Alternator check

[lmo1131]

doktortim..... the photo is not of my alternator (noted).

15.3 volts at the battery with the regulator jumped.

Motorrad Elektrik isn't open on Saturdays.. . . :-( guess I'll have to wait until Tuesday.

[20774]

There are some regulators that can be had at the local parts store...14v regulators are plug-n-play...OK, maybe not adjustable, but IMO I don't think it's really necessary. IBMWR has some replacements listed...search this page for regulators:

http://www.ibmwr.org/otech/partsubs.shtml

I bought a Transpo regulator from a local small engine repair shop...they had a Bosch sign up on the wall, so I asked about repairing starters...they said no problem. I bought a Transpo IB301...I think IB301A is adjustable.

[GlobalRider]

I bought a Transpo IB301...I think IB301A is adjustable.

Its been a long time, but based on my memory, those are the numbers.

I got an e-mail notification to a reply to this thread, but it has since been deleted. The member wrote 13.7V....anything below 14V is too low to fully charge a battery, even with the headlights on and at 3500 rpm.

There is a reason why my car batteries last 16+ years; battery maintenance and a good charging system!!!

[Stan_R80/7]

A lead acid battery cell has a fully charged voltage of 2.1 V. For a six cell (12V) battery, that yields 12.6 V for a fully charged lead acid battery. So, any voltage over 12.6 can fully recharge the battery. However, in practice I agree that 14V does a better job.

[barron_williams]

My bike (1974) is a little different than yours, but close.

Historically, I always had trouble starting once temps got below about 40 degrees. Mostly, I felt it was because the starter didn't spin the motor fast enough.

Over the last couple of years, I have been over all the electrical connections, making sure they were clean and tight. I have added a couple of extra ground wires. I replaced the original voltage regulator (Motorrad Electrik). I replaced the original diode board (Motorrad Electrik). I cleaned up the rotor and stator. I replaced the bundle of three wires from the stator housing to the alternator (internal corrosion). I replaced the original positive and negative battery cables. I rebuilt my original Bosch starter. And finally, the latest step last summer, a PC 680 Odyssey battery.

Seems like it is working pretty good these days. I think all of the individual steps contributed, but it seems like the most dramatic difference was then PC 680. Might just be my imagination though.

I still put it on the battery tender, but now not every day, maybe once a week.

I think the Nippendenso may be my next step if the Bosch wobbles.

Regards,

Barron

[lmo1131]

Historically, I always had trouble starting once temps got below about 40 degrees. Mostly, I felt it was because the starter didn't spin the motor fast enough.

My experience as well.

Barron, where did you apply those additional ground cables?

[20774]

Lew -

One bit of info on grounding:

http://robfrankham.co.uk/bike/earthing_article.htm

Snowbums' page:

http://bmwmotorcycletech.info/diodebds&grdgwires.htm

I bought a pre-made grounding harness from Motorrad Elektrik and installed it when I used his solid diode board mounts. I don't see it on his website, though.

[lmo1131]

Thanks Kurt, the first article makes a lot of sense, with the exception that I have no clue how "30 [and] 15 amp" wires relate to American Wire Gauge.

10 or 12ga?

[20774]

"Amp"acity??

http://www.powerstream.com/Wire_Size.htm

Rob Frankham knows his way around these bikes from an electrical standpoint.

Update:

Someone on Boxerworks explain this of Rob's info:

"In general, 15 amp wire=14 gauge and 30 amp wire = 10 gauge. This varies A LOT with insulation types, conductor types and environmental conditions. The numbers I just threw out are for basic house wiring in conduit."

Also:

http://wiki.xtronics.com/index.php/W..._or_Ampacities

[barron_williams]

Barron, where did you apply those additional ground cables?

Lew, pretty much as described in the articles Kurt posted links to (above) from diode board mount back to common ground point at the coil mount and then back to negative terminal on the battery.

Saw your question on wire size and don't think it matters. 12 or 14 gauge seems ok. Main thing is that you are providing a nice path back, but I don't think you need a battery cable sized wire that takes a torch to solder connections to.

On a different note -- Take a look at your 3-cable bundle coming off the alternator if you still have the original one. Mine was totally corroded under the black connector plug (where you couldn't see it). Really easy to fabricate a new set of wires.

Barron

[lmo1131]

UPDATE.

All terminals cleaned (no corrosion found under the 3-cable bundle).

Additional AWG 12ga. ground cables run from diode board to battery (-) anode, and coil/frame ground.

Voltage regulator replaced (NAPA Echlin ECH-VR503 (equiv.: Borg-Warner R-588/Transpo IB301))

Voltage (measured across battery terminals):
@2500 rpm: 13.1
@4500 rpm: 13.9-14.0

Time for a ride... ... thanks for all the guidance!!!

[GlobalRider]

Voltage (measured across battery terminals):
@2500 rpm: 13.1
@4500 rpm: 13.9-14.0

Just out of curiosity, what is it at idle? I'm surprised it takes so many RPMs for you to get 14V, unless you have some loads drawing a lot of power.

For comparison purposes, I measure 14.0 V to 14.2 V from idle to anywhere up the RPM band.

[lmo1131]

I'll re-check that later this morning when I get back down to the shop.

FWIW, it's better than I had.

[lmo1131]

Alex, here's what I got this afternoon.

Indicated rpm per my /5 tach ... so who knows what the true rpm was.

@ 800-1000 rpm: 13.9

@ 2500 rpm: 14.1

@ 3000 rpm: 14.1

@ 4500 rpm: 14.1

The only difference between the condition of the bike, from yesterday until today, was that the battery was on a charger all night.

[PGlaves]

Alex, here's what I got this afternoon.

Indicated rpm per my /5 tach ... so who knows what the true rpm was.

@ 800-1000 rpm: 13.9

@ 2500 rpm: 14.1

@ 3000 rpm: 14.1

@ 4500 rpm: 14.1

The only difference between the condition of the bike, from yesterday until today, was that the battery was on a charger all night.

Since Airheads use an electromagnetic rotor, alternator output in volts depends to a considerable degree on the starting battery voltage. I typically look for about a 3/4 volt maximum increase from battery standing voltage to alternator output voltage. Often I see .5v or .6 v increase.

The reason today's readings look better than yesterdays is that the battery was more fully charged.

You can't get satisfactory output readings with a poor battery in the system