Having done it myself on my '15 Limited, I'd say 3 hours is closer to accurate. Anyone that can do it in one hour... hats off to them. (Talking factory, internally wired grips)

__________________________________________________ ____
For ROCKOUT information & purchasing please click the LINKS below... For all Twin Cams and Evo Big Twins & Sporsters

 

I have heated gloves, hybrid HD version that uses batteries also as I tried to be wired and hated it. Wife put heated grips on her Freewheeler. She isn't sold on them for the same reason I wasn't, fingertips still get cold. The gloves work fantastic for overall hand warmth, but have to have 2 sets of batteries for anything longer than 2-3 hours on Low and the batteries are bulky feeling but I've gotten used to it. cost for the gloves and batteries is about the same as the grips installed...I suffered for a decade trying big gloves with liners, etc. but still it was painful now the heated gloves solved all my cold finger issues

 

I have heated grips on my breakout. Was great until the backs of my hands froze during longer rides caused by direct wind hitting against them. The fairing, on the other hand, should help mitigate this so you can get heated grips. I only passed on getting them for my SGS because I didn't like the current design. The wiring wasn't internal. (cable is zip tied along the outside perimeter and down the handlebar) and the reviews on the Harley version were 505/50. I also needed a heated liner to wear under my jacket so I decided to go for a heated gear kit. The gloves plug into the liner and the liner plugs into one wire under the seat. Comes with a wireless thermostat/controller that is Velcroed inside the inner wall of the ipod storage cube. Pop open the lid, turn the ****, and you're cookin. Worked out best for me. Keeps my whole body warm. The whole kit rolls up nicely and is stored in one of the saddlebags.

 

Never had heated grips but always used heated gloves on cold days until it came stock on my 15 Limited and since then Jan 3rd of 2015 never use heated gloves, heated grips kept me very comfortable in the 20s and 30s in cold months. I don't have cold hands but on the other hand wife always have heated grips since 2006 and she uses both heated gloves and grips but her hands still get colder then mine, at each stop on cold days I've to warm her hands.

 

took mine off my 17 limited ....I, much, perferred grips that matched my theme (boards, pegs, etc) ......For me, there is a small temperature window where the grips were really nice this past winter. The window was so small that I just prefer to use my heated gloves which heat the entire hand.

And "for me" ......heated grips only keep the palms warm and do nothing for fingers and backs of hands

 

I am not using heated gloves but I am using Heated jacket. It is very good in winter and I ma living in canada.

 

I like the Heat Demons. Put them on my last bike when I installed KST Mayhem bars. Only down side is they take a few minutes warm up, being that they are installed inside the bar.
On my new M8 I'm finding the HD grips are to hot, even on the lowest setting. When I took it in for my 1st service & asked them to take a look, they said all is good ? If I swap out the bars I'll go with Heat Demons again.

 

Well, heated grips and heated gloves aren't an "either/or" situation . . . when it's, say, 50°F, my hands are cold, but heated grips fill the bill just fine. At 40°F, heated grips aren't enough, so I use heated gloves.

That being said, I installed the H-D plain black heated grips on my 2017 Road King in a couple of hours, and I wasn't hurrying anything. Not a big deal to install yourself (though you may choose not to; your choice). The H-D grips make for a nice, neat installation, since they are wired through the bars. I think aftermarket units may be more durable and reliable, but with the throttle-by-wire setup, more difficult to find something that works.

 

I love my HD heated grips. Get hot enough to warm me up when there is a nice chill in the air. While the won't solve the problem of being cold at 30 degrees, they won't hurt either. Usually they are more than enough to keep me comfortable at the temps we ride at here in Texas.

 

I love my heated grips! I won't have another motorcycle without them. As already stated, I always have them, I'm not wearing/bringing heated gloves in the summer but, if it rains or the temps drop a little at night or early morning, a twist of the control on the left grip and my hands are warm.
In the cold cold, I use both, there's no rule against that. ��