Battery Charge Controller
What Does It Do and How Does It Work
Battery chargers vary a great deal in intelligence, the types of
batteries they can charge, how they maintain
batteries, and how long they take to charge. I'd recommend charging batteries at about 10% of their amp hour capacity.
For example, an 80Ah deep cycle battery should
be changed at a rate of about 8A.
Different types of batteries require different charging
regimes. SLA (sealed lead acid), AGM
(absorbent glass mat) and gel batteries are traditionally charged at a
lower voltage than flooded lead acid batteries.
This varies depending on the manufacturer. You should always check what charging
voltage is required before you buy deep cycle
batteries and a battery charger.
simple charger works by providing a constant DC power to the battery. A
simple charger won't alter its output based on
time or the charge on the battery. These type
of battery chargers are usually cheap, but there's a trade-off in
quality. Typically, a simple charger takes a
lot longer to charge a battery, and a battery left
in a simple charger for too long will be ruined by over-charging.
Choosing the Right Battery Charger for Your System
If left in place too long, it will eventually boil
the electrolyte out of the cells or damage the plates. Free hydrogen may accumulate and become
an explosive hazard when sparked.
based chargers operate much like a simple charger, but (as the name
would suggest) they operate on a timer. The
timing regime would be configured for a particular
battery and then left. However, if batteries of lower capacity were charged they would be then overcharged, in addition if
batteries of higher capacity were charged they
would be only partly charged. Timer based chargers also have the drawback that charging batteries that were not fully
discharged, even if those batteries were of the
correct capacity for the particular timed charger, would result in over-charging.
Battery charger output
charger output current depends upon the battery's state. An intelligent
charger may monitor the
battery's voltage, temperature and/or time under charge to determine the optimum charge current at that instant.
Charging is terminated when a combination of
the voltage, temperature and/or time indicates that the battery is fully charged. In a sense, the batteries tell the
charger when they are full.
chargers use Pulse technology or pulse width modulation in which a
pulse is fed to the battery. This DC pulse has
a strictly regulated rise time, shape, pulse width,
frequency and amplitude. This technology works with any size, voltage, capacity or chemistry of batteries, including
automotive and valve-regulated batteries.
Here we go back to system design. What is our current input capacity to
the charger from your solar panels, windmill, auxiliary gasoline
generator, and/or the electric power grid? What is the size and
voltage of the battery bank? Will there be room and inputs for
expansion of the current system? When the batteries are charged, will
the output from the solar panels and/or windmill be automatically
redirected to the inverter?
Your battery charger has to match up with both
your solar and wind generated energy outputs. The output of the auxiliary gasoline generator may have
to be adjusted to match up with the voltage of the battery charger
input. When the batteries are fully charged the solar and wind energy
should be redirected by the charger to the inverter for your use or for
You may decide to charge your battery bank at
night using utility grid power when your max power load is small compared to daytime. This can insure your batteries are always topped off
should you experience an unanticipated utility grid power failure,
extended cloudy days, or calm winds. You can run your inverter during
the hours of your peak daytime activity to reduce your peak daytime
utility grid use.
Cost and Reliability
[Charge Controller Inverter]