Is it OK to float-charge a maintenance-free "sealed" car battery

[Overclocker]

Is it OK to float-charge a maintenance-free "sealed" car battery

lead-acid starter battery. typical 12v found on ICE cars

just wondering if a continuous float charge (around 13.5v) is OK to maintain SOC and prevent sulfation

 

[dogman dan]

Yes, unless the charger is so dumb it forces a high amps charge.( like a broken charger, or a huge 12v starting type charger)

But the typical tiny "battery maintainer" type float charger won't cook off the lead battery. Those are used quite a lot on motorcycles, which have smaller sla type batteries, with no harm done. Price of those maintainer chargers is no obstacle, usually under ten bucks.

 

[john61ct]

Very much depends if it is a good charger and if is user-adjustable (ideally custom setpoints) or at least its fixed adjustments are compatible with what the battery requires.

If that is a quality battery designed for deep cycling, there will be detailed data sheets if not a full owner's manual, and knowledgeable tech support readily available.

As an example, I have a set of Odyssey AGM

Absorb V gets over 14.4, no higher than 14.7V

Float V must be between 13.5V and 13.8V

Absorb (CV) should be held until current tapers to 0.005C, half an amp per 100Ah

only then dropping to Float.

Restarting a Bulk (CC) and Absorb charge cycle after loads have dropped V to say 13.2V, but that can vary.