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Author Topic: 12V 60A car battery , maybe dead?  (Read 236800 times)

Groundloop

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Re: 12V 60A car battery , maybe dead?
« Reply #165 on: February 05, 2015, 10:09:10 AM »
Thanks for the great advice guys. I live in South Africa so it is a challenge to buy stuff off e-bay as many suppliers don't ship here and our postal services are so bad that you are very likely to lose any items of perceived value.

As far as the circuit is concerned I reversed L1 and it does not work. I wonder if the layout of my circuit could have anything to do with the heat issues?

Mars67,

OK. Put the L1 coil back as it where.

What is the type number of your 5 Watt 500 Ohm pot-meter?

GL.

Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #166 on: February 05, 2015, 12:16:11 PM »
Hi GL

Unfortunately I do not have the info on me at work. I will post the details as soon as I get home this evening.

Mars

Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #167 on: February 05, 2015, 08:55:35 PM »
The following info appears on the pot. WX-050 500 Ohm.

I had a 5 Amp ammeter connected in serial on the positive wire of the power input into the circuit and adjusted it to 0.6 Amps as in the photos I posted. Today I got a clamp meter and measured the same wire and got over 1 Amp. I then adjusted the pot for the clamp to read 0.6 and now the regulator is much cooler and D5 is not getting hot. The side of the pot is still warm to the touch.

Groundloop

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Re: 12V 60A car battery , maybe dead?
« Reply #168 on: February 05, 2015, 10:17:47 PM »
The following info appears on the pot. WX-050 500 Ohm.

I had a 5 Amp ammeter connected in serial on the positive wire of the power input into the circuit and adjusted it to 0.6 Amps as in the photos I posted. Today I got a clamp meter and measured the same wire and got over 1 Amp. I then adjusted the pot for the clamp to read 0.6 and now the regulator is much cooler and D5 is not getting hot. The side of the pot is still warm to the touch.

Mars67,

I did check the data sheet for your pot-meter, and did find that it is a 5 Watt type, so no problem there.
So it is a mystery to me why your pot-meter gets warm. I currently have no idea on how to fix that.
Is it possible for you to take a close up photo of your PCB top and bottom and post here?
Also you should check that the capacitor is OK. If the capacitor is leaking DC current to ground,
then that could explain why there is too much current through your pot-meter. Can you put
your ampere meter in series with the pot-meter and measure the current?

GL.


Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #169 on: February 09, 2015, 01:10:44 PM »
OK so I eventually got some time to measure the currents. With the pot set to where it was when getting quite hot (with the analogue ammeter in serial with the 12v positive input into the circuit) I am measuring 1.03 Amps over the same wire with the DC clamp meter (I don't understand why there is that difference) and it measures 94mA over the pot (ie in serial with the pot). The clamp meter over the same wire measures 43mA.

When I increase the resistance in the Pot to and .60 Amps as indicated by the clamp meter over the 12V input into the circuit I get 36mA through the pot with my multi-meter connected in serial.

Here are some close-up pics of the Veroboard.


Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #170 on: February 09, 2015, 08:20:41 PM »
I forgot to mention tha I swapped out the 220nF cap with another braand new one and the heating issues remain the same.

Groundloop

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Re: 12V 60A car battery , maybe dead?
« Reply #171 on: February 09, 2015, 08:31:39 PM »
I forgot to mention tha I swapped out the 220nF cap with another braand new one and the heating issues remain the same.

Mars67,

Thank you for taking time to do the measurements. The clamp meter do measure pulsed DC and your DC ampere meter
measures just current (DC), that is the difference.

I looked at your numbers and can't see that there is any large problems there. The DC bias to the base of the
transistor seems a bit high. One last try, solder your two 100 Ohm resistors in SERIES (instead of parallel) so
that you get 200 Ohm in series with the pot-meter. Connect your test bulb to the output and give it a try.

GL.

Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #172 on: February 11, 2015, 06:18:15 AM »
Hi GL

Unfortunately I did not have time to change the circuit last night but what I did was to undo one resistor. With 100 Ohms I must open the pot fully to get 500mA current draw from the circuit. i.e. with the ammeter in serial with the 12v input into the circuit.
This is with the circuit connected to a 100Ah Deep Cycle battery I am trying to recover. It was not possible to say if D5 or the pot got hot because the 100 Ohm resistor got very hot very quickly. I will change the circuit this evening and see what happens. Thank you again for all the help and information.

Marnus

Groundloop

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Re: 12V 60A car battery , maybe dead?
« Reply #173 on: February 11, 2015, 03:49:12 PM »
Hi GL

Unfortunately I did not have time to change the circuit last night but what I did was to undo one resistor. With 100 Ohms I must open the pot fully to get 500mA current draw from the circuit. i.e. with the ammeter in serial with the 12v input into the circuit.
This is with the circuit connected to a 100Ah Deep Cycle battery I am trying to recover. It was not possible to say if D5 or the pot got hot because the 100 Ohm resistor got very hot very quickly. I will change the circuit this evening and see what happens. Thank you again for all the help and information.

Marnus

Mars67,

It looks like you have a lot of bias current and almost no pulsed current from the L1 coil.
So something is not right in your circuit. Do you have a close up photo of the 220nF capacitor
you are using? Try a larger capacitor 470nF or something like that. Also double check that
your circuit is soldered correctly.

GL.

Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #174 on: February 11, 2015, 07:45:40 PM »
Just to add. I put the two 100 Ohm resistors in serial. With the pot fully open the circuit draws 150mAmps. It does not seem as if the other components are getting hot but the two resistors went up to 120 Degrees F and stays there.

I will check the circuit closely to see if there are any issues.

The charger does seem to work as the battery could only hold a charge of 1.2 Volts but can hold a charge of 10.5 Volts after about two weeks.

Groundloop

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Re: 12V 60A car battery , maybe dead?
« Reply #175 on: February 11, 2015, 11:53:28 PM »
Just to add. I put the two 100 Ohm resistors in serial. With the pot fully open the circuit draws 150mAmps. It does not seem as if the other components are getting hot but the two resistors went up to 120 Degrees F and stays there.

I will check the circuit closely to see if there are any issues.

The charger does seem to work as the battery could only hold a charge of 1.2 Volts but can hold a charge of 10.5 Volts after about two weeks.

Mars67,

You can use resistors with higher wattage ratings. Wire wound resistors is OK to use in this circuit.
Keep charging on your sulfated battery until you get over 12 volt. Then discharge battery (with your bulbs)
down to approx. 12 Volt. Re-charge and repeat. Also check the water level in the battery and add distilled
water if low.

GL.

Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #176 on: February 12, 2015, 05:42:15 AM »
Hi GL
The Capacitor I was using before was rated 220nF 250V. the one I am currently using is an Alcon KPF-9 0.22uF/2000VDC K/CD.

Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #177 on: February 13, 2015, 07:53:04 AM »
Well I checked the circuit very critically and cannot find any glaring errors. What I decided to do was to build another circuit to see if I get a different result. This time I used TinyCAD to draw the circuit and then used a licensed version of VeeCAD to transfer the design onto veroboard and then built the circuit last night. I used the BYV29-300 Diodes that I also got and a 56 Ohm 5W resistor. the rest of the components are the same. I did not integrate the voltage regulator onto the same board and used my lab ps to power the circuit.

The great news is that the circuit worked the first time. I used two 6V 4A batteries that are quite old as a load and tested the circuit. I got the same result. D5 gets hot, R1 gets hot and the pot gets hot. I am really beginning to wonder what is going on here. I know some electronic engineers with very fancy oscilloscopes. I am going to ask them to help me do some measurements.

Any advice on what I need to measure where would be very welcome.

Here are some pics of the circuit. At least the actual circuit is much cleaner. Any comments would be appreciated.

Thank you

Groundloop

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Re: 12V 60A car battery , maybe dead?
« Reply #178 on: February 13, 2015, 03:36:51 PM »
Well I checked the circuit very critically and cannot find any glaring errors. What I decided to do was to build another circuit to see if I get a different result. This time I used TinyCAD to draw the circuit and then used a licensed version of VeeCAD to transfer the design onto veroboard and then built the circuit last night. I used the BYV29-300 Diodes that I also got and a 56 Ohm 5W resistor. the rest of the components are the same. I did not integrate the voltage regulator onto the same board and used my lab ps to power the circuit.

The great news is that the circuit worked the first time. I used two 6V 4A batteries that are quite old as a load and tested the circuit. I got the same result. D5 gets hot, R1 gets hot and the pot gets hot. I am really beginning to wonder what is going on here. I know some electronic engineers with very fancy oscilloscopes. I am going to ask them to help me do some measurements.

Any advice on what I need to measure where would be very welcome.

Here are some pics of the circuit. At least the actual circuit is much cleaner. Any comments would be appreciated.

Thank you

Mars67,

You did a very clean and nice build.

If the components gets hot, but not smoking hot, and the circuits can be run for hours
without failing, then just use the circuit. Put it into a nice plastic box and use a fan
for cooling.

GL.

Mars67

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Re: 12V 60A car battery , maybe dead?
« Reply #179 on: February 20, 2015, 06:48:23 AM »
Thanks Groundloop.
Two things have happened. The 5W pot on the original circuit was damaged (burnt?) at the position where the circuit draws 0.6 Amps. I am assuming this because trying to set it to a current draw of 0.6 it either jumps to 0.4 or 0.8. I have not yet tried a 0.47uF Capacitor but will try it on the original circuit this weekend.

The second is that I have managed to get a used analogue oscilloscope. So the learning curve has suddenly steepened somewhat for me.

It is a Pintek PS-605 60MHz dual trace oscilloscope. I am sure that it will be more than adequate for my purposes. It has a really cool function where you can test different components such as resistors, capacitors, diodes and transistors. I am busy studying the manual and have managed to take some measurements on the second circuit that I built last night. If my calculations are correct the circuit oscillates at 11.9 KHz. (the wave length is 4.2 divisions at a time/div setting of 0.2uS) It was interesting to see that the waveform on the "positive" side of L1 and one of the outputs of L3 looks very similar except that L3 is more "noisy". 

The peak to peak voltage on the positive of L1 (again assuming that my maths/understanding has not failed me) is 40V. (4 Divisions at a setting of volt/div setting of 1V and the probe at 10x gives me 40V)

The Voltage on L3 (L1 and L3 are connected the same way and L2 is reversed) Taken at the same side as L1 looks the same and the frequency appears to be exactly the same. The voltage there is also about 40V.

Does this seem correct?

Here are pics of the two waveforms I am talking about. The second one is L3.

Thanks
Marnus