Clock standby current modification

[Bitsyncmaster]

The OEM clock draws approximately 6.5 ma. of current when your engine is off.

This change will reduce that standby current to 712 ua. (that is 0.712 ma.) or almost one tenth the power.

1) Cut the red wire on between the clock and clock connector.
...note: The clock is on the left side in the photo, connector right side.
2) Solder a 10 Kohm to these cut wires. Can be any wattage size resistor.
...note: If your resistor is color coded...Brown,Black,Orange,gold or silver.
3) Solder the banded end of a diode to the red wire on the clock side.
...note: Any diode will work. I used a 1N4003
4) The other side of the diode is soldered to the green clock wire.

You will need to cover this change with tape. You can use shrink tubing if you pull the pins out of the connector.

My clock would continue working, using up to a 15 Kohm resistor. I am guessing 10 Kohms will work for all the OEM clocks but if you find yours will not keep time with the power off you should try less resistance (5 Kohms). Of course that will increase your standby power a little.

I also inclued a photo of the adjustable capacitor that you can change to make your clock run a little slower or faster.

[Bitsyncmaster]

For your information. You set set your OEM clock to second by setting the minute fast and then you pull the power (fuse #17) for the same seconds you are fast. The clock holds the time longer than 60 seconds without power (it does not count).

Setting the clock to the second lets me check if it is running fast or slow. I used a radio controlled clock as my reference. After 30 hours I found my clock was fast about 12 seconds. I made a guess to turn the adjustable capacitor in the clock module clockwise. I have reset the seconds again and will see if I made if slower or faster.

Today's digital clocks reset the seconds when you change the minutes or stop the time until you exit the program mode.

[cklinejr]

Wow,
Very nice. This info is great.

How long have you had yours modded? Have you noticed a big difference in bat level when the car sits for a while?

-Charles

[Bitsyncmaster]

I just buttoned it all up yesterday after adjusting the oscillator trimmer. Now I have less than a second error after 3 or 4 days. It took about a 1/4 turn on that trimmer capacitor to bring it in.

The power saving is from 6.5 ma. down to about 0.71 ma. Now I think I have less than 4 ma. total load from all the electronics, which would calculate to 250 days to drain half the battery power. I have a 48 amp/hr. yellow top optima

It has been running in my car for a week with no problems.

[cklinejr]

Thank you for taking the Time to post this info for everyone.
I think a lot of people are going to benefit from this.

-Charles

[Ron]

+1

[john05141]

Great idea.

Another question, I have a switch on the battery, and I always close that when I park in my garage, overnight, etc. But the clock is of course always wrong because of this.

I see your idea, this saves battery power. I'm not that much into electronics, but would a simple hook up of a toy battery be sufficient to keep the clock memory for like a few months or so, and at the same time alows me to swich of the cars battery?

John

[Bitsyncmaster]

Originally Posted by john05141

Great idea.

Another question, I have a switch on the battery, and I always close that when I park in my garage, overnight, etc. But the clock is of course always wrong because of this.

I see your idea, this saves battery power. I'm not that much into electronics, but would a simple hook up of a toy battery be sufficient to keep the clock memory for like a few months or so, and at the same time alows me to swich of the cars battery?

John

You would need a 12 volt battery. But if you modify the door lock controller then you would not need to disconnect the battery at all.

You could also cut the power wire to the clock (purple wire on the car connector side) and run a diode from the hot side of your switch to the cut power wire of the clock.

[john05141]

I prefer to disconnect the main battery, because it is fairly safe.
So a 9 volt walie-talkie battery is not the solution.
Small 12 volt rechargeable batteries are available, so how many amps should that be to keep the clocks memory operable for a few months, and how should I hook that up? (without having problems when the battery is on, and all other systems are running.

John

[Bitsyncmaster]

Determin the amp/hour battery rating. Let's say it is 1.0 amp/hour.

Divide the rating by the load......1.0 / .00071 = 1408 hours or 58 days.

You would cut the power wire to the clock. Not sure of the colors on the clock side connector but the mating connector it is purple. Attach the +12 volt battery to that cut clock wire. Ground the neg of the battery. You could also rig up a charger to charge the clock battery when your running the car.

Seem like a lot of work when all you would need is a diode (you can fuse it for safety) to your hot side of your switch.