Batteries charging question

[Tuckerllc]

Hello everyone, I am happy to say that I am finally going to buy my C-Dory, and I have narrowed it down between two boats.

The one that I really like has 4 batteries, a Garmin 4212: Color/Radar/GPS/Fish finder, all in one display, VHF, Stereo, etc. Although it does not have a refridgerator, I do plan on installing one, as well as a Windless.

The dealer that is selling the boat told me that the previous owner had the extra batteries, isolator switch and battery condition meter, professionally installed… my question is , does anyone know if the twin Honda 50s have sufficient charging capabilities (alternators) to charge 4 batteries?




I have been reading this forum for many years now and I look forward to being able to participate as an owner instead of a dreamer.

Thanks in advance…


Tommy

[Sea Wolf]

Tommy-

First of all, Welcome to the C-Brat family!

Your Honda 50's put out 10 amps each when fully charging above about 1500 rpm.

Some outboards put out as much as 40 amps (Suzuki) for a 75-100 hp single engine, but 16-25 is more common.

Whether or not your twin 50's can charge your batteries fast enough depends on how fast you drain them down.

They'll most probably keep up with any drain you put on the batteries while the motors are running, including a refrigerator, but you'll have to figure out how much the refrigerator will draw when on, and what percentage of the time it will be running, while on the hook. The faster you drain them, the more often you'll have to start your engines to charge 'em back up.

Most folks with refrigerators report they can use them while anchored by running the motors only a couple or a few hours a day.

The typical small refrigerator that fits in a C-Dory draws about 3 amps when running, so if the generators put out 15 amps when running at moderately fast idle speed, one would need to run the motor 1 hour for every 5 hours the compressor was running, other power usage not considered, and since the compressor only runs say 1/3 of the time, 8 hours of compressor run time in 24 hours could be offset by about an hour and a half of motor run time.

Add in the other power uses, and maybe 2-3 hours of charge time per day would take care of most situations.

You could also buy a 1000 or 2000 Watt inverter style generator, such as a Honda, and install a larger battery charger, such as I did, that will charge at up to 40 or more amps from the generator's 120 vac output.

The 2000 watt model would also run an air conditioner. How about a blender and some Margaritas?

The other big use might be an inverter to power some other big drain at 120 volts.

While connected to Shore Power, the built in battery charger in the boat will help charge your batteries, but the factory chargers usually only provide 5 or 10 amps per battery, so get a dual voltage refrigerator that will run off 120 vac when on Shore Power and 12 vdc when cruising, so as to let the charger charge the batteries, and the refrigerator take its power directly from the Shore Power connection.

Others will add their 2¢, I'm sure!

(It's late, I hope I haven't made any big omissions!)

Good Luck!

Joe.

[El and Bill]

Tommy -

I'm sure if you have been reading this site for awhile you have read many discussions about the advantages and disadvantages of a refrig on a CD-22. And, you probably also know what I'm going to say before I say it -"Think carefully about adding a refrig - the power demands are high."

We have spent many months on our CD-22 using a nice ice box - easy to use (only disadvantage is adding ice (and that small expense) each time we refuel, and dumping water during refueling) and it makes a great seat with a cushion on top in the cockpit. It ain't the money, it's the advantage of avoiding the electrical complexity. Also, the space used for a refrig is a great food storage space.

Congrats on your decision.

[NewMoon]

Our Norcold 3.1 cubic foot fridge takes 3.5 amps when running, and runs about a third of the time in the PNW. So it uses about 28 amp-hours/day.

If you're charging rate were 14 amps (after keeping the rest of the electrical stuff going) it would take you at least 2 hours of running (actually more, due to inefficiency) to recharge just the amp-hours used by such a fridge.

You might be OK as long as you don't stay at anchor more than one day at a time, and run at planing speed at least 3-4 hours daily, but depending on your traveling pattern and what other electric stuff you run you might be pushing it.

We used a 94 qt Igloo marine cooler on our CD-22, cruising for up to two months at a time.

[Valkyrie]

El and Bill,

Correct me if I am wrong, but once didn't you once have a post that stated that even with your modest electrical use that you had to stay at a marina every four or five days because the alternators of your twin 40's couldn't produce enough power to keep the batteries at operational capacity with your cruising style? I only mention this because it seems to have an application to this thread.

