Check the battery’s fluid levels. If it is a non-sealed battery, ensure the electrolyte covers the plates; top up with distilled water if necessary.
However, like all professional-grade equipment, it requires precise operation to ensure safety and longevity for both the charger and your batteries. selmar-turbo-4-battery-charger-instructions
If your unit has LED indicators, they typically follow these standard industry patterns according to Onboard Charger and YouTube tech guides : Check the battery’s fluid levels