New Battery System

[lorenzo b]

hi folks
so I've got a 63' steel shrimp boat that I've gutted and rebuilt as a passage maker with a 8/71 Detroit Diesel and a Norternlights 20k genset.

I plan to have a really basic electrical system I can build myself. Freezer, washing machine, small refrigerator -but no air con or water heater.

So far I have 2 8D batteries as my starters and plan to use 4 6v golf carts as my house bank. As I plan to anchor out mostly and maybe move around slowly, I expect to run my gen set a couple of hours a day.

Does that all sound reasonable? Any thoughts?
I'm obviously new to all this.

[btrayfors]

Several things to think about:

1. The 20K genset is a very hefty beast. You'll play hell trying to load it sufficiently with the smallish battery bank you're thinking about.

2. Four 6V golf-cart batteries = 450AH total capacity, of which only about 40-50% is really available. Say, 200AH.

3. You didn't say what kind of frig/freezer you're thinking about. Some of the new 12V systems based on new variable speed Danfoss compressors are quite efficient. Only draw less than 50AH per 24-hour period.

4. What kind of washing machine are you thinking of? 115V??? This could draw some power. What about a dryer?

5. Why not a hot water heater? How are you going to wash your clothes? Washing machines LIKE hot water. Wives, girlfriends, and itinerant mermaids INSIST on abundant hot water. Besides, with your 20A genset you could easily make enough hot water for several boats.

6. I think you'll find that 4 golf-carts won't cut it. You'll need at least six, maybe 8. Fewer if AGM. Partly, this is related to how fast/fully you can recharge them.

7. What kind of battery charger are you thinking about? With a 20KW genset, I'd be thinking about a 90A charger at a minimum, or maybe a couple of 75A Iota chargers slaved together which would give 150A charging capacity. That way, you'd only have to run your generator for about an hour a day to replenish the batteries.

8. You need to map out an energy plan: how much you're likely to use per day, and how you're going to replenish that (recharge the batteries).

Hope this helps a bit,

Bill

[BlueSovereign]

While I have a sailboat (is a 'shrimp boat' one?) I strongly suggest you do a "load demand spreadsheet" to determine both your equipment's daily power (i.e. Amp/hrs) requirements, and only then determine what your battery Amp/hr requirements and charging requiremnts are, both at anchor and when on passage.

Provide me with an email address via pvt message and I'll send you mine to give you some idea of what it looks like.

BTW, I had planned to expand my 440 A/hr bank to 670 A/hrs ... until I did my shreapsheet, and am now installing a 900 A/hr bank, with 200amp charging capability.

William

[lorenzo b]

Thank you Bill and William for your helpful comments.
I think I need to back up here a minute and explain my boat and situation more fully. What I have is a 30 year old steel commercial shrimp boat that I got from a bank for a song when diesel was 4.50 a gl ( just a year ago ) and fishermen were going belly up. My wife and I retired and wanted a boat that could go anywhere, like back to Indonesia, and was large enough to live on in comfort but also very basic and easy and cheap to maintain. Good luck on that one.
What I've done so far is strip it of its fishing gear, fish hold, and cabin, rebuild a larger cabin, relocate bulkheads, reduce the fuel tanks to 3000 gls, swap out the 12/71 for a smaller 8/71, redo the bottom and keel coolers, and put in a bow thruster.
My basic problem with figuring out my electrical is that I'm down here in NEW Iberia La. talking with commercial captains, fishermen, and boat builders. These boats don't have batteries, or if they do, its a small one to start their generators. Mostly they start their engines with compressed air and leave the generator on all the time.

[lorenzo b]

Everything they have in the way of appliances is 115v ac, which I like and plan to do myself. So what I thought I could do is crank up the 20k beast, do a load of laundry, run the freezer and refrigerators, turn on my computer and SSB, make toast, fill my diving tanks, and charge all my batteries for an hour or so twice a day.
I will need batteries that will run my lights and helm electronics and some small inverters to support the refrigeration and of course some music.
So maybe two banks of 4 6v golf-cart? Am I crazy?
my e-mail is Lorenzo@backyards.biz
I've got a blog at The Lorenzo and Joyce scow and travel blog with some pics

Thanks again

[Beausoleil]

Lorenzo,

Small world - I'm originally from St. Martinville! I saw your blog reference to Cypremort Point - I haven't been there in ages.

Not to take this thread off topic, but what are the current depths of the approach to the Port of Iberia canal? I'd like to take Beausoleil up there next year to visit family, but I can't believe that the depths are really 4 1/2 feet. How would they get those floating oil rigs in and out if that were really the case?

Anyway, good luck on the re-fit! Like others have said, if you can sufficiently load up the 20kW genset while it's running, you should be fine. You'll just need to calculate the break-even point between battery-bank size & your daily DC requirements, and the total cost of running the genset (fuel + maintenance). I think Calder has a very good chapter on this in his Electrical and Mechanical Encyclopedia for Sailboats (or whatever it's called).

[btrayfors]

Lorenzo,

No, you're not crazy.

I'm confused. If you're planning to run your frig and freezer on 115V by running your genset 2X daily for an hour, are you also planning to run them via the house batteries/inverter(s) while the genset is not running???

If so, you'll need a LOT of battery and inverter capacity, since 115VAC frigs and freezers draw a lot of current. And, they're not particularly well suited for the cruising lifestyle, since they are generally not very well insulated and are not very efficient in terms of energy usage, compared to modern 12V DC options. This is particularly true in tropical climes (like Indonesia). But, if that's what you've got and are gonna go with it, plan on a larger battery bank and a large inverter that will handle the loads and, particularly, the inrush (starting) current on the compressor motors.

I doubt you'll be running the genset 24/7 on a cruising boat, unless you're prepared for the cost of doing that. It's not only the fuel cost which needs calculating, but also the real overall cost, including rebuilding and servicing and filters and oil and.....etc.

Another thing to think about is redundancy. If you plan to have all 115VAC appliances and to run them on the genset, what will happen when (not if) the genset breaks down?

It's a very long way from New Orleans to Indonesia and some of the ocean passages are several thousand miles each. Lots of fuel, lots of heat, lots of hours...time enough for things to break down.

Bill

[gonesail]

why not go with 4 8D batteries?

[lorenzo b]

large ocean shrimp trawlers drawing 9 to 11 ft come into the port of Iberia up to the Diamond B and Geo shipyards all the time along with large barges. Don't see a lot of sailboats though. Are you moving around on the ICW or do you go out to sea?

[Beausoleil]

Originally Posted by lorenzo b

large ocean shrimp trawlers drawing 9 to 11 ft come into the port of Iberia up to the Diamond B and Geo shipyards all the time along with large barges. Don't see a lot of sailboats though. Are you moving around on the ICW or do you go out to sea?

Out to sea. We just got to Hampton, VA from Port Canaveral, FL, sailing outside, with a stop in Charleston, SC. Left Memorial Day (Monday), and got to Hampton on Saturday. Not an ocean crossing, but a bit of bluewater sailing nonetheless. We'll spend the summer in the Chesapeake, then hopefully head south again in the fall and visit family in LA and TX along the Gulf Coast...

Back in December we met a couple from Thibodeaux while in St. Augustine. They'd purchased a trawler in Maryland and were delivering it to Louisiana. While it's not a former shrimp boat, you still might want to hook up with them. PM me for details if you're interested in contacting them...