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hi, need help with a battery problem please.
Over the winter I fitted a new mosfet style reg/rec to my sp1, I tested the voltage at the battery after and it was putting out 14.5 at idle and the same at 4000 rpm I took it that this was ok, it might be worth mentioning the battery was disconnected for a few weeks prior to this point.
I have since ridden the bike several times adding up to about 5 hours in total no problems at all.
Today I go for a 45min ride and on way home call in at parents, went to leave and the battery was flat.
I put it on an optimate charger for a few hours and it brought the battery back to 12.8v and this was enough to start the bike.
I then tested the reg/rec voltage output at the battery and now it is putting out 12.3 at idle and 12.7 at 4000 rpm.
Is this enough output from the reg/rec?
would a knackered battery cause the reg/rec output to be lower than before?
Battery is a YUASA YTZ12S and is about 2.5 years old and is always on a optimate trickle charger.
Any help would be much appreciated.
Cheers

Hi Wiffy,
You are in a catch 22 situation. The manufacturer claim batteries have a 2-3 year life expectancy before they start to drop off or fail. When they fail they can take out the rectifier if they are drawing too much load.
I haven't heard of many reported problems of the rectifier on the SP but I do know it's become all the rage to replace other bikes which have had a problem with a new MOSFET type one. (14.5v charging from yours is a little high for the spec of our battery, it could boil it a bit and shorten its life prematurely)
Another cause could be the alternator (or stator coils if you go American). They generate the AC current which supplies the rectifier. There have been quite a few reports of burnt out coils. I think you should check this first before going out and spending any more money.
My personal opinion is: A battery gets tired, develops a fault, puts extra strain on the regulator and alternator and then one or the other goes pop!
You might be able to recover the battery with your trickle charger but then you will need to use a load tester to see if it's any good. If it's not, you could have the same problem all over again.
I would change the battery, put the regulator back to original and check out the alternator. It's the only sure way to make an effective repair.

Pete

cheers for the reply, i just had battery load tested and one cell is gone so new battery is on order. I have spoken to who supplied the R/R and they will test it for me tomorrow (only 5 miles from where I work) just to take that out of the equation and then i'll test the stator when new battery is fitted. At £85 for these batteries I want to make sure I have all areas covered

Wiffer wrote: At £85 for these batteries I want to make sure I have all areas covered

Too right!
Lets hope it's just the Battery
Good Luck!

Just a quick one, I take it that it is general practice to subtract the ohms resistance of my multimeter leads from my results when testing the stator resistance?

Yep!
Put the two leads together and if you get 4 ohms for example. Use that as you zero point.
so if you read the stator and you get 8 ohms that then means the stator is reading 4

So, bit of a slow response. Been off sick and haven't bothered with anything much this week

pretty obvious I suppose. No worries about response time, hope your not too ill, nice weather coming! Well it looks like the battery died because my stator is knackered , voltage outputs across the phases at idle are 10 - 17 - 23 and at 4000rpm 25 - 35 -55, they are short to ground aswell. Had my reg/rec checked today and that's fine so that's one good thing I suppose. I've been looking at getting the stator rewound, £120. As anyone had this done? Oh I will first check that the wiring from the stator isn't damaged/ shorting, wouldn't want to get it rewound when its a simple wire repair.

Well a bit of an update on this issue, and a bit more help needed please.
I had my stator rewound by west country windings, I checked resistances and voltage outputs and all seemed good, very fast turn around aswell. Got it fitted allowed the bike to warm and tested my charge with both stock and mosfet R/R's heres my results :-

Ignition off 13.6v

STOCK R/R
At idle lights off 14.3v
4000rpm lights off 14.3v
At idle headlight on 14.6v
At idle high beam on 14.0 - 14.8v

MOSFET R/R
At idle lights off 14.4v
4000rpm lights off 14.4v
At idle headlight on 14.5v
At idle high beam on 14.0 - 14.6v

So i'm thinking both R/Rs are in good working order but I'm a bit concerned by the variation in voltage when the high beam is on, I would not expect it to fluctuate up from 14 to 14.8 and 14.6, im thinking I have a grounding problem and the regulator is intermittently getting a good ground to dump the excess voltage? This could make sense as I tried to clean all grounding points in the winter, maybe I disturbed it but didn't clean it well enough? Does this sound reasonable, is this ground the one on the right hand side of the subframe towards the fuel tank?

Something else strange aswell, after I did these checks I plugged my optimate back in and the orange light lit up to say the battery was completely discharged and it starting putting 16v into the battery, I quickly swapped it for another optimate I had and that one just went to the test charge and put 13.6v into the battery, not sure if this was a coincidence that I luckily spotted or if its related to my issues, have never had it before. Its now in the bin.

Sounds like you have it licked if you ask me.
There could well be a slight difference in the grounding between high and low beam but as long as both the lights are working as they should I wouldn't worry about 1/2 a volt. It could even be the difference in current draw, the resistance changes as you turn on the second headlight which in-turn increases the ampage required to run both bulbs and as V=IR you can expect small changes

Wiffer wrote: I quickly swapped it for another optimate i had and that one just went to the test charge and put 13.6v into the battery, not sure if this was a coincidence that I luckily spotted or if its related to my issues, have never had it before. Its now in the bin.

Good catch My optimate always gives out a half hour charge every time it's connected , (which is normal for it) after that initial charge it then decides whether it needs to keep charging or go into maintenance mode, never thought to check it's voltage and see if it's still functioning correclty.

Lets hope all your charging woes are over

Pete

if it wasn't for the reading when the full beam is on I would too but I just think it shouldn't bounce up and down from 14v to 14.6v, in this video from a guy who gets on the US RC51 forum when his full beam is on it reads 14.4v and stays at that, where as mine flickers up and down, up and down. When i get a chance i might do a vid of what mine is doing.

https://www.youtube.com/watch?v=E8Tfdht6exA

i had a closer look at the optimate and i think it might have been a loose connection as the female connectors looked quite open compared to the other charger. Not sure what would have happened if i hadn't noticed. overcharged battery?