Put a digital voltmeter and watch what happens when you turn it on.
On my bike, it runs at 13.9 volts and when I turn on the Gerbing heated jacket at highway speeds, it stays put or goes to 13.7 with the heated grips on high.
With the heated jacket, heated pants, heated socks and heated gloves, it drops to 12.4 volts and quickly goes to 11.9 volts as soon as I slow down.
So with just a heated jacket and heated grips on, you have plenty of juice.. but I'd still recommend you add a digital voltmeter. There's someone in Vendors selling them. A friend got one and it works as advertised.
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