Why does the open circuit voltage of a battery decrease with increase in $\mathrm{pH}$ of electrolyte, but the voltage across a load increase?
I tested a cell which had aluminum sulfate as its anode electrolyte ($\pu{12 g}$ aluminum in $\pu{50 mL}$ water and a $\mathrm{pH}$ of 3.2), and potassium hydroxide as the cathode electrolyte ($\pu{5 g}$ of $\ce{KOH}$ in $\pu{200 g}$ of water, $\mathrm{pH}$ of 12.3). The anode electrode was aluminum foil and the cathode was platinum. The open circuit voltage (OCV) of the cell was $\pu{0.9 V}$, and when connected to a $\pu{1 k\Omega}$ resistor, the voltage was $\pu{0.324 V}$.
When I increased the concentration of $\ce{KOH}$ from $\pu{5 g}$ to $\pu{10 g}$, and all other material concentrations were kept constant, the OCV decreased from $\pu{0.9 V}$ to $\pu{0.7 V}$, but when I attached the $\pu{1 k\Omega}$ resistor, the voltage increased to $\pu{0.42V}$.
I do not understand why increasing $\mathrm{pH}$ is causing the OCV to decrease, but increase the voltage under a load to increase.
I am guessing for the voltage under the load that maybe the higher concentration of $\ce{KOH}$ leads to more ions in solution thus increasing the current flow. But if this assumption/hypothesis were true, shouldn't the OCV also increase?
Can someone please help?