Author Topic: DIY Lucas E3L field coil rewind  (Read 841 times)

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #15 on: 04.04. 2019 20:59 »
Hi Kiwi
Ask for some winding tape at a motor rewind shop
It was cotton I think originally, some sort of composite material nowadays
Usually soaked in insulating varnish once formed into place

John

Excellent idea, but it will be a while before I will get to a town big enough to have a rewind shop (I live in a little rural town of 20,000). The kapton tape can (supposedly) take 400deg c and is very tough (doesn't tear like sellotape for example) I guess I was wondering if (tape) technology has moved on and there are better alternatives to what was used originally. It’s expensive (but not outrageously) so maybe that’s why it’s not used more  *dunno*. I bought it online as no shops around here had high temp tape of any sort.

I’m going to try bending the coil today, I think a bit of 1” pipe, angle iron (as a former) and a vice should do it  *work*
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Online chaterlea25

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Re: DIY Lucas E3L field coil rewind
« Reply #16 on: 04.04. 2019 21:21 »
Hi Kiwi,
20,000 I would regard as a decent size town,
We must be better at burning out motors here as thinking about towns of similar size near here most have a rewind shop ????

John
1961 Super Rocket
1963 RGS (ongoing)

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Re: DIY Lucas E3L field coil rewind
« Reply #17 on: 04.04. 2019 21:30 »
Kiwi, I use cotton tape, 12mm.
I don't soak the coil in varnish but just paint it on, this saves the next bloke who has to refurbish the coil a lot of grief.
Originally the coils are not varnished.
As to bending, I just bend by hand around a piece of about 2" chrome bar, it doesn't take a lot of effort. If the coil is not too rigid it will take shape when pulled in with the pole shoe. This is why cotton tape is so useful, it allows movement.

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #18 on: 05.04. 2019 08:07 »
Kiwi, I use cotton tape, 12mm.
I don't soak the coil in varnish but just paint it on, this saves the next bloke who has to refurbish the coil a lot of grief.
Originally the coils are not varnished.
As to bending, I just bend by hand around a piece of about 2" chrome bar, it doesn't take a lot of effort. If the coil is not too rigid it will take shape when pulled in with the pole shoe. This is why cotton tape is so useful, it allows movement.

Thanks Trevor, I must have wound it a bit tight as I could no way bend it by hand, it went a bit banana shaped in the vice, so I had to mess about with it a bit, but nothing major. It’s back together now.

Dumb question, I’ve got an original Lucas mechanical regulator which I calibrated for 6v some time ago. Will this work on 12v? if so, will it need recallibrating?

I’ve had 2 dvr2 fail with this dynamo, first after a fibre gear (it’s for a b31) let go, second after the main fuse blew when I accidentally shorted the horn feed, so I’m probably going to give a mech regulator a go, before splashing out on a third dvr2. I’ve been told if I fit a diode in the right place it stops the drain caused by mech regs at low revs. I’ll give that a go as I’ve got a diode of several Amps rating with no job to do.
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Online trevinoz

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Re: DIY Lucas E3L field coil rewind
« Reply #19 on: 05.04. 2019 23:38 »
Not a dumb question but the answer is no, the 6V reg will not be any good for 12V. The shunt coils wouldn't like the double voltage.
You could pull the reg apart and use the bobbins from a 12V car type regulator, the resistor will be a little low for 12V but shouldn't cause any grief.
The low output at low revs is a bit of a problem with 6V generators trying to put out 12V.
Better job with a rewound armature and field coil to suit.

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #20 on: 06.04. 2019 01:53 »
Not a dumb question but the answer is no, the 6V reg will not be any good for 12V. The shunt coils wouldn't like the double voltage.
You could pull the reg apart and use the bobbins from a 12V car type regulator, the resistor will be a little low for 12V but shouldn't cause any grief.
The low output at low revs is a bit of a problem with 6V generators trying to put out 12V.
Better job with a rewound armature and field coil to suit.

Thanks again Trev, can I just use a 12v Lucas car type mech reg? I’m a member of the local vintage car club and I’m pretty sure there will plenty of those to choose from in their spare parts shed, for a small “donation”. The 12v battery is new and of lead acid type if that makes a difference, and when it needs replacing I’ll probably revert the bike back to 6v. My A10 is 6v with dvr2 and has given me no problems other the motobatt brand batteries only last a couple of years.
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

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Re: DIY Lucas E3L field coil rewind
« Reply #21 on: 07.04. 2019 00:17 »
Kiwi, there should be plenty of the RB106 regs lying about, you probably know them, they have a Bakelite cover held on with a wire clip like the MCR1 & 2.
Same mech as the bike regs so just set the same.

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #22 on: 07.04. 2019 01:59 »
Kiwi, there should be plenty of the RB106 regs lying about, you probably know them, they have a Bakelite cover held on with a wire clip like the MCR1 & 2.
Same mech as the bike regs so just set the same.

Thanks Trev, I’ll get hold of an rb106 if I can.

The new field coil works ok, at first it did not generate very well, and I found one brush had several ohms resistance, I guess from a poor contact between the copper lead and graphite, very odd!

It now motors ok on 12v and a few amps, but only gets up to 14 volts with f+d joined and spun by a drill, which is low but maybe the drill isn’t fast enough. With 2 amps put through the field and then spun by a drill it gives over 16 volts when charging a 12v battery.

