Hi , need some help here , the dynamo on my bike a ,1954 bsa b33 is a lucas E3 HM-LO 200285
I wanted to do 12v conversion but I'm not sure if parts are available. If this isn't the correct dynamo can someone give me some numbers so I can hopefully find one and convert to 12v . Thanks.
I have the same dynamo on my B32. It didn't work when I bought the bike and when I investigated it I found that it had no brushes and the armature was useless. Sine it needed a rebuild I decided to go for 12V.
There are 2 options:
1. If the dynamos working properly at 6V, simply fit an electronic regulator that will allow it to produce 12V. The downside for this is that the engine will have to be running at higher revs before the dynamo will put out enough volts to charge the battery. So if most of your riding is at in town speeds the battery might not get fully charged.
2. A full 12V conversion. This will need a 12V armature and 12V field coil as well as an electronic regulator. This will provide charging at little more that tickover speeds. The downside is it's much more expensive but since I was doing a full rebuild of the dynamo that wasn't an issue.
Since rebuilding my dynamo I have done 5 or 6 more for other people so I'm quite well acquainted with Lucas dynamos now.
Hi , Thanks for your reply , I couldn't seem to find a 12v kit for this dynamo ? Can you give me a kit number or a company that supplied yours . Cheers
If you just want to change to 12v with your dynamo as it is without upgrading it then you want the DVR2 regulator. https://www.dynamoregulators.com/dvr2.php (https://www.dynamoregulators.com/dvr2.php)
It is switchable for 6V or 12V and is available for both positive and negative earth systems. ( If you are thinking of LED bulbs you may want to consider changing to -ve earth, although many LED bulbs available now will work with both +ve and -ve earth.)
If you want to go the whole hog and fully convert the dynamo you can get the parts from Feked (https://www.feked.com (https://www.feked.com))
12V armature https://www.feked.com/12v-motorcycle-dynamo-armature-179mm.html (https://www.feked.com/12v-motorcycle-dynamo-armature-179mm.html)
12V field coil https://www.feked.com/12v-dynamo-field-coil.html (https://www.feked.com/12v-dynamo-field-coil.html)
I would recommend that you fit new brushes while you are at it.
The E3 HM LO 200285 is a clockwise running 45w version of the Lucas dynamo, it the shorter type (hence 45w rating) and was used up until about 1947 I believe on the BSA singles.
The E3 HM was superseded by the E3LM 2034 which is of course also clockwise (goes with ant-clock M01 magneto on the BSA) which has higher 60w output.
You can convert the dynamo you have to 12v with a modern regulator (the dynamo itself can produce 12v no problem just at higher engine speed) it is the regulator that is important. I have an old Dave Lindsley JG on my 'goldie' which runs +ve earth and has behaved for 20years plus. There are newer ones on the market some sold by Wassell. These are quite cheap but I have heard of a number of premature failures (could just be internet whispers!)
From various recommendations (that I do trust) I know that you can buy the DVR2 for less than £60 and fit it directly in place of your mechanical regulator and it will give you 12v but only at max of 3.75amps.
If you have 35w headlamp, 5w tail and 3w speedo then you are sailing close to the limits (tail light is 21w but hopefully only on intermittently).
Main thing is to make sure that your wiring loom is in good condition and the bullets are all clean and corrosion free (another plug for applying Dielectric grease to each connection) and making sure you have a decent 0v reference by having a star earth in the headlamp shell running back to a star eath on the chassis next to the battery somewhere (I use one of the battery box internal studs to hook the eyelet type ring connectors to).
People do sell conversion kits for a new aramature and field coil but there are space limits inside the dynamo that mean you have to have thinner gauge wire (which is ok because for same power output and 12v you get half the current).
My personal suggestion if you want more juice is get a 60w E3L M 2034 or equivalent and get a DVR2.
(https://www.a7a10.net/forum/index.php?action=dlattach;topic=15534.0;attach=53495)
You should take care if buying an E3L to check that it has been rebuilt (new brushes, clean comm, good bearings probably replaced field coil, tested and guaranteed with some warranty). The direction of rotation is not absolutely critical if you are picking one up because you can change that, what is critical is the tapered end to fit the drive gear vs a sprocket.
I'd love to hear other peoples views and experience.
Oops! I should have read the original post more carefully. I saw it was a 1954 B33 and assumed it was an E3LM as the E3 HM LO was dropped two a year or earlier. There are no 12V conversions for the E3HM LO apart from changing the regulator as Neil suggests. I completely agree with him that whatever road you take changing the dynamo for an E3LM is best.
I thought a proper 12 conversion was looking hard , and after searching thought it was wrong , so the E3LM-..... is correct . your replies much appreciated . Cheers
I have purchased a E3LM-LO from I guy in pilling uk , I hope all is good and he sends it , he sounds genuine 🙏 and I've ordered a 12v kit from Rex's , hopefully it will be good , I will order a DVR2 soon .cheers
When the dynamo arrives you can test it by connecting the D and F terminals together and connecting a battery -ve to the joined wires and the +ve to the dynamo case. It should run as a motor and in the same direction as the arrow on the housing, clockwise for the B33 if I remember correctly. This is a good indicator that the dynamo can be good but not a definite indicator. To be sure, keep the D and F terminals connected and connect a bulb across the joined terminals and the housing. Use an electric drill or whatever other means to spin the dynamo. The bulb should light confirming the dynamo is OK.