alternator /charging problems

tony cbx · Post by **tony cbx** » Tue Apr 15, 2008 2:28 pm

my 79 z is not charging the battery while running,i hve removed the alternator,and the brushes are fine and nothing looks wrong ,is there a way to bench test it ,and if it fine could it be the rectifyer and how do you test these.any awnsers greatfullyrecieved
regards tony
ps otherwize it runs great

EMS · Post by **EMS** » Tue Apr 15, 2008 3:53 pm

There is a check procedure for the rectifier in the service manual. Ican send you copies if you don't have a manual. Make sure all the wire connectors are good. Sometimes it is just poor connections.

alimey4u2 · Post by **alimey4u2** » Tue Apr 15, 2008 3:58 pm

Welcome to the site & club Tony.....

To add to Mikes excellent support & advice, don't forget to check the continuity of the spade connectors ( looks like Mike has covered that.) They are notorious for furring up ( oxidizing.) There may be tell tale signs on the wires, that being, overheated insulation. Is your battery in good condition ?

Please keep us updated on your progress....

tony cbx · Post by **tony cbx** » Tue Apr 15, 2008 4:53 pm

Hi all the conectors seem ok and clean ,battery is nearly new as with brushes ,spring and plates.please can ems send service manual information as i think thats the next step
thanks
tony

alimey4u2 · Post by **alimey4u2** » Tue Apr 15, 2008 6:12 pm

Where abouts in th UK are you Tony ?

tony cbx · Post by **tony cbx** » Wed Apr 16, 2008 2:35 am

Hi I am in horsham west sussex

tony cbx · Post by **tony cbx** » Wed Apr 16, 2008 3:07 am

Hi I have just found my service manual [never tidy your garage ]so hope fully i can now test the system,thanks for your help
regards tony

alimey4u2 · Post by **alimey4u2** » Wed Apr 16, 2008 4:39 am

tony cbx wrote:Hi I am in horsham west sussex

Darn, Pity you weren't closer I could pop over. In any case, see how you get on, if there is a continuing problem I could be available...

daves79x · Post by **daves79x** » Wed Apr 16, 2008 7:20 am

First thing to check is the continuity between the slip rings (copper rings) on the rotor. The early manuals don't give a specified reading, but the late manuals do. The resistance HAS to be between 3.5 and 4.8 OHM. If it is higher or lower(I've seen both) - the rotor is bad and needs rewound. This is by far the most common failure apart from brushes. The stator test is pretty conclusive, but the reg/rectifier test is useless. You just about have to replace it with a known good one. My bet is the rotor. Replace both bearings and seal while you in there.

Dave

alimey4u2 · Post by **alimey4u2** » Wed Apr 16, 2008 8:41 am

I had two just above 4.8 ohms & they did well as paperweights..as for contributory components in an alternator... NFG.
That's when I gave up the battle & became Junged....

CBXRoger · Post by **CBXRoger** » Wed Apr 16, 2008 1:26 pm

Another thing to check, if the electrical checks don't find a problem, is the mechanical clutch that drives the alternator. Occasionally, the spring will loose its tension or the disks will become worn, and the battery will not be charged.

I had a problem on my '82 CBX when returning from the C2C ride across America. At low engine speeds and cold engine, the battery would be charging. At highway speeds, the battery would start to discharge. When I arrived home and inspected the clutch, I could find nothing apparently amiss.I bought a washer and placed it behind the spring to add additional pressure on the clutch, and the problem was solved.

Roger

CBXTony USA · Post by **CBXTony USA** » Fri Apr 18, 2008 9:27 pm

Hello, new to ICOA and glad to be here! I've got an '82 with the exact same problem. Replaced brushes, rectifer/regulator, new battery, continuity checked all the wiring, still no charging. I took all the readings in the manual and the rotor reads 1 ohm or less, so I'm having it rebuilt. Hope that solves the problem. Only had the bike for a year and haven't even had it out for more than a couple of miles. Runs great...on the battery!! Thanks for all the suggestions, I've been reading all the postings.

CBXRoger · Post by **CBXRoger** » Fri Apr 18, 2008 9:46 pm

CBXTony USA,

The other weak link is the red connector under the right side cover. It connects the alternator to the rectifier. Corrosion and resistance will cause it to heat up and melt, as the efficiency of the charging system goes down.

I have had to replace this on both my '82 and '81 CBX'es.

Let us know what you find on your CBX.

Roger

alimey4u2 · Post by **alimey4u2** » Sat Apr 19, 2008 6:23 am

Welcome to the site CBXTony.....

daves79x · Post by **daves79x** » Sun Apr 20, 2008 6:13 am

CBXTONY: Your rewound rotor will fix you right up - that was the problem for sure with an OHM reading of less than 1. As I said above - it's the most common alternator failure except brushes.

Dave

The International CBX Owners Association

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