Tommy,

Congrats on your upcoming purchase and welcome to the C-Brats family!

Regards,

Nick
"Valkyrie"

[marvin4239]

Hi Tommy and congratulations on your purchase. On the Norcold versus ice box there's another option to consider depending on how you use your boat. I like you did a lot of reading on this site. I saw that a few had installed Waeco freezer/refrigerator coolers rather than or in addition to the Norcolds. I made a few trips up to 12 days in the beginning when I first purchased my boat with the 94qt factory ice chest and what I found was it was really over kill took up a lot of space even in the motor well mount and added a lot of weight to the stern. Plus the rear factory camper canvas wouldn't work with the cooler in the well. It also made it really hard to get to the swim step (for me). I opted to install a Waeco freezer under the helm seat. It took a little modifications but I'm really happy with the results. It can be used as a freezer or fridge or both and runs on 12V or 120V and automatically switches to 120 when it's available and has a auto shut off to prevent you from running the batteries to low. I keep medical freezer bags and jugs of water frozen in it and if needed use them in a small cooler. It really works well and on a two week trip last fall I was able to load it with enough meat for the entire two weeks. If fishing I could also filet and freeze my catch. It uses about the same power as the Norcold and while trailering I power it from my tow vehicle. My boat sits at the end of a 760' dock and the freezer is always ready to go with ice and cold drinks. I really like it for the way I use my boat. There are pics of the install in my album. If you are undecided I'd use the boat as is to get a better feel of what would suit your needs. I've got two group 24 house batteries and haven't had a problem with running the batteries to low. My engine is a Suzuki 90 with 40 amp alternator so your results may be different.

[BRAZO]

I noticed that you have listed a 2008 C-Dory 22 under your name.

If you have the new Honda 50's EFI, then they produce 22 amps each with 17 (34 for both) amps usable for battery charging.

[Rob & Karen]

I have a question related to this discussion. It is regarding the size of the alternator vs. the size of the battery bank. Les Lampman made the following comment in another post http://www.c-brats.com/viewtopic.php?t=3286&highlight=inverter regarding inverters.

Quote from Les:
In addition, an engine alternator should see no more than 3-times its output (in amps) in battery capacity (in amp-hours). In this example the alternator used to charge a 200 amp-hour battery bank should be no smaller than 66 amps. So if you're choosing the Honda BF135/150 with a 40-amp alternator a 200 amp-hour battery bank is 5 times the capacity of the alternator...not a good situation. The BF135/150 really should be limited to charging about 125 to 160 amp-hours of batterys...about two group 27 batteries. You don't really need to count the starting battery if it isn't being used to supply house power. So you could have one cranking battery and then two Group 27 house batteries (confgured as one bank).

I have a start battery and a 130 amp hour deep cycle house battery with 25 amp alternator on my engine. I had thought about adding a second deep cycle battery, but Les's comments have me wondering if that is really a good idea. By all accounts, Les is extremely knowledgable, so I have no doubt about what he has said. It just seems that several people are using fairly large battery banks with engines no larger than mine.

Any thoughts on this? Thanks.

Rob

[marvin4239]

That makes sense about not overloading the alternator. About two weeks ago I installed a 1000 watt inverter. At the same time I got a 400/800 watt Optimus heater from Northern Tool. I took the boat out and ran the heater on 400 watts from the inverter. I know this was putting a real drain on the batteries and charging circuit but just wanted to see if it was possible for short periods I monitored the house batteries and they seem to be doing okay running like this for 1/2 hour. I then shut down and checked battery voltage after they had rested for 1/2 hour and the battery voltage was good. Don't remember the exact number I think it was 13.2 . On my return trip I tried it on 800 watts for about 15 minutes at around 3,000 RPM and shut the heater down. I powered up and the engine wouldn't run above 4,000 RPM and I figured I might have fried something. After I cruised for about 10 minutes at 4,000 rpm everything was back to normal and it would run up to 5,500 RPM. I don't think I damaged anything but I don't think I'll try that little trick again.

[Sea Wolf]

I read very carefully what Les wrote, and basically agree with him, with the following observations:

1. Most outboards are not made with big enough alternators to allow large inverters to be used within the guidelines stated.

