Solar-Powered Mobile Toilet Battery
The battery of the solar-powered mobile toilet uses deep-cycle battery packs, primarily lead-acid batteries or lithium-ion batteries, with charge-discharge protection functions to store excess electrical energy for use at night or on cloudy and rainy days.
The battery system of the solar-powered mobile toilet is one of its core components, with its core characteristics reflected in the energy storage method and battery type selection. The energy storage system employs deep-cycle battery packs, which are different from ordinary car starter batteries. Deep-cycle batteries are specifically designed for multiple deep discharges. Their internal structures, such as plate thickness and electrolyte ratios, are optimized to withstand deep discharges of over 80% without significantly reducing their lifespan. This characteristic makes them highly suitable for solar energy applications—storing electrical energy during the day when sunlight is abundant and providing continuous power at night or on cloudy and rainy days, forming a stable energy cycle.
There are two main battery type options: lead-acid batteries and lithium-ion batteries. Lead-acid batteries have mature technology, are relatively low-cost, and have stable low-temperature performance, functioning normally in environments ranging from -20°C to 50°C. Therefore, they are widely used in cost-sensitive scenarios. Lithium-ion batteries, on the other hand, have become the preferred choice for high-end scenarios due to their higher energy density (up to 2-3 times that of lead-acid batteries) and longer cycle life (usually exceeding 2000 cycles, compared to about 300-500 cycles for lead-acid batteries). For example, a public toilet project equipped with a 7kW photovoltaic system uses a lithium-ion battery pack, which can support approximately 3 days of operation on a single charge, significantly reducing maintenance frequency.
The core of the battery's function is the charge-discharge controller. This component achieves three major protection functions by continuously monitoring voltage and current: automatically cutting off the charging circuit to prevent overcharging when the battery voltage approaches the full-charge threshold; stopping power supply to avoid over-discharging when the voltage drops to the discharge limit; and blocking reverse current through diodes or MOSFETs to prevent the battery from discharging back to the photovoltaic panels at night. These protection mechanisms can extend the battery's lifespan by more than 30% and reduce system failure rates.
The battery's application scenario focuses on energy time-space transfer. During the day, the electrical energy generated by the photovoltaic panels is first supplied to the toilet's loads (such as lighting, ventilation, and sewage treatment), with the excess stored in the battery pack through the controller. At night or when sunlight is insufficient, the battery pack automatically switches to power supply mode to ensure 24-hour operation of the equipment. Taking a 7kW photovoltaic system as an example, with an average daily power generation of 28kWh (considering sunlight fluctuations), configuring a 100kWh lithium-ion battery pack can meet the demand for 3 consecutive days of power supply, demonstrating the key role of the battery system in renewable energy utilization.
