The battery in the electrical system is a lot like the check book in a personal financial setting. If the checkbook is continually overdrawn, then 1) you need to get a bigger pay check (put more in), or 2) you need to cut back on your spending (not take as much out).

In the same way with the battery, you can buy a higher output alternator, or you can cut back on the items draining the battery. The second way in both cases is the harder, but much less expensive route. In the end, the optimal method is to try and do a little of both.

So how could you effectively cut the drain on your electrical system ?
• First and foremost, convert ALL bulbs to LED
• Replace the pilot bulb with a 20W version and run this during the day in place of the HL
• Remove or disable any extra brake lamps or running lamps
• Reduce the use of turn signals, especially when stopped
• Do not use the horn

So how could you increase the output on the existing alternator ?
• Try to keep the RPM up. Don't shift under 3200 RPM.
• Check and replace worn alternator brushes
• Take longer rides. Power leaves the battery quickly, but re-charging takes more time.
• Research the Bosch "Police Regulator" available that starts the charging process at lower RPM

And don't forget, the best charger you can buy for use with AGM batteries is only $90. That's far, far less than the cost of the higher output alternator !

Hope this helps.

Hey,

Thanks so much for your reply. Do you have any suggestions about where to get the appropriate LED bulbs?

Also, do you have any experience with Lithium batteries?

• Headlamp bulb - Cyron H4 #ABH4K-A6K ~$30 Amazon

Everything else you can get from SuperBrightLEDs.com
• Use BA9s (96 lumen) in Cool White for the pilot bulb
• Use only Red LEDs in the tail lamp* [exact bulb(s) depends on tail lamp]
• Suggest #194 Green for the gauge illumination
• Suggest BA7s Green for clock and voltmeter illumination

* With a standard white incandescent bulb in the tail lamp, most of the spectrum is filtered out. Red LED bulbs will appear much brighter because All of the generated light passes directly though the Red lens. You'll also want Amber bulbs in the turn signals for the same reason.

Wobbly's recommendations are spot on. I would only re-inforce his point from the second post to keep the RPMs up at all times when in motion. In any "in town" riding, I seldom get my bike higher than second gear. The thing about our airheads is that a person has to teach himself to use the bike for any given situation. If you practice gear selection to maintain high RPMs and reduce the load on the charging system, you should be O.K.

Thanks guys so much for your advice!

Forgive me, but what is the pilot light?

I can't know for sure what Wobbly's terminology refers to, but, on my early Airheads, there is a secondary bulb socket in the headlight for a small bulb that is illuminated when switched to "parking" light function. Some riders run this way in the daylight to meet the requirement for a daytime headlight without running a full blown headlight bulb in order to reduce the electrical demand. On my '88 R100RS this secondary light was not in the headlight, but under a separate lense cover on the fairing some times called an "eyebrow". Perhaps this sort of thing is what he is alluding to. This may not apply to your 1993, R100R.

It also might be worth looking into the possibility of some kind of parasitic draw on your battery with the key turned off.

Motorrad Elekrik Omega charging - no alternation to your existing bike, proven technology, and you can put put around all you want.

I was working with Rick (owner of Motorrad Elektrik) at the MOA Rally in West Virginia years ago. Two GS riders from NY City came in. One bought the Omega - and they installed it in the parking lot. His mate came literally running back in and bought an Omega kit too. Charging starts at 1500 RPM.

Thanks everyone for their replies. Since I'm trying to avoid the cost I'll avoid the Omega, the kit is 600 US.

I'm definitely going to try the led's and replacing the brushes on the alternator. Seriously, thanks everyone for their replies.

Best

And worth every penny. It's also more that 450 watts now, but you will have to talk to Rick Jones about that.

Forgive me, but what is the pilot light?

Elementary error on my part. Apologies. Both my bikes (1979 & 1988) have a small bulb in the headland with a 1/4 inch bayonet base. This is duplicated in the small rectangular lens above the HL on models that carry a full fairing. On the British bikes I work on, these are called "pilot" or "parking" lamps. I'm sure the Germans have an equally strange name, but it hasn't entered my lexicon just yet.

The point is, you can fully illuminate your HL reflector and meet the "lights on in daytime" law with a much lower power bulb than the OEM 55W halogen. There is a 20W incandescent bulb used on "daytime running" in 1990 model cars, or you can go LED at about 5W.

The point is this... in a perfect electrical system any reduction in the power used to illuminate the motorcycle, goes toward charging the battery. So if you reduce your lighting load from 100W (total) to 25W, then an extra 75W (about 5A) is available for charging the battery. (By"perfect" we assume that the diode board and brushes allow full alternator output, AND the battery is electrically and mechanically capable of accepting a charge.)

Hope this helps.

Motobins in the UK sell a electronic voltage regulator that allows the alternator to put out 14.2 volts. I used one on my R75 cafe build and it worked fine at lower rpms. Most batteries work better with a 14-14.5 Volt charging rate at the battery.

LED's work fine in brake & tailight, and signal lights with a resistor. Headlights are a different animal as the stock reflector doesn't match a LED bulb. The stock output on a airhead ( newer models ) is about 240 Watts.

You'll NOT want a red LED for your tail/brake light if it doubles duty to illuminate your license plate. Check to see if the bottom of your taillight lens is clear.

Wobbly, no probs with frying your circuit board w/the Cyron H4 #ABH4K-A6K in the enclosed headlight shell? Does the headlight shell get hot to the touch? Just wondering how much heat the LED generates.

Wobbly, Any problems with frying your circuit board or wiring insulation? How hot does the headlamp shell get? Really wondering how much heat the LED generates.