Post #9736

Do you have a really small generator and want to use it as a backup power source? If you have an "off grid" type inverter, you may be in for a surprise. Inverters come in two flavors, Hybrid and off-grid. When an off-grid inverter is connected to a power source such as grid or a generator, it transfers 100% of the load to that source. It also connects a battery charger to that source. When you program an off grid inverter to only charge the batteries with 10amps in one of the menu settings, that is telling the inveter that if there's less than 10amps demand in the house, it can have the spare power for battery charging. if you turn on a coffee pot, that available power will go down and battery charging will slow. If the house is already using >10amps, battery charging will stop. The inverter cannot control how much power your house pulls. All it can do is allow the battery to charge at an appropriate rate. If you have a hot water heater running and the microwave, your house may pull 20amps and that 20amp must come from the grid or your generator.... and if you generator can't supply that much power the system will rapid cycle on/off generator. Hybrid inverters can be programmed to blend power from two sources. Let's say you have a small 2kw generator and set the limit to 8amps. If you run the microwave and hotwater heater at the same time, your power draw will certainly be higher than 2kw. So the hybrid inverter will pull 2kw from the generator and no more. it will provide the balance of needed power from it's internal circuitry and your battery. When the house loads go away, if the load is less that your 2kw setting, the unit will charge the batteries. The hybrid inverter will allow you to use a smaller generator. There is another way to use a small generator without over loading it. If you get a 48v battery charger like the EG4 Chargeverter, you can program it to the 2kw limit of your small generator and it will directly charge your batteries while an off-grid type inverter continues to power your house unchanged. Hope this makes sense. Now... more about the hybrid inverters. Hybrid inverters such as EG4 hybrid, SMA and Victron can be programmed with a utility/generator limit and will blend power as described above. The SMA and Vic inverters can be programmed if your house pulls more than XX watts for YY minutes, they will auto start the generator. The victron has an additional feature where it protects your generator from surges. Anyone who has been standing next to a generator knows that the generator will suddenly get louder when something big it turned on in the house. Fact is, the generator actually slowed down a bit before it responded and sped back up. if your generator was to be hit with a large enough load, it's frequency could drop below 59hz (49hz) and your inverter would see that as an error and drop the generator. Victron solves this by providing the surge power from batteries and then over the next few seconds, giving that power draw over to the generator. The result is your generator slowly ramps up and never deviates from its 60hz frequency.