The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: Sav on 30.12. 2011 22:35

Title: Dodgy battery (or not?)
Post by: Sav on 30.12. 2011 22:35
Hope you all had a good Christmas!

I bought a new battery for the A7 and mistakenly ordered a B38 instaed of a B39, thought no problem I'll treat the A10 which uses the B38 and has quite an old battery. Then the trouble started

Put the B38 in the A10, all Ok. Had to do a 150 mile return journey so coupled up the satnav for six volts and it worked OK so polarity OK.

Completed the first leg of the journey turned the engine off and noticed the satnav immediately said external power had been lost. Also no lights from battery. Had lights with the engine running so headed for home. I took the battery off and it had two volts and would not charge on the smart charger. Put a 1 amp controlled output through it for a few hours and voltage was up to four, but immediately dropped back to two volts. Faulty battery I guess!

Dealer replaced the battery with another, carefully checked terminals and polarity but lo and behold, thirty miles up the road and two volt battery again!

Any bright ideas guys, coulld the second battery also have a fault I have never heard of? I'm loath to go back to the dealer a second time after new year.

I'm going to have a look at it in the morning and hope I have not damaged the dynamo or DVR2

Sav

Title: Re: Dodgy battery (or not?)
Post by: muskrat on 30.12. 2011 23:47
 g'day sav,
               might have fried the dvr and its giving the battery full charge and cooking it. Others here more up on sparky bitey stuff.
Cheers
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 31.12. 2011 00:03
Muskrat could well be right but I suspect you would have blown your lights had such a charge reached your battery. From what you say it does sound like the battery might have been connected the wrong way round. I know that sounds unlikely but it is possible if something has gone wrong with the circuitry that the dynamo polarity has been inadvertently switched. I would start by checking the dynamo output and polarity (remove dynamo leads, bridge F and D on dynamo, connect voltmeter - to bridge + to frame/earth [assuming+ve earth] start the bike, should give about 8v at fast idle speed). If voltmeter needle swings the wrong way you know your polarity has been switched. If all is Ok refit wires and test output from DVR which should give a steady charge of about 6.5 - 7v.
Title: Re: Dodgy battery (or not?)
Post by: Sav on 31.12. 2011 09:30
Thanks for the suggestions. Battery polarity should have been OK as satnav worked on 6v. DVR2 is a possibilty as satnav would have been protected by the stable voltage gizmo I use.

Preliminary look this morning and nothing from dynamo after several days without battery. I'll get the battery off the A7 and flash the field coil.

What I don't understand is why both now 'dodgy' batteries appear to be working on one of the three cells to give two volts

Sav.
Title: Re: Dodgy battery (or not?)
Post by: bsa-bill on 31.12. 2011 10:23
Quote
nothing from dynamo after several days without battery

I'm no expert Sav but I do think a dynamo should hold it's field coil healthy for much longer than that, points to no charge from dynamo maybe (brushes?)

I've had trouble with two Chinese batteries, good for a short while then won't hold a charge, trouble is even a Lucas battery I had went duff but then again it bore more than a passing resemblance to the two Chinese ones, in fact an exact resemblance.
Got a Varta from my MOT man and it's fine
Title: Re: Dodgy battery (or not?)
Post by: Sav on 31.12. 2011 11:29
Cheers Bill,

The hole deepens!!

Cannot resurrect the dynamo by flashing the field coil now! It was deffo charging before disconnecting the second battery after the VMCC Boxing day run.

Dynamo was rewound by SRM 3½ years ago when engine was completely rebuilt by them. Bike has been rock solid since the rebuild and done almost 10k miles.

One of those jobs you wish you had never started as I'm now worried running the bike with a duff 2v battery may have overloaded the armature or field coil. Electrics and women, the great unsolved mysteries of life!

Starting to feel a pain in the wallet!

Sav
Title: Re: Dodgy battery (or not?)
Post by: Brian on 31.12. 2011 11:40
Just a thought, is the dynamo spinning ? Its not unheard of to have the drive chain break.
Title: Re: Dodgy battery (or not?)
Post by: bsa-bill on 31.12. 2011 11:58
Brian point is good one (belt drives the way to go), if it is spinning check the brushes are free, I had similar problem and a brush was stuck, easy mend
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 31.12. 2011 12:09
Hi Sav. If the dynamo is spinning and has given up there's not a lot you can do other than check the brush and field coil connections, check the brushes for condition and that they are free in their housings. Presumably the commutator is reasonably clean. Occasionally the brush leads come loose in the carbon blocks but this is rare and clutching at straws. To get the dynamo working again, most of the dynamos passing through my workshop need a new armature, often bearings, occasionally brushes, rarely field coils. Fitting a new armature isn't difficult but lots of owners are 'electric averse'!
Title: Re: Dodgy battery (or not?)
Post by: Sav on 31.12. 2011 12:17
Found the current problem and the wallet is lying down recovering from the shock!

