Dear all,
I connected different sensors and a battery on my CR3000 and I would like that the CR show me the mesuring current (Ampere or Ah). Is it possible ?
Regards,
Maxime D
* Last updated by: MaximeD on 2/14/2013 @ 1:46 AM *
Maxime
You would need to use a sensor that measures the current, a toroid or similar.
Dear Grant,
Ok thank your for your answer.
Regards,
Maxime D
Can you please explain again what you are trying to measure. Are you trying to measure the current being sourced by something from a battery. Is that battery powering the logger or is it a separate battery. Also how is the battery referenced to the datalogger (is the -ve output connected to the logger ground for instance?)
I'm trying to measure the current DC from a panel photovoltaics. The problem with a toroid (CS 10 for example) is that I can mesure only a current AC (and not DC).
So, I have thought to a shunt, like that : https://www.campbellsci.com/curs100-overview
What do you think about this ?
IF you can put the shunt resistor in the ground wire of the panel AND that ground is referenced to the ground of the logger then you can use a shunt resistor in the same way as the CURS100 is used. Generally, unless it is a tiny solar panel, the shunt resistor would have a much lower resistance than 100 ohms, often one Ohm or less. You can buy current shunt resistors from standard electronics suppliers (Farnell/Newark, RS etc) and choose one to match the likely current. Remember the logger can measure a few mV full-scale so you do not need to generate a large voltage across the resistor to get a good measurement (you should make a differential measurement in this case). Using two high a resistor will likely upset the charging system.
Just to repeat this will work fine if the resistor is placed in the ground connection from the solar panel.
If however, you cannot put a shunt resistor in the ground rail or are dealing with very large solar panels with high voltages, you would need to look to an isolated measurement device that allows the current to be measured safely. Such devices costs $100+ and would typically output either 4-20 mA or 0-5/10V signals.
Just in case you are just trying to measure the current use of your own measurement system and charging of its own battery, I should mention we now produce our own high efficiency, intelligent charger (the CH200) which can be connected to and interogated by a logger. With that you can get realtime measurements of load and charging currents.
Thank you for your answer !
It's a tiny solar panel (6V/700mA), I found a current shunt resistors for my application:
http://be01.rs-online.com/web/p/shunts/0257391/
But I don't really understand where I can placed the shunt resistor because I cannot placed in the ground connection from the solar panel, I have only the + and - ?
* Last updated by: MaximeD on 2/14/2013 @ 7:04 AM *
By the ground line I mean the negative line and that will be OK as long as the panel is connected by some path to the logger ground.
The issue here is that for the terminals connected across the shunt resistor both must be within +/-5V of the logger ground.