Battery Bank

wxt8981 · Jan 23, 2006

Hi Roger;
I keep 2 batteries for the engine with a switch where I can
use #1 or #2, or both together. I have a third battery
wired for only the interior. I 'used' to have solar, but it
gave up (and I'm thinking to get a new panel). Right now I
don't do any extensive cruising, so I get by with what I
have. I have a charger, again wired to charge #1 and #2, or
#3. But I have a main-disconnect for positive AND negative.
That assures me of avoiding any electrolysis.
Wilhelm, V-257

bobnlesafloat · Jan 25, 2006

Hi Roger,

Lesley & I cruise full time on Spring Fever and organise our sparks: -

We have an isolated 55 amp/hour battery solely for the engine, plus two 85 amp/hour liesure batteries from which all other current is drawn, the latter have an off/b1/b2/both switch wired in, but to be honest it\'s either both or neither, so they\'re effectively used as a single battery.

Since the dynostart charging/starting element of the solenoid died a couple of years ago, the dyno is now a starter only, with all three batteries charging from the alternator. This isn\'t the standard 35 amp/hr unit, but a 65 amp/hr one off which came off a Volkswagen car (polo I think, though it may\'ve been a Golf) it\'s exactly the same size and other than swapping the belt pulley over was a straight exchange. We\'ve also got one of those smart regulators fitted, though other than lookng pretty, I\'m not sure if it does anything (voltage tests whilst charging seem unaffected whether it\'s switched on or off). It\'s a very simple system, insofar as we start the engine, un-isolate the starter battery so that it charges, then after 30 - 45 minutes we isolate it again and leave it off until next time we need to start up. we also have a cheap 6 or 8 amp car battery charger which we connect whenever shore power is available.

Up until this summer when we reached the Med. we always reckoned that running the engine for 45-60 minutes a day was enough to keep us topped up and that we could safely sit at anchor for 48 - 60 hours without a recharge. this summer, despite new batteries, the daily charge requirement has reached 1.5 - 2 hours a day, with a maximum 24 - 36 hours without charging. We\'re putting this down to higher water/air temperatures making the fridge draw too high and hope to help matters by reducing the size/inceasing the insulation to our fridge (it is a fairly big one). Also we\'re going to invest in a 2-stroke suitcase generator, as we can by one for £100 and it has a built in battery charger, the idea is that we can run this for a couple of hours each day, rather than the engine and hopefully improve things by around 20%.

This decision was made after polling lots of other livaboards about alternative energy sources and getting the following results: -

A solar panel set-p would cost us £6-700 and probably improve things by 25-30%

A wind generator would probably cost nearer £900 for a similar gain

Towed water generators are a complete waste of money, we came across five people with them and all were willing to sell theirs to us for half the price new.

Hope this helps

Bob carlisle.

rogervjohnson <rogervjohnson@...> wrote:
Hello All - I\'m curious as to the best way to electrically power your
boat. Do you have a battery bank (of two or more combined batteries),
or do you have one specific battery as your house battery and another
to start your inboard?

And what\'s the best way (most reliable) to recharge the aforementioned
when under sail for extended periods? Wind generator? Water
generator? Solar?

Thanks much for your help and advice!
Roger

millerkm81 · Jan 25, 2006

Hi Roger,

I've been in the process of researching the very same question as my wife and I are getting
ready to cast off our lines this coming November for an extended cruise of the
Caribbean. Our solution is a 220 AmpHour deep cycle battery bank for the house loads
and a separate isolated starting battery. These are charged by an Aerogen 4 wind
generator, a 40 amp (Beta) alternator, and a small solar panel. The second part of the
solution is that we are planning on keeping our daily loads very small. We are not going to
have refrigiration, or AC. So why such a large battery bank? I can refer you to Nigel
Calder's Cruising Handbook, for the logic, but basically, you want to limit the discharge of
your batteries to 30% of their total capacity (for a 200 AH battery bank this would be 60
AH). While the house and starting batteries are isolated when discharged, Blue Sea
Systems has a battery combined that automatically combines the two banks when there is
a charging current available. Thus, the starting battery is always fully charged.

As for the best way to charge your batteries while being "out there" there seems to be a
consensus that it depends on where your are cruising--and what your tolerance is for
running your engine. In the Caribbean, where the trade winds provide a steady 15-20 kts.
of wind on most days, a wind generator makes a lot of sense. We hope to be able to get
by relying only on wind and solar energy, and the occasional full charge from the engine
while motorsailing.

Happy sailing!

Hans Ericsson-Whisper

alan_critchlow · Jan 25, 2006

Hello, I seperated our batteries into two banks. It worked fine as we
motored a lot to get to Florida. Once there, our house battery would
last about 2 days. I went to SALT in Marathon, Boot Key to discuss
this. He was not concerned about a seperate bank for the motor. He
wanted as much battery capacity in a single bank as possible. Just
monitor the voltmeter and make sure it does not go below 12 volts.
This is about half charged. He also suggested a wind generator.

I have two AGM batteres of approximately 180 amp hours together. We
are using a fridge/freezer of 2 cubic feet. It performed as
advertized. I am very pleased. We found our laptop computer a bigger
draw on electricity. We tried LEDs for lighting but the models we
bought were not bright enough. Although the LED running lights are
good.

Alan & Felicity

Battery Bank

rogervjohnson

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wxt8981

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bobnlesafloat

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millerkm81

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alan_critchlow

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