Took the end cap off the dynamo and bits fell out! (the bearing cap and spring washer). The ball race only has half the number of bearings it should have. and there is other swarf.

I'm hoping it is thus safe to assume that the change in battery was an unfortunate coincidence. Wierd as it was definitely charging, but the loose dynamo shaft could have been giving a dead short at times and frying the battery??

Have lunch and start dismantling!

Sav
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 31.12. 2011 12:30
Unfortunately it is quite likely that the disintegrating dynamo has caused problems elsewhere. You might find some useful info on my website.
Title: Re: Dodgy battery (or not?)
Post by: Sav on 31.12. 2011 13:26
Dynamo as opened (http://www.a-r-s-e.co.uk/images/members/sav/dynamo.jpg)

Hello Houston we've got a problem! DVR2 must be suspect after that as well. Been out and bought a new Yuasha battery instead of the cheaper ones that were on there.

Looks like I'll be buying more shares in SRM unless Beezermacc or someone else is recommended by members. The job must be done top knotch and not corner cut as the Rocket is ridden long distances. No offence meant but I'm new to this forum and don't know you guys.

Sav
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 31.12. 2011 14:36
Hi Sav. You can give me a ring if you like 01625 265185. I am happy to guarantee my work for 5 years!
Title: Re: Dodgy battery (or not?)
Post by: Sav on 31.12. 2011 15:05
Cheers Beezermacc will give you a ring. Cannot post until middle of next week anyway with the bank holiday.

It's the bearing that has collapsed looking at it now I've got it off.

Sav
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 31.12. 2011 17:23
Looking forward to hearing from you. Andrew.
Title: Re: Dodgy battery (or not?)
Post by: Sav on 31.12. 2011 19:29
One good thing is it speaks volumes for the little steady voltage five volt output, regardless of input, gizmo I use to run my satnav on lucas 'six' volts variable (and probably highly variable in this case  *smile*).

Guess I'd better drown my sorrows this evening! Have a good New Year all!

Sav (Chris)
Title: Re: Dodgy battery (or not?)
Post by: fido on 31.12. 2011 19:58
I don't understand why the A7 needs a different battery to the A10. The 2 models were originally identical in terms of electrical equipment.
Title: Re: Dodgy battery (or not?)
Post by: Sav on 31.12. 2011 20:20
I don't understand why the A7 needs a different battery to the A10. The 2 models were originally identical in terms of electrical equipment.

Battery cages are different on the two bikes but may well not be original after fifty years, The A10SR has the full width, height and depth cage for the B38 battery and the A7SS has the full width, height but only half depth cage for the B39 sliimmer battery. The A7SS also still has the old mechanical regulator

Sav
Title: Re: Dodgy battery (or not?)
Post by: trevinoz on 01.01. 2012 01:13
Sav,
          How many miles have you done since the dynamo overhaul?
That bearing certainly doesn't look like a 3 1/2 year old item!
Have you done a lot of wet weather riding? The bearing appears to be rusty and seems to be skewed in the housing or is that a lighting trick?
From experience, I would say that the armature has been "poling", due to the collapsed bearing, creating a lot of heat and probably causing the solder on the commutator to throw.
With a bit of luck the armature won't be burnt out but will need to be resoldered. Ensure that all wire ends are clean and not burnt and maybe you will be OK.
Make sure that the comm end bearing is a good fit in the housing and check the armature shaft for straightness, quite often they have a slight bend which can be rectified.

Trev.
Title: Re: Dodgy battery (or not?)
Post by: trevinoz on 01.01. 2012 01:16
Another couple of points, you should have an "O" ring sealing the perimeter of the metal cap and a rubber grommet to seal the wire entry.

Trev.
Title: Re: Dodgy battery (or not?)
Post by: Sav on 01.01. 2012 09:20
Thanks Trev,

The A10SR has been a labour of love!!

It got off to a bad start when a ratchet strap failed on the way home from purchase and the front end got dragged along the road.

The bike was bought having been rebuilt, but it was a kitchen rebuild and fell apart immediately. My mechanical experience at the time was negligible so I had new ends and shells fitted but they turned out to be some of the sub standard 'Italian' ones that were about four years ago and did not even survive a gentle running in.

So I gave the engine to the experts at SRM and said do the lot and fix it! £3.8k, roller bearing conversion and a complete rebuild of engine and electricals later the engine has been brilliant. The only minor problems were the dynamo brushes initially and later a crappy set of points SRM installed where the main spring was too tight so that the mounting pole came loose. After 'discussions' about lack of info on a known possible failure of these points they refunded the cost of the points.

