Question - 9v Battery Heating in simplest circuit

S

sys_spud

Guest
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!
 
On Mon, 20 Oct 2008, sys_spud wrote:

I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!

Huh?
Click to expand...

If it's off, then there will be no current drain from the battery
and thus the battery can't get hot.

Show us what you've done. You should be using only two terminals
on the switch, no matter how many terminals there are.



|--battery+------switch------resistor-----LED---|
| |
|_______________________________________________|

The switch type won't matter one bit, it's an "AC switch" because
that's how it's rated voltage wise, and you are nowhere near the
voltage limit of the switch.

Michael
 
sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.
Click to expand...
The switch should not be connected between +V and GND. When it is
connected this way, the switch is providing a dead short to the battery
when the switch is closed. This results in a very high current coming
from the battery through the switch. You can put a resistor in series
with the switch and LED to limit the current. See below.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?
Click to expand...
Your circuit should have V+ connected to one side of the switch. The
other side of the switch should be connected to one end of a resistor.
THe other end of the resistor should be connected to the LED. The
other side of the LED should connect to GND. When the switch is closed,
there will be current flow through the switch to the resistor and then
to the LED. The resistor should be chosen to limit the LED to the
normal operating current for the LED. A typical red LED will have
about 1.5 volts across it when lit. A typical operating current is
20 milliamps. (If you have the specifications for the LED use the
values that you are given.) The voltage across the resistor will be
9 volts minus the 1.5 volt drop across the LED. This would mean that
the resistor should be (9 - 1.5) / 0.020 = 375 ohms. If you not have
a 375 ohm resistor (it is not a common value), then use the next higer
value that you do have.


A final note: There are several different ways to put this circuit
together. You can change the order of the switch, resistor and LED
without having an effect on the results. The description above is
probably the most common.
 
sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!
Click to expand...
So, if I take the above at face value... in order to switch off the
LED, you're shorting the battery's positive terminal to its negative
terminal, right? I think we've found your problem.
 
On Oct 20, 6:13 pm, Michael Black <et...@ncf.ca> wrote:
On Mon, 20 Oct 2008, sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!

Huh?

If it's off, then there will be no current drain from the battery
and thus the battery can't get hot.

Show us what you've done.  You should be using only two terminals
on the switch, no matter how many terminals there are.

   |--battery+------switch------resistor-----LED---|
   |                                               |
   |_______________________________________________|

The switch type won't matter one bit, it's an "AC switch" because
that's how it's rated voltage wise, and you are nowhere near the
voltage limit of the switch.

   Michael
Click to expand...
The switch only works when connected to +V and GND. I tried it just in-
line on +V and it doesn't work.
So, it's more like this:

| --battery+ --------switch------[optional resistor]-------LED-------|
+V
|
| | |
|___________________ |____________________________ |_______| GND
 
On Oct 20, 6:30 pm, sys_spud <thisoldg...@gmail.com> wrote:
On Oct 20, 6:13 pm, Michael Black <et...@ncf.ca> wrote:



On Mon, 20 Oct 2008, sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!

Huh?

If it's off, then there will be no current drain from the battery
and thus the battery can't get hot.

Show us what you've done.  You should be using only two terminals
on the switch, no matter how many terminals there are.

   |--battery+------switch------resistor-----LED---|
   |                                               |
   |_______________________________________________|

The switch type won't matter one bit, it's an "AC switch" because
that's how it's rated voltage wise, and you are nowhere near the
voltage limit of the switch.

   Michael

The switch only works when connected to +V and GND. I tried it just in-
line on +V and it doesn't work.
So, it's more like this:

| --battery+ --------switch------[optional resistor]-------LED-------|
+V
|
|                                                  |            |
|___________________ |____________________________ |_______| GND
Click to expand...
Well, THAT
 
On Oct 20, 6:30 pm, sys_spud <thisoldg...@gmail.com> wrote:
On Oct 20, 6:13 pm, Michael Black <et...@ncf.ca> wrote:



On Mon, 20 Oct 2008, sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!

Huh?

If it's off, then there will be no current drain from the battery
and thus the battery can't get hot.

