Battery voltage or Amps
Jan 23, 2016 12:37:37 #
Longshadow wrote:
Just remember PIE (P=IxE).
Thankx. Never heard of that one. :thumbup: :thumbup:
Jan 23, 2016 12:42:36 #
radioengineer wrote:
Been doing electronics since 1958, professionally since 1961. 35 years as a broadcast engineer, Extra Class Amateur License, General Class FCC License, Certified Professional Broadcast Engineer. Still in the business.
I love photography and do not profess to offer anything to this group regarding taking pictures.
Dave
I love photography and do not profess to offer anything to this group regarding taking pictures.
Dave
I beg your forgivness, sir
Jan 23, 2016 12:58:48 #
So many times I make the same mistake.
I have to tell you, all these years of experience, being an old fart over 70, I still test the theory on the bench. If designing some special circuit I will grab the decade resistance box, variable voltage power supply and a couple multimeters, one for voltage and one for current. I have an idea about what the values should be but wring it out the old fashion way. Sometimes I am surprised at the findings. I set down and do ohms law and its a slap to the forehead with the hand, opps thinking wrong again.
At the Utilities where I setup the electronics department for 19 years, the Operations Superintendent was one sharp cookie. He however had a problem catching my drift, like on surge suppression. He made the statement, "I'm from Missouri, you have to show me". After taking a cover off a box and showing the wiring, he said I got it.
I am only on this group to learn about one of my favorite hobbies, photography.
I am doing a project at a limestone mine where the digital radio system is controlled by an elaborate wireless industrial wifi with dishes on tall tanks. I purchased a Nikon S9900 couple of weeks ago because of 30X optical in a pocket camera. I had the GPS turned on and shot a bunch of photos of antennas 70 ft in the air and read the model numbers off the photos. After downing Nikons free View NX-I, on a computer the photos showed up over-laid on a Google Earth Map. Click on the blue dot on aerial photo, the picture appears taken at that spot. The embedded compass tells direction of the shot.
All this allowed for exact distance between antennas and to calculate the angle of each.
Wow I had no idea this came with just wanting a pocket camera with 30X optical.
I have to tell you, all these years of experience, being an old fart over 70, I still test the theory on the bench. If designing some special circuit I will grab the decade resistance box, variable voltage power supply and a couple multimeters, one for voltage and one for current. I have an idea about what the values should be but wring it out the old fashion way. Sometimes I am surprised at the findings. I set down and do ohms law and its a slap to the forehead with the hand, opps thinking wrong again.
At the Utilities where I setup the electronics department for 19 years, the Operations Superintendent was one sharp cookie. He however had a problem catching my drift, like on surge suppression. He made the statement, "I'm from Missouri, you have to show me". After taking a cover off a box and showing the wiring, he said I got it.
I am only on this group to learn about one of my favorite hobbies, photography.
I am doing a project at a limestone mine where the digital radio system is controlled by an elaborate wireless industrial wifi with dishes on tall tanks. I purchased a Nikon S9900 couple of weeks ago because of 30X optical in a pocket camera. I had the GPS turned on and shot a bunch of photos of antennas 70 ft in the air and read the model numbers off the photos. After downing Nikons free View NX-I, on a computer the photos showed up over-laid on a Google Earth Map. Click on the blue dot on aerial photo, the picture appears taken at that spot. The embedded compass tells direction of the shot.
All this allowed for exact distance between antennas and to calculate the angle of each.
Wow I had no idea this came with just wanting a pocket camera with 30X optical.
Jan 23, 2016 13:15:57 #
radioengineer wrote:
So many times I make the same mistake. br br I ... (show quote)
Welcome to the Hog.
Jan 23, 2016 13:24:43 #
radioengineer wrote:
So many times I make the same mistake. br br I ... (show quote)
Don't ya hate it when info leaks out of your head? :) :wink:
Jan 23, 2016 13:29:23 #
Thank you.
I will try my best when subjects come up on battery packs, chargers, and related issues.
