The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: zappa on 06.02. 2011 19:33

Title: modificate a dynamo to 12 Volt or new
Post by: zappa on 06.02. 2011 19:33
I want to modicate my dynamo to 12 volt, or is it better to buy a new one from for example Alton?
Title: Re: modificate a dynamo to 12 Volt or new
Post by: Goldy on 06.02. 2011 19:37
I don,t know if your in the uk but Dave Lindsley will give you the answer http://www.davelindsley.co.uk/
Title: Re: modificate a dynamo to 12 Volt or new
Post by: lawnmowerman on 06.02. 2011 21:11
Hi Zappa and welcome to the forum.
I am assuming your dynamo is from an A series. The limiting factor is the wattage, our dynamos will output 12V plus if they are spun a bit faster using one of the belt drive kits available and a new solid state regulator with a 12v battery. The power, however will remain the same.
I believe the Alton is an alternator rather than a dynamo and will produce about 14v regulated and rectified down to just over 12v to charge the battery. Others on the forum have them I am sure and will be able to advise. I think they are quite pricy though.

Jim
Title: Re: modificate a dynamo to 12 Volt or new
Post by: trevinoz on 06.02. 2011 21:21
Jim,
            When the dynamo is run in 12V mode, the power output increases to something in the order of at least 80 watts.
Trev.
Title: Re: modificate a dynamo to 12 Volt or new
Post by: groily on 06.02. 2011 21:39
No need to modify the dynamo at all Zappa to use it at 12volt unless you want to. But you will need to swap the cut-out/regulator for a 12v unit - there are several options - and of course you'll need a 12v battery and bulbs.
If you wanted to, you could replace the armature and field coil with finer-wound so-called 12v parts - the advantage being that these parts allow the dynamo to start charging the battery at lower RPM. If you do that, you get the same 60W limit of the old 6v system; whereas if you keep the older windings, they can safely deliver about 20% more.
A good combination is to use the dynamo you've got, if it works OK, with a solid state regulator like the DVR2 unit often mentioned here, which is a straight swap for the old cut-out/regulator box, costs about £45 and is available in Positive or Negative earth (and also in 6v form if you decided to stay at 6).
Some electronic regulators may require the internal wiring of the field coil and brushes to be swapped round in the dynamo; DVRs and a number of others don't.

If your dynamo doesn't work properly, then folk like Dave Lindsley can certainly fix it very well, but it's not cheap (£200 to £300?), especially with postage included, and could take a good few weeks. But all the parts (original style or fine-wound coils, plus all the consumable bits like brushes) are available off the shelf, and the dynamos are easy to take to bits.
The Alton alternator is a different sort of 12v option, well-proven and high-output, but again quite an expense at about £320 plus another £26 for the rectifier/regulator to go with it, plus VAT at 20% if applicable. Ie over £450.

Title: Re: modificate a dynamo to 12 Volt or new
Post by: lawnmowerman on 06.02. 2011 21:52
Hi Trev

I stand corrected. I guess that if the dynamo is being spun a bit faster with the belt drive kits there is more energy going in so there will be a corresponding increase in power output.
Excellent explanation by Groily.

Jim
Title: Re: modificate a dynamo to 12 Volt or new
Post by: muskrat on 07.02. 2011 13:00
G'day Zappa, welcome to the forum.
                                                 First thing to check is the condition of the dynamo. Do a search for "dynamo" using the search at top left of page. You will find lots of info there.
 If you are handy or know someone who is a rebuild kit is available from here http://www.hawkerelectrical.co.uk/items/17-1_13-lucas-e3l-ac-dynamo-rebuild-kit.htm
Then get a DVR2 regulator http://www.manortec.co.uk/dvr.htm and of course 12v battery and globes.
 If you still have money left a toothed belt drive to finish it all off http://www.srmclassicbikes.com/catalogue/index.php?target=products&product_id=786
I have done both my A's like this.
Cheers
Title: Re: modificate a dynamo to 12 Volt or new
Post by: iansoady on 07.02. 2011 13:54
There was an Alton on my Velo Viper when I bought it and I hated it. Very noisy (and if you can hear it above a Velo fishtail it has to be!) and also very irritating as you had to switch off the battery connection when the bike was stopped otherwise the battery discharged through the regulator.

I fitted a £20 dynamo from ebay that I reconditioned at the cost of around £15 with new brushes and bearings, and skimming the commutator.

There are people who like Altons but I'm not one of them.

Although I converted the Velo to 12V, the A10 seems quite reasonable on 6 so I'll probably leave it like that. But then I don't often ride it at night.
Title: Re: modificate a dynamo to 12 Volt or new
Post by: zappa on 07.02. 2011 21:03
Thank you all for yours reactions, and the welcome. I take some research time for your comments and advice, and come back later when I need more information ore help. About the Alton dynamo, they tell me that there are some generations. the first one`s have a gearbox in it. maybe this generations make the noice. But the last generation have no gearbox in it anymore. And it give more output than the original rewined to 12 V
Can anybody tell me his experience about this one?

I come from holland, ecxuse for my grammar.
Title: Re: modificate a dynamo to 12 Volt or new
Post by: groily on 07.02. 2011 21:59
I don't know about the gearing question on the latest ones Zappa, although I'd be surprised if there wasn't any system to get the axis of the alternator shaft on the centre line. But Yes, you're right, they produce up to 150W, with an easy 80 or 90W at medium speed. This is useful if you want electronic ignition as well as powerful lights.
They are all negative earth.
I think the main difference between early ones and the later ones is that the first versions (or it was an option at least) were three-phase and later ones are all single phase, but there may have been more changes than just that. Someone here will know though, they always do luckily!
The pictures/diagrams on the Alton web site are deliberately vague and do not show the internal construction.
You could also look at www.powerdynamo.biz which is a fascinating site another member referred us to recently. They offer another alternator option which is interesting insofar as it retains the offset spindle for the rotor (like in the Lucas dynamo). They also refer to some of the VAPE things you mentioned in an earlier post (but I don't think their stuff, with the exception of perhaps their voltage regulators, is quite what you need).
Your English is a really good compared to my Dutch!