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Pat B
United Kingdom
66 Posts |
 Posted - 07/09/2006 : 08:06:46
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I had recently installed a brand new modern 2-brush dynamo with matched regulator. Up until yesterday ( ) it was working fine with maximum charge being around 8-10 Amps regardless of revs ie: even at 5,000 revs.
However, I ran the car on a rolling road yesterday with the "tester" taking the car up to around 7,000 revs a couple of times, I noticed the ammeter now deflects fully to the "charge" side anything from 2,000 revs upwards, which it obviously never did before. The other thing I noticed when starting the car after the rolling road session ( and subsequently ) was that the battery seemed to struggle to crank the engine ie: almost flat, whereas it was fully charged beforehand !
Any ideas why this should be ?
Much appreciated, Pat.
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mgmog
United Kingdom
467 Posts |
Posted - 07/09/2006 : 10:57:05
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| Does the problem go away if you change the battery. |
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Pat B
United Kingdom
66 Posts |
Posted - 07/09/2006 : 11:28:04
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I haven't tried changing the battery but why would the battery suddenly drop power when it was OK before ? For info, it's a tiny (in size not in output) sealed DMS Racing battery.
Pat. |
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mgmog
United Kingdom
467 Posts |
Posted - 07/09/2006 : 12:22:54
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| batteries are funny things, dont like to be over charged, especialy the gel types, worth a try. |
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kimber
United Kingdom
1529 Posts |
Posted - 07/09/2006 : 12:46:26
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| Pat, I'd have to agree with the overcharging comment. I know that you have the same type of battery as on my car and the charging instructions were very explicit. A short burst of excessive input might have knackered it. |
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Pat B
United Kingdom
66 Posts |
Posted - 07/09/2006 : 15:10:08
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| Would you, in that case assume that the Regulator malfunctioned allowing more than the "factory set" 8-10 Amps charge to the battery ? Otherwise, the regulator should have maintained a constant output to the battery regardless of the revs. |
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kimber
United Kingdom
1529 Posts |
Posted - 07/09/2006 : 17:08:53
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| I can't remember the charging instructions, but I remember that they recommended a special battery charger for those batteries. 8-10 amps is quite a high charge. Most 'ordinary' car battery chargers, in my experience, low-charge at 2-3 amps and high-charge at around 5 amps. |
Edited by - kimber on 07/09/2006 20:54:53 |
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Pat B
United Kingdom
66 Posts |
Posted - 08/09/2006 : 08:19:50
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I tried a different battery last night and the Ammeter still deflects to full "charge" when the revs rise above 2,000. In fact the gauge deflects so violently that the needle sticks at max deflection and the only way to return it is to gently tap the glass !
It would appear that something must have failed within the Regulator to have over-cooked the battery. For info, this is the second set of Dynamo & matched Regulator (from a supplier in the Cotswolds) as the first Dynamo did not produce any charge at all (measured directly off the Dynamo). So beware ! |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 08/09/2006 : 08:31:12
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Pat In an earlier thread Paul Duncombe suggests that when installing a regulator you retain a three brush dynamo rather than converting to a two brush. You can then set the third brush to 8 amps and guarantee that the current will be limited that maximum. Sounds like a good idea to me.
See 'Dynamo charging control' started by 'John'.
Peter |
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mgmog
United Kingdom
467 Posts |
Posted - 08/09/2006 : 08:44:18
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| Bad luck Pat, thanks for the feedback. |
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Nick Feakes
USA
3376 Posts |
Posted - 13/09/2006 : 13:05:00
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A two brush dynamo with a two bobbin regulator (RF95 or similar) does not have any current control at all! Inside the cover, one bobbin is the cutout (heavy wire wound on the outside of the coil) and is identical in function with the original cut-out. The other bobbin is the 'voltage regulator'. When the output voltage of the dynamo rises above a certain value the armature pulls in and reduces the current to the field. The output voltage falls and the contacts close again. This happens rapidly and so regulates the voltage. The output voltage therefore depends upon the points gap and the strength of the return spring. Depending upon which regulator you have, either the points gap or the spring tension (or both) is adjustable. As long as you have a Lucas regulator (and you let me know exactly which one), I will look up the adjustment process for you.
Nick |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 13/09/2006 : 16:57:07
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An intersting debate for those of us who have a little knowledge about electrics but have never adjusted a regulator. I am going to rewire my car this winter and have yet to decide if I am going to fit a regulator or not. When one of you provide the detailed instructions on how to adjust a regulator please post it on the forum, for us all to see.
Thanks, Peter |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 14/09/2006 : 12:07:36
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Paul
Thanks, Peter |
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Nick Feakes
USA
3376 Posts |
Posted - 14/09/2006 : 12:37:54
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Paul
the issue is not one of semantics. Two bobbin regulators do not limit the current delivered by the dynamo. They certainly regulate the voltage but if you connect a flat battery (or add a row of spotlights to the front of the car) the poor old dynamo will give out as much current as it is able until the armature temperature rises above the the melting point of the soft solder used to connect the windings to the commutator and then you can guess what happens. The compensated regulators have an A1 terminal which has a measure of current limiting to the terminal but is set too high for our purposes. Likewise, the three bobin types have a current regulator bobbin but it is of course set for around 20 - 30 amps.
I will see if I can put the Lucas Technical Bulletins in the Documents download section
Nick |
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Peter Green
United Kingdom
1682 Posts |
Posted - 14/09/2006 : 13:32:44
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Nick,
It would be very helpfull if you could put the Lucas Technical Bulletins onto the 'Document Downloads' page of the website.
Peter. |
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Peter Scott
United Kingdom
1240 Posts |
Posted - 14/09/2006 : 17:00:22
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quote:
Originally posted by Nick Feakes
Paul
the issue is not one of semantics. Two bobbin regulators do not limit the current delivered by the dynamo. They certainly regulate the voltage but if you connect a flat battery (or add a row of spotlights to the front of the car) the poor old dynamo will give out as much current as it is able until the armature temperature rises above the the melting point of the soft solder used to connect the windings to the commutator and then you can guess what happens. The compensated regulators have an A1 terminal which has a measure of current limiting to the terminal but is set too high for our purposes. Likewise, the three bobin types have a current regulator bobbin but it is of course set for around 20 - 30 amps.
I will see if I can put the Lucas Technical Bulletins in the Documents download section
Nick
So Paul's suggestion that, if you wish, you could use a three brush dynamo, set to 8 amps max, with a two bobbin regulator, is a good one. Then the regulator will avoid over charging the battery and the third brush will avoid cooking the dynamo. Thus meeting our two objectives.
Peter |
Edited by - Peter Scott on 14/09/2006 17:01:09 |
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