@Eric (McGruff) posted:Float chargers apply a continuous voltage to the battery, albeit at a level lower than the alternator, just high enough to keep the plates from sulfating. They don't work well with maintenance-free batteries, which have a finite supply of irreplaceable electrolyte. The water slowly boils off, eventually exposing the plates to oxygen, which causes the battery to fail. Float chargers do well with maintenance-accessible batteries, where lost water can be manually replenished. They also do well with sealed, recombinant VRLA batteries.
For maintenance-free batteries, I either use a maintainer-desulfator, or I simply put a timer in front of the float charger so it only runs for an hour each day, which is just enough to boost the battery to a full state of charge. If your vehicle has small parasitic loads, increase the timer's duration to 2 hours.
Sorry I disagree.
Trickle chargers apply a constant albeit small charge. They work well to maintain Ni-Cad or Ni-Mh cells. I agree, TRICKLE chargers are not the best for lead acid batteries, the charge rate is too high to leave on continuously.
Float chargers charge to a certain voltage(2.25 to 2.27 volts per cell, 13.5 to 13.62 for all 6 cells) at a .5 to 1.5 amp usual rate(depending on charger), then switch to maintenance mode. Maintenance mode is a fixed voltage and a much smaller current than a TRICKLE charger. I've used one for 5 years on my maintenance-free motorcycle gel-cell(which is still lead acid). The battery starts as new every spring.
Float chargers are the way to go for most automotive/regular batteries.
You can spend more and get a maintainer/de-sulfator, but it's not necessary IMHO.
I come from a 30 year Telco background, and have been working with Rectifiers/Float chargers and lead acid batteries for a LONG time.