Yet Another DIY Electrical Build-Out

For the entertainment and education of the internets, I will be posting some details of the design and installation of the electrical system from my T1N build out . While I have some budget constraints (cost/value is a consideration) I am attempting to do this right on the first try (I plan on having this van a long time).

Anyways, I welcome comments or suggestions both on the basic design and component selection.

Pertinent Details

• 2004 T1N Cargo – 144in wheelbase - 6ft ceiling.
  
• 90AMP alternator from the factory
  
• No Factory Heater/Booster or AUX battery

Primary Design Parameters

• Single Fuel Only (diesel)
  
• Extensive Dry Camping/Boondocking (Limiting factor being fresh water)
  
• Cold and Warm weather Camping - No rooftop A/C (20-90F)
  
• No Generator (necessitates rooftop solar)

The difficulty with designing an electrical system is that most any appliances in the modern RV use electrical power in some way. For what is essentially a prototype/one off build, this presents the need for several design iterations to achieve a balance between consumption/generation and overall system size. My system is a bit unique because I wanted to avoid needing a second fuel for cooking (Yes, I know how much money I could save with a propane tank and stove).

Anyways, here is a breakdown of the major components. I have narrowed the selection to 2 configurations.

Configuration 1: Loads

• 1800W induction cooktop
  
• Vitrifrigo C115i – DC Fridge
  
• Espar Hydronic 5 heater & Isotemp 4gal Water Heater (coolant/hydronic heated)
  
• 20-50W Fan (used with heater core & hyrdonic for cabin heat)
  
• 40-80W Laptop
  
• 50W LCD TV/Monitor
  
• 20-60W LED Lighting
  
• MaxAir Roof Vent
  
• 10-25W directional Fan

Configuration 1: Power Sources and Storage

• 640W Grape Solar 160Wx4 Monocrystline Panels (already installed on van)
  
• 200A Bosch OEM Alternator (a bit overkill, but not much additional cost over 150A version)
  
• Complete PV/Inverter/Charger/Monitor system From Outback (break out the wallet, cost is $3K )

• 440-660AH Battery Bank (6xGC2 flooded or 2x8D AGM)

Notes:


Configuration 2: Loads

• (same as option 1 with a Webasto X100 Diesel cooktop replacing the Induction unit)
  
• Note: The X100 unit can be fitted with a blower lid for cabin heating; this may allow removal of the cabin heater core, or possibly the hydronic unit if engine heat is sufficient for water.

Configuration 2: Power Generation and Storage

• 640W Grape Solar 160Wx4 Monocrystline Panels (already installed on van)
  
• 200A Bosch OEM Alternator (a bit overkill, but not much additional cost over 150A version)
  
• MorningStar TrackStar MPPT PV controller
  
• Stand-alone shore power charger ~50A
  
• 440AH Battery Bank (4xGC2 flooded or 2x8D AGM)
  
• Stand-alone Battery Monitor (Xantrex or similar)
  
• 500-1000W Pure Sine Inverter for small electronics (most devices will natively accept DC power)

The sizing of the various components (PV panels, batteries etc) is driven by a complete energy budget. A different person using the exact same appliances may have drastically different power consumption. I have attached a PDF with the a few tables showing the load and source expectations for configuration 1. The numbers show a net solar surplus on a normal day with no alternator input.

If I get home before dark tomorrow I will take a few pictures of the solar install on the van.

Many folks think they need to match the solar w-hrs per day to their daily w-hr consumption. Sounds reasonable, no?

Well, it does apply pretty well to large camping trailers that sit still for weeks at a time.

But if you drive more often than that in your class B van the equation is more like:

(Daily w-hrs used) = (daily solar w-hrs produced) + ( total available bank size/ days between alternator recharging)

In my case with zero solar and a 420 ah bank the days between alternator use work out to about four. Our daily ah load is about 50 ah with about 2/3 used by the Engel fridge. No tv but we have a microwave to go with the induction cooktop and similar devices to your description.

