Ammeter Wiring
- Thread starter wufibugs
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Mmhmm. Them's wise words. A good digital, (not analog) meter, for EACH battery bank keeps the diligent apprised. And switch to white wine dammit, the red stuff stains boats. Whoops, wrong pointless cat fight, another post....
Maybe in horsepower? A 100 amp hour battery has, sealed up inside, the capability to make 1.609 horsepower hours of energy .. The starter using 286 amperes at 12 volts is consuming 3432 watts which is the same as 4.6 horsepower. But it only does that for 1 second.. so the energy it used is 1/3600 X 4.6 = 0.00128 horsepower hours.
Power and energy aren't the same. Power can be horsepower but energy is horsepower-hours (or watt hours, or even ampere hours if everyone is talking 12 volts)
The "real" unit in English system would be BTU's or in metric units, Joules.. so the battery would have stored inside, the ability to supply 4095 BTU's... When the starter cranks the engine in 1 second, it has used only 3.31 BTU's .. Just casting around here for some understanding.. when ya have amperes acting over a definite time at a voltage, it doesn't need to be interpreted .. it is a calculable number .. as defined in physics.
Oh.. and don't put an ammeter in the alternator circuit!
Power and energy aren't the same. Power can be horsepower but energy is horsepower-hours (or watt hours, or even ampere hours if everyone is talking 12 volts)
The "real" unit in English system would be BTU's or in metric units, Joules.. so the battery would have stored inside, the ability to supply 4095 BTU's... When the starter cranks the engine in 1 second, it has used only 3.31 BTU's .. Just casting around here for some understanding.. when ya have amperes acting over a definite time at a voltage, it doesn't need to be interpreted .. it is a calculable number .. as defined in physics.
Oh.. and don't put an ammeter in the alternator circuit!
Is this that hard to understand????? I mean really amps times hours and you have to convert most of your appliances from seconds or minutes of use to hours.
OR
you could use (quatloos/fortnigh)*nanoseconds^2*($/quatloos)*(gal of gas/$)*(BTU/gal of gas). quatloos are an obscure measure of the monetary value that can readily be converted to heat given the current conversion to dollars value and price of gas and a fortnight is 14 days. Yes the units come out to energy as heat(also known as power like a BTU) divided by time and then multiplied by time squared is equal to heat times time. course you cannot compare that to ANYTHING so why use it? And that is the real point here IMHO. EVERYBODY uses Ah so you should too (to be politically correct and not offend anybody)
OR
you could use (quatloos/fortnigh)*nanoseconds^2*($/quatloos)*(gal of gas/$)*(BTU/gal of gas). quatloos are an obscure measure of the monetary value that can readily be converted to heat given the current conversion to dollars value and price of gas and a fortnight is 14 days. Yes the units come out to energy as heat(also known as power like a BTU) divided by time and then multiplied by time squared is equal to heat times time. course you cannot compare that to ANYTHING so why use it? And that is the real point here IMHO. EVERYBODY uses Ah so you should too (to be politically correct and not offend anybody)
I certainly agree, Bill.. I have a device that uses some amperes.. I know my battery is supposed to have a number of amp hours in it.. I can easily then figure how long I can run the device with the available battery .. EASY.. that is why it is the convention.. rather than those darned quatloos per fortnight!!
fortunately, we don't have to convert to watt hours or BTUs to get in our heads what we need to know.
fortunately, we don't have to convert to watt hours or BTUs to get in our heads what we need to know.
Yea kloudie1
you use BTUs when it makes sense to and therms when that makes sense and eV when that makes sense. For battery powered DC circuits Ah is the unit of energy of choice because it is easy to use and yields results directly.
you use BTUs when it makes sense to and therms when that makes sense and eV when that makes sense. For battery powered DC circuits Ah is the unit of energy of choice because it is easy to use and yields results directly.
Phew, Bill, you really nailed it. How simple can it be? That's what everybody uses. There is a reason for that. The reason? Like I quoted in an earlier post, the Link 2000 manual defines it.
Wayne had asked for reference sources rather than opinions. Here's another one, The Ample Power Primer, from the guys who "wrote the book" on batteries and battery management.
http://www.amplepower.com/primer/primer.pdf
Page 3, Battery Capacity Management.
Hope Wayne gets to read this reference source.
Wayne had asked for reference sources rather than opinions. Here's another one, The Ample Power Primer, from the guys who "wrote the book" on batteries and battery management.
http://www.amplepower.com/primer/primer.pdf
Page 3, Battery Capacity Management.
Hope Wayne gets to read this reference source.
I have hit upon the universal solution. take the dirty nasty ammeter face off and redo it to read in BTU, or eV or whatever you want and then write your congressman and have him edict that all electrical devices have a placard that displays the energy use in the value that you chose for your meter face.
Then you can say interesting things like: hey my reefer seems to be pulling 3.21 BTU. At that rate my 321 BTU*hour battery bank will be at 50% state of BTU (cause we cant use "charge" anymore!!) in 0.149 fortnights.
pretty silly ain't it?
