M/Meter readings - charging system.

Hi guys,

Got the meter today, cheapo B&Q one.

I'm trying to suss out if i have a dodgy rectifier. Started bike sunday perfectly, went for a ride approx 20 miles then stoped for petrol. Came out to a flat battery.

I recently changed the battery to a new one and it was fully charged before being fitted to the bike. It's ran perfectly until Sunday.

Measured the battery prior to starting read 12.27, when reading through past post, i checked for earth leakage, Ignition on with lights, got reading of 11.81 when meter probes on the terminals and with neg wire attached to engine, so appears thats not a problem

Reading 13.20 - 13.35 @ 5k rpm, would this indicate the reg's on it's way ?, if the charging system doesn't kick in until 5K

Or could it be my slow ass riding and the fact i don't over rev the bike, thats causing it not to charge?

Rob.

that sounds like a short somewhere. try licking the frame when running at 5k

Turn the ignition off, disconnect one battery terminal and measure the current between the battery terminal and the terminal connector. If you've not got an alarm it should read zero (w/ an alarm expect a low rating) - if it doesn't you've got a dodgy connection somewhere.

Originally Posted by custard

that sounds like a short somewhere. try licking the frame when running at 5k

Thanks, looks like a w/end of investigation, oh the joys. I have a intermitten problem with the indicators, sometimes the work other times they don't, do you think that could be the cause?

As for licking the fram, i'll give it a miss, never know where it's been

Rob.

sorry,being facecious.

if a fused circuit is drawing more power than it needs (eg because it is trying to electrify the entire frame) the fuse should blow. so it could be you have a short before the main fuse, or the you have a fault in the charging circuit.

my ktm does it with staggering regularity! this then entails 5 mins of sweating with the kickstart as the battery will invariably be flat.

dunno bout your indies. start with the switch and work your way onwards.

[Spanner Man]

Good evening all.


12.21 volts on a standing battery is pretty low. Most stand when fully charged at around 12.7 volts.

There could be discrepancies in the meters readings, but half a volt is a fair bit, & could account for the slightly low charging readings you're getting.

See if you can borrow a decent battery, & check your readings again.


Cheers.

Hello Peeps

Taken some readings and looks like I'm in need of a Rec/Reg.

Tickover 14.68-14.71

5k rpm Lights on 12.81 - 13.10

5k Full beam on 12.81- 13.16

5 k nothing running 13.8-14.96

Battery after turning engine off 13.50

Battery was full charged and a reading taken first thing this morning before bike started was reading 12.85.

My main reason for posting, is would the voltage be lower with the lights on or should it still be reading around the 13.5-15v ?

Rob.

[Sid Squid]

Those readings are interesting - they're telling me the reg/rec may not be the culprit - under little load the charging system gives good numbers but performance drops off under headlight load.

So check the alternator output:

Originally Posted by Sid Squid

but first a check of the alternator output will determine this, do this: disconnect the reg/rec unit connectors and identify the three yellow wires, these are the alternator connections, and they can be considered to be three pairs, that is if you were to name them A, B and C, you could have a pair A and B, a pair B and C, and a pair A and C. using a voltmeter with an AC setting of about 100V check the output between each of the three pairs, at about 5000 rpm there should be about 70V AC, the most important thing is to satisfy yourself that all three pairs are about the same output, any one markedly different reading will stand out.

If you get poor readings from the alternator test then before condemning it check the wiring, and check resistance between each pair, I can't remember what the allowable figures are but again all three results should be very similar, any difference in the results is telling you something. Also check between each wire and ground, which should be infinite.

interesting one this as i have had similar. still not got to the botom of it....

My readings are.

idleing lights off 14.2 - Lights on 13.8

But when I rev it tp 5000-6000 rpm the reading drops to 13.5-13.6, never below 13.5.

Why is this?