Many people can't do the math on how interspersed driving lowers the size requirement on solar and bank size. The output of my 150a alternator stomps all over the comparatively puny output of a rooftop of solar. Even doing a quick grocery run usually produces at least an extra day's worth of ah's.

We have no installed propane but would not consider it enjoyable camping if we had to cook everything inside the van all the time! We use a propane locker to store an easy-to-fill-or-exchange 20lb bbq tank because the BabyQ grill and high-output campstove keep the heat and mess outside when that is useful.

I'll comment that we have 4 separate switched 2.5w led pucks + one 18w ccfl kitchen light. I'd design the next van with eight of those 2.5w pucks for a total of 20w---lower than your budget and much lower if used one or two at a time.

Seems to me that you have plenty of solar and bank size to go with the more extensive configuration loads. With our outside propane kitchen to back up our electric inside kitchen we could always conserve ah's if we needed to stretch the bank a little. That is not common for our drycamping style with some mobility for boating, biking, fresh food runs.

Dan

Our daily ah load is about 50 ah with about 2/3 used by the Engel fridge.

Click to expand...

Which Engel fridge do you have?

Thanks for the feedback d_bertko. In our previous van we had alternator only charging for 25k miles and got by just fine, so I agree completely that 100% solar is not needed for most applications. Do you know how many charging amps your alternator makes at idle and at speed?

I am glad to hear that LED lights have gotten more efficient. The previous LED units I have used must have been lower efficiency, as I needed about 35W to light a van sized space. We do enjoy being outside the van for cooking, lounging, hammock time. Of course bugs and weather don't always cooperate...

A weekly budget is much more telling than a daily one for sure. We do occasionally camp for up to 9 days without driving so the extra solar is definitely nice. Our loads would normally total around 100 amp-hours with worst case being around 250 (heavy laptop use). Another consideration on bank size is that we occasionally need to park the van a in a secure space (often without sun) for 3-6 days and we need to keep the fridge cold.

A note on fridges, I have found the Danfoss compressor system to be much quieter than the swing type compressor in the Engle units. I am not knocking Engle, they make a great product. I am just a very light sleeper .

With a few modifications the current solar system could probably power a small cabin... So it is definitely over-sized for 90%+ of our usage. For size comparison in our Vanagon Westy 200w of solar and 220A-Hr bank had no issue with powering a truckfridge TF65/laptop/lights/fans 24/7 with minimal alternator charging.

ReGULT51 said:

Which Engel fridge do you have?

Click to expand...

I have the MT60F--a 64 qt model.

It averages @ 75F ambient 18w x 24hr for a daily consumption of ~432 w-hrs or 36 ah's.

That figure came from an obscure Engel web data page originally. I was intrigued and happened to have about two weeks real-world use that measured pretty close to that number.

I have to agree with Midwestdrifter that the fridge noise level is important. I find the Engel is fine as long as it is sitting square enough---ten years use tells me when something is vibrating more than usual.

Dan

Midwestdrifter said:

Thanks for the feedback d_bertko. In our previous van we had alternator only charging for 25k miles and got by just fine, so I agree completely that 100% solar is not needed for most applications. Do you know how many charging amps your alternator makes at idle and at speed?

Click to expand...

I try to minimize any low idling on my 02 158" T1N since it maybe shortens the egr life. (Always assumed idle amp output is quite low.) The solution to that is a high-idle stick but that is too obnoxious for camp use for my tastes.

I've never directly measured the road output of the alternator. Another advantage to a large bank is that it will accept a kw-hr of charge much faster than a bank half the size at the same SoC. So even short grocery runs evidently get me an extra day's worth of bank. The 150a Bosch is called upon to maintain a hefty duty cycle when we pull out of a half-week immobile drycamp---very happy with its ability to handle the 5 battery load for a decade now. Must be well-engineered.

