computer memory battery saver

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  #1  
Old 08-13-10, 11:34 AM
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computer memory battery saver

I just made up one of these "tools" . Its a 9 v battery,a cigarette lighter male plug,and a 9 volt female battery connector.
I'm not sure how to hook this up.
Any help here?

Thanks
 
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  #2  
Old 08-13-10, 12:30 PM
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(QUOTE) I'm not sure how to hook this up.

Neither am I. To be perfectly honest with you I'm not even sure what you've invented here or what you goal is Sounds to me like a "Trickle Charger" is what you're looking for. It's meant to keep a car battery "alive" when the car sits for long periods of times without being DRIVEN. Click on the link below.


http://www.batterystation.com/Battery_Tender_Plus.jpg
 
  #3  
Old 08-13-10, 12:49 PM
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Looking at this might help you Amazon.com: 12V Automotive Settings Keeper w/9V Battery - Keep your Personal Settings when Replacing your Car Battery: Electronics

First, look at 9v battery for + post (i.e., hot); match that post connection to the one matching up to ‘female battery connector’; take that wire, and go to cigarette lighter male plug, connect wire to ‘hot side’ (see pic; tit on end of cig lighter); hook up ground wire.

If you have a continuity light, it would be easy to ID connections at cig lighter if not marked.
 
  #4  
Old 08-13-10, 12:51 PM
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There is the possibility of losing the cars CPU memory function for all operations if the vehicles battery is disconnected for any reason.
The device i asked about is available commercially,but this being a DIY forum,i chose to make one myself.

However,i am needing advice on how its connected such as connect it up first while the Car battery is still hooked up,or disconnect the battery,then hook up the device/tool.

In some circles its known as "Battery computer Memory saver"
 
  #5  
Old 08-13-10, 01:08 PM
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Don’t you think it would defeat the purpose of saving the memory codes/settings if waiting to plug in the device after disconnecting the battery? Just plug it in, and remember to remove it after battery is installed.
 
  #6  
Old 08-13-10, 01:30 PM
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Just some notes for you... Some cars need to have the ignition on for the cigarette lighter to work (others don't). And if this was the case, a 9v battery probably would not supply enough power?

Also vehicles have "diodes" in certain circuits. This is like a one-way valve. Electricity can only flow one direction. There may be some vehicles with diodes in the power line to the cigarette lighter? I don't know. If it did, that would prevent power from going "backwards" from the cigarette lighter to the rest of the vehicle.

I checked the factory wiring diagram for my 90's GM truck and it does not have a diode in this circuit, and btw, the cigarette lighter in that truck works all the time. I checked this because I wanted to use a solar battery maintainer in the cigarette lighter to keep the battery charged.

Then if any lights are on in the vehicle like under the hood light or the interior light or anything else electrical is on, then that 9v battery is not going to provide much power.

I don't know if the voltage in that battery dipped to around 3 volts if that would be enough to maintain the computer memory? (Check with multimeter with car battery disconnected and see what the voltage is.)

Best would be a 12 volt battery connected to the main battery connections to avoid the above problems. However most 12 volt batteries cost a small fortune!

And be aware that by connecting a 9v battery to a 12 volt source, you would be charging the 9v battery! Heat and fire could possibly result? (Don't leave that 9v battery unattended while connected to a 12 volt battery!)
 
  #7  
Old 08-13-10, 01:36 PM
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P.S. With the main battery disconnected and the 9v battery connected to the cigarette lighter, you should see around 9 volts (or something less) at the main battery cables with a voltmeter. That would assure you the cigarette lighter was connected with the ignition off and there was no diode in the circuit...

How to use a multimeter...
how to use a multimeter on a car - Google Search
 
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Old 08-13-10, 02:13 PM
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A 9volt battery that’s connected to a male cigarette lighter adaptor. You guy’s are dangerous. You remind me of “MacGyver” from that 80’s TV show. If you gave MacGyver some wire, chewing gum, and tin foil he’d build a bomb for you. Ok so tell me what I’m missing here? A 9 volt transistor battery to maintain a 12 volt automotive system. Then there’s the issue of amps. Not only is the voltage lessened by 3 volts, but how is that sorry 9 volts going to flow without the “Push” from amperage? Everyone wants to save money, but in the business of “Auto Mechanics and Repair”, “You Can’t Fight A War Without A GUN”. That means an investment in the proper tools is a guarantee that the job will be done right. Click on the link below.

Schumacher INC-7A-OBD - Industrial Series Memory Saver SHU-INC-7A-OBD SHUINC-7A-OBD SHU INC-7A-OBD
 
  #9  
Old 08-13-10, 05:42 PM
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What he is doing is sort of like some electronic things you get for the home which plug into the wall and also have a battery or batteries for "backup".

That is if the power goes out, it keeps its memory.

I've had phone answering machines which had this for example.

Basically the device itself takes a lot of power to "run", but very little power to just keep the memory.

And vehicles are like this as well. When off, they take a low amount of power to just keep the memory in the vehicle computers and radio.

The difference is that things for the home will not turn "on" when there is no power and if you try to turn them on, the battery will continue to protect the memory during a power outage...

...but with this 9v setup, you could open a door (activating a light) or turn something else on, then that would try to run on the 9v battery - the voltage would drop to almost nothing I would think?
 
  #10  
Old 08-13-10, 10:27 PM
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I have one of these & use it all the time.. the Diode in the wiring keeps the battery from exploding when you plug it into the 12v power source.. If your working on the car to just replace the battery or something quick,, they work O.K. & save clock & radio & mirror & seat & other computer memories.. If you have the car apart to replace the tranny,, forget it,, & if you open the door you just killed the "Memory Saver" battery & have to start over again.. Your just powering the memory of the computer... Roger
 
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Old 08-14-10, 08:18 AM
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Are you saying the diode is in the vehicle wiring?
 
  #12  
Old 08-14-10, 08:55 AM
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There can be diodes at some places in vehicle wiring. Again I checked my truck and it did not have one on the lighter circuit.

What the diodes are for is so electricity will not "back feed" into the vehicle electrical system under certain situations.

For example the hazard lights and turn signal light might be the same bulbs. When hazard lights first came out, you could turn on the hazard lights and the turn signal with the key off, then the ignition power would "blink" on/off!

So they installed a "blocking diode" in the turn signal wires so electricity would only go one direction - to the bulb, but not back from the bulb to the turn signal (if the hazard lights were flashing).

Don't worry about any diodes. They are impossible to find because they have them buried in wiring harnesses. Either your gizmo will work via the cigarette lighter or it will not.

Following is an example of diode use. A car might show on the instrument cluster *which* door is open. Then to install an alarm you want to connect all doors. But if you wire them all together, you will also be shorting all the doors together! They show how to use diodes to "isolate" the doors from the alarm...
Blocking Diodes, Isolating Door Triggers and Sensors

This explains how diodes work...
Lessons In Electric Circuits -- Volume III (Semiconductors) - Chapter 3
 
  #13  
Old 08-14-10, 09:17 PM
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Originally Posted by daswede View Post
Are you saying the diode is in the vehicle wiring?
No , the diode is in the memory saver wiring,, That way you don't charge the 9 volt battery with 12 volts,, but it can feed the memorys of your computers & radios once the 12 volt battery is disconnected .. Roger
 
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