Voltage Regulator

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Colin
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Joined: Thu Jul 24, 2014 3:46 pm

Voltage Regulator

Post by Colin » Mon Sep 22, 2014 5:41 pm

Hi Everybody, I am a new owner of a 1939 Rover 14 Sports Saloon. I'm in Sulhamstead near Reading.
My ammeter on the dashboard shows a current varying with engine speed. It quickly gets well past 20 amps and doesn't drop back unless the revs drop to tick over.
I have a modern heavy duty battery and I think it is fully charged. I am only doing very short runs of a mile or so to do the checks - I don't want the battery to cook.
My wiring is original and in need of replacement.
My control box has a good earth and the cut out works.
I have run through the checks in the Lucas Technical Service notes and all seems to check out okay.
Does it indicate that the regulator side of the unit is not working properly? There is a definite gap opening up if you push the armature down manually.
Maybe I just need to go for a longer run?
Any ideas or recommendations welcome....thanks in advance.
Colin.

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paul williams
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Location: Telford,Shropshire
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Re: Voltage Regulator

Post by paul williams » Mon Sep 22, 2014 6:12 pm

Hello Colin and welcome to the forum,

from you description it sounds like the cut out is not working. One check is to put a voltmeter across the battery, the voltage should increase to about 13.5 - 14.5 volts and then stop, if it continues to rise then the cutout in the field circuit of the dynamo is probably faulty. It is possible that there may be an internal short between the field and the output connections on the dynamo. If you disconnect the field connection on the dynamo this should stop the output and no current will be shown on the ammeter.

The control box is a relatively simple device to sort out, although it is often better to replace it if in doubt. There are modern electronic replacements that fit inside the box but they normally need a negative earth.

Hope that helps

Paul

Paul Williams
1929 2litre Saloon
1934 P1 10HP
1951 Rover Cyclops
1974 P6 3500
1998 LR Discovery I


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luli
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Re: Voltage Regulator

Post by luli » Mon Sep 22, 2014 7:18 pm

Just to complete the picture, here is a quotation from the original instruction manual:
"WHAT THE REGULATOR DOES.
A completely automatic control. The regulator causes the dynamo to give an output which varies according to the load and the state of charge of the battery.
When the battery is discharged the dynamo gives a high output, so that the battery receives a quick recharge which brings it back to its normal state in the minimum possible time. On the other hand, if the battery is fully charged, the dynamo is arranged to give only a trickle charge which is sufficient to keep it in good condition without any possibility of causing damage to the battery by overcharging.
In addition to controlling the output of the dynamo according to the condition of the battery, the regulator provides for an increase of output to balance the current taken by the lamps or other accessories whenever they are switched on.
A further refinement causes the charging current to vary to suit all climatic conditions and in addition causes the dynamo to give an increased charge to the battery during the first half-hour after the car is started. This quickly restores to the battery the energy that has been used in the operation of starting.
The regulator unit is accurately set before leaving the Works to suit the requirements of the equipment fitted on your car, and in normal service the battery will be kept in good condition. If, however, you should find that the battery is not kept in a charged condition, or is being excessively overcharged, we advise you to consult your nearest Lucas-C.A.V.-Rotax Service Depot, where any necessary adjustments can be made. We do not recommend owners to attempt the adjustments themselves.
AMMETER READINGS. It must be remembered, when noting ammeter readings, that, normally during daytime running, when the battery is in good condition, the dynamo gives only a trickle charge, so that the charge reading will seldom be more than a few amperes.
A discharge reading may be shown sometimes immediately after switching on the lamps. This usually happens after a long run when the voltage of the battery is high. After a short time, the voltage of the battery will fall and the regulator will respond, causing the dynamo output to balance the load.
When starting the driver will notice the rise of current which reaches a maximum at about 20 miles per hour. The current then falls slowly until after about 30 minutes running it reaches a steady charge which is most suitable for the particular conditions of the battery."
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

Colin
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Joined: Thu Jul 24, 2014 3:46 pm

Re: Voltage Regulator

Post by Colin » Sun Sep 28, 2014 9:03 am

Thanks for that. I took the car for a longer run and it's not charging at all now!! I'm going to rewire the car soon, I have a loom, I'm going to do that first and then see where I am.

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luli
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Re: Voltage Regulator

Post by luli » Sun Sep 28, 2014 10:26 am

Note that in order to replace the loom you have to remove the instrument panel. You can watch pictures of this operation here http://wp.me/pXLKy-26d and in the following posts (on the bottom of the page, click NEXT to view them).
See also here: http://wp.me/pXLKy-12p
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

chris dancey
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Location: Brighton & Paphos, Cyprus

Re: Voltage Regulator

Post by chris dancey » Tue Sep 30, 2014 10:15 am

Hello Colin,

A little tip if you are rewiring. On my restorations I run a small piece of wire from each connection on the rear of the dashboard, say three inches, then splice in a couple of bullet connectors and a junction. This will allow you in the future ( if necessary ) to disconnect the entire dashboard without actually removing from the car. Some of the connections are extremely difficult to get at in their original position, I have found this extremely useful.

Chris
Last edited by chris dancey on Thu Oct 02, 2014 9:46 am, edited 1 time in total.
1934 ( 1935 model ) P1 '10' Saloon RD 6160
1935 P1 '10' Saloon ( originally JB 6729 ) now VSJ 156
1946 P2 '14' Sports Saloon KPG 855
1933 MG J2 Cycle Wing Model APB 560
1933 MG J2 Competition Model ALX 124

Colin
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Joined: Thu Jul 24, 2014 3:46 pm

Re: Voltage Regulator

Post by Colin » Tue Sep 30, 2014 1:25 pm

Thanks Chris. Makes sense - I will do the same. Colin.

chris dancey
Posts: 386
Joined: Tue Oct 20, 2009 8:20 pm
Location: Brighton & Paphos, Cyprus

Re: Voltage Regulator

Post by chris dancey » Thu Oct 02, 2014 9:45 am

Also, when I have a new wiring loom built ( usually by autosparks ) I ask them to add a foot of extra wire to each circuit, this allows for ' adjustments ' to be made...and the extra also to create the 3" sections from the rear of the dashboard. Also get them to add a white covered wire from the ignition ( or the voltage regulator ) to where the electric fuel pump is ( or could be fitted ), looks better ' in the loom ', rather than a seperate run.
1934 ( 1935 model ) P1 '10' Saloon RD 6160
1935 P1 '10' Saloon ( originally JB 6729 ) now VSJ 156
1946 P2 '14' Sports Saloon KPG 855
1933 MG J2 Cycle Wing Model APB 560
1933 MG J2 Competition Model ALX 124

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