Strange? as voltage drops amps draw drops???

[John Smith]

I Was doing some testing today in my camper trailer.
I hooked up a CT 800 watt digital inverter and pluged in a trouble light
with a 9 watt ultra mini CF rated at 9 watts. My 12 volt lead acid was
at 12.5 volts. The draw was 1.2 amps on the DC side.........as the
voltage dropped down to about 11.5 the DC amps draw went down to about
0.8 amps. The reverse of what I expected??? The voltage on the AC side
of the inverter stayed at a constant 117 volts. Any thoughts anyone?

Does any one no how the circuit works inside the base of CF
lighting...IE does it take the AC and rectifie it into DC?

 

[John Smith]

Amp clamp

What were you measuring the DC current with?

 

[John Smith]

My conclusion is that the CF bulbs like the MSW. Has anyone looked inside
the base of a CF to see if one could be hotwired for direct DC?
Dont tell the world about these amazing spiral bulbs....if everybody
switched the power companys will just have to raise the price of power to
make up thier loss LOL.
Where I live the bulbs just took another 1/3 price drop down to about 2 CDN
bucks a piece. Judging by my power bills we are saving about 1000 kwh a
month off the grid and maybe more since we swithced to whole house CF. Got
four teens that don't know what off is on a switch.
Another question is do those double fourty watt four foot flourecent tubes
draw more than CF's for the same amount of light with the CF. I have one
quad and 5 double fixtures to replace yet. My 12 volt mini Flourecnt draws
2.2 amps compared to about .8 on the inverter with on CF.

Why to you think that the inverter is working harder just because the fan
is on?
If its working harder it should be drawing more from the bank......maybe it
is a cheap temp monitor inside....probably does not even monitor temp at
all. It maybe only looking at the input dc and watts out to determine when
the fan is on? Try freezing the inverter

 

[Jim Baber]

Jim wrote:

"Got four teens that don't know what off is on a switch."

Don't feel bad, we've got a 21 year old that we let live here for free,
pay for his college, bought a grand worth of tires for his Jeep, don't
complain about all of the missing condiments that somehow disappear,
don't complain because he apparently doesn't know the difference
between a pot and pan and where to put them away. Oh, yeah, it's
Easter, his mother is sick as a dog and he called her "worthless" this
morning.

I've got a 33 year old who got mad at her landlord 3 months ago and
moved back home until she could get a couple of thousand together (first
and last you know) and find a house to share with a friend. This is not
to mention my 31 year old son who brought his significant other with him
when he moved back home last November. My wife and I had gotten used to
our comfortable quiet coexistence with our 130 pound over aged puppy (a
6 year old Akita) over the prior 5 years. Now we have a house full once
again. And some of you may wonder why I worry about my power bill?

I sympathize with the beemer, but 3 extra adults are worse than 4 teens,
the teens at least sleep more the lights around here are still on at 2-3
AM, and the washer and dryer seem to run continually. Not to mention
there is frequently 3 or 4 separate meals prepared for each mealtime
because of personal preferences.

The amp drop with voltage drop question is interesting, I have noticed
my own CFLs seem to take longer to come to their full lumen output the
older they get, and I wonder, if this is a symptom of the same
situation. I haven't tried to measure the drops on mine, I'm too busy
turning off the lights.

I wouldn't want to freeze the inverter - could crack something when it
heats up.

I assume that the inverter is using a lower voltage to create the 110
thus working harder. I'm looking forward to finding out if it's also
using a lower amp draw at the same time - probably not but the drain
rate off the bank does drop off as it gets to the 60% discharge depth.

Max
http://www.northernmichigansolar.com

--
Jim Baber
Email [email protected]
1350 W Mesa Ave.
Fresno CA, 93711
(559) 435-9068
(559) 905-2204 (Verizon IN cellphone (to other Verizon IN accounts))
See 10kW grid tied solar system at "http://www.baber.org/solarpanels.jpg"
See solar system production data at "http://www.baber.org/solar_status.htm"

 

[Ashley Clarke]

John, during my testing last winter, I noticed something fairly
similar. What I found is that my inverter (I can only speak to my set
up) as the bank voltage drops uses slightly less amps from the bank,
however the cooling fan in the unit runs continous at load which
indicates it is working harder...

