Clouds, haze, shade, heat, dirt and panel angles will all reduce charge rates.
For best performance, be sure to:
- Place the panels outside - you will get half the power and often much fewer hours of direct sunlight behind a window
- Point panels directly at sun - once the panels get past about 45 degrees, power production drops steeply
- Minimize shading and make sure nothing is covering any part of any cell
If you still think the battery is charging abnormally slowly, email technical support with:
- Description or picture of your product and battery (model number is on the back of battery)
- Description of the problem and what you've tested
- Order number for warranty purposes
- Best shipping address