I got involved in designing a solar only gas border station and a lot of research into how to squeeze the last drop out of a system necessary based on average sun days. After over sizing it, for extra weeks of battery power, I got caught with an extended cloudy period 4 years ago one winter. After adding a small wind generator to supplement the solar panel its been hands off since.
Also being a RVer thinking about how long the motorhome battery is going to keep stuff running is all part of the same thinking needed.
I will try my best when subjects come up on battery packs, chargers, and related issues.
I got involved in designing a solar only gas border station and a lot of research into how to squeeze the last drop out of a system necessary based on average sun days. After over sizing it, for extra weeks of battery power, I got caught with an extended cloudy period 4 years ago one winter. After adding a small wind generator to supplement the solar panel its been hands off since.
Also being a RVer thinking about how long the motorhome battery is going to keep stuff running is all part of the same thinking needed.
Jan 23, 2016 14:45:39 #
Marionsho wrote:
R=ExI. 2 ohm (remaining constant.) E=1, I=2. Hense 1x2=2. Drop the voltage to .1, .1x20=2.
It would be soooo convenient if it worked the way you have described it.
It would be soooo convenient if it worked the way you have described it.
No.
R=E/I, E=I*R, I=E/R
(P=E*I)
Jan 23, 2016 14:55:03 #
TriX wrote:
No.
R=E/I, E=I*R, I=E/R
(P=E*I)
R=E/I, E=I*R, I=E/R
(P=E*I)
You are correct. I just dropped the ball, big time.
Can I measure the internal resistance of a battery?
Jan 23, 2016 15:22:05 #
Marionsho wrote:
You are correct. I just dropped the ball, big time.
Can I measure the internal resistance of a battery?
Can I measure the internal resistance of a battery?
You can calculate it:
http://www.instructables.com/id/How-to-measure-the-internal-resistance-of-a-batter/
Jan 23, 2016 15:31:01 #
Dave R. wrote:
If a battery is charged it is charged assuming all things are equal to when new. The amperage should not be affected assuming the battery does not have another fault of some kind which yes it could make a difference. It is a difficult subject to many but if you google ohms law and study it's content it should clarify. Ohms law is in many ways the same as aperture / ISO / and shutter speed. One affects the other when a change is made.
Batteries do go bad. With the old carbon zinc, alkaline and lead acid batteries, they often developed an internal resistance that limited the current flow. Modern batteries not so much--but my knowledge has not kept up with the rapid advances.
The formula is E=IR or I=E/R. Current equals Voltage divided by Resistance. So if the resistance goes up, for the same voltage, the current will go down. The battery doesn't care whether that resistance is part of the camera circuit (Unlikely to change much) or internal to the battery itself.
Jan 23, 2016 15:32:35 #
Yes testing and calculating the internal resistance is OK, but maybe more work than what is practical.
But to keep it simple, put a good load on the battery creating the amount of current it should be producing and measure the sag, the voltage drop.
Checking a car battery as an example, a battery with high internal resistance will likley measure 12 volts with a volt meter and no load. Turn on the headlights for a good load and see if it drops by couple of volts, which would be at least one cell bad. Using a load tester from Harbor Freight that has two meters, Voltage and Amps, turn on the carbon pile load to get amps showing on the Amp Meter. In the car battery test you start to see the battery Volts drop off as 100 amps and more flows.
Here is a link on the subject http://batteryuniversity.com/learn/article/rising_internal_resistance
I think that gets over technical for most of us. Do a little Googling and find a place where based on the Voltage and the mA/Hr or A/Hr rating of the pack and figure out a load. Here is where ohms law can play a part.
An incandescent tail light could be a good load as a tester to test a good size 12V battery pack.
Testing small batteries like a rechargeable 1.5V Nicad or NiMh get an old bulb from a flashlight put it across the battery while testing the voltage. If the bulb is from a 2 cell flashlight which is a 3V bulb, the bulb will be dim, but at least its a load. Placing two of those 3V bulbs in parallel will make a closer load for 1.5Volts. The bulbs will be equally dim because they are only looking at half voltage, but it doubles up the load on the single batter cell.