2. Fairly large inverters can be used safely providing 1. the wiring used is adequate, 2. the load on the battery bank is within reason in terms of amperage, 3. the total drain in amp hours is limited carefully to control the total necessary replacement charging load on the charging system, and 4. the voltage drop of the batteries monitored very thoughfully to limit damage to the batteries' life expectancy.

3. If your system is overloading your outboard charging system, get a generator such as a Honda 1000i or 2000i type to take the 120 VAC load directly and/or use to recharge the batteries through a 40 or more amp charger which you will have to add to your system.

4. If you can't deal with the voltage, amperage, Wattage, and Amp-hour calculations, you may not be a good candidate to be fooling around with all this electrical stuff!!! (No criticism intended, seriously. It just is necessary to keep track of what's going on. Perhaps a friend can get you set up, though, and you can then get some guidelines established to stay within safe limits in operating your resulting system.)

5. Whatever you do, try to use the KISS Principle as much as possible! not !!!

Joe.

[marvin4239]

Joe thanks for the comments I understand the electrical part of it and my inverter is installed correctly. Putting the numbers to it a 400 watt load is actually a little much for the alternator 32 amps figuring 100% effiency at 12.5 volts. I think this particular inverter is 85% efficent. I really didn't install the inverter to power the heater but I had read someone on here has been running the same heater from their alternator. Don't remember what engine he had. I thought that was a stretch but I just had to try it. Actually the inverter was one I had for several years and I installed it to power my laptop, neubulizer and cell phone charger. Really overkill for a 1000 watt inverter but since I already had it why not. I checked my house batteries the following day and they read 13.2 volts so I don't think I harmed them but I'm sure prolonged use with the 400 watt load would even with the alternator feeding them. May even toast the alternator. I've been and electrician for 40 years so I can usually figure out this electrical stuff I had to edit this I spelled electrical wrong

[marvin4239]

DP

[Dene]

[Sea Wolf]

Marvin-

That comment was NOT intended for YOU!!! (Should have spoke in the third person, not the second.)

I write my responses for anyone who is reading this thread, now or in the future, to serve as an informational resource.

It's my training as a teacher, I guess! Always lecturing to the class!....

I'm hoping that these discussions go beyond the few writers involved and stay put in the archives for others to research and learn from down the road, though we do seem to do a lot of repeating topics here and there!

Sorry if there was any confusion or misinterpretation, I know you know exactly what you're thinking and doing, at least as much as any of the rest of us! Ha!

Joe.



I just love electrical projects!

[JamesTXSD]

Welcome aboard Tommy,

Exciting times as you narrow your search! As Bill said, "If you have been reading this site for a while..." you probably know that we enjoy our fridge as much as Bill and El like their icebox. We feel that the more comfortable you can make the boat, the more time you will spend on it. Obviously, you can't fit EVERY comfort of home on a small boat, but you have to make some choices. Bill makes a very good point about storage space on these boats. For complete disclosure, we DO have a cooler on our boat (we won it in last years Lighted Boat Parade)... and we use that for additional storage... it's never had ice in it. It's had extra soda in it (before it goes into the fridge), anchor rode, etc. We don't like the mess of melting ice. Our fridge can make just enough Barbie-doll sized ice cubes each day to take care of our drinks, and eliminate the "search for ice."

Different approaches to enjoying your time on the water. Bill and El are exceptional people, and I mean that with the utmost respect. Truth be told, we do take less stuff than we might otherwise, but we will never be comfortable paring down as much as they do. That doesn't make one way or the other wrong; it's good to be able to find what works for you. We have spent up to 5 months in our boat, and find the fridge is part of the equipment that makes it less like camping and more like home. We can easily fit 10 days worth of food in there.

Now, to get back to your original question - do you have enough charging? Again, it depends on your cruising style. If you are going to be running for several hours everyday, I'd be inclined to think probably so. If you are going to be sitting at anchor for several days, you will need to run the motors or use a generator to keep the batteries topped off. How do you see yourselves using the boat?

It sounds like the boat in consideration has a good set up - being able to monitor the battery condition is certainly helpful. Four batteries (assuming one each for starting batteries and two for the house) will serve you well. We run with 3, but have a single 135 hp motor (1 starting battery and 40 amp alternator).

Good luck with the search.

Best wishes,
Jim B.