Strange Battery Issues

[em2evol]

Hi guys

My boyfriends RVF does this weird thing where it runs badly at first, then gets going ok, but then he goes to turn it off, then 2 mins later he'll go to start it and it would sound like it has a flat battery (won't start), so he'll leave it, then go back a few hours later and it starts on the button as if it was fine all along...

What could be wrong?? Seems very odd...

Thanks!

[speedy231278]

I've had that recently. Haven't got to the bottom of it yet, but it appears that the charging system works intermittently, leaving the battery just flat enough that it won't turn the engine over, but if the battery is given a little recovery time, it just manages to recover enough get up and go to turn it over again. The current theory is that it only charges until something gets up to running temperature, and then stops working. When I see the bike next, I shall be waiting until the issue crops up again, then measuring the output of the alternator to see if that's ging bad when it gets hot, or if the reg/rec is stopping working when it warms up. Will be a week or two before I get to do this, but I'll let you know if it shows anything to be at fault. If the battery is quite low, my bike does seem to run a it lethargically, that's how I knew it wasn't fixed after I redid the wiring. When this first happened to me, I was at Beachy Head! Tempted to pitch the bike off, but it started as if nothing was wrong a couple of hours later.

Measure the voltage across the battery. Before you turn on the ignition, it should be very high 12s or low 13V, ideally it's 12.8 to 13.2. Less than 12.8 and the bike will gradually be harder to start, and when it gets close to 12.0, the starter will barely turn, and eventually the solenoid won't throw and the starter will not get any juice. Should be 13+ at idle, and ideally 14.5V at 5000rpm. If it doesn't change between whatever is being read with the ignition on, with the bike started and with the bike running at 5000rpm, then it's not charging. If you get less than 13.5V at 5000rpm then it's not really charging enough and you could have issues. If it's under 13.0V, you'll probably be walking home if you are not so very lucky! If it's over 15.5V at any point, you're killing the battery with excessive charging, and it will do strange things.

[em2evol]

Thanks for this - that's very helpful. The last owner actually had a volt monitor thing attached to the headlight after he replaced the reg/rec, which we took off so that both headlights now work, but I think it might be time to put it back on again to see what's happening... Cheers

[CMSMJ1]

just, and simply, a poorly battery.

need to know why though so get radical on your checking and see whether you can pinpoint the specific failure point.

There is no shame in a shit charging system..we have all had it. *touches wood*

[speedy231278]

Elsewhere, I've had it suggested that it's most likely not the battery, but clearly until the issue is fixed I won't know. However, I'd rather replace the battery last, simply because if something in the charging system has caused the battery to die rather that the battery just becoming old (bearing in mind I've had the bike nearly 10 years, it came with a battery about two years old, and it lasted until Jan 2009, so this one is still fairly young), as I'd rather not knacker a new battery if something else is duff!

Not sure why having a volt meter attached to the headlight would cause one not to work unless it's been wired dodgily, but that's given me a great idea on how to wire one up without needing it's own switch so it doesn't drain the battery when the ignition is off!

[Neosophist]

Elsewhere, I've had it suggested that it's most likely not the battery, but clearly until the issue is fixed I won't know. However, I'd rather replace the battery last, simply because if something in the charging system has caused the battery to die rather that the battery just becoming old (bearing in mind I've had the bike nearly 10 years, it came with a battery about two years old, and it lasted until Jan 2009, so this one is still fairly young), as I'd rather not knacker a new battery if something else is duff!

Not sure why having a volt meter attached to the headlight would cause one not to work unless it's been wired dodgily, but that's given me a great idea on how to wire one up without needing it's own switch so it doesn't drain the battery when the ignition is off!

I suggested you to fully charge your battery and see it self drains after a few days when it isnt on the bike.

[Davez29]

Maybe check your pulse coil. Here is a post from the cbr srction that sounds similar.

viewtopic.php?f=28&t=35200&p=254254#p254254

dave

[speedy231278]

I suggested you to fully charge your battery and see it self drains after a few days when it isnt on the bike.

..and I'm going to arrange for that to be done in my absence! I shall know by the end of the week.

[Cammo]

I had this very same issue on a vfr once - all charging system checks in spec, new battery, new reg/rec, never did resolve it. I sold the bike.

Intermittent faults like this aren't always easy to find. Having a volt meter attached to the battery (as the previous owner did) would make it a bit easier to see when the faults's occurring.

Not much help I know...

[speedy231278]

Process of elimination. I can't sell the bike as I need transport, but at least I currently don't require it until virtually xmas day, so that gives plenty of time to troubleshoot. The way I see it, I'm going to find one of the following:

Some peculiar characteristic of the battery is dragging the charging system output down to it's own level. Sounds fanciful to me.

Some peculiar characteristic of the battery connector is causing the charging system output to be become disconnected when the bike comes up to running temp, but sufficient output is still being fed into to the loom to keep the bike running. Seems a little less fanciful then above, however in my case I've direct wired the reg/rec, so in theory I should now be losing volts between the battery and loom if this was happening, rather than the other way around.

The alternator output is significantly reduced or zero when it gets hot. Sounds plausible, although would be a worst case scenario if true!

The reg/rec packs up when it gets hot - I reckon this is probably the most likely, but mine isn't exactly very old, though that doesn't really mean anything.

Some other wiring issue in the loom between the stator and the reg/rec only crops up when the bike gets warm.

Only way is to test for each when the output stops, and hope that the issue doesn't 'fix' itself before the test can be done.