Knowledge of Ohms Law is essential for safety when using unregulated mechanical devices because the resistance of the coil build will dictate how much power is drawn from the battery - if you try to pull too much you will be running the risk of the batteries venting, or in the worst case scenario, turning your mod into an explosive device.
When it comes to a regulated mod this should not be an issue as you have control of how much energy is pulled from the batteries. A rule of thumb is to draw a maximum of 3 Watts per Amp per battery so they will not be overstressed even when they are close to low voltage cut off.
You have chosen good 25 Amp batteries, and the Aegis range of mods are good - if you run it at a max of 150 Watts you will be safe (the majority of vapers don't need anywhere near this much power to get a decent vape so you will probably find your sweet spot much lower than this). Really the only thing you have to pay close attention to is the state of your battery wraps - if they get torn, rewrap them.
Your mod runs in series configuration and will provide 8.4 Volts to the board, however - because you decide how much power to send to the coils the board won't necessarily be sending 8.4 Volts to the atomiser. If, for example you are running a 0.11 Ohm build at 105 Watts the screen may show 31 Amps and 3.4 Volts. Although 31 Amps is higher than the 25 Amp rating of your batteries, 31 Amps at 3.4 Volts is not the same as 31 Amps at 8.4 Volts so you will be well within the safety limit of the batteries. As the board is always being provided between 8.4 Volts down to 6.4 Volts when the batteries are low - the circuitry throttles back the power and sends out a lower voltage to provide the Wattage you have selected.
I didn't explain that very well, but if you stick to the 3 Watts, per Amp, per battery you won't be exceeding the Amp limit of the batteries, even if the screen is showing a higher Amp draw.
Nice choice of mod and batteries by the way.
