DC-AC Power Distribution Panel Part 3
By DanW
Intro:
Thanks in advance for your patience ………. I told you that this was a long article! In this part I’ve summarized the project, provided a parts list, and a component functional description to assist you in understanding what each part does. Part 4 is my Construction Notes.
Once again: A note of caution: When working with anything electrical you should always pay heed and follow all safety procedures to prevent harm to yourself or others. I suggest you do not attempt to build and/or use one of these units unless you have a good working knowledge of basic electricity.
Summation:
If you’ve built your Power Panel then congrats! You’ve now got a valuable tool that will help you weather the coming storm. I must admit that there were a few moments during construction that I questioned my sanity ……… it has been a long process but I believe well worth the time, effort and cost.
At this point we’ve got a deep cycle battery (charged by the portable solar power unit or other charger) providing primary power to the Power Distribution Panel, giving us 12, 9, and 6 vdc outputs. A 10 socket power strip offers easy access to 120 vac supplied by the grid, a generator, or the on-board Inverter. Everything is protected with either a circuit breaker or fuse and is ready to power up whichever device we might want to connect. A meter monitors the Main Battery voltage and total current draw. The Tenma Power Panels are displaying their respective load current while dedicated volt meters monitor the voltage being supplied to each unit (12, 9, and 6 vdc). The auto style accessory outlets are ready if needed. Each circuit is controlled by a dedicated On/Off switch. All of this powered by a single deep cycle battery ……….. and fits in a space 24” x 22”. Although I intend to try to limit the total load on my unit to 5 amps, this Power Distribution Panel is designed to be able to safely handle much greater amperage demands if needed …………. Just change the fuse values!
While this project may appear to be very complex it’s really just a bunch of individual circuits assembled on the same mounting panels. Broken down into separate circuits, it’s fairly easy to put it all together. I hope you have found this article to be interesting and decide to build one of these for yourself. It’s a big challenge for anyone, but you can do it!
PARTS LIST:
You’ll notice that I bought the majority of the parts for this project through Amazon. I subscribe to Amazon Prime so most of these items shipped for free ……. which always helps the budget. I didn’t include any of the expense for wood or the metal panel.
Multiple Outlet DC Power Strip, MCM Part #: 72-6627 | Tenma Part #: 72-6627, 3 @ $49.99 ea.
Belkin 10-Socket Metal Surge Master 120 vac power strip 1 @ $23.49 ea.
PST-DCZ0605, 6 Volt/ 5 Amp: 12V to 6V DC/DC Regulating Converter, 1 @ $57.60 ea.
9 Volt/5 Amp: 12 Volt to 9 V DC/DC Regulating Converter, 1 @ $30.95 ea.
Power Bright PW1100-12 Power Inverter 1100 Watt 12 Volt DC to 110 Volt AC, 1 @ $80 ea.
Cooler Master Rifle Bearing 80mm Silent Cooling Fan for Computer Cases and CPU Coolers, 1 @ $4.95 ea.
DROK DC 4.5-30V 100A Digital Volt Amp Panel Meter Red/Blue Dual LED Display + Current Shunt, 1 @ $21.78
DROK 2-wire Car 0.56″ DC 3-30V 12/24V Green LED Small Digital Panel Volt Meter, 3 @ $6.90 ea.
DROK Green 0.56″ LED Digital Voltage Panel Meter, AC 75-300V, 1 @ $8.71 ea.
10 Pcs BLACK Cover 4mm Speaker Wire Cable Banana Plugs Connectors, Set of 10 pcs. @
$3.90/set
10 Pcs RED Cover 4mm Speaker Wire Cable Banana Plugs Connectors, Set of 10 pcs. @ $3.90/set
10PC New 16A 12V Round Rocker Toggle Switch Green LED SPST, 1 set of 10 @ $7.69/set
Cooler Master Rifle Bearing 80mm Silent Cooling Fan for Computer Cases and CPU Coolers, 1 @ $4.95 ea.
