Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
ScottH, Tue Apr 18 2017, 03:34PMJust how when you connect one end of a transformers secondary coil to Earth ground, it becomes the neutral phase, and how the open end becomes the hot phase... now the hots voltage is hot "in relation" to anything Earth potential...
Will the same happen if you ground the negative battery terminal to a low impedance ground rod? Would the positive terminal now be 12v in relation to any grounded object at Earth potential?
Also, what would happen if you grounded the positive to Earth instead?
Re: Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
hen918, Tue Apr 18 2017, 04:08PM
Yes, the positive terminal would be +12 V to earth, however the impedance (resistance) of the ground (the earth) is quite high, meaning that significant current would not flow even if you shorted out the battery via the ground. This is why it isn't done often; at higher voltages the current is obviously higher, and hopefully high enough to blow small fuses or trip RCDs (GFIs to North Americans).
If you connected the positive terminal, the negative terminal would be -12 V in relation to earth.
hen918, Tue Apr 18 2017, 04:08PM
Yes, the positive terminal would be +12 V to earth, however the impedance (resistance) of the ground (the earth) is quite high, meaning that significant current would not flow even if you shorted out the battery via the ground. This is why it isn't done often; at higher voltages the current is obviously higher, and hopefully high enough to blow small fuses or trip RCDs (GFIs to North Americans).
If you connected the positive terminal, the negative terminal would be -12 V in relation to earth.
Re: Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
DerAlbi, Tue Apr 18 2017, 04:56PM
I just want to correct hen918... the conductivity of the earth is not an issue even if its bad. Earth is plentiful available, so there is a lot of bad conducting earth in parallel (its comparable to connecting 1 million 1MOhm resistors in parallel - still 1Ohm). The only problem is how you connect to earth. Power stations have huuUUUge round earth connections buried in the underground - the contact surface of that structure is what determines the actual earths resistance.
This should be testable:
You need a residential area with lightning strike protection on every house. I think if you connect the the battery to 2 lightning rods there should flow a measurable current.
Then use 2 shovels an equal distance apart as earth contact the current flow should vanish.
DerAlbi, Tue Apr 18 2017, 04:56PM
I just want to correct hen918... the conductivity of the earth is not an issue even if its bad. Earth is plentiful available, so there is a lot of bad conducting earth in parallel (its comparable to connecting 1 million 1MOhm resistors in parallel - still 1Ohm). The only problem is how you connect to earth. Power stations have huuUUUge round earth connections buried in the underground - the contact surface of that structure is what determines the actual earths resistance.
This should be testable:
You need a residential area with lightning strike protection on every house. I think if you connect the the battery to 2 lightning rods there should flow a measurable current.
Then use 2 shovels an equal distance apart as earth contact the current flow should vanish.
Re: Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
hen918, Tue Apr 18 2017, 05:25PM
More information can be found here:
hen918, Tue Apr 18 2017, 05:25PM
More information can be found here:
Re: Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
klugesmith, Tue Apr 18 2017, 05:51PM
I think there are still some rural places where electric utility power is delivered with only one wire strung between poles.
HV circuit return is through the earth.
klugesmith, Tue Apr 18 2017, 05:51PM
I think there are still some rural places where electric utility power is delivered with only one wire strung between poles.
HV circuit return is through the earth.
Re: Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
ScottH, Sat Apr 22 2017, 01:49PM
I tried it, and it worked well. I used a portable car battery for the experiment.
ScottH, Sat Apr 22 2017, 01:49PM
I tried it, and it worked well. I used a portable car battery for the experiment.
Re: Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
Sulaiman, Sat Apr 22 2017, 03:47PM
you will find that after a while the current will start to drop as the earth/rod polarizes somewhat,
and electrolytic corrosion is severe, probably at the +ve electrode mostly
a.c. of course does not suffer these effects so much.
I have had great difficulty in getting a <1 Ohm 'earth' in my garden, with multiple rods,
(at 10's MHz I found it impossible, my r.f. 'earth' always seems to equivalent to about 0.5m underground, one of the reasons that I like dipoles).
and just to add to the confusion, earth, ground, protective earth, common, 0V etc. are often used interchangeably.
Sulaiman, Sat Apr 22 2017, 03:47PM
you will find that after a while the current will start to drop as the earth/rod polarizes somewhat,
and electrolytic corrosion is severe, probably at the +ve electrode mostly
a.c. of course does not suffer these effects so much.
I have had great difficulty in getting a <1 Ohm 'earth' in my garden, with multiple rods,
(at 10's MHz I found it impossible, my r.f. 'earth' always seems to equivalent to about 0.5m underground, one of the reasons that I like dipoles).
and just to add to the confusion, earth, ground, protective earth, common, 0V etc. are often used interchangeably.
Re: Can a Car Batterys Voltage be Earth grounded, like a Transformers Voltage?
hen918, Sat Apr 22 2017, 03:49PM
Have you got some results?
The system klugesmith mentioned is called a Single Wire Earth Return by the way.
hen918, Sat Apr 22 2017, 03:49PM
Have you got some results?
The system klugesmith mentioned is called a Single Wire Earth Return by the way.
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