Glowing Security Light with Battery Isolated

[Peter Truman]

I have a simple security flashing warning light in my Vitesse, when Ignition is off the relay is battery sourced and flash's, but when the Ignition is on a relay isolates the LED and the flashing stops. In pic top left red tell tale light.

I have a battery isolating switch on the battery (-) terminal, which when I charge the battery I have isolated, the issue is

• With ignition off and battery connected the Security light flash's - as expected
• Ignition on and battery connected as per normal op, Security light off - as expected
• Ignition off and battery isolated by (-) terminal battery isolation switch and with the Ctek charger connected direct onto the battery terminals ie negative supply to car electrics/chassis isolated, the Security light has a low constant glow, but doesn't flash! Disconnect the charger to the negatie battery terminal the light slowly goes off ie no glow.
• The Battery Isolation Switch is one of those with a green plastic knob you screw down ie isolation relies on a white plastic washer. I also push a thick 3/32in extra plastic sleeved washer direct below the screw down knob.

Any ideas from the brain trust?

Just tried replicating it battery isolated, Ctek charger on all OK initially ie no glow, but after 20 min the Security light has again begun to glow!!! How is electricity slowly bypassing the Battery Isolation switch.

There is NO BYPASS wire around the battery Isolation Switch, as on some models.

 

 

[dannyb]

On the battery isolator is there a small fuse yhat allows for auxiliaries., clock etc ?

What happens if you remove the -ve terminal from the battery.

Danny

[Peter Truman]

Danny there's no bypass, and I've done some further investigation, if I fully remove the Battery Isolator ie the (-) feed cable removed the Security LED still glows, but with the battery isolator reconnected and the (+) feed/lead removed off the battery terminal the LED goes out.

Figure that!

[dougbgt6]

You have a capacitor in there, somewhere!

Doug

[Pete Lewis]

on std points the only capacitor is in the dizzy so does it get some back feed to earth depending where the engine /dizzy cam stops ??? points open or closed ???

Pete

 

[rlubikey]

Is there a dribble of current going through the carbon black in the tyres to the ground, thence to the earth of the charger? (What do you mean - the charger's double insulated!?!?) Try disconnecting the positive battery terminal instead of negative. Or jack all four wheels off the ground (THINKS - would probably earth through jacks) or run the car on to four insulating pads - one under each wheel.

Good luck with this one Pete!!!

Cheers, Richard

[Peter Truman]

Separately Removing the positive supply wire from the battery stopped it no glow but a previous attempt at just removing the negative wire from the battery had no effect.

The only capacitor type thing I have fitted is on the distributor an earth suppressor for the radio oh Pete I have a Accuspark electronic ignition. The glow doesn’t start immediately I connect the Ctek charger it takes around 15 mins so something has to build up 
I like the carbon in the tyres idea out of curiosity might try some thin plywood under them.

[dougbgt6]

4 hours ago, Pete Lewis said:

on std points the only capacitor is in the dizzy

Sometimes there is also the radio interference suppression capacitor, no longer required if you don't use am radio, but frequently left, lurking in the engine bay.

Doug

[rlubikey]

13 minutes ago, Peter Truman said:

Separately Removing the positive supply wire from the battery stopped it no glow ...

I think you mean stopped it glowing, right? Well, I suppose the other alternative could be a trace of dirt from the negative battery terminal to the clamp, or a bare patch on the battery box floor. But my money's on the tyres and the earth of the Ctek charger.

Richard

[Peter Truman]

The battery is housed in the boot in a plastic battery box which is bolted to the boot floor but has a wooden base in it so the battery is insulated all round it.

Re tyres there Michelins courtesy of my son I’ll have a word with him and ask if Michelin have any experience of a similar problem, might get a new set of tyres from him/them.

[Pete Lewis]

tyres certianly can conduct ive said elswhere we had a whole fleet of 8x4 with front axle hub  Cassette bearing failed when a chassis modification at a body builders did some serious welding without grounding the chassis it earthed via the tyes and put a serious etched tarck at each roller bearing contact point  

very whirry  cost them a fortune 

Pete

[Peter Truman]

Update I disconnected all leads from the battery & connected the Ctek direct to the battery, obviously no glow at the alarm/security light, so I reconnected the leads and again after 10 min or so the light glowed again! Bu***r!

