Quick and easy one, hopefully.

[dwire]

Never thought I'd ask this, but I searched here and oddly could not find anything at that one place Google always takes me. I've been pondering now that my life is starting to fall more together instead of apart about the day, hopefully early next season I'll have my 1971 R75/5, done, fully restored and in tip top shape - WHAT THEN? Well, I want to take a trip - not saying where yet. lol... I did find in a search here for a later bike I think a 76 that it had a 240 watt alternator. If memory serves, the early bikes had the most anemic alternators, but nothing I have EVER complained about as they are quie suited to do "only" what they were made for - stuff installed on the bike from the factory.

Well, I was considering perhaps wanting to A) Keep a GPS charged and available so I don't get lost or have to pull pver non-stop to read a map or re-fold it and B) perhaps keep a small HT (handheld amateur radio) charged to send out APRS data so I could be tracked online in my journey(s). I've yet to test either device for their "real World" consumption, both of which would be operating the units at a low level keeping their internal batteries charged, but they still DO CONSUME.

So, does anyone have any idea how much a well maintained 1971 alternator has left, say with all the light on and such for night time driving? All I DO KEEP THINKING OF is people putting on heated grips and such which amount to no more than glove shaped current sucking devices, so maybe I can get away with it; maybe not. If I can get practical data on average bike output(s) I can add up the average consumption specs for the other two devices and know if it is possible or not. I'll likely take a small roll up solar panel with me for other camp-like charging duties if it is within the realm of what I can carry safely on the bike along with, well very little else. (So if I am visiting YOU, I may stink by then...)

Thanks in advance for any help and or advice on the matter.

[Major Softie]

The GPS uses a tiny amount of power, so that will absolutely not be a problem. I very much doubt if the amateur radio will be a problem, but take a look at the charger - it probably uses more than the GPS. I found a typical aftermarket GPS charger that works for a large number of GPS units, and it puts out 5Vdc 2A. That's 5v x 2A = 10w (Watts = Volts x Amps). Check what the radio charger uses and see what you need.

[chasbmw]

The 450w alternator upgrades are also available in a smaller diameter that will fit the 74s, I'm not sure if the 71s had an even smaller alternator. I think that the diameters are 105 and 107 mm.

Oer alternatives are using a 21w QH parking light and using that as a daytime driving light as well as making sure that everything in the electrical circuit is nice and clean so as to reduce any resistances.

[dwire]

Thanks MS and chas...

Ahh, yes Ohms Law - very simple and convenient thing; knowing the relevance and accuracy of partiuarlly the HT (handheld amateur radio) is entirely different; especially since all of the figures are for different duty cycles and such. I've no plans to be talking on a radio on y bike like one might on occasion through repeaters headed down the road in a vehicle, the until is equipped with APRS, but as well a system called ARTS that is a smart system of varying the time interval between position pings (meaning time between sending out a location beacon packet) depending on what speed you are traveling. (This keeps unneeded redundant traffic down on the repeaters - and saves battery power as well...) So if I am headed 70MPH through the Mojave desert, updates would be far more frequent than if I were stuck in traffic in LA or Chicago - or hiking for that matter. So I'll have to do some decent testing to really know how much it is going to use on average. Both units operate and I believe have published specs at 14.x VDC that one would expect see from a vehicle alternator and were designed with that in mind; seems now, the biggest thing is primarily to know real World consumption of the radio as the GPS's duty cycle will likely just be on all the time while I am traveling.

[jtoml]

If anyone is interested in being tracked, my company has developed tracking software for Blackberry and Android smart phones. These devices have GPSs and can also function as personal navigators.

To get back to your original question, the R75/5 has a 180 watt alternator. Average load, including a halogen headlight, would be less than half of that

jtoml
'73 R75/5 SWB

[barryh]

So, does anyone have any idea how much a well maintained 1971 alternator has left, say with all the light on and such for night time driving?

With one exception it's easy enough to add up the minimum Watts.

Halogen Headlight 55 Watts
Tail light 5 Watts
Instrument lights 4 Watts

Ignition is more difficult. Points ignition pulls 4 - 4.5 amps but that's peak current. It rises to the peak as the coil saturates and only flows for the dwell period. I've seen some data by Tony Foale that suggests the average current is 2.5 amps at idle falling to 1.5 amps at cruising revs. (Not as much as I would have thought but the reason the average current falls off at higher revs is because the coils spend less time saturated). Call it 2 amps average so that's 28 watts.

Total 92 watts minimum without intermittent loads like indicators or brake lights.

