-=dwh=- wrote:
The problem with those power supplies as battery chargers, is they are regulated to 13.8v.
That is less voltage than what almost any flooded or AGM battery manufacturer recommends to achieve a full charge on their batteries.
Most 3-stage chargers will do a bulk to 14.4v to 14.8v (depending on who made the charger) and then drop to 14.2v for some hours for the absorb stage, and then drop to 13.2v to 13.8v (again, depending on who made the charger) as the long-term float (maintenance) stage.
So even if the power supply puts out 36a (peak, this would drop off as the battery voltage rises toward 13.8v), it's not going to get the battery fully charged because it will never push the voltage high enough to fully activate the chemistry (never reach full absorption).
It will work to get the battery to 85% or so of a full charge, and will hold it there as long as there is less than 36a of loads on the battery.
But taking the battery to 85% instead of 100% will increase the rate of sulfation, and will not extend the life of the battery as much as it would be extended if the battery were regularly pumped up to 100% with a proper charger.
Seeing as a common vehicle operating voltage is 13.8 V., are you saying that a production car's battery, as designed, never achieves a full state of charge?
That would seem awfully inefficient and would represent awfully negligent design from decades of automotive engineers.
:h
The internet is chock with advice and information about battery charging, with most lore being similar but variations existing. The most telling phrase I encountered is: 'You talk to different engineers, even at the same company, you get different answers.' :B
I'd have to think that the finished and stabilized voltage of an out of circuit wet battery will dictate what the level of charge it containes, and when the full charge voltage is 12.7 and the battery, removed by several hours from a charger, reads 12.7 volts then it is 100% charged, whether it got that way from being on the vehicles' own charging stystem, from being 12 hours on a 'maintainer' that generates no more than 13.8 volts, or whether it got that way from being on a three stage charger for a shorter period of time.
