TNKs, RR et al.
We went thru this 40 years ago with the power supply system for the Viper.
The whiz kids working the flight control computers were given carte blanche. So the basic run-of the-mill folks that did the power supplies provided the specified volts and amps. They also had a simple emergency DC power system using PMG's and run off bleed air from the engine versus the hydrazine-powered "real" emergency system.
Unfortunately, the computer folks used voltage regulators that did not tolerate over-voltage, and would shut down when volts got above "x". So when an uncommanded EPU came on line, the PMG generator exceeded the critical voltage and POOF! No more flight controls. Not good.
We fixed the problem and also had newer solid-state voltage regulators that could handle 90 volts versus 37 volts +/-.
With known problems of the Li-ion batteries going out of control due to over-charging and such, my personal engineering decision would be to use the nickel-metal ones and have slightly less amp-hours, a little more weight, but be safe.