Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
Thanks.
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
Thanks.
You could just use one of the rapid table calculators (google) and
figure out the time yourself.
https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html
A lot will, of course, depend on the efficiency of the current limiter
to power the LEDs. The formulas will only give you run-time with 100%
efficient current limiting.
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
Thanks.
You could just use one of the rapid table calculators (google) and
figure out the time yourself.
https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html
A lot will, of course, depend on the efficiency of the current limiter
to power the LEDs. The formulas will only give you run-time with 100%
efficient current limiting.
I did not see any calculation that determines run time.
I have run leds for 45 minutes and remaining voltage is 11.93 volts.
Andy
There you go then. Just measure the run time.
On Sun, 21 Apr 2019 04:46:56 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
Thanks.
You could just use one of the rapid table calculators (google) and
figure out the time yourself.
https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html
A lot will, of course, depend on the efficiency of the current limiter
to power the LEDs. The formulas will only give you run-time with 100%
efficient current limiting.
I did not see any calculation that determines run time.
I have run leds for 45 minutes and remaining voltage is 11.93 volts.
Andy
There you go then. Just measure the run time.
There's nothing that will give you approximate run times based on the
information you provide. You can get a theoretical run time from
knowing the watts you are dissipating in the leds and dividing that
into the watt-hours you can expect from the battery, the voltage and
current of the source determine the watt-hours it can sustain.
Take the number of LEDs multiply them times the watts each for total
power in watts. 5*8=40
Take the capacity of the battery in amp hours and multiply that times
the voltage and that gives you watt-hours. (3,000 mah = 3 amp hours)
You have the three - 3.7V batteries wired in series for a voltage of
11.1 (not 12V) 11.1 * 3 = 33 watt-hours
Then divide the total watts the leds want into the watt hours the
battery can provide. 33/40=.825 hours
BUT:
Presumably, you have some means of controlling the current the LEDs
can pull? What do you have and how are the leds arranged -
series/parallel? A single white led will need up to 3.5 volts across
it with current limited to about .7 amps.
That (series parallel, and current limiting, and efficiency of the
limiter) is what makes answering your question impossible with the
data you supply.
That and actual real battery voltages and LED voltage drop etc.. I'm
only working with nominal values here.
On Sunday, April 21, 2019 at 8:32:26 AM UTC-5, default wrote:
On Sun, 21 Apr 2019 04:46:56 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
Thanks.
You could just use one of the rapid table calculators (google) and
figure out the time yourself.
https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html
A lot will, of course, depend on the efficiency of the current limiter
to power the LEDs. The formulas will only give you run-time with 100%
efficient current limiting.
I did not see any calculation that determines run time.
I have run leds for 45 minutes and remaining voltage is 11.93 volts.
Andy
There you go then. Just measure the run time.
There's nothing that will give you approximate run times based on the
information you provide. You can get a theoretical run time from
knowing the watts you are dissipating in the leds and dividing that
into the watt-hours you can expect from the battery, the voltage and
current of the source determine the watt-hours it can sustain.
Take the number of LEDs multiply them times the watts each for total
power in watts. 5*8=40
Take the capacity of the battery in amp hours and multiply that times
the voltage and that gives you watt-hours. (3,000 mah = 3 amp hours)
You have the three - 3.7V batteries wired in series for a voltage of
11.1 (not 12V) 11.1 * 3 = 33 watt-hours
Then divide the total watts the leds want into the watt hours the
battery can provide. 33/40=.825 hours
BUT:
Presumably, you have some means of controlling the current the LEDs
can pull? What do you have and how are the leds arranged -
series/parallel? A single white led will need up to 3.5 volts across
it with current limited to about .7 amps.
That (series parallel, and current limiting, and efficiency of the
limiter) is what makes answering your question impossible with the
data you supply.
That and actual real battery voltages and LED voltage drop etc.. I'm
only working with nominal values here.
There is no means of controlling what the leds pull.
They are wired in parallel.
Thanks for your help.
On Mon, 22 Apr 2019 05:02:19 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
On Sunday, April 21, 2019 at 8:32:26 AM UTC-5, default wrote:
On Sun, 21 Apr 2019 04:46:56 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
Thanks.
You could just use one of the rapid table calculators (google) and
figure out the time yourself.
https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html
A lot will, of course, depend on the efficiency of the current limiter
to power the LEDs. The formulas will only give you run-time with 100%
efficient current limiting.
I did not see any calculation that determines run time.
I have run leds for 45 minutes and remaining voltage is 11.93 volts.
Andy
There you go then. Just measure the run time.
