You have a loose connection somewhere if you are measuring the 12 V from a true ground to your house ground. Start at the Ground Rod outside near your meter and make sure the wire is connected securely to the rod. You may want to remove it and clean off the wire and connector with a wire brush. Then check connection at the box and you should see a "Bonding screw" that bonds Neutral to Ground.
black
"What type of capacitor use to stabilize a 12 volt car when the voltage drops and how to wire?"
Parallel.
Red is positive while Black is negative.
The ground wire in a two or three conductor #12 cable is a #14 bare ground wire.
Which wire theres 2....... 12 volt all the time and 12 volt switched?
can 6 ,12 volt battery be wire to make in to one 24 volt battery for solar use in home
black
"What type of capacitor use to stabilize a 12 volt car when the voltage drops and how to wire?"
The gauge of wire that is 12 volt is 18, 14, and 16.
wire it in series
Use 8 gauge wire.
Parallel.
Depends on the battery size. If your boat is a 12 volt system and you wire two 12 volt batteries in series you then have 24 volts. If the batteries are 6 volt batteries you will be fine. If you have a 12 volt system on your boat and want to use two batteries then wire two 12 volt batteries in parallel. You will still have 12 volts but will have double the amperage available and this will extend the running time of the batteries.
For the 1998 BMW 318ti, the radio battery constant 12-volt + wire colors are red and white. The 12-volt radio accessory wire colors are purple and white. The ground wire is brown and the antenna trigger wire is white.
Can you wire a 12 volt DC adaptor into a machine that uses 4 D batteries without ruining it?
12 volt.