Date: Wed, 21 Sep 2011 08:12:14 -0700
Reply-To: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Subject: Re: Vitrifrigo/Truck Fridge power usage
In-Reply-To: <vanagon%2011092101132890@GERRY.VANAGON.COM>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hey Karl, thanks for the details of your testing. That helps a lot and
now I understand how to interpret your figures. It was the word
"average" in the amperage rating you came up with that I was unclear on.
I interpreted it to mean that one could expect a 2.1 current draw when
the compressor was running on the average, depending on how the
thermostat was set and how hot a day it was. Now I understand you're
providing the average current draw over a period of time.
I don't see the higher current at the start of the compressor run than a
few minutes later, and my ammeter is a good one. Maybe they changed the
design or something.
My apologies if you felt like I was accusing you of BS. That was not my
intent. I was trying to convey that it was from your site that I got the
impression that the compressor drew 2.5A when running, and this led to a
lot of confusion here when I installed the thing and found that it drew
quite a bit more.
--
Jack "Rocket j Squirrel" Elliott
Bend, Ore.
1984 Westfalia. A poor but proud people.
1971 "Ladybug"-brand utility trailer ca. 1972 from a defunct company in
San Clemente, Calif., now repurposed as The Westrailia.
Sent from my kitchen.
On 09/20/2011 10:07 PM, Karl Mullendore wrote:
> Hey folks, if you don't want to take my independent testing for real, do
> your friggin' own test! Would I post BS on my own website? Believe me or
> don't believe me, it doesn't matter - but I don't appreciate the snide comments.
>
> Here are the facts - if they don't fit into your mindset, I don't really
> givadamn. :-)
>
> I tested MY VF C51iAC in mid-summer weather a few years ago. Daytime temps
> during the THREE-DAY test were 80-85 F. night time temps at 65-70 F. The
> thermostat was set on the notch clockwise past vertical. I connected a 12V
> analog clock to the fridge fan wires, so that the clock would accurately
> measure the full time the fridge was running. The clock ran exactly 24 hours
> in a 72-hour period. With me so far? OK. I then connected a very accurate
> amp gauge between the fridge power lead and the power supply. On startup,
> the fridge would vary from 2.8-3.0 amps. As it ran, the amperage would
> slowly drop as low as 2.2. Since the run time far outweighs the startup
> time, I figure the average amp draw to be very close to what VF was claiming
> at the time, 2.5. OK - 2.5 multiplied by 8 hours run time per day = 20
> amp-hours.
>
> Karl
> www.westyventures.com
>
>
>>>> So where did I get the idea that the VF draws about the same as the
>>>> Norcold (which I measured at around 2.5 to 2.8 A?)
>>>>
>>>> MULLENDORE!
>>>>
>>>> From<http://www.westyventures.com/parts.html> : "...the fridge
>>>> operates on 12 or 24 volts ... Current draw on 12 volt is 2.5 amps
>>>> (average) with an average daily usage of 22 amp-hours."
>>>
>>> Don't compare apples and oranges (running current vs. average current).
>>> From the same datasheet I linked, the Vitrifrigo is spec'd at 470 Watts
>>> average daily consumption. Now, Watts are power, not energy, so they're
>>> clearly confused about units. But I'd guess they're really talking about
>>> Watt-hours, which would equate to about a 1.6 Amp average draw (~54%
>>> duty cycle, which over 24 hours would be ~38 Amp-hours).
>>>
>>> No idea what westyventures is talking about, a 2.5 A average draw over
>>> 24 hours would be 60 Amp-hours??? Maybe they mean 2.5 A _nominal_, i.e.
>>> the typical draw when the compressor is running? If it really uses only
>>> 22 Amp-hours typical per day, then perhaps it has much better
>>> insulation/more efficient compressor and a much lower duty cycle? ...or
>>> maybe it's all marketing BS. I doubt a Norcold is twice as efficient as
>>> a Vitrifrigo (or 50% worse?), as the numbers imply.
>>
>> It's all very confusing.
>>
>> Someone on the list needs to put a Norcold and a Vitrofrigo in an oven,
>> say, 80 degrees F, and let them run for 24 hours after adjusting their
>> respective thermostats to achieve the same cabinet temp.
>>
>> I need a grant. With that I can buy the reefers, the white lab coat, the
>> clip board, the test equipment, the big oven, and a blonde lab assistant.
>>
>> -- RJS
| 
