Can a loose battery terminal prevent the battery from charging while being able to crank the engine?

This is my brother-in-law ZX6R which drained the battery while trying to restart the bike after running out of petrol some 100 miles from home. After several cranking attempts, the bike failed to start and battery went flat.

We did manage to push start the bike eventually, filled it with petrol and hoping that a bit of riding will put some charge back into the battery.

An hour and a half later, when we stopped for a break, the battery was still flat and bike wouldn't start unless pushed. At this point I suspected a charging problem and decided to carefully head back home.

On our way back, the engine started to hesitate and eventually cut off on the motorway. Lights were flashing heavily pointing to a R/R problem which appear to have been confirmed by the recovery guy who brought the broken down bike home.

I ordered a new R/R but my surprise came when I was about to put the battery on the Optimate. I noticed the positive terminal was quite loose and thought that this could have been causing the problems all along.

With battery fully charged now, bike started fine with the old R/R and battery terminals read 14.45V - 14.60V across the rev range with headlight either on or off.

I'm trying to understand how this works as at this moment I'm not sure weather the RR is faulty and needs replacing or the loose connector was the only problem.

1. Is it possible that a loose connection prevent the battery from charging while being able to crank the engine and drain the battery at the same time?

2. Can a R/R work fine initially and play up later as the bike heats up?

3. Shouldn't the engine be able to run off the generator alone, without a battery? Why the engine cut-off and flashing headlight?

4. Should I replace the R/R anyway or save myself £60 and return the unopened box?

Thanks for your help!

I think a deep discharge can take a LOT of getting back to any sort of decent level. Also with a poor connection you get high resistance which means that putting power in is hard but pulling high current out is less difficult as it can overcome the resistance easier. Im not sure if you can run without a battery, im not sure how you get an earth without one.

Hope that might help

[mikerj]

Originally Posted by ThEGr33k

Also with a poor connection you get high resistance which means that putting power in is hard but pulling high current out is less difficult as it can overcome the resistance easier.

Other way around: high current + high resistance = big voltage drop. If anything a poor connection would permit charging (albeit at a lower current than normal) but would either not allow the starter to turn or it would be very sluggish.

The direction of current flow doesn't matter, you simply get a voltage drop in the opposite direction.

In answer to the OP, yes a RR could potentially become intermittent and stop working at elevated temperatures. However, equally possible is that the poor connection on the battery could get worse with temperature and vibration.

If you are still suspicious of the original RR, why not temporarily rig up a voltmeter (maybe even duct tape/cable tie a small multimeter some near the clocks) so you can keep an eye on the voltage for a few days.

[Wideboy]

I would have though a loose terminal would cause more strain on a regrec with the fluctuating?. I thought that might have been the trigger for the death on my regrec but it still took about 4 months from when I noticed the odd voltage reading to the point where it wouldnt charge at all

[yorkie_chris]

Originally Posted by maxinc

1. Is it possible that a loose connection prevent the battery from charging while being able to crank the engine and drain the battery at the same time?

2. Can a R/R work fine initially and play up later as the bike heats up?

3. Shouldn't the engine be able to run off the generator alone, without a battery? Why the engine cut-off and flashing headlight?

4. Should I replace the R/R anyway or save myself £60 and return the unopened box?

Thanks for your help!

1 yes
2 yes
3 yes you'd think so, but they don't, I think the battery adds a useful smoothing effect and without it then problems occur.
4 do some more tests first then decide. if it is charging ok now then take it out for a spin, measure again and if it is still ok then then save your £60

Thanks guys, that makes a lot of sense. Will keep an eye on it before deciding on the R/R.