A 12V battery that is not correctly maintained above 12.4V will suffer from sulphation, which the main cause of battery died. That's why the vehicle battery easily goes to dead when vehicles are left sitting for too long.
eBay
CN3791 MPPT Solar Panel 3.7V 4.2V Lithium Battery Charging Board Modules 6V 9V 12V Low Power Solar Charger
Aliexpress UK
Short-Circuit Current (Isc): 0.33A. Maximum Power: 7.5W.
eBay
SDLA12TA MPPT Solar Controller Charging Module for 12V 1-1000AH Lead-Acid Battery Solar Panel Regulator Charger Board
Aliexpress UK
First, face the sun with a solar panel, and a red light on the back indicates that the current output is normal. You can also put it on the workbench in front of the dashboard. With advanced polyethylene coating technology, the battery surface is coated with dark blue reflective film, which is uniform and beautiful in color.
eBay
XINPUGUANG 12V 50W Flexible Solar Panel 19.8V 100W Photovoltaic solar panels battery charger for Car Boat home camper balcony
Aliexpress UK
1 x 5W Solar car battery maintainer. Power source Solar Powered. Special feature Short Circuit Protection, Waterproof, Charging Indicator. 1 x 23.62 in Cigarette lighter plug. Mounting type Wall Mount.
eBay
CN3791 MPPT Solar Panel 3.7V 4.2V Lithium Battery Charging Board Modules Low Power Solar Charger 6V 9V 12V
Aliexpress UK
12V 24V LED Work Light Bar Wiring Kit Harness Loom Switch Relay Kit 2 Leads UK. 1200 Plastic Repair Machine Welding Hot Stapler Bumper Fender Welder Staples Kit. 5mm Sound Deadening Mat Car Firewall Heat Shield Thermal Insulation Proofing NEW.
eBay
400W MPPT Solar Charger Controller Step-up/Step-down Real-time Monitoring 10~30V 12V/24Output Voltage Solar Battery Recharging
Aliexpress UK
1 x 60w Solar Panel. Rated power: 60W. Maximum power: 60W. Solar output : 6.2V,4.8A.
eBay
CN3791 MPPT Low Power Solar Charger 6V 9V 12V Solar Panel 3.7V 4.2V Lithium Battery Charging Board Modules
Aliexpress UK
Description: 1.Wide Use: It has a single crystal r chip, lightweight and portable, suitable for outdoor travels. Can charge automobiles, boats, motorcycles, electric fans, emergency lights, solar water pumps, RV batteries or any 12V lead acid battery. 2.Dual USB Output Ports: The back junction box has dual USB ports that can charge two USB devices fast at the same time. The solar panel can charge your phone in emergency. 3.High Charge Efficiency: The solar panel with high conversion rate of 24% charges fast in the direct strong sunlight. .
eBay
1/2PCS Mini Solar Panel 3/2/1/0.4W 12/6/3/1.5V Cell Module Polysilicon Board Outdoor DIY Solar Charger for Battery Phone Charger
Aliexpress UK
Description: 1.Wide Use: It has a single crystal r chip, lightweight and portable, suitable for outdoor travels. Can charge automobiles, boats, motorcycles, electric fans, emergency lights, solar water pumps, RV batteries or any 12V lead acid battery. 2.Dual USB Output Ports: The back junction box has dual USB ports that can charge two USB devices fast at the same time. The solar panel can charge your phone in emergency. 3.High Charge Efficiency: The solar panel with high conversion rate of 24% charges fast in the direct strong sunlight. .
eBay
DC 6-60V 30A Lead-acid Solar Battery Charge Controller Protection Board Charger Time Switch 12V 24V 36V 48V Battery Capacity
Aliexpress UK