Isuzu npr 4wd

[gator70]

I have a six person dinette and it takes up a lot of floor space. The alternative was a side dinette.
With my dinette all three benches are full with equipment. Left side electrical and batteries, Right side grey water tank and water heater. Center bench freshwater tank. So that was a consideration.

Also sleeping for two.

 

[andy_b]

I'm modifying some rear fenders I bought. See the fender picture below? Does anyone have similar fenders over 37's and can give me the measurement of the top surface?

View attachment 909244

Are you asking for a measurement from the ground to the bottom of the horizontal fender above the tire? That is going to vary from vehicle to vehicle - what are you trying to determine?

TBH, why even bother with the top and front of the fender? The flatbed will protect the bottom of the box so you only need the trailing edge for debris protection.

 

[gator70]

Are you asking for a measurement from the ground to the bottom of the horizontal fender above the tire? That is going to vary from vehicle to vehicle - what are you trying to determine?

TBH, why even bother with the top and front of the fender? The flatbed will protect the bottom of the box so you only need the trailing edge for debris protection.

My rig does not have a flatbed.

 

[andy_b]

My rig does not have a flatbed.

Fair enough - my original point still is relevant.

 

[gator70]

Planning for trips to the Pacific northwest and many rainy days. Where solar is not a big benefit.


Perfect — this is exactly how to think about it in the PNW: manage loads, not just generation.
Since your big heat loads are propane (huge win), your electrical profile is actually pretty reasonable. Let’s estimate your real daily amp-hour usage.

---

Estimated Daily 12V Loads​

145L 12V Fridge​

Typical draw:

• 
  
• 4–6A when compressor runs
• 
  
• ~30–50Ah per day in mild weather
• 
  
• In cool PNW temps: likely 30–40Ah/day

Let’s call it:
35Ah/day

---

🛰 Starlink Mini​

Draw: ~20–40W average
At 12V:
30W÷12V≈2.5A30W ÷ 12V ≈ 2.5A30W÷12V≈2.5A
If running 8 hours/day:
2.5A×8h≈20Ah2.5A × 8h ≈ 20Ah2.5A×8h≈20Ah
If 12 hours/day:
2.5A×12h≈30Ah2.5A × 12h ≈ 30Ah2.5A×12h≈30Ah
Let’s assume moderate use:
25Ah/day

---

LED Lights​

Very efficient
Usually: 5–10Ah/day
8Ah/day

---

Laptop Charging​

Typically 60W charger but intermittent use
Say:

• 
  
• 60W × 2 hours = 120Wh

120Wh÷12V≈10Ah120Wh ÷ 12V ≈ 10Ah120Wh÷12V≈10Ah
10Ah/day

---

Water Pump​

Short bursts
Usually: 3–6Ah/day
5Ah/day

---

Misc 12V Loads​

Phone charging, monitor, fans, system idle draw
10–15Ah/day
Let’s call it:
12Ah/day

---

Total Estimated Daily Usage​

Load	Ah/day
Fridge	35
Starlink	25
Lights	8
Laptop	10
Pump	5
Misc	12
TOTAL	95Ah/day

---

🌧 Now Compare to Rainy Solar​

From earlier:
Heavy overcast:

• 
  
• 50–100Ah per day

So on dark days you’re roughly:

• 
  
• Break-even at best
• 
  
• Slight deficit on bad days

That’s actually a very manageable system.

---

With 900Ah Lithium​

Usable capacity (conservatively 85%):
900×0.85≈765Ahusable900 × 0.85 ≈ 765Ah usable900×0.85≈765Ahusable
At 95Ah/day:
765÷95≈8days765 ÷ 95 ≈ 8 days765÷95≈8days
That means:

You could survive ~7–8 days of zero solar before hitting 15% SOC.

And realistically, you’ll still get some solar even in rain.

---

Practical PNW Strategy​

With your setup:

• 
  
• You likely only need shore power every 5–10 days
• 
  
• Not every few days
• 
  
• Unless you increase Starlink hours or add inverter loads

---

The Big Picture​

Your system is actually very well balanced for the PNW:

• 
  
• 1,250W solar
• 
  
• 900Ah lithium
• 
  
• Propane for heat and cooking

That’s a strong off-grid setup.

