monitoring 12vdc power supply with plc

[shooter]

You will have to use a converter running from 8 to 14 volts, as the volt needs to be measured a little better as from 2 to 10 volts for example, btw you can use your mA input direct, just put the battery on it and you will see some digits go but not very precise.

 

[leitmotif]

Hi Guys,
i have a micrologix 1100 and want to use its analogue input to measure a 12v battery voltage level using resistors. I want to know whats the best way to do this and what should i consider. I have tried using the R=V/I to get the size of the resistor at 20mA but when i tries this the current i got going into the analogue module was about 1mA.Can anyone give me the neates solution.

What are you really concerned about - the battery charger operating or the battery itself?

IF the charger continue with your thinking it is good and will be OK

IF the battery is your main concern
AND you can get into each cell connection (not a sealed or automotive type battery) you may be better off monitoring each cell voltage. This wlll give you several readouts that may or may not be important to you
1. Sum of cell voltages = line voltage (either from battery or charger) THIS will also tell you if charger is operating ie 13.5 or so vs 12 or so.
2. Will help protect battery by monitoring for low cell voltage when discharging - prevents reversed cell.
3. A very rough approximation of cell charge - hydrometer is best.

Dan Bentler