There's nothing that will give you approximate run times based on the
information you provide. You can get a theoretical run time from
knowing the watts you are dissipating in the leds and dividing that
into the watt-hours you can expect from the battery, the voltage and
current of the source determine the watt-hours it can sustain.
Take the number of LEDs multiply them times the watts each for total
power in watts. 5*8=40
Take the capacity of the battery in amp hours and multiply that times
the voltage and that gives you watt-hours. (3,000 mah = 3 amp hours)
You have the three - 3.7V batteries wired in series for a voltage of
11.1 (not 12V) 11.1 * 3 = 33 watt-hours
Then divide the total watts the leds want into the watt hours the
battery can provide. 33/40=.825 hours
BUT:
Presumably, you have some means of controlling the current the LEDs
can pull? What do you have and how are the leds arranged -
series/parallel? A single white led will need up to 3.5 volts across
it with current limited to about .7 amps.
That (series parallel, and current limiting, and efficiency of the
limiter) is what makes answering your question impossible with the
data you supply.
That and actual real battery voltages and LED voltage drop etc.. I'm
only working with nominal values here.
There is no means of controlling what the leds pull.
Engineers would design-in some means of current control. If you are
just wiring a bunch of LEDs in parallel and putting them across a
battery, the only thing keeping the LEDs from burning out is the
internal resistance of the power source.
If you haven't burned any out... to date.... you will at some point
if/when you increase the battery pack capacity.
A lot of LED flashlights work the way you are suggesting. They take
three AA or AAA alkaline cells (4.5V nominal) then wire the LEDs in
parallel. The LEDs pull enough current and the battery can only
supply so much current that it works, and is cheap.
But if that same bunch of LEDs was wired to a 4.5 volt power supply
that could supply unlimited current while maintaining 4.5V those LEDs
would be giving off smoke as well as light for a short while.
You may get away with what you are doing, but it isn't good design
practice - particularly in using the lithium batteries in series for
11.1V (nominal). If the batteries aren't protected internally from
over-current failure they may explode.
If they are protected, and that is what is keeping the thing from
blowing up, you or someone replacing the batteries in the future may
put in some unprotected ones and it would be unsafe.
If they are all in parallel, and the LED needs 3.5V, and your battery
is 3.7V, why wire them for 11.1V? Might be safer (if not safe) to
just wire the parallel LEDs to batteries (that are charged and
balanced) in parallel.
The LEDs themselves need some minimum voltage to light at all. A
white LED is really a blue led with phosphors that give off red and
green colors so it appears white to human eyes.
If you used a prism or diffraction grating, to look at the color you'd
see the primary bands of light broken out separately (not a continuous
spectrum from red to violet) A CD ROM makes a good diffraction
grating... tilt it to break out the spectrum.
The reason the LEDs change color slightly when the battery runs down
is because there isn't enough light to excite all the phosphors
equally, so they usually pick up a green tint (green phosphors being
more energetic than red as a general rule)
Take care and be careful with what you are doing. Empirical discovery
and experimentation is fun and helpful, but it helps to understand
enough to stay safe.
They are wired in parallel.
Thanks for your help.
Leds need 12 volts. They are made for cars. Like indicator lights.
They probably expect 13.2v-14.0v. If I did the mat correctly, 3x3.7v is 11..1v. Depending on the internal design of the lamp, this my not be enough to produce any light, or it might glow dimly down to 3v.
There are some LEDs that work on 12V but they are specially made to doOn Monday, April 22, 2019 at 8:08:52 AM UTC-5, default wrote:
On Mon, 22 Apr 2019 05:02:19 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
On Sunday, April 21, 2019 at 8:32:26 AM UTC-5, default wrote:
On Sun, 21 Apr 2019 04:46:56 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
Thanks.
You could just use one of the rapid table calculators (google) and
figure out the time yourself.
https://www.rapidtables.com/calc/electric/Amp_to_Watt_Calculator.html
A lot will, of course, depend on the efficiency of the current limiter
to power the LEDs. The formulas will only give you run-time with 100%
efficient current limiting.
I did not see any calculation that determines run time.
I have run leds for 45 minutes and remaining voltage is 11.93 volts.
Andy
There you go then. Just measure the run time.
There's nothing that will give you approximate run times based on the
information you provide. You can get a theoretical run time from
knowing the watts you are dissipating in the leds and dividing that
into the watt-hours you can expect from the battery, the voltage and
current of the source determine the watt-hours it can sustain.