Consequently I thought is it a Ctek electronics issue so I disconnected it and decided to try my old cheap LEC (UK Farnsborough) transformer/rectifier charger, NO glowing light?

I have another electronic charger similar spec to the Ctek at my daughters (boat battery charging duty) so I'll pick that up tomorrow and try that & report! 

Old technology reigns supreme!

[Neil Clark]

Peter, glad you had a result.   We had a talk at the MG group near me last week on batteries, old types, new types, C Teks etc by a local battery supplier.  The guy made the point that as the batteries age and the plates get eaten by the acid or they even distort inside, a C Tek style maintenance charger eventually won't recover the battery.  He was also pretty scathing on the quality of a lot of the batteries he gets offered by importers with 3 years life being good for some of the worst.  

Made me take the cars out for long runs to top up the charge which he said is the very best way to maintain the batteries over time.  Great excuse for a day out in autumn sunshine!

[DerekS]

I have a CTEK charger connected 24/7, have had it for years now (12/13?) and the odd thing with it is at certain times in it's "cycling" if I brush against the bumpers, wearing shorts, I get a definite sharp tingle. Enough to make me jump! 

Derek.

[Clive]

1 hour ago, DerekS said:

I have a CTEK charger connected 24/7, have had it for years now (12/13?) and the odd thing with it is at certain times in it's "cycling" if I brush against the bumpers, wearing shorts, I get a definite sharp tingle. Enough to make me jump! 

Derek.

I expect the charge output is sitting at maybe 100v over earth. I checked a USB port on a double socket at home as that tingled. Yep   100v over earth. But no real current so not an issue.

[Peter Truman]

Excuse my ignorance but what is 100v over earth. I wouldn’t have thought the Ctek would would operate at those voltages.

[Clive]

earth is whatever it happens to be where you are. 

The output of the CTEK is 12V (ok, a little more) but that 12V is the difference between the two croc clips. It has no earth reference at all. 

Easy to test, when the carger is connected, use a voltmeter (a cheap digital meter will be fine) between the car battery terminals and a electrical earth. Easiest to access is a screwhead on the socket faceplate where the charger is plugged in.

If you want an analagy, think about standing on a chair.  But what is your height? You need to say "height above the floor" or "above sea level" etc.  

 

[NonMember]

The 100V above earth (approximately) comes about with "double insulated" electrical equipment that has a two-pin or two-wire mains cable. Because this equipment has no connection to earth, and nearly always has an isolating transformer in it (which, in modern stuff like the CTEK, is probably a high frequency SMPS unit), the low voltage side floats, as Clive says. But, there is still a shared PCB between the mains input and the low voltage stuff, and PCB substrate is not a completely perfect insulator. The result is that, in the absence of any reference connection, it all floats towards the mid-point between the two mains wires. That mid-point is 120VAC, since the neutral wire is earthed at some point near your incoming supply.

[Peter Truman]

I think I understand I’ll have a play tomorrow.

[rlubikey]

3 hours ago, NonMember said:

The 100V above earth (approximately) comes about with "double insulated" electrical equipment that has a two-pin or two-wire mains cable. Because this equipment has no connection to earth, and nearly always has an isolating transformer in it (which, in modern stuff like the CTEK, is probably a high frequency SMPS unit), the low voltage side floats, as Clive says. But, there is still a shared PCB between the mains input and the low voltage stuff, and PCB substrate is not a completely perfect insulator. The result is that, in the absence of any reference connection, it all floats towards the mid-point between the two mains wires. That mid-point is 120VAC, since the neutral wire is earthed at some point near your incoming supply.

That's it! Many of these double insulated power supplies - especially the type where a "brick" power supply plugs into the wall - are designed for world-wide usage and many countries (USA, Europe, etc.) don't have a dedicated live and neutral. You can turn the plug round 180 degrees. So as NM says, they can't tie the power out to neutral because you don't know which pin of the wall socket that is. A FEW of the ones moulded like a UK mains plug, they make the extra effort and use a small component (a capacitor to neutral) to stop this half-mains voltage from being - as Clive says - superimposed on the output. We had this at work a few years ago, causing problems with sensitive equipment and had to search for a properly designed UK "brick" power supply. We had to buy several and try them!