Both my dud dvr2s will charge a battery but ONLY if the field is supplied current from another source, this indicates to me the faults are (just) on the field control side of the dvr2s. The side that allows current to pass from the armature to the battery (but not vice versa) is still working, but of course is unregulated.
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #23 on: 07.04. 2019 02:05 »
Hi Kiwi,
20,000 I would regard as a decent size town,
We must be better at burning out motors here as thinking about towns of similar size near here most have a rewind shop ????

John

I’ll have another look! There is an auto electrical shop/workshop which has some NOS Lucas stuff, I was very surprised to find that (and one of the owners has a plunger a10)
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #24 on: 09.04. 2019 02:20 »
Well after some crude testing I’ve bought a new 6v battery and 6v bulbs and reverted to the oem mechanical regulator by Lucas.

I’ll see how this goes but will probably get another dvr2 and run that at 6v.

What I found from my crude testing was that the field current was MUCH higher using a 12v battery than with 6v, and the revs have to be MUCH higher to get a net charge after deducting the current taken by the field.

So whilst I’ve can see the std 6v dynamo CAN be run at 12v I've formed the view (rightly or wrongly) it is not a good idea and will likely result in a fried field coil (or regulator) unless the dynamo is in first class condition, and not put under extra load eg from higher wattage bulbs etc.

Before this experimenting I had the view that the dynamo would not be under more “stress” when run at 12v as the (armature) current theoretically halves, but in fact, from my crude testing the armature (at 12v) is providing significantly more current to the field coil than at 6v (so the armature current doesn't halve in practice) and with the field coil taking quite a lot more current, it is o& course getting hotter and “wasting” some of the charging capacity.

I tried a diode in the circuit to stop “backwards” current drain at low rpm, it did not work as it prevented the dynamo from “self generating” the necessary start up voltage. On my bike the reverse  current drain only occurred on tickover, it charges on a fast tick over, so it’s unlikely to be a problem (especially in nz).

Lastly the mcr2 with its brass cover looks cool!



New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Online Bsareg

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Re: DIY Lucas E3L field coil rewind
« Reply #25 on: 09.04. 2019 09:57 »
I agree that putting 12v through a coil designed for 6v is not going to end well. When I build my own 12v electronic regulators, I make sure that the field coil can never receive more than 6v. The disadvantage though is reduced  magnetic field and higher dynamo revs before achieving 12v output. That doesn't matter here in the sticks but can cause problems in towns and cities.
C11,B40,B44 Victor,A10,RGS,M21,Rocket3,REBSA

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Re: DIY Lucas E3L field coil rewind
« Reply #26 on: 09.04. 2019 22:07 »
Another point is that doubling the current in the field coil results in quadrupling the power absorbed by the coil. Much more heat.

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #27 on: 10.04. 2019 03:37 »
Me and the mcr2 are not getting on!

All is well for a few miles then it stops charging, I clean the regulator contacts (wet and dry 400 grit, then brake clean) and it starts charging again but only for another few miles. The cut out appears to be working ok, it’s adjusted so it does not cut out even at very low tickover.

Any ideas on what needs fixing?

Edit: just a thought, if the regulator contacts get dirty and don’t connect, does this result in “no charging” or just “reduced charging”? (Provided the cut out contacts are closed)

Also, I’m measuring the battery voltage when I say it’s developed a fault and is discharging, (eg gone below 6.4v, the no load voltage, even at high rpm) and as well as that the ammeter shows a discharge when the lights are switched on, at high rpm.
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet

Offline BSA_54A10

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Re: DIY Lucas E3L field coil rewind
« Reply #28 on: 10.04. 2019 09:29 »
You sound like you are falling for a newbie non-problem.
The dynamo is regullated.
If the battery is fully charged it does not generate so the ampmeter shows "0" until you do something that requires battery voltage.
If you want to test the regulator you need to be riding lights on when if all is well the needle will swing negative at idle then positive as you accelerate and drop back a bit after a few minutes when the battery has recovered from powering the headlights at idle.

My dynamo works perfectly and the amp meter reads 0 nearly all of the time
Bike Beesa
Trevor

Offline KiwiGF

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Re: DIY Lucas E3L field coil rewind
« Reply #29 on: 10.04. 2019 10:41 »
You sound like you are falling for a newbie non-problem.
The dynamo is regullated.
If the battery is fully charged it does not generate so the ampmeter shows "0" until you do something that requires battery voltage.
If you want to test the regulator you need to be riding lights on when if all is well the needle will swing negative at idle then positive as you accelerate and drop back a bit after a few minutes when the battery has recovered from powering the headlights at idle.

My dynamo works perfectly and the amp meter reads 0 nearly all of the time

Hi, that did occur to me BUT the battery is definitely discharging ALL the time when the fault occurs, but as you say the most obvious evidence of this is the ammeter showing (the same) high discharge at idle and high revs.

When it’s NOT got the fault the dynamo is able to keep the needle at 0 or showing charging at just a medium tickover, but this only lasts for a few miles (with the lights on) then the ammeter needle goes hard to the left when the fault occurs, and the only way I’ve found of getting it to charge again is clean the regulator contacts, but it may not be the contacts at fault but something is cooling down or *dunno*

The reg side contacts are sparking when the fault is NOT present, is that “normal” ? (they stop sparking when the fault occurs).
New Zealand

Last had an A10 in 1976, in 2011 it was time for my 2nd one.

1956 Flash Frame EA7-168x Eng. CA10 913x, left BSA together for Liverpool, 5th Dec 1955.

B31 “hot rod” (yeah right)

Armstrong Siddeley Whitley for rainy days (with wife).

GL1800 Goldwing not sure why yet