Morning All,
I’m looking some help with this project.
What I’m trying to do is monitor the generator 12V output, whilst its running and charging the batteries.
I’m already monitoring the 12Vs going into the radio rack and the current draw but I can’t figure out how to do the generator side without affecting the voltage going to the battery’s.
The attached diagram might clarify the setup
Your suggestions would be appreciated.
Bob
System block diagram.pdf (89.6 KB)
You do not say how you are monitoring the voltage going to the radio but why can't you use the same method to monitor the generator output ?
You could just measure current flowing to the batteries with a non-invasive cable clamp sensor. When it tails off, stop the generator.
You already measure current and voltage so you can calculate how much power the radios have consumed. You could base the generator runtime on that (plus some margin).
You need to show the schematic, measuring the generator voltage should have no effect on battery voltage. Are the grounds common?
Hi Guys and thanks for the reply's.
To clarify, the generator is not remote start/stop so the plan is to run it 'till it runs out of gas and then resort to battery power. This should double the run time before we have to visit site.
The generator output will be in paralel with the battery so the Arduino will be "seeing" both through the voltage divider which is the problem for monitoring the genny output seperately. I don't want to put a diode in series with the genny o/p as it will reduce the voltage going to the battery.
I'm using an ACS current sensor module from Polu for the battery monitoring.
An option would be to just have a True/False for the generator output.
I'm using an ACS current sensor module from Polu for the battery monitoring.
Which one? Unidirectional or bidirectional?
Hi,
The generator output will be in paralel with the battery so the Arduino will be "seeing" both through the voltage divider which is the problem for monitoring the genny output seperately. I don't want to put a diode in series with the genny o/p as it will reduce the voltage going to the battery.
All you need to measure is;
As you have noted, Battery and Generator voltage will be the same.
Generator current magnitude will depend on battery/load while the generator is running.
Battery current magnitude and direction will depend on charging or discharging depending on load.
So you need to measure two currents and one voltage.
Tom... 
JCA34F:
https://www.pololu.com/search?query=ACS+current+sensor&x=3&y=5
Which one? Unidirectional or bidirectional?
I’m using the Bidirectional +_15V
TomGeorge:
Hi,
All you need to measure is;
- Battery Voltage
- Generator Current
- Battery Current
As you have noted, Battery and Generator voltage will be the same.
Generator current magnitude will depend on battery/load while the generator is running.
Battery current magnitude and direction will depend on charging or discharging depending on load.So you need to measure two currents and one voltage.
Tom...
Thanks for the reply Tom,
What I want to use the generator voltage for is as an indication that the generator is running so we know when it stops!
Bob
rover-bob:
Thanks for the reply Tom,
What I want to use the generator voltage for is as an indication that the generator is running so we know when it stops!
Bob
Can you get to the oil pressure switch?
Most have them now as a safety for the motor.
Tom...
Hi Tom,
Unfortunately these ones don’t have one >:(
What I’m going to have to do is use the voltage and set limits for generator on/ running on battery and" OH Heck" for low battery volts to indicate that we need to get someone to the site ASAP to refuel and start the genny.
Thanks for all the thoughts!
Bob
Is the generator output AC or DC?
What are the actual voltages and currents in this setup?
How does the radio switch over from generator to batteries?
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