[Sentoa] Domestic power
FFB13 at aol.com
FFB13 at aol.com
Sun Nov 6 08:42:38 EST 2016
the reasons i have a northern light 6k generator in my 32'
and food for thought to some .......
I keep my boat in key biscayne fla.---hot hot hot ..
and i turn on my generator every time i go out .why ?? the weather
need to run my 2 a/c's---
and when i go to Bimini , or the keys ,or bahamas in summer i arrive there
fresh and cool and stay so.
also my refrigerator .. i gave up with the expensive dual (inverters for
battery use and electricity ) refrigerators and just went out and got a
$250.00 refrigerator from sears ...and have had it now for 7 years or so ...my
previous 3 refrigerators with the built in inverter and high price ( over
$2.0 ) did not last as long .
additionally, when i keep the boat behind my house the generator serves
as a back up to my home's electrical panel in case of storms when we may
loose our electricity . ( i had a conversion made to my electrical panel, and
an outside plug placed in my rear wall facing the dock and a 110 foot cable
(very heavy )...)it will give me enough electricity for 2 spare a/c wall
units (not for central air )
lights ,ceiling fans
and i supply my neighbor with electricity for their refrigerator and a few
and of course a complete check list on how to turn it on and connect it to
the panel to prevent damage to others and my house .
32 ft #36
In a message dated 11/6/2016 7:53:59 A.M. Eastern Standard Time,
sentoa at lists.sentoa.org writes:
Date: Sun, 6 Nov 2016 07:53:13 -0500
From: Dave Jones <senojev at aol.com>
To: sentoa at lists.sentoa.org
Cc: dave at tek5systems.com
Subject: Re: [Sentoa] Domestic power
You raise a number of questions with your request for generator advice.
In answer to part of your questions, you need new batteries if you are
sure they are toast.
Should you have a generator? It depends on a number of factors. If you
never leave the dock, a genset does not make sense assuming you have shore
power. If you only travel marina to marina, other than some very hot days, a
genset is not really needed. If you anchor one or two nights at a time, you
can get by without a genset if your battery bank is properly sized -
assuming A/C and a good supply of hot water is not required. If you anchor for
extended periods of time (no engine running), you need some way to charge
your house bank unless you have a huge battery bank. A genset is one way to
achieve this. An alternative is to use solar panels of the right size to keep
your house bank charged or limit its discharge. Relying on running the
main engine at anchor to charge batteries is not good: it will be so lightly
loaded that it will not reach a good operating temperature. The standard
alternator, although rated at 125 amps, for example, is only producing a
fraction of this at low rpm and ideal temperature conditions. Unless it is
converted to external regulation, it does not provide optimal charging
characteristics for a house bank. It is only designed to keep up with the loads you
normally see in an automotive application, such as lighting, heater motor,
You should start your decision making by doing an analysis of what your
power needs really are. There are several ways to do this - the best being
actual data if you have some type of battery monitor so you can measure daily
usage. Failing that, make an estimate of all of the loads on your house
bank and duration to come up with a daily consumption and what it is
projected to be. Plan for the future: are your cruising plans likely to inlclude
the Loop. For example, you run interior lights totaling 96 watts ( or 8 amps
draw) at 12V for two hours a day = 16 amps/day; run stereo drawing 4 amps
for six hours a day = 24 amps/day, etc. Include as many loads as you can
including water pumps. Add in any intermittantly used 120V items such as a
microwave, TV, coffee pot and reduce the consumption to12V ..... a 1200 watt
microwave used for 15 minutes a day uses 25 amps/day via the inverter. Sum
all these loads to arrive at a good approximation of your daily needs.
Based on several years of typical cruising, we use around 200 amps per day from
our house bank.
The load analysis will give you at a good idea of how to size your house
bank. The house bank should not be discharged to less than 50% of its
capacity on a regular basis before recharging. Occasional discharge to less than
50% is OK but should be avoided. Battery life is closely linked to depth of
discharge; the less of a discharge, the longer the life ... almost a
straight line relationship. Another issue with deeper discharges is the amount
of time it takes to recharge the battery bank. If you use 200 amps from a
400 amp bank and your charger is rated at 100 amps, it will take more than 2
hours to charge the bank to 100%: probably close to 2.75 hours. Not
charging the bank to 100% regularly shortens its life significantly. A good rule
of thumb is to size the battery at 4 times your daily needs, i.e. if you use
200 amps per day, the bank should be 800 amp capacity. This means you can
run two days without charging but remember you will have to put that 400
amps back in somehow.