I am glad to hear that LED lights have gotten more efficient. The previous LED units I have used must have been lower efficiency, as I needed about 35W to light a van sized space. We do enjoy being outside the van for cooking, lounging, hammock time. Of course bugs and weather don't always cooperate...

Click to expand...

Indeed, CCFLs slightly outranked most LEDs back in 04. (Hence my kitchen light) But incremental improvements mean the best LEDs are now ~20% better than anything else. (Don't buy the cheapest ones without excellent lumens per watt spec.) LEDs naturally provide good task lighting with their narrow dispersion angles--an opportunity to save watts if the job is a reading light over the bed instead of a multi-led fixture to provide general lighting.

Since I paddle the wet East Coast a lot there are typically annoying insects. The blackflies in ME and NH probably serve to suppress the human population density! That caused us to modify a FirstUp quickshelter screen set to mate with our awning. Add a van skirt and we get 140 sq ft of screened space that lets us keep the slider open and the cooking outside. (We do find the screening not needed in much of the dry West---an exception was the biting flies in Joshua National Park--a high desert camp.)

A weekly budget is much more telling than a daily one for sure. We do occasionally camp for up to 9 days without driving so the extra solar is definitely nice. Our loads would normally total around 100 amp-hours with worst case being around 250 (heavy laptop use). Another consideration on bank size is that we occasionally need to park the van a in a secure space (often without sun) for 3-6 days and we need to keep the fridge cold.

Click to expand...

The newest Intel cpu's are on the order of an order of magnitude more efficient than a few years ago. Perhaps a new laptop or tablet could be justified for all the expensive drycamp ah's it would save?

My project list has an easy-to-use fridge quilt on it. That is a much easier design if it doesn't have to be for daily use. Just take a bedroom heavy down comforter and fit it around the fridge when it will sit unused for a few days. One of the things I love about my Engel chest is that all of the contents can go back and forth to the stickhouse by transferring the wire baskets. So we rarely keep the Engel on when not in daily use. I did use its fridge-freezer capability on a weeklong wilderness paddle. I froze about six gallons of water containers on the last driving day and the Engel kept the leftover perishables cold for a week while turned off. (Our "center console" is a good size ice chest. Meant to handle temporary extra food its real use is as a flat table with four extra cupholders molded into the top. Maps, binoculars, other ready items typically are kept there.)

Enjoy the design work!

Dan

It averages @ 75F ambient 18w x 24hr for a daily consumption of ~432 w-hrs or 36 ah's

Click to expand...

I have a MT35. I've wondered what the daily draw would be with in on 24/7. I'm figuring it'll be a little less with the smaller fridge, but it does get warm in the summer so it'll run more often. Hoping to mitigate that with a Maxxair fan...

Thanks.

I have two 6v 220amp batteries hooked up to my 200amp alternator and I drive about 30 minutes of highway driving a day and the batteries stay around 12 volts. but dip below if i dont go anywhere for a day and the fridge will turn off. the only thing the batteries power is the fridge and lights. Lights are on about 2 min a week these days. Im looking at getting a 100 watt solar panel.

chrispsprint said:

I have two 6v 220amp batteries hooked up to my 200amp alternator and I drive about 30 minutes of highway driving a day and the batteries stay around 12 volts. but dip below if i dont go anywhere for a day and the fridge will turn off. the only thing the batteries power is the fridge and lights. Lights are on about 2 min a week these days. Im looking at getting a 100 watt solar panel.

Click to expand...

Repeatedly discharging your batteries that low is a sure way to give them an early death. Lead acid batteries need to get a full charge regularly for a long life (usually at ~14.4 volts until the current tapers to a few percent of the AH capacity).

With only 30 minutes of driving you are probably putting less than 50AH back into those batteries (maybe even less depending on wire sizing). A 100 watt panel may be marginal depending on how much sun it sees.


I have received about 80% of my electrical components. I will get this thread up to date this weekend sometime. Proper circuit protection just keeps getting more expensive... As a plus all the pretty bits and pieces look great on my coffee table.

