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Go Back   SailNet Community > On Board > Gear & Maintenance
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  #1  
Old 01-15-2008
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Charging / Battery questions

I am upgrading my charging system and getting conflicting information, so I was hoping to get better input here.

I have a 1981 Gulfstar 39' Sailmaster with a Perkins 4-108. The current charging system has a 50amp alt., Heart 2000R monitor, and a old charger (not sure of the make). There is no inverter. The house batteries are 4 Trojan T-60 6 volts (< 1 year old) for a total of 420 amp hours.

We are planning on cruising the East coast and Florida and spending the non hurricane months in the Bahamas. We will need the ref., Nav instruments, lights, a P.C., stereo, water pressure pump, bilge pump and maybe the hot water heater.

One marine electrician is saying I have enough batteries and need to upgrade to a 75amp Balmar alt. and a Freedom 25 inv/charger.

Another is telling me I need to keep the existing alt. for the starting battery and get a Balmar 95-210 (210 amps) alt. with the Freedom 25 and when the batteries go out go to at least 700 amp hours preferably 100 amp hours.

I was thinking of a Balmar 7-110 with the Freedom 25, the problem is that I will need to up-grade to a 1/2" belt and can't find the pulleys, the 2nd electrician says I can't up-grade to the 1/2" because of water pump side loading. I found a Serpentine belt system for $575 which includes a new water pump, but what if the pump went out while cruising could I find a replacement?

What are you other cruisers using and what suggestions do you have?
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Old 01-15-2008
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Ideally, a bigger altenator would do you better and be more in line with the size of your current house bank.
Whether or not you need to upsize your house bank depends on how many amphours you use per day - your bank at 420 ah is sized for a 120 - 150 amp hour draw per day (low for live on, but not too low) - and that will take your current altenator several hours to replace (it does not put out 50 amphours at idle rpm, and slows down as it reachs full) - there's a lot of formula's for it and i'm sure someone will post them later.
I personally would save the money on a new alternator and engine mods and go with a pair of 100 watt solar panels (600 - 800 installed and wired) - a better, silent, works forever type power source. You can expect to get 70-90 amp hours per day out of 2x100 watt panels properly wired and mounted. A wind generator added on to that would cost 1 - 1.5k, and make it so you seldom need a engine at all.
As to inverter - not on my boat - I carry a small 100w (cell phones and battery recharger) and a 300w that are 12v lighter plug type portables for tv, laptops etc, and for tools a I have a alligator clip 700w inverter- I'm not wanting to put a real inverter on and suck my batteries dry. It also doubles the cost of a good charger.

Edit - I did not note that you have to do the refer as well, if it's engine driven then you have to run the motor anyway - having said that, I'd still go with solar and or wind, it's good to have a backup. I use a propane powered refer/freezer from Dometric - no power draw so for me 120 ah a day is good to go. I've run all week in the chesapeake and only run the engine for a total of 3 hours to catch up on battery charging with my single 100w panel.

Last edited by chucklesR; 01-15-2008 at 12:50 PM.
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Old 01-15-2008
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Unless you plan to upgrade your battery bank, I see no need to get the Balmar 110amp model (which I have) as you will not be wanting to charge at more than 70 amps given wet cell charging parameters of 15% of capacity.
I will assume you will be using 100-125 ah's a day which would mean about 1-2 hours of engine running time per day for charging needs.
Since you are considering the Freedom25, I will futher assume that you need AC power but you will need to throttle back on the bulk charging mode to take proper care of your batteries.
You do KNOW that charging batts via the Perkins is BAD for the engine right? Alternatives at anchor would be Honda Generator, Wind Generator or solar panels...with the cheapest being the Honda. Unless you are going cruising for several years...this is probably your best bet.
I would go with a Balmar 70-80 & ARS5 regulator if you do decide to upgrade the alternator and keep the battery bank the same...
I would trust your mechanic about the side loading of a larger alternator on that Perkins...I have mine on the 4236 and it is still a heck of a load.
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Old 01-15-2008
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BTW, the Dometic propane powered refrigerators can't be used safely on a monohull, since they heel too much.
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Old 01-15-2008
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Went through the same decision process when we cruised with similar alternator and battery bank as you currently have - the only difference with our situation is that we also ran a refer and freezer off the batteries.

