Battery DIS-charge information ?

I just plug mine in a it goes until I unplug it or turn it off. Other things to do apart from measure my battery voltage when running my fridge....

"fully charged 12.66v"?? When I went to trade school a charged battery was 12.8 or above. However, why would you expect 100% recovery of the batteries charge state after using power for 14 hours? Or perhaps you were anticipating the result, but would like a comparison of another battery brand? Recovery time would best be measured by recharging the batteries to the same specific gravity level that they started at and noting the time to do this. As the battery ages, this time, naturally will extend to the point where it cannot recharge at all. In other words, you have reached the practical life span of the battery.

G'day Mainey,

I can feel another big debate coming on here!!

Ron

Mainey

So at the end of this test you know the battery will last 14 hours, with an empty fridge and door open. Call this the minimum it will last in real use, as in real use it will have some contents & the door will be shut. But to draw any conclusions as to how long it will last in normal use is very difficult.

It would be more realistic to do the test with it say half full and the door shut and test how long it can last then. This would give you a more realistic test.

Alan

Mainey

You are serious? There's no such thing as a free lunch.
Collyn

Sounds to me like your batteries are in good nick.
But they'll never regain their 12.66v without some energy being put back in- as CR said are you serious??
Depending on battery type, temp, etc around 12.6-12.7v is pretty full.
12.49v 1 hour after discharge indicates to me batteries are probably 75% full.
BUT voltage is a very poor indicator of state of charge, especially till they have sat for preferably 24 hours- no charge OR discharge, so it's not an ideal way to try to ascertain state of charge. (You'll even get variations on "identical" batteries)
Cheers

Mainey
By the comment that the voltage MAY not get back up etc after subtracting from it the considerable energy required to run a fridge (with lid open or not) for many hours and finding rested battery voltage lower than before.

I an genuinely puzzled by the posting. Have I and others misunderstood what you are saying?
Collyn Rivers

What did I tell you eh?

LOL

Ron

Mainey
I now understand what you are seeking to do.

There are however quite a few problems in the method used.

Firstly I think you are assuming (as are most of the respondents) that an open chest fridge will use a lot more energy than if closed. It is likely to use more - but necessarily that much more. This is because all that is being cooled is air, and this requires only very small amounts of energy. Cold air falls and hot air rises - so there is not that much heat transfer either. (That's why Coles can have open chest fridges without pulling all the wires out of the local power station. The glass slides on ice-cream fridges are mostly to stop rug rats sticking their grotty little fingers into the merchandise!).

The voltage drop related to consumption also includes the voltage drop between battery and fridge - and hence we do not know much of the energy used is fridge consumption - or heating up whatever bit of Oz you live in via cord losses.

We have no idea of the ambient temperature, nor changes in that temperature, nor of the the themostat setting of the fridge, nor the temperature at the bottom of that fridge.

In other words there are so many independent and interdependant variables that the experiment really has no meaning.

A more meaningful experiment would be have the fridge loaded with a few litres of water (at a known insertion temperature) with the lid closed. A constant load of about 5% of the batteries total Ah capacity. An ammeter monitoring current drawn and a voltmeter monitoring the voltage directly across the fridge (which ideally would be within 0.1% of battery voltage. There's probably little you could about keeping the ambient temperature stable - but if this could be recorded every hour or so one can make a fairly accurate mathematical correction (energy used increases by approx 5% for every 1 degree C increase).

Sorry to seem such a wet blanket re what you are doing - but results based on hairy methodology become next month's website folklaw!
Collyn Rivers

Wow !

What amps does that fridge draw again ?

14 Hours door open, was the thermostat set at room temperature ?

Helloooo ! Lights on but nobody home !

10,9,8,7,...........

This should be good :-))))))

Sounds Like a email I just received...

Last weekend I saw something at Larry's Pistol & Pawn Shop that sparked my
interest. The occasion was our 22nd anniversary and I was looking for a
little something extra for my wife Toni. What I came across was a
100,000-volt, pocket/purse-sized taser. The effects of the taser were
supposed to be short lived, with no long-term adverse affect on your
assailant, allowing her adequate time to retreat to safety... WAY TOO COOL!

Long story short, I bought the device and brought it home. I loaded two
triple-A batteries in the darn thing and pushed the button. Nothing! I was
disappointed. I learned, however, that if I pushed the button AND pressed it
against a metal surface at the same time; I'd get the blue arc of
electricity darting back and forth between the prongs.Awesome!!!
Unfortunately, I have yet to explain to Toni what that burn spot is on the
face of her microwave.

Okay, so I was home alone with this new toy, thinking to myself that it
couldn't be all that bad with only two triple-A batteries, right? There I
sat in my recliner, my cat Gracie looking on intently (trusting little soul)
while I was reading the directions and thinking that I really needed to try
this thing out on a flesh & blood moving target. I must admit I thought
about zapping Gracie (for a fraction of a second) and thought better of it.
She is such a sweet cat. But, if I was going to give this thing to my wife
to protect herself against a mugger, I did want some assurance that it would
work as advertised. Am I wrong?

