Flickering headlights

Post by **alainmoran** » Mon Dec 01, 2003 4:17 pm

Hmm ... Dynamo driven engines might, but alternator driven motors shouldnt unless there is something wrong.

Post by **brixtonmorris** » Mon Dec 01, 2003 8:07 pm

at tick over the morris will be runnung only off the battery. voltage regulator switches when revs increased

Post by **Scott** » Mon Dec 01, 2003 11:50 pm

You should NEVER disconnect the battery from a running engine epipped with an alternator! This can fry the internals quicksmart. The alternator requires some battery power for the exciter diodes, which is why an alternator won't charge a completely flat battery.
Also, in regards to the voltage test: if the battery is on the way out, the regulator can be fooled & pump more charge into the battery. This quickly reduces the life of the battery even more & can result in the battery acid bubbling out. A battery load test should be done first. If in doubt, fit a good battery, then check the charging system.

Post by **brixtonmorris** » Tue Dec 02, 2003 6:34 pm

what ive always wondered is what goes wrong with voltage regs and how do we recondition them

Post by **Willie** » Tue Dec 02, 2003 7:33 pm

I only ever had trouble from one regulator,on an MGB.
Since I had installed an ammeter I was able to observe the
results of my attempted repairs......total chaos. The
adjustments are temperature dependent so I would
recommend a replacement unit, they are not too expensive.

Post by **brixtonmorris** » Tue Dec 02, 2003 7:59 pm

. they do give some kind of trouble otherwise i would not have a box full of them

Post by **Kevin** » Tue Dec 02, 2003 9:51 pm

the car can run without a battery. start it and disconect the battery if charging system is working morris will run without bat

at tick over the morris will be runnung only off the battery. voltage regulator switches when revs increased

Does that mean you can start the car without a battery and just on the starting handle ?

Post by **rayofleamington** » Tue Dec 02, 2003 10:23 pm

Does that mean you can start the car without a battery and just on the starting handle ?

nope!
you need more engine speed to produce enough power to run the engine.
However if you live on a very steep hill it may work to bump start it with no battery.. but it all depends if the alternator/dynamo will self energise.
If it does, with a dynamo it will die at tickover. With an alternator you run the risk of damaged electrics.
If it doesn't you'll be stuck at the bottom of the hill.

Post by **Kevin** » Tue Dec 02, 2003 10:51 pm

you need more engine speed to produce enough power to run the engine.

I see what you are saying Ray but if a flat battery was in place you cant use the starting handle any faster.
I am getting a trifle confused here because without the battery how does the ignition circuit work

, as you can tell my electrical knowledge is vague to say the least.

Post by **Benjy** » Wed Dec 03, 2003 10:53 am

You can't get enough speed on the handle to get anything usefull from the dynamo, so with a completely dead battery, you'll have a job starting the car.

BUT a 6v lantern battery (or 2 in series if your car's a poor starter) will provide enough power to run the ignition circuit while you start the car on the handle. Make sure the lights are all off though! These batteries are only a couple of pounds from most DIY / hardware stores, they're the largish (roughly 8cm x 8cm x 12cm) square box ones with springs on top.

A friend of mine always used to carry around a lantern battery and a length of wire for such emergencies!

Once the car is started, keeping the revs at fast tickover will provide enough power to keep things going, so do disconnect the 6v batteries once it's started or they'll likely explode!

Ben

Post by **brixtonmorris** » Wed Dec 03, 2003 11:13 am

well done benji. it works. that starter sucks all the life out of a dead bat. all you need is a good spark.

Post by **Kevin** » Wed Dec 03, 2003 11:18 am

But Brixton you said to check the charging circuit start the car and remove the battery, why not use a voltmeter it must be safer.

Post by **olly** » Wed Dec 03, 2003 2:54 pm

Modern alternators are not damaged by running open-circuit for short periods of time

Post by **rayofleamington** » Wed Dec 03, 2003 6:17 pm

ah yes - th torch battery trick. I've heard of that before.
Do you mean the big (huge) rectangular battery?

Post by **Benjy** » Thu Dec 11, 2003 1:46 pm

It's not huge, about the size of 4 'D' cells arranged 2x2 and a little taller. Infact, I've seen adaptors that you slot 4 D cells into and then use in place of a lantern battery.

Ben

Post by **Cam** » Thu Dec 11, 2003 1:47 pm

Like this:

Post by **MrA.Series** » Thu Dec 11, 2003 2:25 pm

Yup, they're the ones!

Post by **rayofleamington** » Thu Dec 11, 2003 2:45 pm

Like this

lol - yes the huge one!

Post by **winger300** » Thu Jan 01, 2004 5:44 pm

i used some of those battery tablets, and topped up the fluid levels. It seems to be a lot better now, however after an hour long motorway run, with lights, heater, cdplayer etc i end up with a flat battery.

I had a word with the previous owner, he tells me the dynamo cant keep up above 60mph.

Is this likely to be the case? and will new brushes solve matters?

Post by **rayofleamington** » Thu Jan 01, 2004 5:59 pm

on the motorway there's no point having the heater fan on, as it doesn't ad any extra air flow at speed
I've never had a problem on the motorway with lights etc.. Sounds a bit odd, but if the dynamo is worn out (worn brushes and/or commutator) then that might account for it.
so maybe a recon dynamo would be worth considering?

Morris Minor Owners Club

Flickering headlights

regulators