Update:

I have received most of the electrical components, and completed the mounting and wiring of the solar panels.

Below are photos of the mounted solar panels. I used 1/4-20 rivet nuts and 1/8" aluminum angle stock for the frame. I used polyurethane adhesive to attach the brackets to the roof. The panels are wired in series parallel, making 18 amps or so at 36+ volts. The panels weight about 25lbs each.

I was using some masking take when caulking the wiring pass through. When I peel the tape off it took the paint and the second primer layer with it!!! Such poor paint on the roof! After seeing how weak the inter-layer adhesion was, I decided to add a few #8 sheet metal screws to the mounts for peace of mind.

The aft three panel group is mounted together and attached at the front and rear. I was getting some unwanted flexing mid-span on these three panels. I remedied this by adding two small mounts in the middle using VHB tape (Great stuff btw). If anyone wants more details let me know and I can post them up.

I have about 500 miles with the panels on the van, no issues yet.

. by luthj87, on Flickr

DSC07786 by luthj87, on Flickr
DSC07783 by luthj87, on Flickr

Below is a block diagram of my main DC layout. The attached PDF contains some of the images in this post in case my host goes down in the distant future.


Electrical Layout by luthj87, on Flickr

I am currently waiting on batteries and some electrical connectors. I then am planning on wiring everything up for a few test runs and some basic programming.

I recommend doing a layout test with all the major items and some of the wire that will be used. It can be a challenge to wire up a system if the locations and wire routing paths are not planned well. Below are shots of my layout and some of the electrical components.

DSC07817 by luthj87, on Flickr

DSC07815 by luthj87, on Flickr

DSC07814 by luthj87, on Flickr

If you have to use 2/0 gauge cable, make sure to get the super flexible stuff. Routing stiff cables of this size would be a pain.
DSC07816 by luthj87, on Flickr

Are you sure that the 2/0 is large enough? 2800watts / 12v = 233 A
Not that you will be drawing that all the time but wires need to be sized for full loads.

hein said:

Are you sure that the 2/0 is large enough? 2800watts / 12v = 233 A
Not that you will be drawing that all the time but wires need to be sized for full loads.

Click to expand...

I agree will you 100%. I am using marine wire rated at 105C, so I am going by this chart.

https://www.bluesea.com/resources/529/Allowable_Amperage_in_Conductors_-_Wire_Sizing_Chart
105C 2/0 wire is rated for 330 amps.



It's been posted a few times but this calculator is a helpful tool for those starting their electrical designs.
http://circuitwizard.bluesea.com

I have a Magnum 2812 (2800 watt) and used their recommendations. They call for 4/0 and even 2x4/0 for any run over 5 feet. I snipped the relevant charts out of their manual below. In my view 2/0 is insufficient.

Hmm, I see your point. My VFX2812 inverter will pull a maximum of 265A continuously when supplying its rated output. 2/0 would still be acceptable from the ampacity charts, and would yeild 3% or less voltage drop.

My research indicates that the primary reason for the large cable sizing requirements for these inverters is to prevent output surges from generating a large voltage drop. ( such as starting AC motors). This inverter can surge to ~400A for 5 seconds which would result in a ~5% voltage drop over 10 feet (2x5ft). That amount of drop could result in non-satisfactory inverter performance.

I do not have any such motors/loads in my conversion. My typical AC usage will be 1200-1800W. If I power all the AC devices at the same the load should never exceed 2500W.


All that being said, you are correct (as usual) 4/0 gauge would be better for this application. Since I am now looking into under chassis mounting for the batteries. I will most likely be switching to 4/0 gauge due to the longer runs needed.

Outback also recommends 4/0 for your inverter. See page 51 in the manual below.

http://www.outbackpower.com/downloads/documents/fx_vfx_series/fxseries_installmanual.pdf

Some progress has been made. I decided to move the batteries under the van to improve storage in the cabin. I wanted the batteries mounted as close to the floor as possible to reduce chances of rock strikes or similar. After some extensive measuring the only place they would fit is where the spare tire mounts.

