My tractor starter motor draws way more amps than my alternator can supply and therefore I should not start my tractor engine? Will I burn up my alternator?
I install and repair very big UPS systems for a chemical plant. Imagine an entire romm with only a charger, inverter, and batteries. I'll argue against some of the above posts all day long and prove they are wrong.
The case for an inverter is not for steady state heavy loads like a home electric furnace, clothes dryer, or water heater. Most field uses of power are for power tools. Like your starter motor that draws hundreds of amps, your table saw or electric chain saw will be used for perhaps 15 seconds every few minutes. It is the battery capacity in amp-hours that is most important, not the alternator capacity. You probably could run very heavy loads for short times with the tractor OFF, then start the tractor and let the battery charge. No more risk than putting a somewhat low battery in the tractor and starting the tractor to charge it. The trick is knowing how low is too low before a diesel will not start. If your load is not high and constant then you probably will not burn up an alternator.
My pick for an inverter will be a new Coleman Powermate 2000/4000 watt unit off ebay. New cost is about $170 + ship. The larger capacity is needed for the inrush or starting current for electric motors, as discussed in above posts. This unit should easily operate hand electric tools and may start my table or radial saw OK. It will not start a 2 hp air compressor because an air compressor starts under full torque load, difficult for an electric motor.
If you have a good battery you will not have a problem. My plan is to make an esay carry package of inverter attached to a battery, with a clips or cig. lighter adapter to let it charge.
An 80 amp-hour 12v battery should provide 960 watt-hours of power. Derate this by 5% to 912 watt-hour due to inverter ineffency. This means a 15 amp (1800 watt) circular saw should opeerate under full load for 36 minutes. A 60 watt drop light would operate 15 hours. This is battery only, no alternator.
Modern inverters have good controls that meassure input and output voltage and shut off when battry voltage gets low, protecting the tool (computer) from undervoltage. Inverters also need some load before they ramp up to rated output voltage. To test output voltage plug in a drop light or other light bulb type lamp, then measure output while the lamp puts some load on the inverter.
I'd be glad to help with questions.
jrpoux@wcnet.net
