Wednesday, Jul 09, 2003 at 09:40
Hi Leroy,
A 3 stage charger has as the name suggests, 3 stages to the charging cycle.
First is the BULK charge, this cycle typically runs until the battery reaches 85% of full charge, charging current is typically very high during this cycle and the voltage is not constant.
Second is the ABSORPTION charge, a constant charge voltage is now applied until the battery reaches 100% charge. The constant voltage limits the charging current and prevents excessive gassing of the battery which results in loss of electrolyte.
Third is the FLOAT charge, a lower charge voltage is applied to the battery such that current supplied is minimal and gassing does not occur, it is safe to leave the charger in this mode indefinitely.
An optional EQUALIZATION charge can also be applied periodically if you are using wet batteries, say once a month, this boosts the charge voltage to something around 15 or 16 volts and causes the electrolyte to gas, theory is it will equalize the charge between cells. Not for use with sealed batteries.
As an example for an AGM battery:
BULK charge voltage can be from 10.5 to 14.5 volts at a current up to 75% of the batteries capacity. So for a 100AH battery charging current could be as high as 75 Amps ( for a 100A/H wet cell battery you would normally limit current to 10 or 15 Amps ).
ABSORPTION Charge voltage is constant voltage and is in the range of 14.2 to 14.7 volts.
FLOAT Charge voltage is constant voltage and is in the range of 12.8 to 13.8 volts.
The above is an example for an AGM battery.
You would set the various voltages and current limits to suit the type of battery you are using, the manufacturers data sheet should state the ideal charging parameters.
The Plasmatronics PL series regulators also have some standard programs installed if you do not wish to go into great depth, although the units are very easy to program.
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