Good batteries on board are so important. Even with solar panels, high output alternators, and wind/water generators… you still need a healthy house and motor bank of batteries.
If you have standard batteries (not lithium)… one of the most important rules to follow is to NEVER let your batteries fall below 50%. It is important to have a device that counts amperage in and out… but nothing is more accurate than measuring voltage at rest. For example… if you have 12v batteries… 12.20 volts is THE ABSOLUTE LOWEST you should ever see.