How to Build a Solar Battery Charger for Household Applications
Learning how to
build a solar battery charger is an easy introduction to
solar power generation. The free
energy provided by the sun can be harnessed by inexpensive
solar cells and stored in batteries
for later use. These solar collectors are practical for charging
batteries used in electronic gadgets, cell phones, car batteries
and even larger RV and boat power storage systems.
Solar battery chargers are much smaller than the big solar
panel installations used to power homes. The required power is
much less and only one panel may be needed to generate enough
electric current to recharge a battery. These systems operate
on direct current (DC) and therefore no inverter is needed to
generate 120V/240V alternating current (AC). With fewer
inefficiencies to overcome and less equipment required,
a solar battery charger is cheap to install and easy to
Solar Charger for AA, AAA, C, D Batteries
Many rechargeable battery companies offer a solar power
recharger for their products. It incorporates a solar cell, a
charger controller and a holder for the different battery types.
These units come with small solar panels which usually takes a
couple of days in direct sunlight to recharge an AAA battery.
If you would like to create a more powerful solar battery
recharger, look for a unit with a cigarette lighter connector.
These have a charge controller that can be directly connected
to a larger solar panel that also has an appropriate connector.
The higher the power rating on the solar panel, the more
current it will supply thus speeding up the recharging
process. With a 20W solar panel, it may take only 3-4
hours to charge AA & AAA batteries; and 7-8 hours for
C & D batteries.
Solar Charger for Cell Phone & Camera Batteries
These lithium-ion batteries hold more energy and take longer
to charge. Youíll need a 12 V car charger for appropriate for
your phone or camera battery, a charge controller and a larger
solar panel of at least 20W, higher if possible. The charge
controller is placed between the solar panel and the phone
or battery and will disconnect the electric current when
the battery is fully recharged.
Solar Charger for 12 V Car Batteries
When a car isnít used for a long period of time, the battery
slowly discharges. A solar cell is practical for helping to maintain
the charge. Select a solar panel with a power rating as high as
possible that will conveniently rest in the windshield or hang
on the window. Look for one that can easily be plugged into the
cigarette lighter. These panels usually use a trickle charger
but since the capacity of the battery is so large, there is
little worry of overcharging. No charge controller is necessary.
Solar Chargers for RV & Boat Power Storage Systems
Large solar battery rechargers are great for RVs & boats.
The open roof or deck is fully exposed to the sun all day and can
charge multiple batteries. Ensure to use a charge controller with
a Maximum Power Point Tracking (MMPT) circuit thatís placed between
the solar panels and the batteries. Its current capacity should be
able to handle the maximum amount of current from all of the panels.
The MMPT circuit will optimize the voltage and current produced by
the solar panels to maximize the battery recharging.
Look for solar panels that are weather-tight and have a light-weight
and strong aluminum frame. The mounting flanges should be compatible
with the surface of your boat or RV.
Never charge regular alkaline batteries in a solar charger. The
battery may rupture, leak and could possible explode. Also, for boat
& RV systems, check with the battery manufacturer to see if explosive
hydrogen gas is vented when charging. Extra ventilation may be required.
Solar battery chargers are more than just novelty devices. They
provide a reassuring power source when youíre away from the electric
grid and in times of emergencies. "Free energy" is available,
and a solar battery charger is an inexpensive way to tap into it.
What to look for:
- Trickle charger ≠ These provide a constant charge
whether the battery is fully charged or not. These should only
be used for where the unit will be disconnected after a few days
(i.e. AA/AAA, cell phone and car batteries). Leaving these
continuously connected may boil the electrolyte or damage the
plates within the battery.
- Float charger ≠ These have circuitry that will stop
the charging once the battery has reached its maximum storage
capacity. You never need to worry about Ďover-chargingí the battery.
- Charge indicators ≠ Most units have Light Emitting
Diodes (LEDs) that indicate if the unit is charging or if the
batteries are fully charged.
- Weather-proofing ≠ Not all solar battery rechargers
are weather-tight, especially for small appliances. Check if
the model is rated for outdoor use.
- Size ≠ The larger the solar cells, the more electrical
power is produced. Buy a unit that will provide enough power thatís
still easy to handle and store.
- Car battery charger ≠ Look for units that come with a
connector that can easily plug into the cigarette lighter.
- Flexible versus solid solar cells ≠ Flexible solar foil
are convenient and easy to handle but produce less electricity than
their solid counterparts. Determine if the practicality of a flexible
unit more than justifies the lower power generation.
- Mounting hardware ≠ Larger units for boats & RVs need
to be attached to the deck or roof so they can maximize the daylight
hours. Look for units with light-weight, yet strong aluminum frames
with mounting flanges that are compatible with the surface of your
boat or RV.
Knowing how to build a solar battery charger is a great way to
contribute to the eco-friendly movement, while also enjoying the
benefits of an alternate source of energy.