is this one Calder"

Another one I like is Boatowners Illustrated Electrical Handbook by Charlie Wing.

Write everything down.
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Old 12-07-2018, 09:07 AM   #18
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Next time I’m at the boat I’ll spend some time with the electrical system.

The mechanic I’m using is a really nice guy. I’m sure he won’t mind spending a few minutes to run through the system with me.

Just in case...

A mechanic and a boat electrician are two different animals. Your guy may be able to give you a rough overview... but for in-depth analysis and especially for changes, sounds like you need a real boat electrician.

-Chris
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Old 12-08-2018, 05:51 AM   #19
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As you explore your new boat one simple trick is wire markers.

This is a pad of numbers that can be simply stuck on breakers, wires and power users.

One method is to turn on say all the lights then use the system breaker to turn everything off.

AS you switch on a single breaker stick the same number both on the breaker and on the lamp, socket , whatever.

The single tabs are quite small so are not a visual bother.

Now when something doesn't work its quick to note the number and check that breaker.

Have fun,

https://www.homedepot.com/p/Ideal-Wi...-102/100118882
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Old 12-08-2018, 07:30 AM   #20
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Write everything down.
Good advice and I’ll offer a variation: record everything.

I use my iPhone recorder app (with permission) to document every conversation I have with tech experts. It frees me from having to write, allows me to focus on what’s being said and allows for capturing MUCH more info in a given amount of time. I’m a decent note-taker, but it’s amazing how much detail and nuance I can miss when writing stuff down.
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