Was over charging now under. 16.7v to 12.2v

[totty]

EDIT first post relates to over charging, later posts relate to under charging after fitting combined reg/rec.


I'm waiting for a combined reg/rec to arrive. I've read that they're easily fried, so I'm wondering if there's any tests I should do before fitting it?

The current status is 16.7v across the battery at 3,500rpm, the rectifier has a terminal snapped off and the potting compound gouged out to remake the connection, the red/white wire had at some point been replaced bypassing all plugs and its insulation is burnt. I figured it was a good time to fit a modern combined unit. The burnt wire has been cut out and replaced. The battery a recent motobatt still seems OK, but I doubt it'll last as long as a one not subjected to this. All other connections on the panel and in the headlight look fine, no sign of overheating. The bike wont be used until fixed, I don't fancy letting the smoke out of the wires.

Thanks

Allan

[Gixxer-18]

This'll help, it's for British bikes, but it will work on Japanese ones.
  [ Guests cannot view attachments ]

[totty]

Lucas, the prince of darkness, I needed a couple of those jars when I owned Scimitars :-)

Good old 3 position switches - smoke, smolder and burn.

[totty]

After fitting the combined unit:
12.18v to 12.24v dependent on revs.
Turning on the lights lowers it to 11.84 rising with revs but only to hitting around 12v at 3,000rpm.

So it's too high with the old parts and to low with the new.

This isn't making much sense to me, unless both are faulty. I can't see there being an issue on the AC generation side of things or it wouldn't have had the capacity to over charge with the old parts. With one plug and two wires all with matching colours connecting it up wrong seems unlikely.

Battery seems good 12.64v when I started working on it today.

Any ideas?

[Johnwebley]

  how are you getting the readings?

 if you just put the probes on the battery terminals,you will just get battery voltage,

 if you want to check charging rate,you will need to check between reg unit and battery,

 

[totty]

Tested at the battery, are you certain that's not correct?
I've just read 4 online guides that also said test at the battery.

[totty]

Just tested and the voltage between the red wire from the reg/rec to battery -tv was 12.21 the same as at the battery.
However what doesn't seem right is the voltage on the black wire was only 11.30v

[mike the bike]

It should be the same as the battery voltage.  You need to check where the volt drop is, ie. A bad connection,  dodgy fuse holder etc.

[Yoshi823]

Using your resistance meter, test across the red & black wire of the ignition switch. It sounds like the  internal contacts are corroded.

I had this on my CB125T2

[totty]

I packed up before reading these posts, I'll test as suggested one evening through the week.

I cleaned several connections, the top plug of the three down the side of the electrics panel made a difference bringing the black wire up to 0.2v below battery, but surprisingly it didn't affect charging.

The ignition switch wiring could do with some work, externally the switch looks new, but the wires to it are a little corroded and covered in a different tape with a lump in it. It looks like a spliced in replacement but I haven't unpicked it yet. I could probably do with a replacement one if anyone's got a loom they're cutting up.

[Bryanj]

The earth on the reg/rec needs to be excellent as does the sensed voltage (normally black wire) need to be the same as battery

[totty]

I don't think I checked the earth,  I'll have look at it as well.

[totty]

I've got new terminals, terminal cleaning tools, dialectic grease and half a used CB650 loom on order. That lot combined with the guidance I've received on this thread should be all I need to get it sorted.
Thanks everyone. I'll post results.

[totty]

Still won't charge at more than 12.2. Drops to 11.9 if the lights are switched on.

Ignition switch wiring wasn't as bad as I thought, cut out one bit of corrosion where I think a scotch lock had been, sorted out the badly soldered red wire.

Black voltage sense wire is just 0.04v below battery.
Reg/rec earth to battery is 0.7ohm as is red to black at ignition switch. The meters leads show 0.6ohm which implies the tested wires are just 0.1.

All connectors are clean and tight.

I think I'm going to have to retry the old reg and rec, but lost patience and went home for beer and motogp qualifying.

Unless I work on it again tomorrow it'll be 2 to 3 weeks till the next attempt.

[totty]

Charging now within spec. The points gap on the original regulator was far smaller than spec.
Carbs balanced while I was on.