How to put back that 400 amps is another decision point. Disregarding the
engine alternator option, there are only two ways to do this:
* A genset with a large inverter/charger. Do not make the mistake of
getting a stand-alone inverter and relying on the wimpy 40 amp charger
likely installed by the factory.
* Solar or windpower
* A combination of the above
Solar should be given strong consideration for several reasons. It is
relatively inexpensive to buy and install, requires little to no maintenance,
is silent and unobtrusive, and requires little attention. On our 37, I have
two 310 watt panels which would probably fit on a 32 pilot house roof. On a
reasonably clear summer day in the northern US, I can top up my 880 amp
house bank by noon or early afternoon. If I time my use of AC loads, I could
even run the hot water heater for 20 minutes and still make that up by
nightfall. My system ran around $1800 self-installed in one day, The cost was
reduced significantly by taking the energy related tax credit available at
the time (think this has been extended) as the boat qualifies as a second
Wind power is also an option but has some disadvantages such as noise and
can be obtrusive. It does have some advantages including the possibility of
round the clock generation (if there is a wind). Combined with solar it
may be a good combination.
A genset in combination with a large inverter/charger (2500 watt 150A
charger) is the only way to go if you anticipate high longer duration AC needs
such as A/C and electric oven or cooktop. This option is expensive and
takes a significant amount of space. A 5kw genset would be in the ballpark of
$10,000 installed last I heard and may well be more. Add in another $3,500
for the inverter/charger and you are talking big bucks. Depending upon your
engine room layout, the install may be simple or complex if the factory
used the space tradtionally occupied by the genset. If you choose this option,
size the genset appropriately based on your load analysis; underloading
the genset is as bad as underloading the main engine. A 5kw genset would
probably be adequate for your needs. Do not undersize the inverter/charger
(especially the charger side) as you want to have the highest capability
possibility and the incremental cost for the greater output is small.
Your new house bank should be capable of being charged at a higher rate
than any available charger. For Lifeline AGM batteries, they recommend bulk
charging at no less than 0.2 x the bank amp rating, i.e, 80A for a 400 amp
bank, to avoid any loss of life. Charging to 5x capacity is possible with
AGMs. Flooded lead acid batteries should also be charged at a similar minimum
Regarding the use of a genset in an anchorage brought up by another
responder - do not worry! A modern genset with a good sound enclosure and exhaust
system is almost silent a boat length away.
In conclusion, you need to determine what your current and projected needs
are and then design an electrical system to meet those needs. IMHO, a
small genset in combination with a large inverter/charger and solar panels is
the ideal solution.
Hope this helps you decide what to do.
Feel free to email me if you want to discuss anything more.
Sir Tugley Blue
Wintering in Brooklin, ME
From: Al Johnson via Sentoa <sentoa at lists.sentoa.org>
To: David Denu <dave at tek5systems.com>
Cc: Al Johnson <johnson.alan.b at gmail.com>; sentoa
<sentoa at lists.sentoa.org>
Sent: Thu, Nov 3, 2016 10:48 pm
Subject: Re: [Sentoa] Domestic power
>From Al Johnson <johnson.alan.b at gmail.com> To David Denu
<dave at tek5systems.com> Cc sentoa at lists.sentoa.org <sentoa at lists.sentoa.org> Subject Re:
Domestic power Date Thu, 3 Nov 2016 22:47:43 -0400
Have you considered solar panels? A friend just added two panels to his
sailboat (for a bank of four batteries) and has more power than he knows what
to do with. He is also based on Lake Champlain.
Sent from my iPhone
On Nov 3, 2016, at 8:56 PM, David Denu <dave at tek5systems.com> wrote:
It's becoming winter here in Vermont and the Tug is on the hard and
winterized (I hope).
Anyway - my house batteries have morphed into serveral hundred pounds of
useless dead weight. They won't hold a charge more than a few days.
The setup on my boat is like this:
- House batteries two 4D wired in parallel
- dedicated diesel starter battery
- two large-ish (group 24?) batteries in parallel for bow thrust/windlass
That's a lot of batteries.
As it sits, there is no 115v unless connected to shore power. So, I'm
thinking about the option of retrofitting a generator into my NT32. The other
option is new batteries and a decent sized inverter.
Obviously a generator is beaucoup dollars, but we would have all the
modern conveniences (microwave, AC) at anchor.
Anyone know how much of a challenge it is to do the work? Open to other
Sent from a mobile device ...
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