Glove box outlet: already in use for cell phone and NAV devices.
Battery Tender: drives the heated seat OR the battery tender as needed. (you'd never do both at the same time.)
1. What is a "momentary" switch? Just a simple ON/OFF toggle switch?
2. I connected the Voltage meter wires to the right-front running light (always ON when key is ON) and got a 12.2 reading. Great. Let's turn on the heated grips and heated seat and watch the # go down.... NO change! Hmm... voltage meter isn't aware of the heated grips or heated seat. Hmmm.... As usual, I don't understand how voltage meters work... Where you connect them seems to matter A LOT.
3. I'm hoping to connect the voltage meter wires so that the readout tells me when the heated grips/seat are drawing power, but it's starting to be not worth the effort. Both heating devices work AND the battery still charges when I ride. What more do I need to know?
1. A doorbell is a momentary switch. When your finger is not
on the button, no power flows. The doorbell (or meter) will be Off then.
2. You want to measure Amps, not Volts, for those heaters. The Voltage Regulator (or a good strong battery) will not allow (show) much Voltage drop on a meter when things get added. Grips and seat warmers do not draw huge currents, usually. The controllers "pulse" power to the grips/seat, so actually the power may be Off more than On in time, when the heaters draw power. Your DC Voltmeter can't respond fast enough to show the DC Voltage drop because the draw is "intermittent," not constant. Try reading those gadgets as AC power, and you will see the "ripple Voltage" that the heaters cause in the DC Voltage. (Do not try this reading with a plug-in Voltmeter, use only a hand-held battery-powered meter.)
2a. As a side note, you want the Voltmeter connected across the battery + and Ground terminals. If THAT voltage starts to drop in-flight, there is a REAL problem.
2b. If you put an instrument light bulb between the heater lead and ground, you will see the bulb glow as you start to draw power, and a brighter glow when you draw more power. We are using the bulb as a quick-n-dirty (cheap) Amp meter. It will only show current
flow, which is what you want to see there.
3. What you want to know is the actual Voltage of the operating electrical system. See 2a. Connect the Voltmeter + lead to the fuse or relay closest (electrically) to the battery + terminal, if you want to see the Voltmeter working at all times the key is On, and then shut Off when the key is removed (which is recommended). A Fuse Tap makes it easy to tap a Voltage from any fuse position. Car parts stores will have Fuse Taps. Insert the Fuse Tap so the Tap wire has no power when the original fuse is removed. The Fuse Tap usually has a separate new fuse for that Tap line. Questions are welcome here.