Dear Sirs!

I'd like to measure discharge curves of 48V telecom batteries. Each of batteries have two parallel strings and each of strings have eight 6V or four 12V accu blocks.

I will measure also temperatures of the batteries with LM 35 sensors and currents of each branches with external shunt resistors. I'd like to use independent (unshared) inputs of DT 85 Series 2.

Analog ground of DT 85 wouldn't be connected anywhere. My question is: Should I use external attenuator for voltage inputs from accu blocks or can I connect voltages from accu blocks direct to independent (unshared) inputs of DT 85?

Thanks for suggestions.
BR,
joe

Good morning Joe,

DT80 range has internal attenuator allowing then to read Voltages up to 30 VDC. All you need to do is wire your inputs and select the High Voltage (HV) channel type.

In DeLogger select Voltage as you Signal then select HV (High Voltage) under the Type column.

Cheers,
Roger

Hi Roger!

Thank you for the answer. As I understand it will be no problems (no harmful for the logger), that every accu blocks in a battery row is in the different potential to battery "ground" (from 0 to 48V).

I am somehow afraid about that: Common mode range: 3.5V or 35V on 30V range.

Cheers,
Joe

Good morning Joe,

Should be no problem, We designed DT80 with just this type of application in mind. DT80 has up to 100 VDC isolation between channels.

Please be careful with these higher voltage potentials and consider the safety of your set up. You should consider using a licensed electrician for the wiring.

Cheers,
Roger

Hi Roger!

Is DT85 input impedance enough accurate and stable to use it as a part of external attenuator for measuring 48 VDC voltage?

Cheers,
Joe

Good morning Joe,

Yes, no problem. If you are using external attenuator, use V channel type not HV.

Cheers,
Roger