Show us what you've done.  You should be using only two terminals
on the switch, no matter how many terminals there are.

   |--battery+------switch------resistor-----LED---|
   |                                               |
   |_______________________________________________|

The switch type won't matter one bit, it's an "AC switch" because
that's how it's rated voltage wise, and you are nowhere near the
voltage limit of the switch.

   Michael

The switch only works when connected to +V and GND. I tried it just in-
line on +V and it doesn't work.
So, it's more like this:

| --battery+ --------switch------[optional resistor]-------LED-------|
+V
|
|                                                  |            |
|___________________ |____________________________ |_______| GND
Click to expand...
Well, THAT didn't format very well! Battery, switch and LED are tied
to GND.
 
On Oct 20, 6:33 pm, Dan Coby <adc...@earthlink.net> wrote:
sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

The switch should not be connected between +V and GND.  When it is
connected this way, the switch is providing a dead short to the battery
when the switch is closed.  This results in a very high current coming
from the battery through the switch.  You can put a resistor in series
with the switch and LED to limit the current.  See below.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Your circuit should have V+ connected to one side of the switch.  The
other side of the switch should be connected to one end of a resistor.
THe other end of the resistor should be connected to the LED.  The
other side of the LED should connect to GND.  When the switch is closed,
there will be current flow through the switch to the resistor and then
to the LED.  The resistor should be chosen to limit the LED to the
normal operating current for the LED.  A typical red LED will have
about 1.5 volts across it when lit.  A typical operating current is
20 milliamps.  (If you have the specifications for the LED use the
values that you are given.)  The voltage across the resistor will be
9 volts minus the 1.5 volt drop across the LED.  This would mean that
the resistor should be (9 - 1.5) / 0.020 = 375 ohms.  If you not have
a 375 ohm resistor (it is not a common value), then use the next higer
value that you do have.

A final note:  There are several different ways to put this circuit
together.  You can change the order of the switch, resistor and LED
without having an effect on the results.  The description above is
probably the most common.
Click to expand...
Thanks VERY much! That was a very thorough and informative answer.
 
On Oct 21, 12:04 pm, sys_spud <thisoldg...@gmail.com> wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!
Click to expand...
You are obviously shorting out the switch (in parallel) - that's BAD.
Your switch must go in series with the LED and resistor.
http://en.wikipedia.org/wiki/Series_and_parallel_circuits

IT had nothing to do with the AC or DC rating of the switch.

Dave.
 
On Mon, 20 Oct 2008 20:22:38 -0700 (PDT), sys_spud
<thisoldgeek@gmail.com> wrote:

On Oct 20, 7:51 pm, d...@manx.misty.com (Don Klipstein) wrote:
In <47f3c57c-b8f7-4508-940d-b0f7b000f...@l42g2000hsc.googlegroups.com>,



sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!

  This is a problem so basic that I am even getting a "Troll-O-Meter"
reading.
  However, for better chance to good for the world including electronics
newbies, I will go along.

  If the switch is across +V amd GND, it will short the battery rather
than interrupt the current through the LED.  I do suspect that is known to
most who know enough to mention the specific abbreviations of +V and GND.
That is why I am getting a "Troll-O-Meter" reading.

  If you are not aware that a resistor (that you did not mention) is
necessary for most LEDs with 9V batteries to an extent to have been
mentioned by you, you should be - lack of mention of resistor contributes
to my "Troll-O-Meter" reading.

  If you need to hurry out and grab a resistor, get 330 ohm 1/2 watt or
470 ohm in either 1/2 watt or 1/4 watt.  But adding a resistor won't solve
the switch problem - the switch needs to interrupt the current supplied to
the LED for "off" rather than short the power supply.

 - Hope I am not doing too much troll feeding,
 - Don Klipstein (d...@misty.com)

Well, don't know how to disprove I'm a troll. I'm an old retired guy
with no experience in electronics or electricity, never taken a class,
and just dove into the deep end of the pool and started swimming. I
have no mentors, no one knowledgeable to talk to, so I'm dependent on
what I learn on the internet, a couple of books and by following and
posting to forums. My gulf of misunderstanding is wide an deep.

