Car Ammeter

[barry wilkins]

After a number of expreiments I gave up the torroid idea.
Could not over come the zero problems ,it has to be the B/H curve the flux in the ferrite does not return to the same point ,so after the first current you get an offset which must remanence .
I did think of a flux gate like you can have a compass ,a coil wound all the way around the coil and is energised, this might degauss the core but I dont know

I had a request for help from abroad out of the blue ,so I had to dig out some info on elemental anlysis , I found my origonal notes from years ago I did on My Honda car measuring the voltage drop from battery to the earth point .My tests made the resistance to be 15 milliohms.
Interstingly on My Citreon C3 there is awire connected to the negative post on the battery, there is a economy mode on the car wich switches off the power after a while when the engine is not running.
I might look into this a bit later on and find out what it is.

Barry

[redwire]

Re: Car Ammeter

That's too bad a Hall-effect current sensor did not work out. It's what the DC clamp-on ammeters use, some even go to mA level. I have had those get magnetized jaws and then the readings get "sticky" so it reads OK in one direction but the other direction reads way low because the ferrite is magentized in the opposite flux polarity. After I demagnetized them they work better. You could also try using more turns?
15mV/A means 150mV for 10A with a gain of 10 should be good to use.

[sam_sam_sam]

Re: Car Ammeter

After a number of expreiments I gave up the torroid idea.
Could not over come the zero problems ,it has to be the B/H curve the flux in the ferrite does not return to the same point ,so after the first current you get an offset which must remanence .
I did think of a flux gate like you can have a compass ,a coil wound all the way around the coil and is energised, this might degauss the core but I dont know

I had a request for help from abroad out of the blue ,so I had to dig out some info on elemental anlysis , I found my origonal notes from years ago I did on My Honda car measuring the voltage drop from battery to the earth point .My tests made the resistance to be 15 milliohms.
Interstingly on My Citreon C3 there is awire connected to the negative post on the battery, there is a economy mode on the car wich switches off the power after a while when the engine is not running.
I might look into this a bit later on and find out what it is.

Barry

You might be interested in this product

https://www.allegromicro.com/en/prod...sor-ics/acs772

I have used this product in the past and the results are decent

You do have to use a micro controller with this device to get best results

You can use it with out the use of a micro controller but you would have to do the math

100 amp version / 5 volt scale = 20 amp per volt output

This is what I found when I used this device in a application that I was doing

One note if your output voltage value reaches 4.5 volts and higher the accuracy is not quite as good the lower the output voltages the more accurate it is

Also at voltage output less than 0.50 the accuracy is also less accurate

But overall the accuracy of the device is decent for the price of the device

This was at the time that I did this project