Thus everything is as rebuilt. the grommet is on place but I am not aware of a O ring for the cap edge. The bike has done 9k in all weathers since the rebuild, many long runs and rallies including hundreds of miles all over the Pyrennees, Manx GP's and Colombres rallies in Spain. It pulls like a train and sounds gorgeous as there is nothing up the silencers.

The dynamo bearing looks bone dry as far as lubrication is concerned and I must admit the cover has not been off in three years, though I would not have seen much with the covering bearing plate (or are they sealed?). The bearing shells have thus given way

So I'll give the dynamo to the experts and try to make sure it is done properly as that's the bike I use and rely upon.

Sav.
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 01.01. 2012 10:04
I have repaired a few armatures the way Trevinoz suggests, particularly when replacement armatures have been unavailable. I'm not taking issue with Trev's advice - this is a perfectly good repair for those who like a challenge and don't have to guarantee the longevity of the armature. The armature in Sav's bike has had quite a battering so I would be reluctant to refit this. I've come across quite few dynamos which have been completely wrecked due to the commutator segments coming loose from the armature, bashing against the brushes, smashing the brush holders and bearing carrier, and snapping the dynamo chain! (Ouch!). The vibration and the battering the commutator has suffered may have weakened the bond between the commutator segments and the armature. Fortunately new armatures are readily available and the ones supplied by the UK manufacturer are of a very high quality and capable of driving a 12v. system. I agree with Trevinoz, the bearing has a somewhat 'antique' appearance! Most restorers have been using sealed bearings for a number of years so I'm surprised Sav's isn't of that type. Happy New Year!
Title: Re: Dodgy battery (or not?)
Post by: Sav on 01.01. 2012 11:57
Looking at the SRM bill it would appear that the bearing was not changed. The mag rewind and rebuild cost £230 plus vat. The dynamo just has check and rebuild £35 (plus brushes and nickel plating). It would thus appear that nothing else was changed. That surprises me with the great lengths to which they went to replace everything in sight on the mechanical side and make sure everything else was absolutely A1.

Sav
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 01.01. 2012 12:18
The mag rewind and rebuild cost £230 plus vat.
... which included gold plating of course! Maybe the owner was starting to run out of cash. As can be seen, false economy not to have things done properly!
Title: Re: Dodgy battery (or not?)
Post by: Sav on 01.01. 2012 14:01
The mag rewind and rebuild cost £230 plus vat.
... which included gold plating of course! Maybe the owner was starting to run out of cash. As can be seen, false economy not to have things done properly!

Certainly seems a false economy when I paid £3.8k plus delivery and collection for the rest of the rebuild! The rest of the rebuild has been absolutely first rate, but they had the dynamo back immediately as it was not charging due to sticky brushes. Thus they got to look at that bit of kit twice.

Sav
Title: Re: Dodgy battery (or not?)
Post by: beezermacc on 01.01. 2012 16:52
Hi Sav, OOps! Sorry, I forgot you had the SRM job done; I was thinking that it had been done by the previous owner for a (senile!) moment. All the magnetos and dynamos going through my workshop get new armatures unless they have been exchanged recently and the reason for rebuild is apparent elsewhere. A friend of mine has two BSA's with SRM engines and they both run faultlessly. You can sometimes tell when the commutator is about to burst as the segments start to twist very slightly so they are not guite parallel to the central axis of the armature. This is a sure sign that the bond between the commutator and the armature is failing.
Title: Re: Dodgy battery (or not?)
Post by: trevinoz on 01.01. 2012 21:34
Sav,
          The "O" ring sits in a recess in the end plate below the brush plate, if you have the correct end plate.
Trev.
Title: Re: Dodgy battery (or not?)
Post by: Sav on 02.01. 2012 11:36
Cheers Trev,

All dismantled and ready to go in the post tomorrow.

I can see the groove under where the cap slides on but no O ring in there.

Sav.
Title: Re: Dodgy battery (or not?)
Post by: Sav on 21.01. 2012 21:48
Thanks to beezermacc for giving my dynamo and DVR2 the once over.

Took the opportunity to do a Hawker belt conversion at the same time.

Put it all back together again and tried the electrics out in stages and could find absolutely nothing. Bikes had a run now with everything connected and appears to be workmg perfectly.

Looks now like I was dealing with two completely unrelated faults and the dynamo bearing going at the most awkward time as I know it was charging when the battery fault first appeared.

Good quality Yuasha battery in situ now.

Thanks to all for suggestions given.

Chris.