Electrical Power Box

[LawAbidingCitizen]

Electrical Power Box (emergency or outdoor use, camping/wilderness, even for barbq’s)

As part of my preps I have built power boxes using 12 volt deep cycle batteries. I was asked by a member on another thread how I put these together so I have put together a guide and posted it here for anyone interested. This particular one uses a flight case for it’s construction but it can be made with any suitable electrical enclosure. I have made this particular model ‘modular’ based so that the parts can be easily replaced or upgraded if needed.

PARTS USED

One 12 volt deep cycle battery (mine is rated 42AH but can use larger or smaller rating, which of course will determine the time it lasts before needing to be recharged).
One flight case (large enough to contain the deep cycle battery and Control Unit).
One solar regulator (mine has a maximum 10 amp rating but higher ratings are available).
Three rocker switches.
One Voltage Monitor.
Red and Black electrical cable.
Four male and female power connectors.
Two cigarette lighter receptacles.
An electrical enclosure box of a suitable size to contain the various parts (this is used to construct the control unit).
Velcro tape.

ASSEMBLY

The control unit forms the basis of the control functions of the unit. Three switches are used and relevant size holes need to be cut into the top side of the box in order to fit them. The Voltage Monitor is also inserted into the top side of the box in the same way.

The solar regulator is fitted inside the electrical enclosure (control unit) and secured in an appropriate manner, either by screws and/or Velcro tape. The regulator forms the heart of the input and output of the system - its function is threefold, 1) to regulate the voltage coming in to charge the battery so that it does not exceed around about 14-14.5 volts, otherwise the battery will charge too quickly and the electrolyte can start to bubble and overheat. 2) to sense when the battery is fully charged and to cut off any further charge when it is, in order to stop it overcharging. 3) to stop any current leaking back into the device that is charging it. If for example you connected a solar panel to a fully charged battery directly the potential would most likely be higher at the battery end, therefore current would flow the other way from the battery to the panel and risk damaging it.

Four holes are drilled into the side of the control unit and suitable female electrical connectors are fitted into these. I used the large type audio jack female connectors for the connectors on the control unit itself and for the interconnects inside the flight case I used the large male type audio jack female connectors. These are ok when dealing with current of only several amps but if the unit is to be used for very heavy duty purposes then higher rated interconnects should be used. Two appropriate size holes are drilled into one side of the flight case and the two car cigarette lighter receptacles are fitted into these.

The unit is then wired as such: One set of cables is wired from the battery to a male jack cable and then plugs into a female connector on the Control Unit. Inside the Control Unit, this is then wired to the ‘Battery Out Terminal’ of the solar regulator - the live side is wired (soldered) through one of the rocker switches and becomes the ‘Charge On’ switch on the Control Unit. A set of cables is then wired from the ‘Solar Panel In Terminal’ of the solar regulator to one of the female connectors on the inside of the control unit, and this in turn connects on the outside of the Control Unit to a set of cables soldered to one of the car cigarette lighter receptacles on the inside of the flight case (again connected to the Control Unit by a male jack plug). Another set of cables is wired from the battery to a male jack cable and then plugs into a female connector on the control unit. Inside the Control Unit, this is then wired to another of the female connectors on the inside of the Control Unit - the live side is wired (soldered) through one of the rocker switches and becomes the ‘Power On’ switch on the Control Unit, and this in turn connects on the outside of the Control Unit to a set of cables connecting (soldered) to one of the car cigarette receptacles on the inside of the flight case (again connected to the control unit by a male jack plug). The Voltage Monitor is connected to any of the battery terminals on the inside of the Control Unit and the live side is wired (soldered) through the last of the rocker switches to make the Voltage Monitor turn on and off.

Is was going to Velcro down the battery to the bottom of the flight case but after putting it in I realised it was so heavy that I didn’t really need to as the weight ensures it doesn’t move. The control unit is then velcro’d to the top of the battery. The voltage in and voltage out of the car cigarette lighter receptacles on the flight case and the switches on the Control Unit are then marked accordingly using a suitable labeller such as a Dymo

FURTHER NOTES

The unit can be charged though the car cigarette lighter receptacle connector by using a solar panel, or by using a male to male cigarette lighter lead from a vehicle’s cigarette lighter socket (effectively charging from the vehicle’s car alternator when the engine is on).

Although deep cycle batteries can be allowed to completely discharge before being recharged, ideally they should be re-charged when they get down to about 40% capacity. In all cases they should be recharged if they are completely drained as the chemicals can erode the battery cells if left in that state. The Power box can be used and charged at the same time.

The unit is very versatile and can power 12 volt devices directly through the common car cigarette lighter type connector or 240 volt devices through the use of a 12 volt to 240 volt inverter.

The only downside is the unit is very very heavy, however moving the unit is made easier by the heavy duty handle on the flight case.

Most of the parts I purchased from Amazon, Ebay, and Maplins

Finally I would say that this is of course a guide and if you are unfamiliar with electrical engineering concepts it would be advisable to obtain further study or advise in the area as I cannot be held responsible for any mishaps or accidents.

LAC