Date:         Sat, 4 Aug 2007 08:29:09 -0700
Reply-To:     Michael Elliott <camping.elliott@GMAIL.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Michael Elliott <camping.elliott@GMAIL.COM>
Subject:      Re: Comments wanted on this portable fridge
In-Reply-To:  <46B4899D.1020309@cox.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Thanks, Mark, I couldn't find the current draw for the Coolmatic. Their
power spec was written a little weirdly and I didn't feel comfortable
with it.

So, using the battery demand calculator, we find that if the Coolmatic
runs for one hour at 7 amps, it would consume 7Ah, but let's use the
mfgr's spec of 22% duty cycle @ 86F = 1.5Ah/hour or 37Ah/24-hour period.
Using the 68F duty cycle of 18% we get 1.3Ah/h, or 30Ah over a 24-hour
period.

The Norcold DC0040 draws 2.7A and in hot weather the duty cycle
approaches 50%, so that's 1.4Ah/h (32Ah/24 hours), while at night
(colder than 68F) it's closer to 20% duty cycle, so that's .5Ah/h, or
12Ah/24 hours).

Not exactly apples to apples comparison, but these rough numbers show
that the Coolmatic isn't any kind of breakthrough, efficiency-wise,
compared to the Norcold. They both seem to use the same compressor
technology but the Coolmatic draws more than twice the current when
running.

For the fellow that doesn't want to mount a Norcold, or likes the
portability of the Coolmatic, it could be a good option.


--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR



Mark Drillock typed:
> The "45 watts" spec does not hold up to any close scrutiny. For one
> thing the manufacturers tech specs, well hidden though they seem to be,
> show a 6 or 7 amp draw. I guess that is why they say "average power
> consumption 45 watts". They mean including duty cycle. Divide by 12
> volts and you get over 3Ah.
>
> There is also a magazine review/test showing a Group 24 80Ah battery
> running it for 2 days before low voltage, on a CF-50
>
> Still a tempting product, I may get a CF-50.
>
> Mark
>
>
>
> Michael Elliott wrote:
>> Let's see how much power this thing wants. Time for the Battery Demand
>> Calculator at http://www.altavistaaudio.com/Westy/Vanagon/battcalc.html
>>
>> 45 watts at 12 volts = 3.8Ah if running 100% of the time. Mfgr claims
>> 18% run time @ 68F, 22% @ 86F. Those are .7Ah and .83Ah, respectively.
>>
>> That's amazingly low energy consumption for a cooler.
>>
>> It uses a Danfoss compressor, as does the Norcold DC0040 which we use
>> and which uses quite a bit more energy. Better insulation? Better
>> cooling unit?
>>
>> The compressor used in the Coolmatic is the Danfoss BD35F which is
>> claimed to be 40% more efficient than the older Danfoss BD3. I can't
>> find the model number of the compressor used in the Norcold DC0040, but
>> if it's the same compressor, I would have to see some test results from
>> the Coolmatic to believe their ratings. If it's Danfoss's latest and
>> greatest compressor, their claims might be inflated, see for example
>>
>> http://www.kollmann-marine.com/test8.html
>>
>> which shows test results which look to bust that claim, getting only an
>> 11% reduction in energy consumption.*
>>
>> But hey - this could be a swell refrigerator!
>>
>> -----
>> * Interesting site, they also show that a small fan in a refrigerator
>> increases the efficiency of the refrigerator.
>>
>> --
>> Mike "Rocket J Squirrel" Elliott
>> 71 Type 2: the Wonderbus
>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
>> KG6RCR
>>
>>
>>
>> Frank Condelli typed:
>>
>>> Any comments on this as an extra portable  fridge for the Vanagon
>>> Westy ?
>>> _Click here:  CoolMaticCF-40_
>>> (http://www.sealandsanitation.com/new_page_16.htm)
>>>
>>>
>>> Cheers,
>>>
>>> Frank  Condelli
>>> Almonte, Ontario, Canada
>>> '87 Westy & Lionel Trains (_Collection for sale_
>>> (http://members.aol.com/Fkc43/trainsal.htm) )
>>> _Frank Condelli &  Associates_
>>> (http://members.aol.com/Fkc43/busindex.html)
>>> - Vanagon/Vanagon Westfalia Service in the Ottawa Valley
>>> _Vanagon Stainless Steel Exhaust  Systems_
>>> (http://members.aol.com/Fkc43/stebro.htm)
>>> _BusFusion_ (http://members.aol.com/BusFusion/bfhome.htm)  a VW Camper
>>> camping event, Almonte, ON, June 07 ~ 10,  2007
>>>
>>
>