Flat Battery Again

[brian gains]

All ready for a ride yesterday and the battery was flat , again. This is a new lead acid battery fitted a year ago by the seller. This is the second time I've gone to start the machine and there is no charge,
The thing that frustrates me is having left the machine for a week + there have been no issues, on this occasion it had only stood for two days.
The electrics are wired + earth, fitted with Kubota alternator, key position does not have park and no electrical fixture left switched on. Only exceptional event was I had removed and replaced the battery, with no issues, for access to a carb' on this occasion.
Can anyome suggest what I should be looking for, I hold my hands up when it comes to electrics 'the wiring is there to keep the smoke in' level of understanding. Yes, no problem to replace with a new battery and see what happens but would rather there was a regular consistent fault to be identified rather than an erratic one dealt with by a multiple process of elimination approach and above all to have a reliable machine.

 

[Bill Thomas]

By Kubota, Do you mean a Mcdouglator ?, Only mine is Neg earth.
Unless John changed something with the regulator He supplied ??.

Can somebody back me up, Just in case ??.

 

[Peter Holmes]

This information will probably be of little assistance with your flat battery problem, I also have fitted what is commonly referred to as a Kubota alternator, but not the small (pancake) type that John Mcdougal used, the one I use is in the same configuration as a Walkernator, in fact the components were supplied and fitted by Norman Walker, and it has proved to be excellent in service. Like Bill, mine is wired for negative earth, not positive as your bike is, my system requires a small wattage bulb turning on to create a current draw to turn the alternator on for use, I think the technical term is "to excite the alternator", when you stop you have to turn the bulb off. I have never suffered a flat battery with this system, my guess is you have a fault somewhere in the system, I doubt that it a direct short as that normally takes the wiring with it in a fairly dramatic fashion. I think the early Alton alternators could drain a battery, but I forget how and why.

 

[Bill Thomas]

Didn't know Norman did a Kubota, Love to see a photo, I thought I had an early Walkernator,
Never did fit it, , But going on the 560.
Just looking for options if I need something for another Bike.

 

[timetraveller]

There is some misunderstanding about Kubota alternators. Some people refer to Kubota alternators because they were taken off, or supplied for, a Kubota engine. As Peter writes above the small pancake ones used on some of those engines might indeed be manufactured by Kubota but I have never fitted or used one of those. I am not a fan of permanent magnet types. The one which Bill has was an Iskra as fitted to many of the smaller Citroen cars. They are very robust and can produce up to 30 amps. I then fitted a Nippon Denso alternator for Peter, These are slightly smaller in diameter when compared to the Iskra and slightly longer. These can produce 40 amps and are also very robust. Their big advantage is that the regulator is built into the alternator itself. All the early ones, perhaps 70 or 80 were the Iskra ones and the last few have been either the Nippon Denso or Densos. The Densos might be copies of the Nippon Denso ones (they look the same) and are cheaper. However, they have been 'discovered' by the kit car builders and supplies are often limited and the prices have gone up.
All are negative earth and all take current to the field windings. If you leave the 'ignition' on with the alternator powered up then that will drain the battery in a few hours. If you lack any electrical skills and do not have access to a multi meter then the best I can suggest is that you charge your battery, take off the wire which goes to the field winding on the alternator (that will be the smaller of the two) and then just flash the wire against the terminal. If there is a spark then current is being taken and that is what is draining the battery. If I have understood correctly then this did not happen originally and if that is the case then something has changed. Assuming that what is being discussed is one the 'proper' alternators then I do not understand why it is positive earth. It must be a nightmare to install it so that it is not shorting out as some stage.

 

[Mikethebike]

Hi Brian. Looking for simple answers, have you got a USB / cigar lighter port fitted? These drain the battery. Mine has a short section of plastic tube over the main contact when not in use.
Mike

 

[Bill Thomas]

While we are talking alternators T.T. I am sure I have the instructions somewhere, But I had a house move years ago, I found a big O ring with your early kit, Is it really for holding the regulator on to the alternator ?.
And does the reg' have to be earthed ?. Cheers Bill.

 

[Bill Cannon]

I think +earth is the problem. I don't think it has ever been used on an alternator based system so I doubt the regulator/rectifier could handle it.
Good luck Bill

 

[timetraveller]

Hi Bill, the big 'o' ring is to seal the drive from the primary chain to the dynamo replacement. There are differences from bike to bike and the back of the hole which takes the original dynamo drive can vary from a machined cone, to a cast cone to a flat. That might not have included all variations. The idea, and what you should have, is not an 'o' ring but rather a piece of soft rubber 'o' ring material that can be cut to length and then glued to be the right size to fit whatever type of recess you have. I have also supplied silicon tubing for the same purpose to those who are using ATF in their primary drives. The ends of that have to be glued using clear silicon mastic.
The regulator does have to be earthed and one of the three wires on that has to go to earth, otherwise it charges flat out. There is no need for any other earth. There is a wiring diagram in the instructions. It sounds to me as though I ought to send you another copy of the fitting instructions. These will arrive as an attachment to an email. Are you still at vincent.bournemouth? The separate regulator for those alternators has to be bolted where you like. Mine is under the battery carrier.

 

[roy the mechanic]

The only positive earth alternators were fitted to austin/morris vans in the mid sixties, that old junk would not fit a vin. Reverse the battery, but you may well have fried the alternator, hope you haven't.