[Rhodes22-list] Thermoelectric cooler

The Rhodes 22 Email List rhodes22-list at rhodes22.org
Mon May 18 12:39:38 EDT 2015


Susan,
I will try to answer your question.

No.  The solar panels will not keep up with your cooler forever.  It will
however, keep up for a while.  If you leave it on while on shore without
the suggested charger your batteries will be drained dead in a day or
less.  Maybe longer if you use both batteries.

Here is some Math.

As indicated a typical battery might be 90 Amp-hours capacity.  I often see
products listed with Amps per hour as mentioned.  However there really is
no such thing.  What really should be listed is just plain Amps or
 Amp-hours per hour, which would be an average, assuming your cooler
doesn't run all the time (turning off and on via thermostat like your
fridge).  In hot weather I would assume the worst, in the typical example
mentioned (3-6) I would use 6 Amps.  So in a perfect world one battery
would last 15 hours.

90 amp-hours/6 amps = 15 hours

If your panels are from GB they are probably 15 Watts.  They might be
configured one panel per battery.  Assuming you have your battery selector
set to 1, and saving your other in case you need it for electric start.

1 Panel = 15 Watts (Volt-Amp) / 12 Volts = 1.25 Amps.

You might have clouds and your panel is probably mounted flat and not
pointed directly at the sun, maybe aged, maybe dirty, maybe it is
nighttime.  So 1 Amp would be a very generous assumption.  But to keep the
math easy lets use 1 amp.

6 amps used - 1 amp provided = 5 amps net draw. You are now at
90 amp-hours/5 amps = 18 hours

Now, your battery is also probably not new and won't be able to provide a
full 90 Amp-hours.  Probably much less.  So you could probably double that
time for two batteries and two panels if you don't use any lights, but I
would cut it in half again to account for older batteries.

If you killed a battery dead, turned off your cooler, and left the boat for
the week, to regain the full 90 Amp-hours at the 1 amp of the panel it
would take 90 hours of good sunlight to fully recharge with perfect
efficiency, which is not realistic.  So it would take at about  a week to
recharge (12 hours of sun per day) 90/12=7.5 days.

Also, your panels might only be 5 or 10 watts.  I have just heard other
listers report that they had 15 watt panels.

So, if you have the shore battery charger you can probably use the cooler
for day trips or two.  You can help the situation as you mentioned by
freezing some drinks ahead of time etc.  If you count on electric start I
would keep one battery full.

My only experience with this is I once (about ten years ago) plugged one
into my vehicle the night before a trip so it would be cool.  Instead found
the battery dead and drinks warm. So I checked the math....and returned the
cooler.

-Patrick



On Mon, May 18, 2015 at 6:39 AM, The Rhodes 22 Email List <
rhodes22-list at rhodes22.org> wrote:

> Thanks for that link.  I did look at your project and it is probably a bit
> beyond my capabilities, but it shows what you can do.  I was just trying to
> find a way to get around carrying ice and having to replace it all the
> time.
> I just want to keep drinks cool.  With the thermoelectric cooler, I could
> plug it into shore power when not on the boat and things would be cool when
> I got there.  The other trick is to add frozen bottled water to the cooler
> instead of ice which would help keep things cool if I can't run it off the
> battery.
>
> Susan
>
> -----Original Message-----
> From: rhodes22-list-bounces at rhodes22.org
> [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of The Rhodes 22
> Email
> List
> Sent: Monday, May 18, 2015 1:11 AM
> To: The Rhodes 22 Email List
> Subject: Re: [Rhodes22-list] Thermoelectric cooler
>
> Hi Susan,
>              You have a great boat and a great bunch of people to help you.
> We all were in your position once, really, even Rummy.  Well he might not
> have been up right be he is much better not, or more often. We spend long
> periods on the boat and I faced the same dillema and tried a couple of
> combinations.  I finally setteled on a rebuild of the ice box.  The results
> were very good.  With careful use It keeps a 5# block of ice for 4-5 days
> in
> Chesapeak weather, longer in Canada.  Below is a link to the project.
>
>
> On Sun, May 17, 2015 at 6:45 PM, The Rhodes 22 Email List <
> rhodes22-list at rhodes22.org> wrote:
>
> > You'll need to install a battery charger (if you don't have one
> > already), but shore power makes for a much easier install. Simply plug
> > the charger into one of your available AC outlets and connect to your two
> batteries.
> > Here is an example
> > http://www.amazon.com/Guest-2611A-Battery-Charger-24-Volt/dp/B000NHZV1
> > S
> >
> > With this option, your batteries will charge while you are plugged
> > into shore power.
> >
> > When looking at refrigerators, be sure to look at amount of amps
> > consumed per hour. I think you find most use in the 3-6 amps per hour
> range.
> >
> > As far as your battery capacity, each group 27 battery has about 90
> > amp hours.
> >
> > That's said, I agree with the others. I'd stick with a quality cooler
> > and block ice.
> >
> > Cheers,
> > Ted
> >
> > > On May 17, 2015, at 5:47 PM, The Rhodes 22 Email List <
> > rhodes22-list at rhodes22.org> wrote:
> > >
> > > I asked Stan the same question about my solar panels and batteries
> > > last
> > September when I got my recycled boat and he said shore power does not
> > charge them.
> > >
> > > Robert Weiss
> > > Professor/Director Emeritus, SIUC
> > > Director of Music, 1st U. Methodist Carbondale IL
> > >
> > >> On May 17, 2015, at 3:42 PM, The Rhodes 22 Email List <
> > rhodes22-list at rhodes22.org> wrote:
> > >>
> > >> All your responses have been very helpful, and I would like to know
> > >> if plugging into shore power charges my batteries.  Is that
> > >> standard or
> > how do
> > >> I check that?
> > >>
> > >> Susan
> > >> New Rhodes owner and not very knowledgeable about electrical stuff.
> > >>
> > >> -----Original Message-----
> > >> From: rhodes22-list-bounces at rhodes22.org
> > >> [mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of The Rhodes
> > >> 22
> > Email
> > >> List
> > >> Sent: Sunday, May 17, 2015 1:31 PM
> > >> To: The Rhodes 22 Email List
> > >> Subject: Re: [Rhodes22-list] Thermoelectric cooler
> > >>
> > >> Susan,
> > >>
> > >> Do you plug into shore power to charge batteries when you're not
> > sailing?
> > >>
> > >> Cheers,
> > >> Ted
> > >>
> > >> S/V AIRPOWER
> > >> 1991/2013 R22
> > >> Jacksonville, FL
> > >>
> > >>
> > >>
> > >>>> On May 17, 2015, at 1:18 PM, The Rhodes 22 Email List
> > >>> <rhodes22-list at rhodes22.org> wrote:
> > >>>
> > >>> I am getting my (1986/2000) Rhodes ready for the summer and was
> > thinking
> > >>> about putting a thermoelectric 12 V cooler on the boat so I don't
> > >>> have
> > to
> > >>> worry about replenishing ice all the time.  I have two batteries
> > >>> and
> > two
> > >>> solar panels.  If I left something like this plugged in all the
> > >>> time,
> > >> would
> > >>> it be likely to run my batteries down or would the solar panels be
> > able to
> > >>> keep up with the demand?  I'm not very good with this electrical
> > >>> stuff
> > so
> > >>> looking for advice.
> > >>>
> > >>> Susan
> > >>> Purchased AT EASE from Lee Kuhn last fall and still looking for
> > >>> new
> > name
> > >>>
> > >>> __________________________________________________
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> > >>>
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> > >>
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