I'm not exactly sure when the various OEM alternator improvements were introduced, but I imagine that you are going to be cutting it fairly close. Understand this, the major reason for concern is that in all the electrical system, the battery gets its share LAST. Most Airhead riders would be left with a dead battery and no way to start their bike, but the 1974 model still has the manual "kick" start. So it's certainly worth a try.

► I would do several easy things to give yourself the BEST chances at success:

1. Install an LED head lamp bulb. That one step will save you at least 40W alone. Adding LED tail lamp, parking lamp and gauge lamp bulbs will save you even more. 

2. Disconnect any frontal "road lamps", CB Radios, older GPS and music systems that are not cell phone based. (Charging your cell phone for the purpose of GPS navigation or music will still be OK.)

3. Consider a tune-up for your charging system by installing a solid-state voltage regulator and replacing the alternator brushes... especially if you don't know when new brushes were last installed.

4. Then, make a conscious effort not to run the jacket until your bike is out on the open highway running continuously above 3000 RPM. Obviously, 1 stop sign every 40 miles is not a deal breaker. What I'm warning against is an hour of low RPM in-town riding. What matters here is the daily average alternator output; you'll want to keep the average high.

► All this is assuming that your jacket has some type of internal thermal control unit, and is very rarely set to the highest (65W) setting.

After all these preventative steps, if you start seeing dim headlamps or sensing your battery in a low state of charge, then you'll know that despite your efforts, you need to start looking around for a high-output alternator. 

► Additionally, the electrical connector you'll be adding for the jacket should have a separate fuse (I highly suggest 15A flatpack style). You'll most likely not want to take power directly from the ignition switch, but rather from a relay powered by the Gray/Black wires. If you connect directly to the battery, then you'll need to disconnect at every fuel stop and eatery.

Hope this helps.

Thanks for the reply!

I have brushes to replace the originals (never been replaced) but they are still on the shelf...

Thanks for the tip about the LED headlight. I swapped the Wixom bag tail lights to LED and I didn't even think about the main tail light...I will do that.

I retrofitted the instrument panel harness with an LED harness a couple of years ago and I have a USB dongle to plug into my SAE plug when I want to charge my phone or Sena.

I added a cafe fairing a couple of decades ago so I have an active volt meter on the bike (green letters, couldn't find the white).

I rarely ever run the heater on high...generally it is on low or medium, so it sounds like I will go ahead and wire the Tourmaster connector in, and it does have its own inline fuse.

Appreciate the input, Jim

Posted by: @10385

Thanks for the tip about the LED headlight. I swapped the Wixom bag tail lights to LED and I didn't even think about the main tail light...I will do that.

Jim -

The headlamp is the single largest user of power in the entire OEM electrical system, so that's where you want to start. Obviously, changing the tail lamp and gauge lamp bulbs over to LED help, but not to the extent of saving 30W.

Changing items like the horn, brake lamps and turn signals have the least gain because their percentage of active use is so very low.

► When you add your LED headlamp bulb you'll also want to remove the sub-reflector from the main reflector. To do this you simply separate the glass from the reflector, then unclip the tripod and discard.

Hope this helps.

Thanks for the info...I removed the sub reflector years ago (for some reason)

@10385 Let us know how it goes.

OK I will!

I became skeptical about finding a quality LED headlight after reading all the pros and cons, but then I found one at EME and I bought it, for I have bought tons of stuff there with no issue. Installing the light was less than a minute...pulling and replacing the S fairing took a little bit longer. While I was at it, I replaced the lights in my Wixom bags with LEDs and they are certainly brighter. I had already replaced the cluster with a Katdash a couple of years ago.

Jim

BTW, here's a pic of the bike taken yesterday.

After riding the bike with the new LED headlight I can tell an immediate difference in the volt meter.

It seems to be about 1/2 volt happier across the board...I didn't realize how much draw a halogen headlight demanded.

I haven't plugged in the heated jacket liner yet, but I can't imagine it would draw as much as the old headlight.

Jim

Very glad you're happy so far.

If you want to be sure about the charging situation, then you can temporarily add a DC ammeter between the battery post and battery cable. The meter should be capable of 10A or higher. With that meter you can map out current consumption within the bike's electrical system for both 'engine running' and 'engine off'. 

'Engine off' shows you the pure loads within the system. 'Engine on' (above 3000 RPM) will show you how much the alternator is adding back. [Of course the issue is that if your bike has electric-start-only, then you can't start the bike with the ammeter in the circuit.] While system voltage is the best way to see that the charging system is generally "OK", system current is the best way to make sure the battery is being kept in the positive end of the number scale (what is generally known as "charged"). And since the battery is the Queen who must be kept happy, meter readings can be an easier-to-manage indicator, as opposed to getting 100 miles down the road and discovering your bike won't crank to get you home.

Thanks for the info. As far as keeping the battery topped off, I rotate a battery tender between my parked bikes to keep the batteries "topped off" at home.

Posted by: @10385

Thanks for the info. As far as keeping the battery topped off, I rotate a battery tender between my parked bikes to keep the batteries "topped off" at home.

That's not always such a good idea.

✦ Research has shown batteries don't always like to be held at full charge. Batteries prefer to be regularly "exercised" over a wide range.

✦ If any of my batteries are not going to be used within a week, I simply disconnect one of the battery cables. The main cause of "discharge" is not the battery itself, but the battery being connected full time to the rectifier. I use a battery disconnect device on my riding lawn mower, but that has a lot more space around the battery posts than an Airhead. That battery stays unused, uncharged and totally un-maintained in an unheated out building from September to March, and it never fails to crank a 700cc V-twin mower within the first 4 seconds.

✦ While some of the $80+ "maintenance chargers" are quite good and have a anti-sulfation mode, I believe the vast majority of basic battery "tenders" are actually cooking the batteries into a shorter life. You might wish to measure the voltage and current levels of the tender's output just so you know what it's doing. 

Hope this helps.

It seems I am constantly learning something I didn't know about these bikes.

Thanks heaps for the info!

Jim

Suggestion: You could easily "relax" the battery tender charging program by plugging it into a common "home lamp timer", and then setting the timer for 30 min per day.