Testing a good sized 6V battery pack try a taillight. There are two filaments in a taillight one for the regular light and the other for brakes. The filament for the brakes is lower resistance, bigger load.
Play around some with what you have on hand and compare a good cell or good pack to your test setup and make notes. You may find something that works good for you.
But to keep it simple, put a good load on the battery creating the amount of current it should be producing and measure the sag, the voltage drop.
Checking a car battery as an example, a battery with high internal resistance will likley measure 12 volts with a volt meter and no load. Turn on the headlights for a good load and see if it drops by couple of volts, which would be at least one cell bad. Using a load tester from Harbor Freight that has two meters, Voltage and Amps, turn on the carbon pile load to get amps showing on the Amp Meter. In the car battery test you start to see the battery Volts drop off as 100 amps and more flows.
Here is a link on the subject http://batteryuniversity.com/learn/article/rising_internal_resistance
I think that gets over technical for most of us. Do a little Googling and find a place where based on the Voltage and the mA/Hr or A/Hr rating of the pack and figure out a load. Here is where ohms law can play a part.
An incandescent tail light could be a good load as a tester to test a good size 12V battery pack.
Testing small batteries like a rechargeable 1.5V Nicad or NiMh get an old bulb from a flashlight put it across the battery while testing the voltage. If the bulb is from a 2 cell flashlight which is a 3V bulb, the bulb will be dim, but at least its a load. Placing two of those 3V bulbs in parallel will make a closer load for 1.5Volts. The bulbs will be equally dim because they are only looking at half voltage, but it doubles up the load on the single batter cell.
Testing a good sized 6V battery pack try a taillight. There are two filaments in a taillight one for the regular light and the other for brakes. The filament for the brakes is lower resistance, bigger load.
Play around some with what you have on hand and compare a good cell or good pack to your test setup and make notes. You may find something that works good for you.
Jan 23, 2016 15:41:13 #
Dave R. wrote:
Thank you. I seriously doubt anything has changed after 45 years plus as a licensed master electrician. :thumbup:
:lol: Back when I learned electronics in the Navy (we were still using sails) voltage was expressed as "E" electro motive force. The formula is still the same though.
Jan 23, 2016 15:53:23 #
Apaflo wrote:
The only way to test a battery is to measure the voltage while pulling a full load (whatever amperage it is rated for).
You can measure the voltage without a load, but it doesn't mean just a whole lot unless you know positively that the battery is good.
The internal resistance of a battery should be very low, but if it isn't then even a small drain will result in a very low battery voltage under load, and a normal voltage with no load.
You can measure the voltage without a load, but it doesn't mean just a whole lot unless you know positively that the battery is good.
The internal resistance of a battery should be very low, but if it isn't then even a small drain will result in a very low battery voltage under load, and a normal voltage with no load.
:thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup:
Jan 23, 2016 15:54:35 #
Yes sir Dave R you are correct.
And I is intensity or commonly referred to as amps.
R never had its name changed.
And I is intensity or commonly referred to as amps.
R never had its name changed.
Jan 23, 2016 15:59:41 #
Apalfo,
You are correct, but even at loads somewhat less, if there is a battery issue it starts to show up as a Votage sag. Depends on how bad the battery maybe.
Comparisons are always a good benchmark. If you have data on what a good battery does with your given load over a period of time, then anything less you can judge.
My thought always is even at a 50% load rating is better than no load rating at all. More is better in this case, certainly
You are correct, but even at loads somewhat less, if there is a battery issue it starts to show up as a Votage sag. Depends on how bad the battery maybe.
Comparisons are always a good benchmark. If you have data on what a good battery does with your given load over a period of time, then anything less you can judge.
My thought always is even at a 50% load rating is better than no load rating at all. More is better in this case, certainly
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