My mental model was completely wrong for how a switch works. Yeah, I
know it's among the most basic of concepts, but what can I say... I
try to work things out by myself, analyze, try something else and that
usually clarifies things for me. I don't like to bother people in
forums with trivial questions, I try to find things out myself first.
However in this case, I got so far off on the wrong foot that that
style of debugging wasn't going to work for me.

Anyhow, Thanks to everyone who responded, it was really good info.
Click to expand...
I stuck a 9 volt battery in my pocket a while back, and it managed to
face down into some coins and get shorted. It got HOT! Weird
sensation.

John
 
In <47f3c57c-b8f7-4508-940d-b0f7b000f8bd@l42g2000hsc.googlegroups.com>,
sys_spud wrote:

I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!
Click to expand...
This is a problem so basic that I am even getting a "Troll-O-Meter"
reading.
However, for better chance to good for the world including electronics
newbies, I will go along.

If the switch is across +V amd GND, it will short the battery rather
than interrupt the current through the LED. I do suspect that is known to
most who know enough to mention the specific abbreviations of +V and GND.
That is why I am getting a "Troll-O-Meter" reading.

If you are not aware that a resistor (that you did not mention) is
necessary for most LEDs with 9V batteries to an extent to have been
mentioned by you, you should be - lack of mention of resistor contributes
to my "Troll-O-Meter" reading.

If you need to hurry out and grab a resistor, get 330 ohm 1/2 watt or
470 ohm in either 1/2 watt or 1/4 watt. But adding a resistor won't solve
the switch problem - the switch needs to interrupt the current supplied to
the LED for "off" rather than short the power supply.

- Hope I am not doing too much troll feeding,
- Don Klipstein (don@misty.com)
 
On Oct 20, 7:51 pm, d...@manx.misty.com (Don Klipstein) wrote:
In <47f3c57c-b8f7-4508-940d-b0f7b000f...@l42g2000hsc.googlegroups.com>,



sys_spud wrote:
I'm a noob doing some projects with the arduino development
environment and learning as I go.

I have a problem with a very simple test circuit I made on a
breadboard consisting of a 9v battery, some jumpers, a switch and an
LED. This is obviously a DC circuit but the switch I'm using is a
Radio Shack AC switch rated at 250VAC and 1.5A. The switch is
connected between +V and GND and works with expected results turning
the LED off and on.

However, in the off position, the 9v battery starts to heat up
significantly. Can somebody hazard a guess as to what is going on? Is
it the switch, do I need a DC-rated switch? Or, can I fix this some
way by adding a resistor, capacitor or diode?

Thanks in advance for any insight you can offer!

  This is a problem so basic that I am even getting a "Troll-O-Meter"
reading.
  However, for better chance to good for the world including electronics
newbies, I will go along.

  If the switch is across +V amd GND, it will short the battery rather
than interrupt the current through the LED.  I do suspect that is known to
most who know enough to mention the specific abbreviations of +V and GND.
That is why I am getting a "Troll-O-Meter" reading.

  If you are not aware that a resistor (that you did not mention) is
necessary for most LEDs with 9V batteries to an extent to have been
mentioned by you, you should be - lack of mention of resistor contributes
to my "Troll-O-Meter" reading.

  If you need to hurry out and grab a resistor, get 330 ohm 1/2 watt or
470 ohm in either 1/2 watt or 1/4 watt.  But adding a resistor won't solve
the switch problem - the switch needs to interrupt the current supplied to
the LED for "off" rather than short the power supply.

 - Hope I am not doing too much troll feeding,
 - Don Klipstein (d...@misty.com)
Click to expand...
Well, don't know how to disprove I'm a troll. I'm an old retired guy
with no experience in electronics or electricity, never taken a class,
and just dove into the deep end of the pool and started swimming. I
have no mentors, no one knowledgeable to talk to, so I'm dependent on
what I learn on the internet, a couple of books and by following and
posting to forums. My gulf of misunderstanding is wide an deep.

My mental model was completely wrong for how a switch works. Yeah, I
know it's among the most basic of concepts, but what can I say... I
try to work things out by myself, analyze, try something else and that
usually clarifies things for me. I don't like to bother people in
forums with trivial questions, I try to find things out myself first.
However in this case, I got so far off on the wrong foot that that
style of debugging wasn't going to work for me.

