Ammeter/electrical help requested

Gents,

My 1950 Big 4 had an old, poor battery; when I put the headlight on with the bike not running it could barely ignite the headlight bulb.

So I bought a new battery, a Wiseco AGM 6 volt 13Ah (ES 13-6). I believe the battery arrives fully charged and indeed with the engine not running it lights the headlamp up very brightly.

This was all good news until I went for a ride and the ammeter needle, which is usually dead centre was at the far right hand side of the dial when I had the headlight on and midway on the right hand side when I had the headlight off.

I do not have much understanding of the Lucas system or electrics in general but some web searching suggests the battery is taking a lot of charge from the dynamo. I have ordered a 6 volt charger so I can test the theory the battery is actually flattish - but the bright headlight with engine off does not support this hypothesis?

If any experienced folks could advise I'd much appreciate it. I am concerned I may damage the electrical system on a 100 mile run next week.

Regards

Dave

Previously david_simmons wrote:

Gents,

My 1950 Big 4 had an old, poor battery; when I put the headlight on with the bike not running it could barely ignite the headlight bulb.

So I bought a new battery, a Wiseco AGM 6 volt 13Ah (ES 13-6). I believe the battery arrives fully charged and indeed with the engine not running it lights the headlamp up very brightly.

This was all good news until I went for a ride and the ammeter needle, which is usually dead centre was at the far right hand side of the dial when I had the headlight on and midway on the right hand side when I had the headlight off.

I do not have much understanding of the Lucas system or electrics in general but some web searching suggests the battery is taking a lot of charge from the dynamo. I have ordered a 6 volt charger so I can test the theory the battery is actually flattish - but the bright headlight with engine off does not support this hypothesis?

If any experienced folks could advise I'd much appreciate it. I am concerned I may damage the electrical system on a 100 mile run next week.

Regards

Dave

G'day Dave,

Sounds like a regulator problem. A solid state regulator may be the answer

Cheers,

Peter

Your ammeter wiring connections are reversed!

It should swing to the left showing the discharge....check this by switching on the lights with the engine stationary....Let me know what you find please.

Although the lights are bright when the engine is not running it could be that the battery is fully charged, but is not being charged anymore by the dynamo, so eventually the battery will be discharged by using the lights.

Therecould also be another reason...the wiring is wrong from the CVC unit to the ammeter and from the ammeter back to the battery....we will have to work through the problem.

Les

PS Just read your question again and it seems there is a possibility you have replaced the new battery with the polarity reversed...This would explain all the symptoms.....Les

Hi Dave ....the earth as standard is POSITIVE

There is just a chance that a former owner has reversed the polarity as this is easy to do by connecting the battery with the reversed polarity and "flashing" the dynamo(sending a pulse of battery current into the dynamo to change the magnetic "remnance" of the poles). This can be reversed again at will, but positive is standard and supposedly there are advantages with this ...so best to keep it that that way.....Les

To David Cooper...you said above:

Quote::"I might as well be the first to point out this would have been better placed under 'electrical' where it might attract a slightly different readership."

Really?....so the possible replies given by the "slightly different readership"would have been preferred?....is that what you were saying?? .....Because if you are, I'm deeply offended!!!. That is outrageous!

Les

Might be the ampmeter is over-reading ,check the wattage of the lighting and compare with the ampmeter reading when not running.Does sound like the regulator though.

Hi David. Yes certainly sounds like a regulator problem. Strange though that your dynamo is capable of pumping out so much current. Thelights will consume about 6 amps at least and the meter is usually full scale at 8A so to get a full charge deflection means the dynamo appears to be knocking out 12-14Awhich is 72W- 84W...well over it's capabilities especially as the batteries voltage is right up.

What you need to do as a check is to remove the live lead (NEGATIVE) from the battery and connect a multi-meter (15A-20A capacity) in series with the this wire. Make sure the connection is very secure and monitor the three main conditions IE: lights on engine stopped....lights OFF engine running at various speeds.....lights on running at various speeds. See what you get and note the findings....Note the multi-meter will show a negative symbol for any discharge if connected correctly...see what you get and post... it will be interesting....A further note: The meter will obviously need to be switched to AMPS which in most cases means you will need to change the "Live" test lead to a separate Amps socket on the meters front...just in case you forget to....and DO NOT switch the meter away from the HIGH AMPS range when connected up....although the High Amps range is usually a separate internalshunt so possibly no damageshould occur.

As Robert above has suggested it could be that the ammeter is the wrong type (too sensitive with arange of only 4A...but not that likely though, but possible)

The old regulators can be tweaked down quite easily but many use the solid state electronic control units and themost rated one currently is the DVR2 ...the price delivered is now £51 quite a bit but the better charge control will ensure you get a better life out of your new expensive battery so a pretty good investment.

Les

Hi Dave....Thanks for the results....pleased to have caught your post this morning.

The "Lights on ...engine NOT running" reading of 5.06A is a minus figure I will assume....IE: a discharge.

The figures look pretty realistic and not overly high. However the Lights off figures would be better if they reduced somewhat when the battery was fully charged and by fully charged the on charge voltage of the battery should be 7.25. At this point the charge should ideally reduce to virtually nothing or just a few milliamps.

So a final check is required. With the multi-meter set on DC volts measure the voltage across the batteries terminals (make sure the test leads are in the right sockets)....With the enginerunning and with no lights onwait for the battery voltage to reach 7.25V. Note: I am assuming the battery is currentlyfully charged and is newish and fault freeor you might have to wait for a longish time. When you have reached this voltage you need to check the charge rate current. Ideally you need two meters...an ammeter and the voltmeter but you can get by with the one by swapping over the leads and selector to check the charge current as you did before...OR make sure the bike's own ammeter is barely reading a charge by not moving away from its rested position....Do this test with the same engine speed.

If the charge current is over1A with the voltage at 7.25V then you do stand a chance of overcharging the battery. ...the more amps the more serious the effect) This can be tweaked down on the Control Unit but in the short term it might be best to run with your lights on (you may well do this anyway) to reduce the charge into the battery and safe-guard against overchargingit.

So yes...it does look like the ammeter is over sensitive but it doesn't mean you have to change it. The meter is more important for showing a discharge or charge so the actual amount showing is not important as long as you have checked it as you will have done.

I would say the ride should be OK Dave, in that both battery and dynamo should survive ....

Hope you have a trouble free day....ATB.....Les