The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Rich_A on September 18, 2025, 11:08:03 PM
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I've owned my 1980 R65 for 7 years now. Since the beginning there were always issues with the batteries dying. it came with a tiny antigravity lithium that I have changed to a AGM recently. The main problem is my work is a ten min ride from my house through a busy city. The constant short trips are just brutal for the batteries. I'm finally ready to upgrade the alternator.
I was originally going to buy a Omega 600w. but now I've read some good reviews and info on the Enduralast 4 450w. Also I just learned about the Silent Hektik brushless 410w but this one is €600 and ships from Europe :/
What do you guys think? Can anyone share their experience with any of these units?
Thanks so much!
Rich
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I had the same issue when I lived in. Chicago . Been in Phoenix for 32 years now .
I did a lot of city riding and my battery would not start the engine in about two weeks. I got a battery tender and left it on there all the time . I moved to Phoenix in mid 1993 . I have a fifteen minute ride to work at highway speeds 65 mph 105 kph and then one stop light. No charging issues now . I'm not so sure that a alternator will solve your issue with the type of riding you do. The alternator does not do much battery charging at lower engine speed . Another option less costly would be an aftermarket voltage regulator that has a higher voltage at lower engine speeds .
There are two aftermarket parts suppliers in the US that have a version of this. Motorrad Electric and Euromoto Electric around $40 USD . Check the condition of the battery cables not uncommon for corrosion to develop onder the insulation .
Another thing to consider, is reducing the load on the electrical system . The constant use items, the headlight and taillight.
There are LED replacements now .
I have a voltmeter on the Guzzi and saw how much of a voltage drop the happened when they were being used at low speeds .
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I have the Silent Hectik alternator and ignition. Both are fabulous. What's a charging lamp? ;D
Combined, they push the bike 30 years into the future from when it was made. No charging issues, instant starts, excellent pickup and metronome idling. Not cheap, but definitely performance bling ;D
The alternator is permanent magnet with no slip rings. It maintains a charge below 800RPM (cold, no choke, engine barely running). The wiring is simple and simplified. If I buy another airhead, it, the SH ignition and a fork brace would be top of the list of things to get. The standard alternator is adequate with cleaned sliprings, brand new brushes and LED lights. In town? not really.
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Thanks so much for the feed back! I am definitely leaning more toward Silent Hektik alt and ignition. The alternator and ignition are separate kits right? the info is not great on these. did you order straight for Germany or any place states side?
Thanks!
Rich
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I commuted 3.5 mils each way with the stock charging system for 18 years and never had the slightest problem with charging even though there was seldom an opportunity to much exceed 3000 rpm. The only modification I made was tweaking the voltage regulator up to 14.6 volts when hot which is essentially what they did with the upgraded regulator for Police patrol bikes. This ensured a good charging rate at any revs above idle. The stock system must have been in good fettle because the charging light went out above 1000 rpm although that wouldn't have been down to the regulator, it just meant good brushes and clean connections. The battery was a generic AGM which lasted 12 years.
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+1 on the clean slip rings (new brushes) and tweaked regulator. AGM cells need more voltage than the original wet cells the bike was designed for. I'd forgotten I tweaked mine up also. These things make a difference.
The SH kit I ordered direct from Germany. I'm in the UK.
It is still night and day (literally) in terms of charging. Fitted and forgotten 😉
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Hello,
During around 30 years, I used my R65 for commuting to work every day. (it was my sole vehicle).
I ride between 5 to 10 km one leg. Never had to top up the battery (which were flooded one ) provided I used the red capped regulator (tweaked for the LEO bikes). My ride was around 95 % in city walls, sometimes on highways (rarely), so a lot of stop and go and traffic lights.
IMHO the original charging system is fine provided in good shape and not overloaded with heated grips and auxiliary lights.
If you change for a more powerful charging system, stay with a system using brushes to pilot the charge. The systems without brushes use a permanent magnet which produce as much electricity as the alternator can and most of it is wasted into heat by the regulator. So you waste expensive petrol to produce heat with no use for it.
Of course, if you need heated vest and such, you may need as much electricity as you may get. So my above remark do not stand... Consider also the cost of these systems. How long will you have to run your bike to recoup the cost ?