So, there I sat in a pair of shorts and a tank top with my reading glasses
perched delicately on the bridge of my nose, directions in one hand, taser
in another. The directions said that a one-second burst would shock and
disorient your assailant; a two-second burst was supposed to cause muscle
spasms and a major loss of bodily control; a three-second burst would
purportedly make your assailant flop on the ground like a fish out of water.
Any burst longer than three seconds would be wasting the batteries.All the
while I'm looking at this little device measuring about 5" long, less than
3/4 inch in circumference; pretty cute really and loaded with two itsy,
bitsy triple-A batteries) thinking to myself, "no possible way!"What
happened next is almost beyond description, but I'll do my best...

I'm sitting there alone, Gracie looking on with her head thingyed to one
side as if to say, "don't do it master," reasoning that a one-second burst
from such a tiny little ole thing couldn't hurt all that bad... I decided to
give myself a one-second burst just for the heck of it. I touched the prongs
to my naked thigh, pushed the button, and HOLY MOTHER, WEAPONS OF MASS
DESTRUCTION!@&$!%!@*!!!I'm pretty sure Jessie Ventura ran in through the
side door, picked me up in the recliner, then body slammed us both on the
carpet, over and over and over again. I vaguely recall waking up on my side
in the fetal position, with tears in my eyes, body soaking wet, both nipples
on fire, testicles nowhere to be found, with my left arm tucked under my
body in the oddest position, and a tingling in my legs.

The cat was standing over me making meowing sounds I had never heard before,
licking my face, undoubtedly thinking, "do it again, do it again!"Note: If
you ever feel compelled to "mug" yourself with a taser, one note of caution:
there is no such thing as a one-second burst when you zap yourself. You will
not let go of that thing until it is dislodged from your hand by a violent
thrashing about on the floor. A three second burst would be considered
conservative. SON-OF-A-*&^%* that hurt like hell!!!

A minute or so later (I can't be sure, as time was a relative thing at that
point), collected my wits (what little I had left), sat up and surveyed the
landscape. My bent reading glasses were on the mantel of the fireplace. How
did they up get there? My triceps, right thigh and both nipples were still
twitching. My face felt like it had been shot up with Novocaine, and my
bottom lip weighed 88 lbs. I'm still looking for my testicles! I'm offering
a significant reward for their safe return. Still in shock.Eric

Regards Derek from ABR www.sidewinder.com.au

In reality jokes aside... LOL ... Still love that Taser joke !!

2x 80ah = 160ah

Fridge ?? Like I said what is the amp draw but if we take a average of 3 amps running with the silly door open we should see those batteries die in about 53 hours give or take ?? The voltage recovery after doing such a silly thing for 14 hours is quite normal for 160 ah that has only used 42ah or less. 25 % down from a full charge on a charger.

Hope you had at least a few coldies in the other fridge while this was going on.

Nobody can give you any accurate figures on your lab test at this stage but I will keep reading.

Regards Derek.

A brief comment on the posting - '8-amps, not a very efficient fridge then'.

This can be true - but it does not necessarily follow that it is.

Fridges cycle on and off, and the ratio of 'on' time to 'off' time affects the overall current drawn. Thus a fridge that _Affordable_Storage_Drawers.aspx 2.5 amps but is 'on' for a total of eight hours a day (20 Ah/day) has the same daily draw as another that _Affordable_Storage_Drawers.aspx 2.0 amps but is on for ten (20 Ah/day).

The main determinant is thermal mass. Heavier fridges are likely to have longer cycle times. This is desirable as the start-up current of a fridge compressor motor is much greater than its running current. Because of this a motor drawing a steady current of 2 amps but cycling on and off every minute or two (in a 1:1 ratio) may well draw a lot more curent in an hour than one drawing 3 amps but cycling on and off for five minutes (at the same 1:1 ratio).

This happens. An Autofridge _Affordable_Storage_Drawers.aspx 5-6 amps. But if used in the usual pumped down mode it is typically on for only four hours a day (20-24 Ah). A generally similar-sized biggish Engel _Affordable_Storage_Drawers.aspx about 3.5 amps but, (in similar usage) is on for eight to nine hours (28 Ah/day min).

To save people disputing the above example - I have two such fridges (73-litre Autofridge and new 60-litre Engel) - and I quote what they actually do. Both are great fridges, but with different characteristics. The Autofridge uses less energy but only if in more or less permanantly use (which ours is) because it takes quite a few hours to drop from (say) 30 degrees C to 4 degrees C.

The Engel however will drop from 35 degrees to 7 degrees during the 30-minute shlepp into Broome. It uses a fair bit more power in doing so but readily lends itself to turning on and off only for short times if so needed.

Once at the same operating temperature the Autofridge still has a fair edge, but is less convenient to use as it must be turned off and on morning and evening (they are typically on from 7-9 am - and if needed 5-7 pm - less if in cooler areas).

The present marketing emphasis on low current steady state consumption is little more than hype. Except that heavier cable is needed, it make little odds whether a fridge _Affordable_Storage_Drawers.aspx 10 amps for three hours a day - or 2 amps for 15 hours a day.

Watch those low-amps claims - you are simply being suckered! It's totally meaningless unless you know the average daily draw.
Collyn Rivers