My last option, which we eliminated because of the issues with belts and add'l engine wear, was the bigger alternator. We also considered solar panels but they are over-rated in terms of daily output for any of a number of reasons including bad weather, inefficiencies, etc. What we did, and found the majority of other cruisers did also, was to use a small portable gas genset, the most prevalent being the Honda 2000. A collateral benefit was allowing the use of our A/C when the weather required it for comfort.

The drawbacks with a gas genset were considered minimal, the two most often quoted ones being noise and inherent danger with gasoline storage. We found the noise to be equivalent or less than that from operating the engine to recharge and the gasoline issue a moot point as we all had gas powered outboard dinks already. If you go this route, buy a CO monitor which most have already

It comes down to personal preference. My admittedly unscientfic, statistically invalid opinion formed while cruising and talking with other cruisers is that big alternators were the least popular, most expensive and most troublesome alternative.
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Old 01-15-2008
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Ah yessss. It is easy for me to forget that.

SD, did you manage to drain the C cell batteries on that telstar yet, or did you upgrade to the double D cell?
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Actually, Chuckles, I went with the 6V Ni-Cad lantern battery...
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New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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Old 01-15-2008
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Sorry man, just trying to fill in for Gui in his absence....
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Old 01-15-2008
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Well, the first question would be "have you drawn up an energy budget for when you will be cruising?" as opposed to what you are using/doing now.

If you approach this logically, all the answers will fill themselves out and the only real question will be which price range you want to select the answer from.

For instance, with your existing battery bank "for a total of 420 amp hours" and a rule of thumb that you can usuaully safely charge batteries at 1/5th of their rating (i.e. 80+Amp charge rate) over five hours, your existing battery bank would call for an 80-85 Amp alternator for efficient charging, plus naother 10-15% for charging losses....but since battery banks get much better life when discharged only to the 50% level, you can get all the power you need from a 45-50A alernator, and still recharge your batteries in the shortest "safe" time. That's also assuming you have an external marine regulator, because the ones built into alternators are designed for cars, running all day and not OVER charging the batteries. Their logic cuts output very quickly--and won't charge deep cycle batteries properly without extensive hours.

So for what you've got...an external alternator might be the only upgrade you need. And as Balmar will tell you, once you get over 80A capacity, you cross into the land where you need either double belts, or a ribbed belt, and then you may need a pillow block to offset the load on the engine bearings. Cross that 80A line and your expenses and installation JUMP. For power that you will never need without a bigger battery bank.

But back to question #1: What will your energy budget be while cruising? Do you want an inverter that can occasionally power a hair dryer (1600 watts these days!) or just an electric drill or saw? (400-1000W)

With a 39' boat you have room for solar or a wind generator, there are threads about the pros/cons of each. Solar is a longterm investment--you've got to save a lot of fuel to pay for the installation, so just taking a year off may not return the investment.

One of the big hogs in the energy budget can be the masthead/nav lights, and paying the stiff fees for LED replacements can often make good sense because of the charging time and battery capacity you'll be saving.

But, you can't tell without pencilling in an energy budget. Where you need to guess, write down a "probably" and a "maximum" number, that's enough to start with.
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Old 01-15-2008
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The alternator you get really depends on how large your battery bank is and what type of batteries it is made up of. AGM batteries can tolerate a much higher charge acceptance level, so if your bank consists of AGM batteries, you can probably go with a larger alternator than if you had wet-cell batteries.

That said, you really do need to create a realistic electrical budget, based on what you will be using, as HS has pointed out. Your battery bank should be 2-3 times the use between charging. BTW, whatever number you come up with for your daily budget, you'll probably want to add 15-20% to that number to come up with the real usage... since often an electrical budget will under-estimate certain power requirements. For instance, when you're looking at the refrigerator, it will be less efficient in hotter climates, so if you're headed off to the tropics... it will be running more often than you think.

For instance, if you have calculated a daily usage budget 70 amp-hours... you might want to use an adjusted figure of 80 amp-hours daily. If you want to go three days between charging the batteries, you'd have a total use of 240 amp-hours and would want a 500-750 amp-hour battery bank.

Certain areas, it makes sense to spend the extra money for LED-based lights. An LED-based masthead anchor/tricolor light is a wise idea since an anchor light or tricolor is one of the navigation lights you'll be using most often, and it will save you quite a bit of electricity. But, another, often overlooked advantage of an LED-based masthead light is their durability and longevity—which often means lower maintenance and fewer trips up the mast to replace bulbs.
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You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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