7 hours ago, DerekS said:

I have a CTEK charger connected 24/7, have had it for years now (12/13?) and the odd thing with it is at certain times in it's "cycling" if I brush against the bumpers, wearing shorts, I get a definite sharp tingle. Enough to make me jump! 

Derek.

It may be 120V ac but the current is exceedingly low. So small that some people might get a little tingle, but nothing more. You know how you get this when you put your tongue on a 9V battery. DON'T TRY THIS, but I imagine the effect might be similar. As soon as you connect the voltage output to earth - connecting up HiFi for example - the 120V will disappear. The tiny current still flows but it usually doesn't cause a problem.

13 hours ago, Peter Truman said:

Consequently I thought is it a Ctek electronics issue so I disconnected it and decided to try my old cheap LEC (UK Farnsborough) transformer/rectifier charger, NO glowing light?

I have another electronic charger similar spec to the Ctek at my daughters (boat battery charging duty) so I'll pick that up tomorrow and try that & report! 

Old technology reigns supreme!

The thing about LEDs is that they will glow with remarkably tiny amounts of current, and this is what's happening with yours Pete. The tiny current from the (unintentional) 120V of the CTek, the carbon black of the tyres, and your garage floor are enough to cause the glow. Other than that it's nothing to worry about. I don't believe the CTek is faulty.

Cheers, Richard

[Peter Truman]

Thanks for everyone’s comments and esp the explanations even Me a civil engineer could follow

I think the originating glowing LED it’s cause & explanation need publicising so I feel an article for our local club magazine is due, summarised and hopefully simplified.

will advise of the alternative smart charger use tomorrow

[Peter Truman]

Well I don't know whether to call this a Blonde Moment or not!!

I tried the Ctek on the Dolly Sprint which has a similar arrangement ie normally closed relay but instead of feeding a (Navara) LED Flasher Can it directly feeds a Dash Red Flashing LED from the NC Relay, a test with the battery earth isolated and charging no glowing LED lite it fully went out!

So the issue appeared to be the LED Flashing Can and a normally on LED dash lite which is made to flash by the Flasher Can. 

I then double checked the recommended wiring for the Navara LED Flasher Can & the 3rd terminal was shown as earthed? So I did this POP went the 5A fuse and the Can was now fully on ie damaged.

So I changed the Flasher Can for another LED version ie did the same battery on charge & negative supply isolated the alarm light still Glowed (Bug##r), Then I thought change the LED dash bulb from LED to the standard 2.2W instrument incandescent bulb, flashed OK when Ignition switched OFF & when I put the battery on charge with the negative feed isolated NO GLOW, SUCCESS!! The incandescent bulb is bright enough so it can stay like that!!!!

Problem solved QED. I have some white flashing LED's coming to put in the instrument indicator which will enable the LED Flasher Can to be removed ie the NC Relay will directly feed the Alarm Dash Instrument Flashing LED.

[Peter Truman]

Continuing the saga I re-engineered the circuit by removing the flasher can from the circuit and wired direct from the normally closed relay to a flashing LED with an in series resistor in the (+) anode

I brought a pack of 25 Flashing LED's @ $10, and a pack of 270 ohm resistors $3, wired it in and it flashed as expected and when the Ctek connected to the isolated battery no glow at the tell tale LED, Success! The 270 ohm resistor was necessary to avoid blowing the LED and value calculated by R=V/I where the Volts was (12-3.6), and current I was 30mA info taken from the LED's spec sheet.

Now I wanted to fit the assembly into a bulb Ba7s dash instrument light (normally 2.2Watt), so a DIY job was necessary I dismantled a std Ba7s Incandescent bulb shell/body, fitted the resistor in line with the LED (+) anode, insulated the (+) supply thro the bulb body with a length of plastic tube, a smaller tube fitted inside with small soldered brass washer provided the bulbs connection into the bayonet fitting, see photo's it all works but a bit of faffing about. Oh the (-) LEd lead is soldered to the bulbs brass Ba7s body.

Does anybody know if a Ba7s flashing LED is manufactured, it would be a lot easier?

Oh flasher LED works and when the battery on charge with Ctek with (-) terminal isolated via battery isolator there's NO GLOW, problem solved!