I'd love to have a definitive number, voltage wise, when 12 volt vehicular electronics enter their uncomfortable voltage zone. I think they are pretty robust. Look at all the people who remove a battery lead with engine running to "test" the alternator these days, and don't fry their engine computer with the voltage spikes from an alternator load dump.
I know in some RV's with absorption fridges, that 15.5V is the limit on the fridge's circuit board. Rv batteries can need voltage above this number when cycled deeply often, and problems can arise if the operator has a voltage source capable of 15.5V+.
I use an adjustable voltage Switching power supply capable of 41 amps as a Manual charger, and while it will got 19.23V, I never set it higher than 16V.
I do disconnect the battery from all loads when I apply this high Equalization voltage, and I dip my hydrometer every 10 minutes and Stop charging when Specific Gravity no longer rises, or it reaches ~1.285, temperature compensated or battery temperature approaches 120F.
I don't trust these well marketed 'one size fits all' automatic chargers. Perhaps on a starting battery every so often they are fine. But not a deep cycle battery cycled deeply, nightly.
Some of these chargers might get confused when they are charging, and you open the doors and 0.8amps worth of lights come on. The charger will need to increase current a bit to maintain the float voltage, and when the doors are shut, the 0.8 amp load removed, voltage will rise, and the charger will need to back off current trying to maintain a float voltage.
This might cause the unit to shut off as it thinks there is something wrong with the battery, rather than a load on the battery switching on and off.
I have a Schumacher sc2500A whose voltage would yoyo from 13.6 to 16.5v when a 2.7 amp load cycle on and off the battery. Often it would shut itself off. If it did not, then overcharging and positive plate degradation would occur.
It is good to get, and keep a lead acid battery at 100% charged. Many charging sources that indicate when a battery is fully charged, would have a hydrometer disagree.
Many smart chargers when first turned on, shortly after the car is driven, are fooled by Surface charge, and will go into low current, low voltage float mode, instead of bringing battery voltage upto the mid 14's where it absorbs the charge as current required to hold mid'14s tapers off.
Might want to leave those lights on after driving to take off the surface charge, before hooking up and starting the charger. An 80% charged battery will only need 0.3 amps to hold it at 13.6V, but it can take 14 amps to get that same battery at that same state of charge upto 14.5V . So 0.3 amps for 14 hours is not going to replenish what 14.5v could in 45 minutes.
I've done tests recently with voltage and on my Deep cycle battery. 5 days at 13.6v was not enough to max out Specific gravity, and I can accomplish this in a few hours with voltages upto 14.9v at amperages upto 41, initially.
'Trickle' gets a lot of hype. Low and slow charging is easier on a battery, but will it get the battery fully charged in time?
Often, not.