1981 CB750k not charging the battery

[Cabreco]

sgtslag wrote

Nice thing about this unit, is that it can be moved from vehicle, to vehicle, as needed; it can also be removed during storage periods.  Only downside I can see is that it sticks out a bit, and may be prone to snagging.  Thanks for sharing, though.  Cheers!

Absolutely! Not only for the above but it's a great tool to have when you're buying a bike. I also have an extra socket with terminal clamps in case the bike doesn't have a cigarette lighter socket on it.

The snagging isn't a problem as this unit has a hinge.

So it can be folded while it's onboard to suit your fit.
I installed my 12v aux power on the instrument cluster.


So this is how the unit looks on my bike.


Kinda like a factory guage.  

[sgtslag]

Brilliant mounting location and technique!  I agree, it looks almost factory with the hinge lowering it over the gauge lights -- did not know it was hinged.  My '79 has a Vindicator fairing, which had a cap over the hole for a cigarette lighter -- I just bought a socket at Wal-Mart, and wired it in place.  I use my socket for the cell phone, though, as I have a Sunpro Automotive Volt Meter, mounted in the right-hand fairing pocket cover (the cover is hard plastic, so I cut a hole, and mounted the gauge).  Your method is ingenious, and I suspect many will borrow your idea.  Thanks for sharing!  Cheers!

[Lucky 1]

Good job using the multi meter and book to diagnose your electrical problem.
I am starting to notice that a lot of these old bikes have those rectangular plug in connectors
and the plastic seems to be degrading. The plastic looks dried out, brittle etc.,.

I have see one plug that was near the metal frame of the motorcycle and a 1/16 inch round hole
developed and current had arced through that hole to ground. The contacts inside the rectangular plug connector may not be isolated from each other because of the degrade plastic.

Just something to be looking at on all of these older motorcycles.

BTW when the battery is charging it should get higher than 13.8 volts
See a 12 volt battery has 6 cells and each one is at least 2.1 volts. (lets not quibble),
So 2.1 volts (per cell) x 6=12.6 volts- So a 12 volt battery is more than 12 volts, and can be as high as 13.8 volts when
the motorcycle is NOT running. Then when it is running and above 1500 rpm it could be charging at around 15-17 volts.

[cheesehead]

Well it's charging fine and has started every time now and doesn't get higher than 13.8. I believe you, but that's what mine is charging at.

[Cabreco]

13.8 should do fine with the load these bikes carry.
Each battery cell is 2.1v so 12.6 total. Charge is 1.2v trickle charge!

[Lucky 1]

It just means the battery is full.
Turn on your headlight and the charging rate should go up.

Sounds like everything is fine.