A 1.5 watt solar battery charger is a small, portable solar panel designed to slowly charge 12V batteries using power from the sun. With a power output of just 1.5 watts, these ultra-compact panels are not designed for fast charging. Instead, they provide a convenient way to maintain your batteries at full charge when regular charging is not available.
1.5 watt solar chargers are commonly used for keeping batteries topped up in stored vehicles, boats, RVs and summer cottages when not in use. Their small size also makes them handy for providing backup charging of AA/AAA batteries or small devices when camping or off-grid. While limited in capability, these budget-friendly chargers offer independence from the power grid.
Key Specifications
Typical specifications for a 1.5 watt solar battery charger include:
- Power Rating: 1.5 watts
- Voltage: 12V or 24V
- Current: 80-120mA
- Size: 5 x 6 inches up to 15 x 15 inches
- Weight: 8-16 oz
High quality panels from reputable brands like Harbor Freight can cost $15-$25. Cheaper no-name panels are also available but may suffer from quality and durability issues.
How Do 1.5 Watt Solar Chargers Work?
While limited in capability due to their tiny size, these solar chargers use the same fundamental technology as larger panels. Here’s a quick overview:
- Solar cells made of silicon convert sunlight directly into DC electricity through the photovoltaic effect.
- Multiple solar cells are connected together into solar cell circuits and encapsulated to form a weatherproof solar panel.
- The solar panel has positive and negative terminals that output a nominal 12V or 24V.
- This DC voltage charges batteries directly or with a simple charge controller to prevent overcharging.
1.5 watt solar panels are designed specifically for trickle charging batteries. They do not produce enough power for directly running devices or equipment. The key is keeping batteries topped up over long periods of time.
What Can You Power with a 1.5 Watt Solar Charger?
While 1.5 watts is not a lot of power, these micro solar panels can be very useful for:
- Maintaining charge of 12V batteries in stored vehicles, boats, summer cottages to prevent discharge over time
- Charging AA/AAA batteries for flashlights, radios or other low power devices
- Providing backup charging for smartphones, GPS and other small electronics when camping or off-grid
- Powering ultra low-power devices like LED lights, solar fountains etc.
The tiny solar panel can sit unattended, slowly building up charge in 12V batteries during daylight hours. Just a few hours per week may be enough to keep batteries at peak voltage.
Of course, given their 1.5 watt power rating, these solar chargers do have significant limitations…
Limitations of 1.5 Watt Solar Battery Chargers
While handy for trickle charging, 1.5 watt solar panels have some significant constraints:
- Very slow charging – It can take weeks to fully charge a large 100Ah battery
- Minimal power output – Cannot drive motors, pumps or other loads directly
- Heavily dependent on sunlight – Output varies widely depending on weather and latitude
- Permanent fixed mounting required – No shade or obstructions can block panel
Testing by independent reviewers has confirmed these limitations. In a recent test charging a 35Ah battery, a 1.5W panel produced only 60mA in full sunlight. Even in ideal conditions, it would take over 2 weeks to fully charge this small battery!
So while these tiny solar panels make great emergency chargers, they are no replacement for larger solar arrays that can provide real usable power.
What to Look for When Buying a 1.5 Watt Charger
While a 1.5 watt solar panel cannot drive large loads, it can still be extremely useful for keeping your batteries topped up. Here is what to consider when selecting one of these mini chargers:
Voltage and Current Ratings
- Select a panel with voltage matched to your battery – usually 12V or 24V
- Current output should be 80mA or higher (power = voltage x current)
Rugged Construction
- Ensure waterproof, scratch resistant design to withstand outdoor use
- Check solar cell lamination and casing quality
Mounting Options
- Suction cups, dash mount, external permanent mount etc.
- Easy to mount on car windshield, boat deck, cottage roof
Connectors and Wiring
- Cigarette lighter plug, battery clamps, SAE connectors etc.
- Sufficient wire length to reach battery
Reputable Brand and Warranty
- Established manufacturers like Harbor Freight
- At least 1 year replacement warranty
Review solar charger product specs carefully to verify suitability for your application.
Conclusion
While their small size limits their capability, 1.5 watt solar battery chargers provide a useful portable power source for keeping batteries topped up. Key highlights:
- Ultra-compact 5-15W panels for maintaining charge when grid power not available
- Keep vehicles, boats, summer cottage batteries charged during storage
- Slow charge AA/AAA batteries for radios, flashlights etc.
- Provide backup charging for phones and devices when off-grid
For $15-$25, a tiny 1.5 watt solar panel can make a great addition to your emergency preparedness kit or off-grid power toolbox. Just size your expectations properly and ensure proper mounting to maximize sunlight exposure.
With the right expectations, a 1.5 watt charger can be an invaluable tool for harnessing solar energy to keep your batteries fully charged!