Just my 2¢ worth of advice...
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Hi Georges, It seems we all agree the standard system is good if well maintained, regulated for AGM and used with sensible loads. The Hectik loss at full RPM and very little load, I guess is around 20W by looking at the size of the heatsink, not enough to annoy me at the pump ;D
Rich_A, if you do stick with standard (I'm not saying don't do that), the regulator adjustment is inside the 'tin' module in your pics. Taking the lid off the tin simply means unwrapping the red tape. The pot is a single turn skeleton type, so needs a bit of finesse to set the voltage. it may also have a dob of glue that needs removing. I set mine up on the bench with a variable power supply.
OR you could just buy the uprated replacement - there were a lot of plastic encapsulated HUCO ones on Ebay for about £30 that work well. I got Mobiletron VR-B191. Fits various old cars and tractors as well as our 2 wheel lawn mowers ;D
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Thanks a lot for all the info and feed back guys, appreciated. I switched all the light to leds when i got the bike. i replaced the alternator rotor and brushes last year. There are no other electric accessories on the bike like heated vest. I might give the Voltage reg a try and report back.
Thanks
Rich
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I put a stock-spec rotor from EME, along with adjustable VR, on my R100 and the combo works great!
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Another suggestion, if you can get a voltmeter on the bike see what kind of voltage output the charging system is producing in your usual riding .
If you go the adjustable voltage regulator see if it improves the charging voltage .
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I second Bob advice.
I put a digital voltmeter with a large display on top of my tank bag, permanently plugged on one way to the alternator output and back home to the to the battery and went for a ride.
I discovered that, even if the alternator was pushing a lot of current out, not all of it arrived at the battery
The culprits were oxydized copper wiring from old age and bad ground connections; also due to old age corrosion.
Once the harness renewed and the ground connections cleaned, the situation went very very well and smooth.
Hint : if the wires in your harness are stiff, they are corroded.... Time to do something. (this does not apply to the large red wire going from the battery to the starter motor ... THis one is stiff even from factory ;-) )
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Here's a few thingd I did to the charging system .
My Guzzi has the same charging system that the R65 has, the stator and rotor are a different size .
The diode board on the Guzzi is mounted under the left side panel, alot better cooling than the R65 .
I noticed that there are two terminals for diode board output .
I made up two heavier gauge wires and connected them to the battery .
I don't know if this makes any real difference in real world application or not .
I replaced the negative battery cable, got a heavy gauge cable from an auto parts store the correct length .
I mounted it to the lower right engine to transmission bolt .
The second gen bikes made 9/80 and later most of the ground circuits are ganged together at the voltage regulator .
The ground path goes to the frame the engine mount studs to the engine case then the transmission case where the negative cable is secured at the speedometer drive .
I made up a heavy gauge wire from the mounting point at the regulator back to the negative post of the battery .
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My wife's '80 R65 has similar charging sypmptoms - the battery doesn't charge properly no matter how much or little use the bike gets. I'll try all the suggestions listed here, thanks for the replies. While I don't think a higher output alternator will change the problem, both my airheads have Omega 600W alternators fitted. I like a) how the included regulator starts charging at lower RPM and, b) I can now wear heated gear in this morthern climate. One caveat: check the clearance between the output leads on the new, included, diode board. The stiffer wires can easily short to the cover.
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My wife's '80 R65 has similar charging sypmptoms - the battery doesn't charge properly no matter how much or little use the bike gets. I'll try all the suggestions listed here, thanks for the replies. While I don't think a higher output alternator will change the problem, both my airheads have Omega 600W alternators fitted. I like a) how the included regulator starts charging at lower RPM and, b) I can now wear heated gear in this morthern climate. One caveat: check the clearance between the output leads on the new, included, diode board. The stiffer wires can easily short to the cover.
The problem is presumably in the voltage regulator or diode board, what sort of charging voltage is it achieving ?
I think my 79 has the same set up i.e. an electro mechanical VR. I have no problems keeping the battery charged with a complete original system. The only thing I've done is to adjust the VR to 14.6 volts to suit an AGM battery. If the stock 280W is deemed insufficient there is always the option of LED replacement bulbs to give a bit more headroom.