You can wire an alternator that way and it will work...but it is kind of missing the point. The purpose of the exciter wire is to excite the fields inside of the alternator when you turn the key on so the alternator will begin producing current as soon as the engine is running. It is indeed better to connect the exciter wire to the ignition or (+) side of the coil or the coil terminal on the ignition switch. You will have a slight but constant electrical draw if you connect the exciter wire to the battery instead. If you drive your truck everyday you can get by. Keep in mind that if you are replacing a generator with an alternator and you do not have the more modern accessory type ignition switch that the engine may keep running after you turn the key off because the alternator is still producing current at idle whereas the generator did not. The fix is a DA Plug which will make everything work as it did before. and you will live happily ever after....

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