So I ordered a Surco spare tire mount for the rear door. It installed fairly easy. I replaced the hardware it came with and used a much large backing plate on the inside of the door.



I then removed the tire frame from under the van and started fabbing a new one for the batteries.











You can see in this photo that I had to bend the right side mount slightly to get the batteries to fit. These 8D batteries are wider at the top.



I used 2"x1/8" steel angle stock. The frame attaches to the van with 8x5/16th rivnuts. The rivnuts are in the cross member/support for the floor (FWD) and the rear bumper structure (AFT). They are loaded mostly in shear and are the over sized type (larger OD).

May be worthwhile adding a few comments. My Magnum inverter has a low battery cutoff voltage of 10V. That is, if the battery voltage (at the inverter terminals) drops below 10V the inverter turns off. Also the inverter will deliver the loaded power (lets say 1000W) regardless of the DC input voltage. So at the input voltage goes down the DC current goes up. For example at 14V the current would be 71.4A, while just before cutoff at 10V the current would be 100A. Plus, as mentioned before, many loads have a short term surge that you need to deal with.

In general, if find the tables fairly useless. They are focused on safety and not letting your wire get so hot that the insulation melts or it bursts into flames.

For most of us, we need to preserve what little power we have and not waste it on heating up wire and having reduced system performance because it runs at unnecessarily low voltages.

If you look at the discharge curve for a 100AH lead acid battery you will see that the battery voltage at 50% discharge (50AH) and 100A load is about 9.2V. So you can't even get the "full" available power of the batter at a 10V lower battery voltage cutoff.

Typically I look at the worst case current an try to select a cable that drops less than .2V. If that is too expensive, too heavy or just won't fit in the available space I allow more voltage drop knowing that I'll get less usable battery power. I'll double check against the tables but low voltage drop cables are always much bigger than defined by the tables. Also, don't forget the connectors and connections, the week line in the system. It is best if there are only 2 (one at the battery and one at the inverter), anything else (like having that pesky fuse) just adds more loss. Also (again) typically I use a beefy ground connection to the chassis next to the battery. If not you need to treat the ground cables they same as the 12V cable.
Ron

Updates!

I have the batteries mounted. They have been under the van for about 1000 miles, and no issues to report. I have been working on the rest of the van so electrical has been on hold while I try to complete some of the cabinetry.







There was about 3/8" of seam sealer which was interfering with running the interconnect cables. A bit of time with a scraper cleared the way. The boxed beam above the batteries is not a constant cross section, and is not the same thickness left to right, this made fitting the 4/0 cables a bit tight. In hindsight dropping the batteries another 1/2" would have made fitting much easier and would not have impacted ground clearance or departure angle.






After some design swapping, the electrical "nexus" has been moved to the passenger side of the bench seat. The primary reason was to balance the weight, as the drivers side was getting a bit out of balance.

The bench seat itself is a final unit, the hinged cover is prototype for cable making and component placement. The final unit will be 1/2 plywood or possibly 1/8" steel plate if I can get some time on a friends burn table (CNC plasma cutter).









Once I get the rest of the core components located, I can cut my pass through holes in the floor, and run the battery connection cables. I am using 4/0 cable for the battery to nexus runs, and 2/0 for the nexus to alternator runs. I am hoping the voltage drops are acceptable with 4/0. If not I can always double up the 4/0.

Midwestdrifter said:

[*]Complete PV/Inverter/Charger/Monitor system From Outback (break out the wallet, cost is $3K )
[/LIST]

• VFX2812M Inverter Charger
  
• Flexmax 60 MPPT charge controller
  
• Mate 2 System Controller/Display
  
• FlexNet DC Monitor
  
• Hub-4 Interconnect Device

Click to expand...

Who did you source from?

LooseRocks said:

Who did you source from?

Click to expand...

I sourced the outback specific components from here.
http://www.altestore.com/store/