only getting 12.10 volts when running

Post by **jetblack** » Sun Jul 03, 2011 6:47 pm

Hi.

Took the bike out for a ride today and the battery died on me.

Managed to get it home after replacing the battery at a local bike shop.

Just checked the voltage across the battery when the bike is runing at 5,500 rpm and i'm only getting 12.10 volts.

Any ideas why its not throwing out a higher votage - i would expect baround 14.4v to charge the battery?

on the plus side i guess if the reg/rec was shot it would be throwing out 18v or there abouts?

Post by **hallsie** » Sun Jul 03, 2011 7:43 pm

Generator coil , just had the same thing on my NC29 , really easy to do and I got mine from G F .

Post by **jetblack** » Sun Jul 03, 2011 8:24 pm

is that the same as the alternator coil?
How can i test it conclusively?
If it is knackered what do i replace? just the coils or the whole alternator?
how much is it gonna set me back?

Cheers.

Post by **hallsie** » Sun Jul 03, 2011 9:51 pm

It's the windings that fail , I bought my replacement from Graeme France off here for £45 posted. It isn't a hard job to do , drain the oil , remove the engine casing and change the coil then put it back with a new gasket and job done . If you start your bike and put a volt meter across the terminals as you rev the voltage will drop as the bike is running from battery not alternator , I was getting just under 12v and this dropped rapidly when the bike was running - I am now getting 14.4/14.6 when the bike is running at 5000 rpm.

domski1 · Post by **domski1** » Sun Jul 03, 2011 10:16 pm

checked the voltages to the rectifier and also the condition of the plug, at about 5000rpm you should have around 50 volts out of each of the yellow wires the come from the coil.

amorti · Post by **amorti** » Mon Jul 04, 2011 9:45 am

Guessing is the worst thing you can do.
http://www.electrosport.com/technical-r ... iagram.pdf
Use this guide to help you pinpoint the fault before throwing money at parts which might be OK. Occasionally (rare, I admit) rectifiers can fail low rather than high. You'll be annoyed if you spend £50 on a generator to find out your regulator (a £10 part on eBay these days) is what's failed. Or you could have a failed connector somewhere.

So yeh, don't guess, be scientific.

Post by **jetblack** » Mon Jul 04, 2011 1:31 pm

Ill get the covers off and visually inspect all the connectors, wires etc. thinking about it, the voltage was the same with the bike running as it was when not running. So perhaps no charge is getting to the b
attery at all and all im seeing is the residual voltage in the new battery.

Post by **CMSMJ1** » Mon Jul 04, 2011 1:45 pm

is the genny plugged into the reg rec?

Post by **Neosophist** » Mon Jul 04, 2011 2:03 pm

I had a reg-rec fail and it wasn't throwing out any voltage.

Check the altenator for output firstly.

make sure its' connected (no1.)

It's the plug with the three yellow wires.

Set your meter to AC volts and measure between two of the yellow wires and see if you get at least 50v at 5000rpm.

If you call the wires A,B,C

Disconnect the plug and Measure between

AB,
AC,
BC.

You should get the same reading on all 3.

Then, if there not low turn the bike off and set the meter to ohms and measure the wires.

You shoudl get between 0.1-1.0ohm resistance. and no resistance between a,b,c and the frame.

If it passes these then replace the reg-rec.. if it fails replace genny and check reg/rec

Post by **oldgreyandslow** » Mon Jul 04, 2011 2:22 pm

Neosophist wrote:I had a reg-rec fail and it wasn't throwing out any voltage.

Check the altenator for output firstly.

make sure its' connected (no1.)

It's the plug with the three yellow wires.

Set your meter to AC volts and measure between two of the yellow wires and see if you get at least 50v at 5000rpm.

If you call the wires A,B,C

Disconnect the plug and Measure between

AB,
AC,
BC.

You should get the same reading on all 3.

Then, if there not low turn the bike off and set the meter to ohms and measure the wires.

You shoudl get between 0.1-1.0ohm resistance. and no resistance between a,b,c and the frame.

If it passes these then replace the reg-rec.. if it fails replace genny and check reg/rec

Just a quick question, is it OK to run the engine with the generator/reg rec disconnected to check for 50v between phases?