Electric testing

[bikemonkey]

My NC30 still has a leak in the electrics somewhere as it's still flattening my battery.

I have 3 days off work next week and plan to test the entire system.

I was wondering if there were any key areas I should test first to potentially save me going through the whole bike?

As far as the bike goes the electrics are standard apart from an aftermarket regulator and CDI, and a manual fan switch added (with some dodgy wiring so I took that off and don't have a fan atm). All the fuses are intact etc and I have a Acumen tempest CAT1 alarm fitted, which I hope won't make testing difficult.

Any advice will be greatly appreciated and I will be updating next week with voltages etc when I get round to testing everything.

[CRM]

might sound daft and a bit obvious - but it's not the battery is it ?

[bikemonkey]

Unfortunately not, I bought a new battery for it a few weeks ago, and it drains in like a week.

[kevprojex]

Is it charging ?.

[bikemonkey]

On a charger yeah, I'm not on the bike atm, seeing as I haven't passed my mod2 yet. Only realised the battery was draining when I went to get the alarm fitted and then the other day when I had to move it out the garage for my dad for a bit. (too lazy to push it up the gravel drive)

[magg]

Measure the current flow in the negative battery lead to confirm that the battery is actually discharging when the ignition switch is in the OFF position. If you have a current flow greater than few milliamps then I would disconnect the rect/reg and measure again. A discharge from the battery of a few miiliamps is ok, it is what the alarm unit needs to operate.

You also need to load test your battery, as repeated deep discharging ie going flat, will stuff it and recharging will not restore it to full capacity.

[kevprojex]

Is it charging ?.

I mean with the engine running !, most battery problems on vfrs are down to the charging system on the bike. start the bike and test the voltage at the battery.

[bikemonkey]

Okay so my multimeter is a piece of crap, but I managed to get voltage readings across the battery with the engine off and running.

Engine off reading 13volts
Engine running reading 12.8volts (idle and revving to 5K)

For some reason my multimeter wont give me a current reading anywhere.

Could this say anything? guessing the voltage shouldnt be lower?

As I said, got plenty of time next week to test properly, but this is all I got for now.

[kevprojex]

Okay so my multimeter is a piece of crap, but I managed to get voltage readings across the battery with the engine off and running.

Engine off reading 13volts
Engine running reading 12.8volts (idle and revving to 5K)

You should have around 13.7-14 volts with the engine running. it looks like you have a charging fault on the bike not a battery drain.
Unplug the reg rec and test the output from the windings(three yellow wires) across all three windings and check them down to earth, if the readings are ok your reg rec is probably fubar.

[V4WTF]

I have the same problem, I have gone through 2 Dekka batteries for my NC35 and 2 reg/recs.

The AC voltage between the alternator windings started around 11.7V at idle and then dropped to about 7V under 5krpm.

The windings gave all the right resistance readings.

But I think maybe my rotor isn't spinning? When I was going to remove the alternator cover to inspect the alternator, step 7 in the removal instructions in the Haynes manual reads:

"To remove the rotor bolt it is necessary to stop the rotor from turning. If a rotor holding strap or tool is not available, place the transmission in gear and have an assistant apply the rear break, then unscrew the bolt."

Well in my situation the rotor holding tool was not available, so I put the bike in gear, applied the rear brake and began twisting the rotor bolt, however the whole assembly spun with it and the rear wheel remained still.

I ended up making a rotor holding tool to get it off.

Anyway, in step 8 it goes on to say.

"To remove the rotor from the shaft it is necessary to use a rotor puller. Thread the rotor puller into the centre of the rotor and turn it until the rotor is displaced from the shaft"

In my situation, the rotor came off with little more than a pull, magnetism was the only thing holding it to the shaft, does that sound right?

Also when I start the bike, then remove the battery, it almost dies, the revs go way down below 1k and the lights dim significantly.