Portable battery charger made from a car alternator
#1 This is the field terminal which is marked field or #1 on the alternator. It needs
12V all the time. It’s is best to mount a toggle switch #5, so you can turn it off when
the alternator is not running. Otherwise it will drain the battery.
#2 This is the voltage sensing terminal. It can be hooked up directly to +12V. It should be run all the way to the battery with a separate wire #6. Otherwise it will not detect the voltage drop if the battery cables are longer.
#3 & #4 I used heavy battery cables
The pulley on the engine should be twice the diameter of the alternator pulley.
The alternator should run at least 2000 RPM.
12V all the time. It’s is best to mount a toggle switch #5, so you can turn it off when
the alternator is not running. Otherwise it will drain the battery.
#2 This is the voltage sensing terminal. It can be hooked up directly to +12V. It should be run all the way to the battery with a separate wire #6. Otherwise it will not detect the voltage drop if the battery cables are longer.
#3 & #4 I used heavy battery cables
The pulley on the engine should be twice the diameter of the alternator pulley.
The alternator should run at least 2000 RPM.
Watch a video on the home made charger
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