What are the differences between float charging and boost charging in solar power battery systems?

Answer 1

The difference between a float charger and a trickle

charger is that the float has circuitry to prevent

overcharging. It senses when the battery voltage is at the

maximum level and temporarily shuts off the charge (floats

voltage at zero or a very minimal charge until it senses

that the battery output voltage has fallen, then resumes

charging ). You can keep it connected indefinitely.

A trickle charger, on the other hand, will charge no matter

whether the battery is fully charged or not. So it needs to

be connected and disconnected periodically. If left in

place too long it'll eventually boil the electrolyte out of

the cells or damage the plates. Trickle chargers will work

to keep the battery charged if used once a month or so for

a day or 2, but the float chargers can be left connected

indefinitely without potential harm to the battery.

For example, a 24 volt battery pack, comprising 12 2-volt

flooded lead-acid cells, which has been deeply discharged,

would normally be restored by a boost charge of

approximately 2.4 volts per cell for a short time (perhaps

around 72 hours). Once the collective cell voltage reaches

a surface charge of 28.8 volts (2.4 volts x 12 cells), the

charge rate would be switched to the sustained lower float-

charging rate of typically 2.23 volts.

Eventually, with the Boost charge removed, the surface

charge will diminish slightly and the battery-bank voltage

will stabilise at a preset float voltage, in the case of

the example above to approximately 27 volts (2.23 volts x

12).