Then you can say interesting things like: hey my reefer seems to be pulling 3.21 BTU. At that rate my 321 BTU*hour battery bank will be at 50% state of BTU (cause we cant use "charge" anymore!!) in 0.149 fortnights.
pretty silly ain't it?
for completeness (cause you knew I would) ;-)
if you use the instantaneous voltage, instantaneous amps and very small units of time (converted to hours of course) you don't have to account for Mr. Peukert effect with our battery monitor. Course you still have to account for charge and discharge efficiencies at the various voltages that your system operates at........
perhaps even Mr. Peukert's approximation is appropriate even if it is only an approximation.
course if you wanted just an approximation of wither your batteries are being charged or that there was a problem with them holding a charge you could just install a volt meter at the motor panel. if the volts increase when you turn on the motor the alternator is working. if the volts drop dramatically when you hit the starter you might want to check into the batteries health as that is a good indicator that something is wrong.
Just sayin
if you use the instantaneous voltage, instantaneous amps and very small units of time (converted to hours of course) you don't have to account for Mr. Peukert effect with our battery monitor. Course you still have to account for charge and discharge efficiencies at the various voltages that your system operates at........
perhaps even Mr. Peukert's approximation is appropriate even if it is only an approximation.
course if you wanted just an approximation of wither your batteries are being charged or that there was a problem with them holding a charge you could just install a volt meter at the motor panel. if the volts increase when you turn on the motor the alternator is working. if the volts drop dramatically when you hit the starter you might want to check into the batteries health as that is a good indicator that something is wrong.
Just sayin
Sailvayu I think i understand where your difficulty arises.
Your extrapolation of the formula from calders example that you post is incorrect.
"He does not give a formula but uses the example of a 400 amp motor running for 15 seconds.
400/(4*60)=1.66
So we can extrapolate this to a formula of A/H=Ah, A being Amps and H being hours. "
The formula is actually 400 x 1/4 of a minute (15seconds) x 1/60th of an hour to get 1.66AH or 400x1/4x1/60=1.66AH or 400x1/(4*60)=1.66AH or simplifying further 400/(4x60)=1.66AH
The correct formula as others have stated is A x H = AH where A is amps and H is HOURS not A/H as you have extrapolated.
In the example if you ran the load for 1 hour it would use 400 amps per hour A/H and the same number of amp hours, 400AH. If you ran the load for two hours you would use 800amps over 2 hours giving you still 400 amps per hour - A/H but you would have used 800AH.
The one gives you a rate of consumption. The other gives you the total consumed.
Your extrapolation of the formula from calders example that you post is incorrect.
"He does not give a formula but uses the example of a 400 amp motor running for 15 seconds.
400/(4*60)=1.66
So we can extrapolate this to a formula of A/H=Ah, A being Amps and H being hours. "
The formula is actually 400 x 1/4 of a minute (15seconds) x 1/60th of an hour to get 1.66AH or 400x1/4x1/60=1.66AH or 400x1/(4*60)=1.66AH or simplifying further 400/(4x60)=1.66AH
The correct formula as others have stated is A x H = AH where A is amps and H is HOURS not A/H as you have extrapolated.
In the example if you ran the load for 1 hour it would use 400 amps per hour A/H and the same number of amp hours, 400AH. If you ran the load for two hours you would use 800amps over 2 hours giving you still 400 amps per hour - A/H but you would have used 800AH.
The one gives you a rate of consumption. The other gives you the total consumed.
Ah= Amps * hours of use
or
Ah = amps * minutes of use * (1/60 hour/minute)
or
Ah = amps * seconds of use * (1/3600 hours/second)
now if you can conceive that 15 minutes is 0.25 hours....... (15*(1/60)) you are apparently WAAAAY ahead of the pack.
or
Ah = amps * minutes of use * (1/60 hour/minute)
or
Ah = amps * seconds of use * (1/3600 hours/second)
now if you can conceive that 15 minutes is 0.25 hours....... (15*(1/60)) you are apparently WAAAAY ahead of the pack.
real men (or women for that matter) don't divide when doing electrical calculations.
Where did we get that Ah is amps divided by hours anyway?
Where did we get that Ah is amps divided by hours anyway?
Off cruising with spotty coverage but PLEASE read Bill's post until it sinks in. This is easy stuff..
And yes Peukert is always there but I will stay out of that to keep it simple. For now simple Ah's seem to be causing confusion.. ....
Ah = 400 amps * 1/4 minute * (1/60 hours/minute)
Ah = 400 * (1/4*1/60)
Ah = 400*(1/(4*60))
Ah = 400*1/(4*60)
Ah = 400/(4*60)
or as Calders stated:
400/(4*60)=1.66
now if I ran a 1.2 amp anchor light for 12 hours and 15 minutes we would conclude
Ah consumed = 1.2 amps * (12 hours + (15 minutes *1/60 hours/minute))
or
Ah consumed = 1.2 amps * (12 +15/60)hours
or
Ah consumed = 1.2 amps * 12.25 hours
Ah = 400 * (1/4*1/60)
Ah = 400*(1/(4*60))
Ah = 400*1/(4*60)
Ah = 400/(4*60)
or as Calders stated:
400/(4*60)=1.66
now if I ran a 1.2 amp anchor light for 12 hours and 15 minutes we would conclude
Ah consumed = 1.2 amps * (12 hours + (15 minutes *1/60 hours/minute))
or
Ah consumed = 1.2 amps * (12 +15/60)hours
or
Ah consumed = 1.2 amps * 12.25 hours
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