< <

ELECTRICAL

The Transit conversion has a different electrical system than most RV's. Most RV's directly connect the house battery to the vehicle battery with a relay for charging. There are several reasons why this is not ideal:

  1. House battery is not charged with a 3 stage (bulk/absorb/float) charger that is programed to match the charge profile recommended by the battery manufacturer.
  2. Not advised to connect two different type /size/age/mfg. batteries together for charging.
  3. A low house battery "state of charge" can put a heavy draw on the alternator.
  4. Large quage cables required to connect the batteries from front of van to the back house battery. 12 volt requires 10 times the wire size compared to 120 volt.
  5. House 12 volt system must be grounded to chassis.

Instead of connecting the batteries together I have a second 1000 watt "vehicle" pure sine inverter powered by the Transit 12 volt system. This provides 120 volt AC power with engine running. I use the output for three purposes. "Shore power" for charging or heating shower water or powering a electric baseboard heater. The 300 watt solar panel is my primary method of charging the house battery. The "vehicle" inverter can supply "shore power" for charging as a backup in case weather conditions require its use. The water heating is done in a stainless steel non pressure tank using a 625 watt heating element. The air heating baseboard heater is a 750 watt electric heater located in the back of the van. The design always uses a quality 3 stage charger to charge the house battery with the proper charge profile by both the solar controller or the house Magnum charger.


Below is the block diagram of the Electrical System:

block diagram drawing ODJ127-08.jpg

The Electrical System design has 3 selector switches to direct the power for different uses.

  1. A selector to choose either real shore power or "shore power" from the vehicle inverter.
  2. A selector switch to select charging or water heating or air heating. Only one can be used. Selector switch prevents two being used at the same time.
  3. A selector switch to select water heating with 120 volt power from 3 different sources. Shore power or vehicle inverter "shore power" or from the house 1000 watt inverter powered by the house battery. Depending on weather conditions, sometimes I can use the house battery for water heating if I know the sun will be out and I will have excess power available from the solar panel. If weather conditions do not permit using the house battery, I can run the Transit engine for about 30 minutes to heat water or from shore power.


Below is the Electrical diagram for the conversion:

CLICK ON THE DRAWING FILE TO DOWNLOAD IT-- > ODJ127-37.pdf

To load file into your Adobe Reader program right click the drawing and "save as" a document on your computer. Then select the file and open it into/with the Adobe PDF Reader.

The Magnum MMS1012 is a pure sine 1000 watt "house" inverter/charger/transfer switch. It is a combination of a inverter/charger/transfer switch in one unit. It has both the ME-BMK battery monitor and the ME-RC50 remote. The remote is used to program the Magnum and as a display to show the "state of charge" of the house battery. It also can display amps in/out and totals etc. I could care less about what is happening. I just want to know how much of the house battery capacity I have used. The transfer switch in the Magnum allows one set of duplex plugs powered by either shore power or vehicle inverter "shore power" or 120 volt power from the Magnum inverter. The transfer switch just transfers available shore power through the unit if it is available without the inverter being on. In my case the inverter is always off unless I need 120 volt house supplied by the Magnum house inverter. Idling the Magnum consumes too much power to be left on.

The 1000 watt Magnum with my 255 amp-hr battery will power a 600 watt microwave. The Proctor-Silex (K-Mart) microwave draws 1140 watts. That puts the inverter into its surge capacity but it works.

The house 12 volt system is not grounded to the vehicle chassis. Two wires to every load. Does not require grounding because the house battery is not directly connected to the vehicle battery for charging.

The shore power connectrion is just a 3 prong male plug hung below the driver's door on a aluminum angle. Out of sight when not in use. Out of the weather when connected to an extention cord. A 15 amp shore power connection is all that is required for a small conversion. It is also more convenient for my use because I connect to houses more often than to an RV park 30 amp receptical. I do carry a 30 amp plug to 3 prong 15 amp adapter. I avoid RV parks as much as possible and prefer to dry camp with a stealth van.


