Calculating total current consumed over time?

Question

I'm currently building a battery testing rig which drains a battery and then charges it continuously and monitors/logs all associated data (voltage, run time, and instantaneous current discharged/charged).

I'd like to determine the current discharged over time, but not sure how to calculate that.

> For example: Say I at program time 00:00:01s the current consumed is
> 15mA, and then at program time 00:00:02s the current consumed is 20mA
> (so on and so forth).

Currently my program is just logging the instantaneous current every second. Beyond that I'm not sure what calculations are needed.

Answer 1

For system power consumption it's more normal to write things as either peak or average power consumption in either Watts or amps. Total power/current is then calculated by multiplying the average power/current by the operating time.

If however you are sure what you want is total current over time then that would be measured in Ah (Amp-hours). It's normally only used when talking about battery capacities rather than system power consumption but I suppose could be useful if you are measuring how much battery you have used.
The calculation is fairly trivial. Assuming you have a measurement once per second and want the answer in Ah then it's:
Total current at time t = Total current at time t-1 + Current at time t/3600

Answer 2

• If you import into a spreadsheet.
• C=Q/V and dQ/dt=I
• "CURRENT OVER TIME" = integral of Idt = Q
  • or the sum of all your I*t readings in seconds and converted to amp-hours.
• Power,P over time= V* I* t = Energy [Joules]
  • E=[watt-seconds]=[Volt*Amp-hour*3600s/h]

.

• the capacity of one cell is bigger than an ultracap using Ic=C(Vmax-Vmin)/dt ( converting hours to seconds) using cumulative Amp-seconds =sum(Idt)
• Cumulative I*t is the integral of I(t) or Ah total for Charge vs discharge.
• Power likewise can be computed during each phase, charge-discharge for each sample and accumulated. VIt duration added to previous value.
• You will be able to compute charger losses, and discharge losses or efficiency of Storage
• with a complex model of the battery you can compute battery Ah capacity and Wh capacity, ESR vs SoC, leakage R, and if you also measured case temp, T compute efficacy of ESR and C vs T ( improves but ages with higher T) and then compute battery life vs depth of discharge and depth of charge for cumulative Ah delivered where if SoC remains between 50% & 75% for LiPo, you get > 2x the lifetime Ah