Accessory/Lighter Socket Panel Outlet, 12v Marine/Motorcycle, set of 4 @ $28.48
SMAKN 2pcs Black & Red Plastic Shell Dual Banana Plug Jack Binding Post, Amazon.com, $6.66
Metal Main Panel: Aluminum panel 21” x 18” x 1/8” thick, Local metal shop @ $16.15
30 Amp Circuit Breaker: Buss CBC-30HB, 30A @ 12 vdc, Type 1 Cycling, NAPA #782-3105, 1 @ $3.69
Panel Toggle Switch: Double pole, Single Throw (On/Off): 120 VAC @ 20 amp rating min. Ace Hardware, 7 @ $3.00 ea.
Panel Toggle Switch: Double pole, Triple Throw (ON/OFF/ON): 120 VAC @ 15 amp rating, Ace Hardware, 1 @ $10.00 ea.
Electrical Panel Buss Bar: GQ Homeline (Square D), metal 7 slot, screw attach, Lowes or Home Depot, 2 @ $4.71 ea.
Panel Mount Fuse Holder: 3 AG Type, Screw-Cap, Radio Shack, 7 @ $2.49 each
AGC Fuses: 1 pack of 5 ea./pk, 10 amp @ 32 v, Napa, Each pack @ $2.49
AGC Fuses: 3 packs of 5 ea./pk, 5 amp @ 32 v, NAPA, Each pack @ $2.49
Optional Items:
Cord Away Master Wire Clips, 6-Pack, Black (00204), 1 package of 6 clips @ $6.42
Charger/dp/B000CITK8S/ref=pd_sim_auto_2 Battery Tender 021-0123 Battery Tender Junior 12V Battery Charger, 1 @ $23 ea.
i4 Intellicharge Universal Smart Battery Charger (Ver. 2) For 18650 RCR123 AA 18500 14500 18350 16340 18700 with Ac and 12V DC (Car) power cords, 2 x Edison Bright AA to D type battery spacer/converters, 1 @ $21.99 ea.
Tools for enlarging holes to mount switches, etc. Neiko 3-Piece Titanium Step Drill Bits Set of three M2 Steel – 28 Sizes, SAE, @ $12.71
QuestCraft 10 steps Titanium Step Drill Bit 1/4″ to 1-3/8″ 1/8″, 1 @ $11.99
Stack-On PG-19 19-Inch Professional Multi-Purpose Plastic Tool Box, Green, 1 @ $19.91
Latches: Spring Loaded Latch/Catch, Lowes, 1 pack of 2 at $4.50
Power Distribution Panel Schematic
Component Description
30 Amp Circuit Breaker – Automatic Resettype. Protects Battery from damage due to excessive current draw.
S 1 – DP/ST Disconnects 12 vdc Deep Cycle Battery from the Power Panel. Both positive and
Negative wires are controlled by the switch.
S 2 – DP/ST Disconnects Battery Input (12 vdc) from the 12 vdc Tenma Power Panel. Both
positive and negative wires are controlled by the switch.
S 3 – DP/ST Disconnects 12 vdc Battery power From the Fan.
S 4 – DP/ST Disconnects Battery power to the 12 vdc to 9 vdc Voltage Reducer and (9 vdc)
Tenma Power Panel. Both positive and negative wires are controlled by the switch.
S 5 – DP/ST Disconnects Battery 12 vdc input to the automotive style outlets. Both positive
and negative wires are controlled by the switch.
S 6 – DP/ST Disconnects Battery power to the 12 vdc to 6 vdc Voltage Reducer and (6 vdc)
Tenma Power Panel. Both positive and negative wires are controlled by the switch.
S 7 – DP/ST Disconnects Battery 12vdc from the Inverter input. Both positive
and negative wires are controlled by the switch.