Almost definately a heating problem causing high resistance somewhere.
It could be in the Battery Bank itself or just a main connecting wire?
More than likely before the inverter.

 

[Me]

I've got a 33 year old who got mad at her landlord 3 months ago and
moved back home until she could get a couple of thousand together (first
and last you know) and find a house to share with a friend. This is not
to mention my 31 year old son who brought his significant other with him
when he moved back home last November. My wife and I had gotten used to
our comfortable quiet coexistence with our 130 pound over aged puppy (a
6 year old Akita) over the prior 5 years. Now we have a house full once
again. And some of you may wonder why I worry about my power bill?

Your problem is that you were to nice to them as Teenagers, and they
still think they are.....You just weren't Mean enough to them, so that
at their 18th birthday, they took the presents and RAN, as fast and as
far as possible....... Then after they turned 23 or so....and had LEARNED
enough to actually live on their own, they could come back for
Thanksgiving, Christmas, and Easter.......

You guys got to LEARN, that once these kids move away, they only get to
come back once, after that it is "Stop by for a visit but plan on
leaving in a day or two", UNLESS you got Grandkids, and then it is out
by midnight.....but feel free to let GrandMa babysit as long as you
promise to come get them before MIDNIGHT....and we can SPOIL them Rotten,
fill them up with Sugar, tell them all the things you did as a child,
and still you MUST pick them up by MIDNIGHT....

Me been there, done that, and GrandMa still sets
the RULES... Midnight.... Right?

 

[Malc]

Yo John... don't amp clamps read AC current?

Not necessarily. It could have a Hall effect device in it.

 

[Malc]

Your problem is that you were to nice to them as Teenagers, and they
still think they are.....You just weren't Mean enough to them, so that
at their 18th birthday, they took the presents and RAN, as fast and as
far as possible....... Then after they turned 23 or so....and had LEARNED
enough to actually live on their own, they could come back for
Thanksgiving, Christmas, and Easter.......

I've told my kids that just as Homer Simpson says, "Once you're 18 you're
out the door."

 

[John Smith]

YA I guess they do???
And mine reads DC as well...mind you you gotta rotate the switch to the
DC- position and when reading Ac back to Amps~..........lo and behold
thanks for the hot tip by jesus.

 

[John Smith]

NO really! All along I thought it was the moons gravity and the neighbours
dc viberator that I was compensating for.

 

[sylvan butler]

why this happens. I would thing that an inverter would draw higher amps
at lower voltages.

Yup.

If output load on the inverter is constant (measure voltage and amps
while powering a pure resistive load) then the input power would remain
constant IFF the inverter efficiency remains constant.

I suspect that when input power decreases, your inverters output power
is also decreasing.

sdb

 

[sylvan butler]

Nope, constant. I have a meter on the output during my tests to see if
anything hinky (I love that word) happens as the bank draws down.

Well, unless you want to start arguing that your inverter violates the
laws of physics or is pulling zero point energy from the ether, you are
missing something. If the input power decreases the output power must
also decrease. Doesn't matter what you think your meter is telling you.

It takes four good measures at near the the same moment in time to do
this... input voltage, input current, output voltage, output current.
And since the output is A.C., it has to be a nearly pure resistive load.

sdb

 

[You]

Well, unless you want to start arguing that your inverter violates the
laws of physics or is pulling zero point energy from the ether, you are
missing something. If the input power decreases the output power must
also decrease. Doesn't matter what you think your meter is telling you.

It takes four good measures at near the the same moment in time to do
this... input voltage, input current, output voltage, output current.
And since the output is A.C., it has to be a nearly pure resistive load.

sdb

time for you'all to drag out the old Tek Dual Trace Scope and really
"SEE" what is going on. Lock one Trace to the output waveform voltage
probe, and lock the second to a current probe. Look at waveform, power
factor, ect. and make some better judgements of the situation.......

 

[sylvan butler]

time for you'all to drag out the old Tek Dual Trace Scope and really
"SEE" what is going on. Lock one Trace to the output waveform voltage

Yup. (Well, I've got an old HP 'scope, but yeah.

sdb