Adding battery on/off switch to car?

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Old 01-12-19, 11:05 AM
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Adding battery on/off switch to car?

Hi, I want to extend the negative cable to the car battery terminal, so that I can install an on/ off battery switch inside the car where it would be conveniemt to access. Would it be ok to use an additional 1 meter of normal battery cable for this project? Thanks
 
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Old 01-12-19, 11:50 AM
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Assuming this a regular gas powered automobile......
Extending the negative line into the vehicle to be switched is not practical or safe.
When you extend high amperage wiring..... you'd need to increase the size

The only type of safe battery cutoff is the type that mounts directly on the battery.

Now..... with that being said.... why do you want to do this ?
 
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Old 01-12-19, 01:43 PM
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Ok, I'm having second thoughts about adding the extra cable. And not sure about the switch on the negative terminal ether because I think it may leave some of the terminal a bit exposed to being accidently touched by a hand, and hence cause a shock?
My objective was to eliminate power from the battery to the Álock, especially. And the reason is because if parking the car in potentially sub zero temperatures for about 4 days (continuous). a week. Thanks
 
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Old 01-12-19, 01:52 PM
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The best way to handle that situation is to get a small solar battery charger.
The basic ones plug right into the cigarette lighter as long as it's always live.

I have a mid sized one in my van that works great to keep the battery up.
This posted as an example because there are many available.
Solar car charger.
 
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Old 01-12-19, 02:05 PM
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could probably use a continuous duty solenoid as a switch to cut off battery then you could wire it to switch inside the car but not sure it would be a good idea on a modern car that has computers and learn strategies to constantly be disconnecting the battery to them.
 
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Old 01-12-19, 06:17 PM
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And the reason is because if parking the car in potentially sub zero temperatures for about 4 days (continuous). a week.

.....and? The reason is what?
 
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Old 01-13-19, 08:35 AM
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I hope the car is old enough so as not to have other settings besides the clock that the battery maintains. A clock alone is not a problem for a battery in good condition. For example, even on some older cars, the radio needs a code to restart if power is removed (theft protection), you might lucky if you still know where to find the code.
 
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Old 01-13-19, 10:33 AM
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I think it may leave some of the terminal a bit exposed to being accidently touched by a hand, and hence cause a shock?
You will not get shock from 12V or even 24V battery.

Extending negative cable by 1m will be ok as long as you use large enough wire.
I don't think there will be any safety issue here. It is negative which will be grounded to chassis therefore you won't have short to ground.
Worst case scenario will be wire shorted to chassis with disconnect switch off, and then there can be overheat where the short is if high current device is activated. (such as headlight and starter motor)

The biggest issue is that you will reset ECM every time you disconnect battery is the ECM has to learn things like air to fuel mixture, shift points all over again. If your throttle or idle air control valve is clogged, your vehicle will stall in idle until ECM learns how much throttle or IAC valve needs to be opened to keep your vehicle idle.

With GM trucks, you have to turn key to on (without starting), after about 10 seconds turn it back off, then start engine. This is because ECM has to calibrate throttle position sensor.
With Toyota, you will have very slow idle until ECM calibrate correct idle position. If you drive before this happens, vehicle will stall when stopped.

I don't know how it is with other vehicles.

Parking 4 days in sub-zero temperature shouldn't be a problem as long as your battery is fully charged and your vehicle does not have abnormal current draw.

I would not put a disconnect switch unless the vehicle will not be driven for a month or so.
 
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Old 01-13-19, 11:34 AM
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Don't they make electric heating mats powered by the battery itself that you place beneath the battery that keep it from going into the deep freeze? Of do they consume more charge than they preserve?
 
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Old 01-13-19, 12:15 PM
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So this is kind of like the myth that turning on your headlamps warms up the battery before starting.

They do make heating mats/blankets but they are not powered by the battery?

A battery in good condition will not freeze to way, way below zero so keeping the charge up is best solution!
 
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Old 01-13-19, 12:57 PM
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would also suspect the battery is bad or the vehicle has a parasitic draw from something that needs addressed.
 
 

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