HOUSE 12 VOLT SYSTEM

The house 12 volt system is located in the center of the van to limit wire lengths and where I had space available. The 8D AGM battery is located in front of the driver's side rear wheel well housing under the bench seat. The fuse, disconnect switch, shunt, positive busbar and negative busbar are located above the battery and below the seat top. The 1000 watt Magnum MMS1012 inverter/charger/transfer switch is located above the left wheel well housing. The longest # 2 AWG cable is about 17" long.

  • 100_1360_320
  • 100_1358_320
  • 100_1359_320


Below is the Electrical diagram for the HOUSE 12 VOLT SYSTEM:

CLICK ON THE DRAWING FILE TO DOWNLOAD IT-- > ODJ127-38.pdf

To load file into your Adobe Reader program right click the drawing and "save as" a document on your computer. Then select the file and open it into/with the Adobe PDF Reader.

Wanted the 8D battery inside to limit the cable lengths and eliminate the holes in the floor. Bought the 255 amp-hr 8D instead of multiple batteries to keep the wiring simpler and to make it easier to install. The 8D is oversize for my application. The oversize battery may be the reason I can power a 600 watt microwave.

The Magnum inverter/charger/transfer switch also makes the system simpler. I can power the charger either from shore power or "shore power" from my second vehicle powered inverter. The 1000 watts will also just power the 600 watt microwave. Microwave draws 1140 watts which puts inverter into the surge capacity of the Magnum. Once ran the same combination for 10 minutes in the Sprinter conversion. I like the transfer switch function. If 120 volt shore power is available, then the Magnum just passes the power through the unit to the duplex plugs without the inverter turned on. One set of daisy chained 120 volt duplex plugs are connected to the Magnum. They are either powered by shore power or from the Magnum when it is turned on. The house electrical cabinet is located at bottom of the refrigerator wall. It has the 12 position DC fuse block, the Morningstar solar controller, the battery conditioner and the shunt controller on the panel. The 12 volt house battery power is connected to a Blue Sea # 5026 twelve position fuse block. DC loads on the left side of van are powered from the 12 position fuse block. A second Blue Sea # 5025 six position fuse block is located on right side of van under the sink and powered from the 12 position fuse block. The DC loads on that side of the van are powered from the the 6 position fuse block.

The house 12 volt system is not grounded to the chassis. Two wires to every load. The system would work if it was removed from the van and set on the driveway. The reason it does not need to be grounded to the chassis is I do not directly charge from the vehicle alternator. There are three methods of charging the house battery. The primary method is the 300 watt solar panel. If that does not provide enough power, I can use the Magnum charger function. The charger can be powered by shore power or "shore power" from the vehicle powered second inverter. All charging is done with a quality 3 stage charger that is programmed to match the charge profile suggested for the 8D battery. The house battery is never directly connected to the vehicle battery. My experience with the Sprinter's 205 watt solar panel was I did not need to use the second inverter's "shore power" for charging. The "shore power" is a backup in case of extended grey days. Last year of Sprinter conversion never required the use of the backup charger.

All wiring in the van is done with "SO" cords instead of wires in a conduit. The cords are much easier to run and can make sharper turns. No wiring buried in the walls. All cords are run behind or inside the cabinets. The only wire that is buried is the cord to the Maxxair fan in the ceiling. There are three cords that run across the van in the floor to get power to the right side of van. Two for AC and one for DC. The DC powers the six position fuse block, one AC cord powers the electric heater and the second AC cord powers the duplex plugs on that side of the van.


VEHICLE POWERED INVERTER SYSTEM

This information will be posted at a later date after it is installed. The vehicle powered inverter will be a pure sine 1000 watt Samlex # SA-1000K-112 with a S-R8 remote. A set of selector switches will be used to direct the power for charging or heating shower water or for rear of van air heating.

© Dave Orton 2015   © Dave Orton 2016   © Dave Orton 2017      All Rights Reserved