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Soft-start circuit for refrigerator? - Page 2

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Posted by danny burstein on December 13, 2021, 7:00 pm
 
[snippeth]


Here's one which, of course, is no longer available.

My guess [TM] is to look for any model
numbers with an "EB" at the end.

https://www.yamahagenerators.com/EF3000iSEB-p/ef3000iseb.htm  


--  
_____________________________________________________
Knowledge may be power, but communications is the key
             dannyb@panix.com  
[to foil spammers, my address has been double rot-13 encoded]

Posted by Jim Wilkins on December 13, 2021, 9:10 pm
 

[snippeth]


Here's one which, of course, is no longer available.

My guess [TM] is to look for any model
numbers with an "EB" at the end.

https://www.yamahagenerators.com/EF3000iSEB-p/ef3000iseb.htm  
------------------------------

The special cord that enables two inverter Hondas to parallel is simply a  
double jumper with shielded banana plugs on the ends, which connect directly  
to the AC outputs. The only special part is the shield that prevents  
unplugged ends from shorting. It looks to me like any other true sine 120VAC  
source might work.


Posted by bob prohaska on December 13, 2021, 6:46 pm
 
That's an informative if somewhat discouraging link.  


Indeed, nor do I.  

  

The only part of the starting surge that can profitably be suppressed is
the inertial stage, before differential pressure builds. Do your measurements
show a double peak? 600 mS seems too long for motor acceleration alone,
by then I'd think head pressure would be coming up, which is real work
that has to be done.  



My problem isn't urgent enough to justify buying anything just yet. The
fridge I have is a very ordinary Amana ~15 cu ft bottom freezer. If I want
to spend money the most productive thing seems like a current probe and
a scope.  
    

Cost of fuel isn't really an issue. Storage and availability of fuel are
bigger concerns. I'm in the 'burbs, so gas in my vehicles is the easiest
supply. Space is kinda tight, so a second fridge isn't attractive.  


If I'm not mistaken, an EU1000i is generally not considered suitable for a
normal domestic fridge, leaving the EU2200i as the smallest choice. If I  
could figure out how to use an EU1000i with my fridge that would, I think,  
cut fuel consumption nearly in half.  


To a great extent the same is true of me. I acquired a generator to play
with, began to appreciate the very great penalty of appliances that need
high starting currents and started to look for remedies, if they exist.  

It's looking like maybe they don't.  

Thanks for writing!

bob prohaska



Posted by Jim Wilkins on December 13, 2021, 8:54 pm
 
................

The only part of the starting surge that can profitably be suppressed is
the inertial stage, before differential pressure builds. Do your  
measurements
show a double peak? 600 mS seems too long for motor acceleration alone,
by then I'd think head pressure would be coming up, which is real work
that has to be done.

{{{{{{{{{{{{{{{
IIRC the current surge was constant, then very rapidly decayed to the run  
current. The scope is an 80's HP boat anchor with HPIB output I can't save.  
I recently acquired a Tenma DSO that saves screenshots to USB but I haven't  
captured a motor startup with it yet.
}}}}}}}}}}}}}}}

If I'm not mistaken, an EU1000i is generally not considered suitable for a
normal domestic fridge, leaving the EU2200i as the smallest choice. If I
could figure out how to use an EU1000i with my fridge that would, I think,
cut fuel consumption nearly in half.

{{{{{{{{{{{{{{{
I haven't tried running the Magic Chef directly from the EU1000, which  
tripped off at slightly over 1100 Watts. The APC1400 starts the fridge and  
the Honda recharges its battery bank if the sun isn't out. My plan is to run  
the EU1000i  in the driveway while I'm clearing it and the path around the  
back to the shed, then switch to the 2200W HF inverter genny, assuming it  
still works. At my age that could take all day, especially if there are  
ice-covered fallen trees to clear.  The EU1000i is stored in the house empty  
and I've practiced filling and draining it without spilling gas. The carb  
drain hose is a big help there. I made a carb bowl drain screw hose spigot  
for the HF but gas spills while I'm installing it. The issue is fumes  
reaching the wood stove.

Perhaps you could try a 2KW sine inverter with enough battery backup to give  
you time to connect your generator to charge it.  I think some of them can  
sense demand and turn on only when needed. Then you have a good start on a  
solar system. A sine UPS like I have might work but they are usually more  
expensive and recharge the battery slowly at the float voltage, to avoid  
gassing.
}}}}}}}}}}}}}}}


Posted by Jim Wilkins on December 14, 2021, 1:51 pm
 

Does anybody have experience with soft-start circuits for domestic
refrigerators? The goal would be to minimize the size of inverter
or generator needed to run a fridge during an outage.

---------------------------

Stepping back from what should work by spec to what might by experiment, if  
you buy the DSO and current probe you can determine the starting current  
capacity you really need which is the first step toward finding the most  
economical generator that can handle it. I assume it would be an inverter  
model in ECO mode, the problem then is finding one that can respond to the  
surge fast enough, which you might have to determine by test if no one else  
has measured and posted it. I used a clamp-on current probe meant for a DVM,  
with a sense resistor to convert to voltage. For my 80i-400 Fluke specifies  
a shunt resistance of less than 12 Ohms to maintain accuracy. The output is  
1mA/A so 12A gives 120mV thru 10 Ohms. RMS is peak-to-peak times 0.35, if  
the scope can't do that for you.

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29964567/print/true.cfm  
"  it looks like people haven't really done your type of testing on it. Or  
at least uploaded it for viewing."

I loaded my 2200W HF inverter generator to its 19A overload trip with coffee  
pots and a hotplate, with one coffee pot on a Variac to adjust the load  
current. Unlike a compressor motor this mostly resistive load isn't harmed  
by low voltage. I could have set the load to the 12A surge of the small  
fridge and switched it on in ECO mode to see how fast the genny responded.  
If the waveform looks promising you could try the fridge. I'd keep any added  
extension cords short and thick and be ready to pull the plug if the fridge  
current surge doesn't quickly fall to its normal running value.

I didn't do this possibly risky surge test because by then the 2200W model  
had been replaced with an 1800W one, with no explanation why. I didn't want  
to replace a generator that can run my microwave with one that might not.

If my overload simulator performs to spec and burns up the customer's  
product that's his problem, and I've watched it happen. I try not to destroy  
my own stuff, especially the emergency backups which will be irreplaceable  
when needed. I test it to its written limits and then stay below them.

AFAIK HF will accept returns without question, as long as you have drained  
the gas and oil. I don't know other stores' return policies.


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