Anyhow, Thanks to everyone who responded, it was really good info.
 
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:8jnqf4t3b92t9lku1j6jurmhkb2q23bpan@4ax.com...
I stuck a 9 volt battery in my pocket a while back, and it managed to
face down into some coins and get shorted. It got HOT! Weird
sensation.
Click to expand...
Just last night I helped someone measure the voltages of a bag full of
assorted batteries, and she had no idea that it could cause problems if the
terminals shorted out. The 9 volt batteries are the worst offenders, with
two closely spaced bare terminals, and it could be tempting for someone to
stick two of them together by mating the male to female.

I have heard of fairly serious burns from Lithium batteries in cell phones
that people have had in their pocket, and it is suggested to carry them in
an external case. I think NiMH batteries are also capable of dangerous
overheating and possibly fire if shorted.

I replaced two AA cells in a flexible head LED flashlight with a couple of
freshly charged NiMH batteries, and I noticed a small arc when I screwed
the end cap on. The LED flashed a little and went out. Then I noticed one
end of the metal canister getting hot. I took it apart and found that the
connection to the flexible stalk was a spring inside a plastic insulator,
but the spring was distorted and somehow shorted to the metal case, and
partially melted the plastic part. I was able to fix it, but I'm keeping
the batteries out just in case it shorts out again. AA cells have as much
as 2500 mAH of energy, and can probably generate enough power to cause a
fire.

Paul
 
On 2008-10-21, Paul E. Schoen <pstech@smart.net> wrote:

I replaced two AA cells in a flexible head LED flashlight with a couple of
freshly charged NiMH batteries, and I noticed a small arc when I screwed
the end cap on. The LED flashed a little and went out. Then I noticed one
end of the metal canister getting hot. I took it apart and found that the
connection to the flexible stalk was a spring inside a plastic insulator,
but the spring was distorted and somehow shorted to the metal case, and
partially melted the plastic part. I was able to fix it, but I'm keeping
the batteries out just in case it shorts out again. AA cells have as much
as 2500 mAH of energy, and can probably generate enough power to cause a
fire.
Click to expand...
yeah,

Baked Beans 420g = 1620 Kj
NiMH AA, 2500mAh = 3000 Kj

Bye.
Jasen
 
"Jasen Betts the Sheep Shagging Fuckwit"

Baked Beans 420g = 1620 Kj
NiMH AA, 2500mAh = 3000 Kj
Click to expand...

** Utter bullshit !!!!!!!!!!!!!!!!!!!

1.2 x 2.5 x 3600 = 10.8 kJ

You fucking idiot !!!!!!!!!!




...... Phil
 
Paul E. Schoen wrote:
"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:8jnqf4t3b92t9lku1j6jurmhkb2q23bpan@4ax.com...
I stuck a 9 volt battery in my pocket a while back, and it managed to
face down into some coins and get shorted. It got HOT! Weird
sensation.

Just last night I helped someone measure the voltages of a bag full of
assorted batteries, and she had no idea that it could cause problems if the
terminals shorted out. The 9 volt batteries are the worst offenders, with
two closely spaced bare terminals, and it could be tempting for someone to
stick two of them together by mating the male to female.

I have heard of fairly serious burns from Lithium batteries in cell phones
that people have had in their pocket, and it is suggested to carry them in
an external case. I think NiMH batteries are also capable of dangerous
overheating and possibly fire if shorted.

I replaced two AA cells in a flexible head LED flashlight with a couple of
freshly charged NiMH batteries, and I noticed a small arc when I screwed
the end cap on. The LED flashed a little and went out. Then I noticed one
end of the metal canister getting hot. I took it apart and found that the
connection to the flexible stalk was a spring inside a plastic insulator,
but the spring was distorted and somehow shorted to the metal case, and
partially melted the plastic part. I was able to fix it, but I'm keeping
the batteries out just in case it shorts out again. AA cells have as much
as 2500 mAH of energy, and can probably generate enough power to cause a
fire.

Paul


NiMH (and NiCd) batteries _are_ capable of dangerous overheating if
Click to expand...
shorted. They won't catch on fire themselves AFAIK, but they'll
certainly burn the insulation right off of the wire that's shorting them
out!

