Very low charge rate 250 NC 60w converted to 12v

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Bevel bob
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Very low charge rate 250 NC 60w converted to 12v

Postby Bevel bob » Sat Sep 01, 2018 8:38 am

While riding in the Isle of Man the battery went flat, I was able to continue running providing I kept the revs up (4k) and did not use lights. Took the outputs from the alt and tested resistance and voltage ,AC output about 6v per lead, Coils are linked with earth wires taken off the plate.Modern reg/rec under seat, Leads show no connection to earth and low resistance to each other. Any thoughts before I pull all apart??.

ducwiz
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Re: Very low charge rate 250 NC 60w converted to 12v

Postby ducwiz » Sat Sep 01, 2018 10:36 am

Following the given details, the situation stays unclear for me.
You measured ~6V AC on each lead against the chassis? Was this done while the leads were disconnected from the R-R or not, and did you measure at idle speed or higher revs, i. e. 4k?
You quoted the leads having no connection to chassis ground/earth. Does this mean you or a previous owner had cut the original ground connection on the stator plate? This is the usual way to make the 12V conversion of the 60W alternator. If so, the measurement of each open lead against ground makes no sense, because the windings are floating against chassis ground; if the leads stayed connected, 6V is too low, the rotor might decreased in magnetism.
Please measure the AC voltage between the two leads, at different revs, disconneted from the R-R. Or measure the DC current into or from the battery, at different revs, lights on and off.
Btw, which kind of R-R do you have?

Hans

Bevel bob
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Re: Very low charge rate 250 NC 60w converted to 12v

Postby Bevel bob » Sat Sep 01, 2018 11:09 am

Your thoughts were what I need, The bike will be back in the garage by tomorrow and I will take some readings, This is one of three bikes that need tlc after the IOM trip ,so any help is apprieciated.

ducwiz
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Re: Very low charge rate 250 NC 60w converted to 12v

Postby ducwiz » Sat Sep 01, 2018 11:41 am

Here is some more info about the 12V conversion issue, in-depth explained by senior forum member dew-cat-tea-bob (r.i.p.)

http://www.motoscrubs.com/forum/viewtopic.php?t=1471

Beware: You need to afford a lot of time for reading and understanding :)

cheers Hans

Bevel bob
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Location: Bromley Kent UK.

Re: Very low charge rate 250 NC 60w converted to 12v

Postby Bevel bob » Fri Mar 01, 2019 3:09 pm

I have been off bikes for a series of operations ,Back into sorting out the electrics. The battery seems to lose its charge out of use faster than expected, Did a resistance check on the disconnected battery leads and they read 26K . Don't know if that's significant Not really fit enough to start the beast up yet. Certainly would not attempt a kick start .Will have to be a run and bump and a proper warm up before I try. Had some uplifting experience working on the DOHC 125 works GP bike putting the two piece handmade alloy fairing on , very pretty bike. I have read all Dew-Cati Bob's notes on the 12v conversion, but am not much the wiser!, I would like to add some indicators to the bike so am considering what to do with my in series 60w 2 wire stator conections in order to "release" a bit more power and also allow some daylite running lights.70/80 watts at 4000 revs would do.

ranton_rambler
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Re: Very low charge rate 250 NC 60w converted to 12v

Postby ranton_rambler » Fri Mar 01, 2019 8:24 pm

I'm not an electrical engineer, but seems to me you have 2 options - either buy an Electrex generator or similar , or swap your bulbs to LED to reduce the load.

Bevel bob
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Re: Very low charge rate 250 NC 60w converted to 12v

Postby Bevel bob » Sat Mar 02, 2019 7:34 am

That would appear to be the quick solution, however with my history of flops with new aftermarket products (50% failure at least) ,I will retain original stuff until absolutely sure its dud. Am considering LED but bike is pos earth with small 130 mm headlight crammed full already. Don't ride at night .

ducwiz
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Re: Very low charge rate 250 NC 60w converted to 12v

Postby ducwiz » Sat Mar 02, 2019 11:56 am

Hi Bob,

imho it is not possible to get more than the original 60W from the 4-coil alternator - no hidden trick here.
A load reduction is a good idea, but I'm afraid the LED bulbs are made for 12 Volts, so you have to make the conversion and need a (cheap) new 12V R-R. I never tried it, but it might be possible to fit a wide case 6-coil alternator, which puts out up to 90W. This is absolutely enough power to run the bike in todays traffic. I did this for many years (also converted to 12V), never running the battery out of charge. However, I had reduced power consumption slightly, by using barend or "bull's eye" flashers https://www.classicbikeshop.co.uk/7-8-handlebar-bar-end-indicators-flashers.html.

Hans

Bevel bob
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Joined: Thu Apr 15, 2010 8:01 am
Location: Bromley Kent UK.

Re: Very low charge rate 250 NC 60w converted to 12v

Postby Bevel bob » Sat Mar 02, 2019 7:18 pm

Hi Hans, I think I have gone a bit too far with power use and looking at "BOBS" graphs the load appears to drive the output down due to the odd way the coils work when connected in series. I have a modern RR and a good 12v battery.

LaceyDucati
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Re: Very low charge rate 250 NC 60w converted to 12v

Postby LaceyDucati » Sat Mar 02, 2019 9:01 pm

Bob
Just a note about "aftermarket" parts, we have sold literally hundreds of Electrex alternator kits over more than 10 years and never had one reported failure. So I certainly wouldn't concern myself about failure, unless you feel particularly unlucky :-)

To be fair on my widecase 350 I am still running the standard alternator with a Honda reg/rec. So I can sympathise with the if it ain't broken don't fix it! Also for many who don't ride at night or require indicators, there is little point in converting to 12v.

Just my thoughts.

Regards Nigel


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