Dodgy battery (or not?)

[Sav]

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

[muskrat]

 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

[beezermacc]

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.

[Sav]

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.

[bsa- bill]

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

[Sav]

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

[Brian]

Just a thought, is the dynamo spinning ? Its not unheard of to have the drive chain break.

[bsa- bill]

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

[beezermacc]

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'!

[Sav]

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

[beezermacc]

Unfortunately it is quite likely that the disintegrating dynamo has caused problems elsewhere. You might find some useful info on my website.

[Sav]

Dynamo as opened

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

[beezermacc]

Hi Sav. You can give me a ring if you like 01625 265185. I am happy to guarantee my work for 5 years!

[Sav]

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

[beezermacc]

Looking forward to hearing from you. Andrew.

[Sav]

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  ).

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

Sav (Chris)

[fido]

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.

[Sav]

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

[trevinoz]

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.

[trevinoz]

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.