Lithium batteries _will_ (once again, AFIAK) burn directly -- lithium
burns in air, and they're pretty hot by the time they burst open.

When model airplane enthusiasts started using lithium polymer batteries
instead of NiCd to power airplanes, we found out this distinction --
with NiCd you may scorch the inside of a fuselage; with LiPo batteries
you may catch your house on fire.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
 
On Mon, 20 Oct 2008 18:33:29 -0700, sys_spud wrote:
....
Well, THAT didn't format very well! Battery, switch and LED are tied
to GND.
Click to expand...
The switch shouldn't be connected to ground at all. You're shorting out
the battery. Like Michael said, you should use only TWO terminals on the
switch - the one labeled "C" (common) and the one labeled "NO" (normally
open).

To do ascii diagrams, youi need to set your newsreader for fixed font.
I think this is possible even on google.

What you want is this:

Switch
c no
+-----------------o/ o-------[R]------+
| |
[battery] [LED]
| |
+-------------------------------------+

Good Luck!
Rich
 
"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:gdkck8$u22$1@reversiblemaps.ath.cx...
On 2008-10-21, Paul E. Schoen <pstech@smart.net> wrote:

Baked Beans 420g = 1620 Kj
NiMH AA, 2500mAh = 3000 Kj

Bye.
Jasen
Click to expand...
Obviously not.

Carbohydrates are about 5 food calories per gram, so a pound of beans is
about 2250 food calories.
1 food cal = 1 kcal, and times 4.186 joules per cal the beans are 9.2 MJ,
thats megajoules.

The AA bat is about 10 kilojoules total. Thats 10 kJ
Besides, most AA cells are under 2 Ah.

These are trivial calculations, you should check them yourself.
 
bw a écrit :
"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:gdkck8$u22$1@reversiblemaps.ath.cx...
On 2008-10-21, Paul E. Schoen <pstech@smart.net> wrote:

Baked Beans 420g = 1620 Kj
NiMH AA, 2500mAh = 3000 Kj

Bye.
Jasen

Obviously not.

Carbohydrates are about 5 food calories per gram, so a pound of beans is
about 2250 food calories.
1 food cal = 1 kcal, and times 4.186 joules per cal the beans are 9.2 MJ,
thats megajoules.

The AA bat is about 10 kilojoules total. Thats 10 kJ
Besides, most AA cells are under 2 Ah.

These are trivial calculations, you should check them yourself.


And every time I read your post I get 1000 times more!
Click to expand...
check your units please.
POM
 
On 2008-10-22, bw <bwegher@hotmail.com> wrote:
"Jasen Betts" <jasen@xnet.co.nz> wrote in message
news:gdkck8$u22$1@reversiblemaps.ath.cx...
On 2008-10-21, Paul E. Schoen <pstech@smart.net> wrote:

Baked Beans 420g = 1620 Kj
NiMH AA, 2500mAh = 3000 Kj
Click to expand...
yeah, open mouth, insert foot, tell the world, I got the units wrong
too, and after being corrected only a few days ago.

Carbohydrates are about 5 food calories per gram, so a pound of beans is
about 2250 food calories.
Click to expand...
closer to 470, baked beans are mostly water.

1 food cal = 1 kcal, and times 4.186 joules per cal the beans are 9.2 MJ,
thats megajoules.
Click to expand...
the figures are straight from the can, Nutritional energy is measured
in SI units here (the 470 is extrapolated from a different brand of beans
advertised on the web as 105cal/100g)

The AA bat is about 10 kilojoules total. Thats 10 kJ
Besides, most AA cells are under 2 Ah.
Click to expand...
New ones like that are hard to find.
Within reach I had a Sanyo 2.5, Energiser 2.5 and (the oldest one) a Lenmar 2.3,

These are trivial calculations, you should check them yourself.
Click to expand...
yeah, I should have. 10.8kJ is right.

that puts things in perspective
NiMH 10.8kJ/31g = 0.35kJ/g
Beans 1620kJ/420g = 3.8 kJ/g

Beans is over 10 times better (more if dried)
but NiMH is self contained, beans need oxygen.

Bye.
Jasen
 
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