S 8 – TP/TT Selects input source of 120 vac for the 10 Socket Switched Power Strip. 120vac is
supplied to the power strip by grid power or by the 12 vdc to 120 vac Inverter. When in
the mid position switch removes all power to the Power Strip.
SP/ST These small round single pole single throw rocker switches are wired into the 12 vdc positive feed wire to each meter (the AC Voltage Meter is not switched). These switches are not necessary but will help to reduce the current load on the battery by shutting off the meters if they are not needed. It’s a rather small improvement in load reduction, but every milliamp helps.
M1 – DC Voltage & Current Meter Monitors the Battery input voltage level and the total
current load on the battery. A shunt is required and is included with the meter. As a side
note: This meter will not measure currents of less than 1 amp.
M2 – DC Volt Meter Monitors Battery voltage to the 12vdc Tenma unit.
M3 – DC Volt Meter Monitors Reducer voltage to the 9vdc Tenma unit.
M4 -DC Volt Meter Monitors Reducer voltage to the 6vdc Tenma unit.
M5 – AC Volt Meter Monitors AC voltage to the 10 Socket Power Strip.
Inverter – Has an integral on/off switch and a meter to display either current load or watts being used. Since the Inverter will not be readily accessible (in my application) the Inverter integral switch is left on. This allows switch S8 to control the On/Off status of the Inverter.
10 Socket AC Power Strip – Has an integral On/Off switch with LED power on light. An AC ground stud is provided on the strip. This strip was chosen due to wider than normal spacing of the individual sockets. If you are going to be using multiple small plug-in transformers this is a feature that is worth a few extra pennies.
Tenma DC Power Panels – Each of the three power panels are identical and has the following features:
- Section One:
- Two sets of heavy duty, individually fused binding posts, non-switched
- Current capacity is 35A on either set
- Total max combined capacity 35A
- 0~35A analog ammeter
- LED status indicator
Section Two:
- Six sets of 10A binding posts, 15A max total capacity
- 15A fuse for entire set (I installed an External access 5 amp AGC Fuse holder.)
- 0~15A analog ammeter
- Rocker switch with LED status indicator controls the six sets of binding posts
Power Bright PW1100-12 Power Inverter 1100 Watt 12 Volt DC To 110 Volt AC
The Inverter has the following features.
- 1100 watts continuous power
- 1200 watts peak power
- Anodized aluminum case provides durability
- Built-in Cooling Fan
- 3 FT Battery Cables
Electrical Brief:
I’m not trying to teach a definitive course on basic electrical theory but figured some comments about AC & DC Voltages & Grounding might be informative. Since the Power panel will have both AC and DC components it is important to understand the relationship between these two types of power. A DC voltage/current source is basically a two wire “closed” system. It is not measured relative to earth ground but the positive and the negative terminals of the DC voltage are only referenced to each other. The supply may be a battery or an electrical power supply that converts an AC voltage to a DC voltage; in either situation, once the DC voltage is produced, it will be relative only to itself and in most cases should not be connected to an AC source or earth ground. AC power (produced by electric companies or your generator) is referenced to earth ground.
The three wires of a 120 vac AC Circuit are: Hot, Neutral, and Earth Ground. For practical purposes, the voltage measured between the Hot wire and Neutral wire (or the Hot wire and Ground wire) should be the same if all wires and the Earth Ground connection are in good condition and correctly connected. A measurement of voltage between Neutral and Earth Ground should also be zero volts if everything is connected properly. Note that the normal AC Ground connection in a duplex outlet (standard home outlet) will still be good even if the grid is down. There are surely people reading this article that have way more electrical knowledge than I do, so this superficial explanation is only intended to be a quick primer on this topic. There is plenty of information on the net if you want to research or verify my comments.
To Be Continued: Part 4 will be published soon and is the Construction Notes that detail some of the design and assembly process. It’s kind of like a short cut to figuring out how to deal with (or least how I did) some of the layout and assembly issues.