Electrical fault - Battery not charging properly

Hi guys! Ive just purchased my Y curvy SV and am more than pleased with my purchase I picked her up for £800 from a friend with the only known fault being this one gremlin in the electrics, which today bit me in the a55.

The bike appears to charge its battery if you leave it sat with the engine running, however if you rev the the engine, the battery appears to stop being charged for whatever reason. I have had this confirmed by the nice RAC man who today had to jump me because a copper tugged me and I forgot to leave the engine running for a few seconds and then tried to start her up with everything switched on (doh)

I was wondering if anyone else had had the issue - RAC dude seemed to think that the rectifier or alternator was at fault... But reccomended replacing the battery anyway because he said this kind of problem will most probably have put it past its best.

First: Any ideas? Anyone with the same problem thats fixed it?

Second: (dependant on answer to first) does anyone have a rectifier / alternator they wish to sell me before I head off to scamBay / a breakers yard?

Cheers!

Matt

The first thing to do is get some numbers from a multimeter Check the voltage when the engine is:

Idling (lights off)
at 5000 rpm (lights off)

Idling (lights on)
at 5000 rpm (lights on)

You can get a multimeter for not alot of money at all from somewhere like maplins

The earlier SV 650's do have issues concerning the regulator rectifer, that certainly is true, but we need to do some tests to work out what exactly it could be. Just out of interest, how many miles on the bike?

Matt

Hi! Thanks for the swift reply

Will have to wait until tues evening to run a meter across it - unforunately RAC man didnt give me the damn voltages. If im right (or should i say, my SV book is right..) the voltage should be between 13.5 and 15v a 5krpm with the lights on right?

27k miles on the bike

Also if anyone viewing this knows (without wanting to derail my own topic) is there anywhere I can replace the rubber / nylon of some crash bobbins? The metal bits are there, but the protective bit isnt :S

Yea, preferebly though between 13.5 and 14.5 V. It'll be lowest at tickover (natrually) and rise in the first few thousand revs, but never exceed the maximum through the whole rev-range

27k miles? nice, if the reg/rec has gone (not saying it has, not saying it hasnt!) it lasted longer than my first one Its important too to rule out the alternator being a bit silly, but I'm not completly certain of how to test that, I know you have to get readings from the wires leading to the reg/rec itself though (someone on here should be able to guide you properly there)

I dont know the charging circuit of the SV intimately but from a general viewpoint I would expect 3 wires to be coming from the alternator to the reg/rec. There may be more but these three should be carrying an AC voltage (the reg/rec turns this into DC voltage). You need to check that all three have ac V's on them and that remains when the speed of the alternator increases. The voltage will increase with speed of rotation but it should be constant across all three phases. If this isw correct then there is a strong possibility the reg/rec has gone. Now all we need is someone with knowkedge of the system to tell you what voltages you can expect out of the alternator!

There are 3 yellow wires from the alternator. They need to be checked in pairs, 1&2, 1&3, 2&3, and the ac voltage across should be approx 70v. As long as each pair has the same reading the alternator is fine.

Changed my reg/rec yesterday because i had this problem.

Before: idle speed 13.4 v,
at 4k rpm 8-9v (not good, should be between 12 and 15)


After: idle speed 13.4v
at 4k rpm 13.1v (am hoping this is problem solved )

HTH x

[dizzyblonde]

Glad to see you have probably cured your gremlins KellyJo.

Really must get round to putting multimeter over mine, but theres no rush.

Originally Posted by dizzyblonde

Glad to see you have probably cured your gremlins KellyJo.

Really must get round to putting multimeter over mine, but theres no rush.

Im sure to those more mechanically minded it's an easy job to do, but having never seen a multi meter in my life before this week i was well chuffed with myself for getting it sorted alone

Right, got the seat off at work today and got some readings

Bike switched off after a five minute run and half a minute at idle: 9-9.5v
Bike running at idle lights off: 9.5-10v
Bike running at idle lights on: ^^^^^
Bike at 5krpm lights off: Needle went past the 12v so assume its more like 13/14
Bike 5krmp lights on: 9v

Do these help in any way?

All readings taken from the battery btw