Take the number of LEDs multiply them times the watts each for total
power in watts. 5*8=40
Take the capacity of the battery in amp hours and multiply that times
the voltage and that gives you watt-hours. (3,000 mah = 3 amp hours)
You have the three - 3.7V batteries wired in series for a voltage of
11.1 (not 12V) 11.1 * 3 = 33 watt-hours
Then divide the total watts the leds want into the watt hours the
battery can provide. 33/40=.825 hours
BUT:
Presumably, you have some means of controlling the current the LEDs
can pull? What do you have and how are the leds arranged -
series/parallel? A single white led will need up to 3.5 volts across
it with current limited to about .7 amps.
That (series parallel, and current limiting, and efficiency of the
limiter) is what makes answering your question impossible with the
data you supply.
That and actual real battery voltages and LED voltage drop etc.. I'm
only working with nominal values here.
There is no means of controlling what the leds pull.
Engineers would design-in some means of current control. If you are
just wiring a bunch of LEDs in parallel and putting them across a
battery, the only thing keeping the LEDs from burning out is the
internal resistance of the power source.
If you haven't burned any out... to date.... you will at some point
if/when you increase the battery pack capacity.
A lot of LED flashlights work the way you are suggesting. They take
three AA or AAA alkaline cells (4.5V nominal) then wire the LEDs in
parallel. The LEDs pull enough current and the battery can only
supply so much current that it works, and is cheap.
But if that same bunch of LEDs was wired to a 4.5 volt power supply
that could supply unlimited current while maintaining 4.5V those LEDs
would be giving off smoke as well as light for a short while.
You may get away with what you are doing, but it isn't good design
practice - particularly in using the lithium batteries in series for
11.1V (nominal). If the batteries aren't protected internally from
over-current failure they may explode.
If they are protected, and that is what is keeping the thing from
blowing up, you or someone replacing the batteries in the future may
put in some unprotected ones and it would be unsafe.
If they are all in parallel, and the LED needs 3.5V, and your battery
is 3.7V, why wire them for 11.1V? Might be safer (if not safe) to
just wire the parallel LEDs to batteries (that are charged and
balanced) in parallel.
The LEDs themselves need some minimum voltage to light at all. A
white LED is really a blue led with phosphors that give off red and
green colors so it appears white to human eyes.
If you used a prism or diffraction grating, to look at the color you'd
see the primary bands of light broken out separately (not a continuous
spectrum from red to violet) A CD ROM makes a good diffraction
grating... tilt it to break out the spectrum.
The reason the LEDs change color slightly when the battery runs down
is because there isn't enough light to excite all the phosphors
equally, so they usually pick up a green tint (green phosphors being
more energetic than red as a general rule)
Take care and be careful with what you are doing. Empirical discovery
and experimentation is fun and helpful, but it helps to understand
enough to stay safe.
They are wired in parallel.
Thanks for your help.
Leds need 12 volts. They are made for cars. Like indicator lights.
Andy
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I did not see any calculation that determines run time.
On Sunday, April 21, 2019 at 4:46:59 AM UTC-7, AK wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I did not see any calculation that determines run time.
Oh, that's easy; the 18650 batteries are 4V each, so to get 12V you
have them in series. 12V * 3000 mAh = energy in the batteries
about 36 watt-hours. So, 7 hours at 5W (one LED), or under an hour
with eight at a time.
That assumes no energy-losing other components (which is unlikely; most
LED assemblies for "12V" nominal input have some required ballast resistance.
On Tuesday, April 23, 2019 at 1:00:45 AM UTC-5, whit3rd wrote:
On Sunday, April 21, 2019 at 4:46:59 AM UTC-7, AK wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I did not see any calculation that determines run time.
Oh, that's easy; the 18650 batteries are 4V each, so to get 12V you
have them in series. 12V * 3000 mAh = energy in the batteries
about 36 watt-hours. So, 7 hours at 5W (one LED), or under an hour
with eight at a time.
That assumes no energy-losing other components (which is unlikely; most
LED assemblies for "12V" nominal input have some required ballast resistance.
This is what I have.
"https://www.ebay.com/itm/10PCS-12v-Super-Bright-T10-5050-W5W-5SMD-Yellow-Wedge-Fog-158-168-194-LED-Bulbs/283422908666?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649"
The leds are strange looking and there are 5 of them.
On Tuesday, April 23, 2019 at 1:00:45 AM UTC-5, whit3rd wrote:
On Sunday, April 21, 2019 at 4:46:59 AM UTC-7, AK wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I did not see any calculation that determines run time.
Oh, that's easy; the 18650 batteries are 4V each, so to get 12V you
have them in series. 12V * 3000 mAh = energy in the batteries
about 36 watt-hours. So, 7 hours at 5W (one LED), or under an hour
with eight at a time.
