Sealed lead-acid battery woe,s

[Worty]

The DVR2 will have a very small reverse current - milliamps - and they say it will drain a battery in a few months.  This will not heat it up, but if the electronic component has failed and is allowing a bigger reverse current it will get very hot and flatten the battery.  I think you need to get the DVR2 on the bench and check its reverse resistance.  Electronic components do fail, even quality ones, so it is possible.

This seems to fit.  I'm sure BB said his battery was draining very quickly.  Will look back over the posts.

[Billybream]

The DV2R has been back to the manufacturer for test and was tested all ok

[limeyrob]

OK that's done for my theory.  The DVR2 can only get hot if its flowing current when the dynamo is stationary and its designed not to do that.  Since the reverse current circuit is a diode I think the next question is the polarity of the DVR2 - pos or neg earth (they do 2 versions), the polarity of the battery and the polarity of the dynamo.  I run my A10 neg earth with a neg earth DVR2, battery neg to earth and a dynamo flashed and checked for correct polarity on the bench and its all fine, but a neg earth Wassel unit did not work.

[Billybream]

It's all on positive earth, no problems until fire up after winter layup up, no wiring changes, total puzzle to me, could the ammeter be shorting out and giving power to DV2R.
Will continue testing individual components, think I have a spare ammeter.
The petrol tank was taken off during winter lay up, might have to remove and check for potential damaged wiring if nothing else tests faulty.

[limeyrob]

Hmmm.  Thinking out loud here:
The DVR2 supplies current to the field winding so its worth checking whether that's got shorted under the tank.
Dynamo brushes can stick but I can't see that causing this problem, have a look under the end cover and see if everything is where it should be.  The brush cables run very close to the cover, its a bit tight so one could be earthing, but one is earthed anyway.
Not much to go wrong with an ammeter as its insulated from the headlight and has a very low resistance anyway.

[Billybream]

Thanks Rob for your help, the Dynamo has not be disturbed, but will check out the connections and brushes, if that fails will take the tank off and check wiring

[Billybream]

Checked out dynamo with end cover off and all appears OK with wiring and brushes, decided to disconnect yellow wire to F connection at DV2R and reconnected fully charged battery, no heat build up to DV2R and no high discharge on ammeter, so now assume must be short somewhere along the run of this wire from the dynamo, will now connect temporary connection and retest

[limeyrob]

Makes sense as I think its the only wire that could pull a lot of current off the DVR2.  It runs under the top tube then down the front, it could be rubbing on the engine steady or where it goes through the hole in the back of the tool box.  I'd start with those two first.

[Billybream]

Still in trouble with short, just about replaced or resoldered all connections, checked continuity on most wires. Used a bulb wired into battery to check for short, only suspect was fuse on earth from battery to frame, removed fuse and bulb went out, decided to wire out the fuse but bulb still went out, everything seems to work but obviously battery dies very quickly.

[Worty]

Still in trouble with short, just about replaced or resoldered all connections, checked continuity on most wires. Used a bulb wired into battery to check for short, only suspect was fuse on earth from battery to frame, removed fuse and bulb went out, decided to wire out the fuse but bulb still went out, everything seems to work but obviously battery dies very quickly.

 

[Bsareg]

When you reconnected the field wire and the ampmeter showed a discharge, was the engine running ? If not, surely the field should only be energised when the engine is running. When the engine is stopped all current to the field is removed.

[KiwiGF]

From memory it can be quite tricky to make sure headlight switch connections dont contact the nacelle/shell, possibly ammeter connections also, worth a look anyway.

[Billybream]

What a plonker, having spent hours tracing my short, resoldering connections, finally discovered the problem, I had a pigy back connector on the earth terminal on the battery but mistakely reconnected the earth lead to the DV2R to power feed on the battery. No more sparks when connecting up the battery, everything now works fine, thanks to everybody who offered advice.
Another slight issue the tickler on my fairly new Amal Monobloc is very slow to exit fuel, seems to take ages holding the button down before fuel wets my finger?

[Worty]

Well sussed BB!!

As for the tickler, I also had a new carb and it can take a bit of time for fuel to come through, especially if it's been standing a while.  I'd investigate further only if running is affected.

[limeyrob]

At least you found it.  I know how easy these things are, I hit a bump towing and one rear light went out.  Next day I found a bullet connector un-plugged (is a 60 year old Army trailer) so I plugged it back where "it obviously went".  Well it didn't and 2 hours later after downloading the whole wring diagram and lying under the trailer with a multi-meter I finally got it fixed.  I plugged one wire in wrong but when I "corrected" my mistake I actually moved a different wire so I had 2 faults, after that it was hopeless.