The real question is at what revs does the alternator output exceed 92 watts ? You would need 4000+ RPM to get close to the full 180 Watts.

[dwire]

If anyone is interested in being tracked, my company has developed tracking software for Blackberry and Android smart phones. These devices have GPSs and can also function as personal navigators.

To get back to your original question, the R75/5 has a 180 watt alternator. Average load, including a halogen headlight, would be less than half of that

jtoml
'73 R75/5 SWB

No, no; yes that technology in one form or another truly has been around since the "man" opened up the GPS system to the general public. Addition of smart phones now all these years later means like I hear so many people saying, "there's an app for that..." Yeah. lol I have no doubt the product, application and development is a good deal, but I have not a smart phone and don't plan on using one (a smart one that is...) and have personal reasons for wanting to use the APRS system as well. - A project I'm involved with on the side as an amateur operator. Besides, some such remote places, if I actually am able to make it back to them, radio technology will be all that is likely to affordably meet the need as last time I checked, there were no cell towers and no plans for them to ever be installed. Radio is what is relied on by those there and since I'd be traveling alone; (a very stupid thing to be doing in the back country) these places I'd like to traverse a little bit on my way through, leaving my itinerary with rangers and such along with the radio's transponder frequency is likely the only way I would ever be found other than as a pile of old bones if things go wrong...

Who knows, much is likely to change before it becomes warm again next year and both I and the bike are ready for a REAL adventure - truly we both need work; I as much as the bike does. Myself perhaps even more! But this is all good information though to know and your mention of the Blackberry app here may be just the ticket for some others that wonder along as surely more have smart phones than have compact handheld decent power and range amateur radios on hand. I'm sure someone will benefit from your mention of the Blackberry app here...

[dwire]

With one exception it's easy enough to add up the minimum Watts.

Halogen Headlight 55 Watts
Tail light 5 Watts
Instrument lights 4 Watts

Ignition is more difficult. Points ignition pulls 4 - 4.5 amps but that's peak current. It rises to the peak as the coil saturates and only flows for the dwell period. I've seen some data by Tony Foale that suggests the average current is 2.5 amps at idle falling to 1.5 amps at cruising revs. (Not as much as I would have thought but the reason the average current falls off at higher revs is because the coils spend less time saturated). Call it 2 amps average so that's 28 watts.

Total 92 watts minimum without intermittent loads like indicators or brake lights.

The real question is at what revs does the alternator output exceed 92 watts ? You would need 4000+ RPM to get close to the full 180 Watts.

I know - you just walked through what I did. I have the same questions as I can add it all up with the known variables, but there are a great deal of unknowns I cannot readily figure for. I suppose I'll know better when I put everything back together and simply start testing, for I too was wondering how I was going to account for the spark - as well as my driving habits; which could vary a great deal just based on what road one takes - or a traffic jam... GPS takes very little current to keep it topped off as well as operating. The radio, well that is a different story, that all depends on TX'ing (transmitting) at full power, a little conversation under a bridge in the rain could even draw the bike's battery down, as one would be surprised how much current they (a little HT) consume under a "constant use" sort of situation. Thankfully, it will only be sending out a little packet here and there most of the time - I doubt I'll be using it for an AM/FM stereo radio via Bluetooth while riding down the road! (Don't ask me why the radio is capable of such a thing - no one including myself knows...)

[Motorhead]

you could do a 14.2 volt regulator like I did, run the lights full time to keep from boiling the water out like I did

even improve the system with LED nothin like a hot 80 watt H4 high beam you can charge the phone during the ride even charge over nite

If you make your bike LWB use the bigger battery the 14.2 volt will charge the bigger battery fine.....

as proven and tested by me

[dwire]

My regulator is set properly - err, it is somewhere in the 14 volt range at least that, no boiling or heat in the battery...

All Connections are new and or improved to everything from diode board to frame - well everywhere. Even with the bike off, the factory rear blinkers will blind you if you look at them, so I think the electrical system was covered well enough long ago in that sort of sense. LED's ? Well not really my style, I am old-school and prefer the more original looking filaments.

Turning a perfectly good SWB into a LWB to carry a GPS and radio sounds a bit out there and I would go as far as to say turning a perfectly good SWB into a LWB is far out there for me; unless of course one had another reason than the battery to do so, or better yet, absolutely no other choice.

Just my OPINONS is all; nothing more. I'd like keep it a stock machine - nothing I'd take with me or do to the bike will disrupt that save some added wires unseen in the loom and replacing the pussy horn with two really loud ones that frighten me when I honk at someone. Otherwise, I'd like to say I am restoring it, not "re-making " it.