That assumes no energy-losing other components (which is unlikely; most
LED assemblies for "12V" nominal input have some required ballast resistance.
This is what I have.
"https://www.ebay.com/itm/10PCS-12v-Super-Bright-T10-5050-W5W-5SMD-Yellow-Wedge-Fog-158-168-194-LED-Bulbs/283422908666?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649"
The leds are strange looking and there are 5 of them.
On Tue, 23 Apr 2019 12:09:43 -0700 (PDT), Andy
andrewkennedy775@gmail.com> wrote:
.24 watts X 3 = .72 watts. Is that current or light output?
The original post:
I have (8) 5 watt LEDs that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
40 watts dissipated by LEDs with maybe 33 amp-hours of battery.
I looked at the link and don't see where he gets 5 watts per bulb
though... The incandescent 158 lamp they are intended to replace
only dissipates 3.4 watts at 14 volts.
On Tuesday, April 23, 2019 at 5:26:24 PM UTC-5, default wrote:
On Tue, 23 Apr 2019 12:09:43 -0700 (PDT), Andy
andrewkennedy775@gmail.com> wrote:
.24 watts X 3 = .72 watts. Is that current or light output?
The original post:
I have (8) 5 watt LEDs that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
40 watts dissipated by LEDs with maybe 33 amp-hours of battery.
I looked at the link and don't see where he gets 5 watts per bulb
though... The incandescent 158 lamp they are intended to replace
only dissipates 3.4 watts at 14 volts.
Current used is 87 milliamps for one led.
Andy
On Wed, 24 Apr 2019 09:03:45 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
On Tuesday, April 23, 2019 at 5:26:24 PM UTC-5, default wrote:
On Tue, 23 Apr 2019 12:09:43 -0700 (PDT), Andy
andrewkennedy775@gmail.com> wrote:
.24 watts X 3 = .72 watts. Is that current or light output?
The original post:
I have (8) 5 watt LEDs that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I want to know the approx run time.
40 watts dissipated by LEDs with maybe 33 amp-hours of battery.
I looked at the link and don't see where he gets 5 watts per bulb
though... The incandescent 158 lamp they are intended to replace
only dissipates 3.4 watts at 14 volts.
Current used is 87 milliamps for one led.
Andy
.087 amps X 12 volts = 1.044 watts for one LAMP, each lamp
incorporates several discrete LEDs.
On Tuesday, April 23, 2019 at 1:00:45 AM UTC-5, whit3rd wrote:
On Sunday, April 21, 2019 at 4:46:59 AM UTC-7, AK wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I did not see any calculation that determines run time.
Oh, that's easy; the 18650 batteries are 4V each, so to get 12V you
have them in series. 12V * 3000 mAh = energy in the batteries
about 36 watt-hours. So, 7 hours at 5W (one LED), or under an hour
with eight at a time.
That assumes no energy-losing other components (which is unlikely; most
LED assemblies for "12V" nominal input have some required ballast resistance.
This is what I have.
"https://www.ebay.com/itm/10PCS-12v-Super-Bright-T10-5050-W5W-5SMD-Yellow-Wedge-Fog-158-168-194-LED-Bulbs/283422908666?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649"
The leds are strange looking and there are 5 of them.
On Tuesday, April 23, 2019 at 1:21:43 PM UTC-4, AK wrote:
On Tuesday, April 23, 2019 at 1:00:45 AM UTC-5, whit3rd wrote:
On Sunday, April 21, 2019 at 4:46:59 AM UTC-7, AK wrote:
On Sunday, April 21, 2019 at 5:10:50 AM UTC-5, default wrote:
On Sat, 20 Apr 2019 20:18:46 -0700 (PDT), AK
scientist77017@gmail.com> wrote:
I have (8) 5 watt leds that are run from a 12VDC source.
(3 18650 batteries at 3000 Ma hrs each.
I did not see any calculation that determines run time.
Oh, that's easy; the 18650 batteries are 4V each, so to get 12V you
have them in series. 12V * 3000 mAh = energy in the batteries
about 36 watt-hours. So, 7 hours at 5W (one LED), or under an hour
with eight at a time.
That assumes no energy-losing other components (which is unlikely; most
LED assemblies for "12V" nominal input have some required ballast resistance.
This is what I have.
"https://www.ebay.com/itm/10PCS-12v-Super-Bright-T10-5050-W5W-5SMD-Yellow-Wedge-Fog-158-168-194-LED-Bulbs/283422908666?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649"
The leds are strange looking and there are 5 of them.
Ahh. Say have you pulled one apart and looked inside? There may be
some sort of switching IC controlling the current.
George