Topic: 1983 CB650 Charging Issues

[karben]

I bought my first bike, a 1983 CB650SC Nighthawk Tuesday 4/7. So, last week I went to the gas station to gas up.  Turned off bike, filled, went to start it... Got it to cycle through ~4 turns 3-4 times before battery crapped out.  Come to find out that some how the electrolyte level was zero, nada.  So Batteries + Bulbs refills and recharges.  Claims the battery is still in good shape.  Bike starts right up and off I go.  As i begin researching what could have caused this I run into everyone and their parents having rotor issues with their CBs.  Dammit I hope the PO just got a crappy battery or someone forgot to fill the thing.  I don't know. 

Today, I bought a multimeter. I flip the MM to 12V and pop the black wire to the battery ground and the positive to the + terminal on the battery.  Was getting ~12v @ idle and just under 13V at a very fast RPM though, not quite redline... my tach doesn't work, FML.  Anyways, I just got back from a quick ride back to the same gas station, only 2-3 miles or so from the house and check my battery without the key in the ignition it was sitting @ ~12.3 volts.  Are these numbers right? I thought I read somewhere I should be getting close to 14 volts, maybe that was through the regulator/rectifier.   

What's my next step here? Do those numbers seem OK or a bit low to you? How do i go about testing my r/r.  I'm going to attach pictures of my MM and R/R as I have no clue where the ohms setting is.  Do I keep my r/r plugged in? I've seen some 'guides' on testing the r/r but they're all very vague and I believe you need some general electrical know-how to read/understand them. 


Thanks!

[karben]

Reg/Rec

http://i.imgur.com/ZFaQS8M.jpg

Multimeter

http://i.imgur.com/OZaomxX.jpg

[calj737]

Your tests on the battery are slightly inconclusive. Stock charging systems are a bit anemic, and don't really produce enough output until you reach above 2k rpms. So, after a short, in town ride to your gas station, I would not be at all surprised to see the battery a bit low having been used by the bike to serve the electrical system.

First order of business is to verify you have a good, solid battery. Have a charger? If so, charge the battery, then let it rest for 2 hours off the charger. Then test its voltage standalone. What reading do you get?

Then, with bike running (your going to have to guess as you have no tach) measure the voltage at the battery at 2, 3, 4 and 5k rpms. Record these. You should see up to 14.5v by 5,000 if the regulator and battery are working. Now, you may see lower due to the battery not requiring the charging system to "restore" it, but essentially you are looking for maximum V produced, and verifying that more than 13v does get sent.

This is the simple/stupid way to test for us electrical neophytes..

If you feel a bit more brave, then we can go through the R/R but let's start with the above^^^. I think from your first description of low levels, the battery was definitely in need and not able to handle the charge.

[karben]

OK. Got my battery on my 750ma trickler last night. Woke up to a solid green light (flashing green is 80% then the charger goes to maintainer, solid green is supposedly fully charged) so when I get home what kinda voltage should I get on a fully charged battery after sitting for 8 hours? I'll reply after I've done the multimeter tests on the revved battery. Is grounding the mm okay at the battery ground?

[calj737]

At least 12.4v

[curemode2002]

Also one thing to watch out for are dirty connections they can cut the charging voltage you are seeing. Make sure your main connections are clean and the ground is clean.

[karben]

I just got done riding. Maybe 5 min after shut off, I started the bike back up and took some reads. I'm gonna let the bike cool back down before taking more (necessary?).

12.6 v key out of ignition - I took this ~5min after I shut her down
12.4 idle
13.6 revved up to maybe 2-3k rpm (I have no tach, but I didn't give much throttle at all)

AFAIK these are perfect numbers. But again I didn't let the bike sit at all. Does that void my readings?

Before I took the beast out I cleaned all the connections that are directly connected to the battery. The positive terminal to the starter? was a bit gunky and the negative terminal from the starter? was loose. And when I say loose I mean the nut was still on the bolt but there was maybe a centimeter between the nut and the bolt.



** I say 'starter?' Because I'm not quite sure what it is. The positive off the battery connects to a little box with a cylinder on the bottom of it. The piece fits into a little sleeve directly to the left of my recessed battery cubby deal.

[calj737]

That little box is the solenoid. The starter is atop the motor, beneath a cover.

[links56]

If its starting and everything for you now, I would just ride it and see if it keeps the battery up. I think your readings are within the norm.

[karben]

Apparently it was due to me riding the bike like a granny. Keep them revs high! Haven't had a single issue since I've started keeping my rpms up. I'm used to driving a civic... Haha.