In the world of renewable energy, solar charge controllers are pivotal in ensuring the longevity and efficiency of battery systems. These devices manage the power going into the battery bank from the solar array to ensure that the batteries do not get overcharged during the day and that the power does not run backward to the solar panels overnight, which could deplete the batteries. Traditionally, solar panels are the go-to power source for charging batteries. However, there are scenarios where alternative power sources may be necessary.
One such scenario was encountered by a camper van owner who shared their experience on the northernarizona-windandsun forum. The van was equipped with an 85W solar panel and a SunSaver Duo charge controller, a device designed to charge both the house (RV) battery and the starting battery independently. Unfortunately, the van was mostly parked in a garage, rendering the solar panel ineffective as the built-in charger of the van was non-functional. In a bid to find a solution, the owner decided to experiment by substituting the solar panel with a cheap adjustable voltage DC power supply.
The setup involved setting the DC power supply to 16VDC and connecting it to the SunSaver charge controller in place of the solar panel. Initially, the experiment seemed successful; the SunSaver charge controller appeared to accept the DC power as if it were coming from the solar panel, subsequently charging both batteries. However, this success was short-lived as the power supply started to run very hot and eventually failed after about 20 uses.
The failure of the DC power supply raised several questions. Was the failure due to the use of a cheap DC power supply, or was it a result of hooking any DC power supply to a PWM charge controller? The owner was left contemplating two options: (A) purchasing a purpose-built charger with the capability of charging two batteries or (B) buying a high-quality 16VDC power supply.
While option (A) seemed like the safer bet, the owner, in the spirit of scientific inquiry, was inclined towards option (B). However, they were also considering whether adding a large capacitor in-line might help prevent the power supply from being damaged by the PWM chop.
The dilemma faced by the camper van owner is not uncommon for individuals relying on solar power in locations with limited sunlight. Let’s explore the two potential solutions:
A purpose-built charger designed to charge two batteries independently could be a reliable solution. These chargers are specifically designed for scenarios like this and come with built-in safety features to prevent damage to the batteries and the charger itself.
- Specifically designed for charging multiple batteries.
- Built-in safety features.
- Less risk of compatibility issues with the charge controller.
- Potentially more expensive.
- Less flexibility as it can only be used for its intended purpose.
High-Quality 16VDC Power Supply
Using a high-quality 16VDC power supply is another option. However, it is crucial to consider the compatibility with the PWM charge controller and whether the power supply can handle the PWM waveform.
- More flexibility as it can be used for other purposes when not charging batteries.
- Potentially less expensive than a purpose-built charger.
- Risk of compatibility issues with the PWM charge controller.
- May require additional components, such as a large capacitor, to prevent damage.
The experiment conducted by the camper van owner highlights the challenges faced by many individuals relying on solar power in locations with limited sunlight. While the initial success of using a DC power supply was promising, the subsequent failure underscores the importance of considering the compatibility of all components in a solar power system.
For those facing similar challenges, a purpose-built charger may be the safest and most reliable option, despite its higher cost and lack of flexibility. However, for those willing to take on a bit more risk and who have a good understanding of electrical systems, a high-quality 16VDC power supply with the necessary modifications may be a viable alternative.
Ultimately, the best solution will depend on individual circumstances, including the available budget, technical knowledge, and willingness to take on risk. It is always recommended to consult with a professional or conduct thorough research before making any modifications to a solar power system.