Battery drain on start up

[thunderace]

On a normal fully working system, I'd expect a drop of no more than 0.5v. The battery should certainly not drop below a minimum of about 11.5v when the starter is pressed.

A couple of suggestions:

Check for drain as you are doing but pull one auxiliary fuse at a time until it stops. If it doesn't stop, that rules out all circuits apart from the starter circuit.

Then try pulling the main fuse and see if the drain stops. If it doesn't, then the fault is between the battery/solenoid/starter motor. If the drain does stop with the main fuse out, then it points towards the charging system (stator or reg/rec and/or wiring).

The other possibility is that the battery is fubar but there must be a reason why, even if it's only a case of a cell has died. Nip down Halfrauds for a load test.

[Davez29]

A good idea.. Why did i not think of that. I will give it a go in the morning. The batteies well they srem ok, one two year old, Yuasa. the other Lucas maybe 4 month old.

Thanks again

dave

[Davez29]

ok.. while i have very little time until sunday i managed to do the fuse pull and suprisingly the only time the battery didnt show a drain and stopped compleatly was when i pulled a 10a fuse that does the indicators, horn, rear lights and brake switches.. so a bit of an eye opener and not anything i thought it might be. So looks like there is a problem there. Due to lack of time i have not tried everything yet but have discounted the left switch gear and horn as i disconnected them fully, i also pulled rear the rear bulbs so no drain from them. i should be able to disconnect a couple more things tomorrow and finally find out if its a component or loom fault. Any bets on what it could be?

Dave

[thunderace]

Are the indicators functioning correctly? And the brake switches? They are about the only items left to fail, apart from shorted bulb filaments.

[Davez29]

yep they work fine. im a stickler for testing them in normal use and its one of those things i checked when i first got this problem. Now that i think its in this area they will get special treatment. a mate said i should check earths from each part with a seperate lead, this will also be done.

[Davez29]

ok just a final update on this.

To be honest im still unsure what caused this but it appears to be a combination of dirty wiring and a lucas battery which is only four month old going bad on me. The battery is now loosing around 0.01v a second with ignition on, a lot less than 0.1v a second. Is this more acceptable?

I have had the bike apart and cleaned every switch, plug and earth I could find. I had to replace an instrument bulb tween the tacho and temp gauge, not sure if that had a bearing but it had been off for a while. in fact i cant remember it being on for years but it may have caused a short.

The battery is the strange one as no matter what the optimate says this battery cant sustain a load and drops immediatly to 8v. The other battery a Varta (not a Yuasa as said earlier) was much older and I may have mislead myself as this one appears to still crank out around 11v on startup. So now im thinking maybe i have somehow always used the Lucas when wondering why im getting 8v on start up. I do know that it was the Varta that pulled me outa the shit when the bike would not start. So maybe this higher Lucas CCA battery is great for a short while but burns out quickly, dunno? I do know that my next back up battery will be not a Lucas.

[thunderace]

Lucas batteries aren't the best IME. If you're on a budget, see if you can get a Rob Hunter in the right size.

[Davez29]

yep well i have bought another Varta as i like to carry a spare working so far from home.Rob Hunter? will check them out. Thanks for your input thunderace it was a big help. bike and lo beam relay seems fully functioning, for now..