Even if I could check the voltage, keeping the Maximus at 40 - 50% capacity and/or in the fridge (anywhere but the car) would deny the purpose. I am actually keeping it full, in the car, for being able to use it at max capacity if/when I need. It is in a dark compartment with lid so not the hottest spot in the car but yes, the car will get hot in summer from time to time, when parked under the sun, albeit rarely, and with an effective windshield sun-shade (very reflective, highly insulated and cut to measure). I can't improve the storage conditions as this is a headlamp dedicated to the car but shall I exercise the Maximus (discharge the battery and recharge) from time to time? How often? Discharging to what extent?
What I have in mind is turning it on at about half power, monthly, until the battery indicator shows half charge and then, fully recharge. Is this a good plan? Given that the Maximus will be kept fully charged, in the car, would another plan be better?
Thank you and I am sorry, once again, for not being aware of your reply earlier.