---

 

[gator70]

When I decided on a spec for the habitat. I planned on 12v air conditioning for the USA southwest summers.

Travels north is a different plan.

 

[Peter_n_Margaret]

I planned on 12v air conditioning for the USA southwest summers.

12v A/C are typically very expensive and very poor efficiency.
My new build will include provision for a small domestic mains powered split A/C run from an inverter.

And realistically, you’ll still get some solar even in rain.

I have 1160W of solar and a 20 year old PWM controller. Modern MPPT controllers would be considerably better in poor conditions.

It is raining.
Enough harvest to run the compressor fridge plus freezer.


Rain stopped and 100% cloud cover.


Cloud breaking up
.
Cheers,
Peter
OKA196 motorhome

 

[gator70]

12v A/C are typically very expensive and very poor efficiency.
My new build will include provision for a small domestic mains powered split A/C run from an inverter.

I have 1160W of solar and a 20 year old PWM controller. Modern MPPT controllers would be considerably better in poor conditions.

It is raining.
View attachment 909362

Rain stopped and 100% cloud cover.
View attachment 909363

Cloud breaking up
.View attachment 909364
Cheers,
Peter
OKA196 motorhome

My 12v AC is the best, runs at 22 amps on eco DC

 

[Peter_n_Margaret]

My 12v AC is the best, runs at 22 amps on eco DC

What is the COP (Coefficient of Performance)?
Cheers,
Peter
OKA196 motorhome

 

[gator70]

Since my rear bumper is my own design the location it is mounted in is still not fully known. The bumper is 85x9.
Once the habitat is mounted to the truck frame, the bumper location will be known.

Must calculate departure angle

Bottom of bumper should be 35 inch's off the ground
From rear axle center to bottom edge of bumper is 57 inches
Tire is a 37

To calculate departure angle, we use this formula:

Departure Angle=arctan⁡(HeightHorizontal Distance)\textbf{Departure Angle} = \arctan\left(\frac{\text{Height}}{\text{Horizontal Distance}}\right)Departure Angle=arctan(Horizontal DistanceHeight)
Where:

• Height = bottom of bumper off the ground
• Horizontal distance = rear axle center to bumper edge

---

Your numbers:​

• Height = 35 inches
• Distance from rear axle to bumper = 57 inches
• Tire size = 37” (This confirms axle center height is ~18.5", but since you already gave bumper height from ground, we don’t need tire size for the calculation.)

---

Calculation:​

arctan⁡(3557)\arctan\left(\frac{35}{57}\right)arctan(5735)35÷57=0.61435 ÷ 57 = 0.61435÷57=0.614arctan⁡(0.614)≈31.6∘\arctan(0.614) ≈ 31.6^\circarctan(0.614)≈31.6∘

---

​

Your Departure Angle ≈ 31.6°

---

What That Means​

• 30°+ is solid for an expedition vehicle.

 

[gator70]

Below is a picture of the wood buffer between the subframe and truck frame. How does other builder do it?

View attachment 909194

With all calculations and this wood buffer the cab over bed sits 4 3/4 inches above the truck cab

Now if there was only highway driving this clearance should only be one inch.

Yet with the subframe articulation off-road the clearance should be as planned, for side to side movement.

However after some thought this could be adjustable when I arrive on dirt. Its time to think about how to do that.

And, this is the time, before the marriage of the habitat to the truck

Theses can support 1.5 tons each (Trapezoidal screws)

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[gator70]

Pass through engineering example

(hmm, pop rivets and glue?)

 

[gator70]

Since my rear bumper is my own design the location it is mounted in is still not fully known. The bumper is 85x9.
Once the habitat is mounted to the truck frame, the bumper location will be known.

Must calculate departure angle

Bottom of bumper should be 35 inch's off the ground
From rear axle center to bottom edge of bumper is 57 inches
Tire is a 37

To calculate departure angle, we use this formula:

Departure Angle=arctan⁡(HeightHorizontal Distance)\textbf{Departure Angle} = \arctan\left(\frac{\text{Height}}{\text{Horizontal Distance}}\right)Departure Angle=arctan(Horizontal DistanceHeight)
Where:

• Height = bottom of bumper off the ground
• Horizontal distance = rear axle center to bumper edge

---

Your numbers:​

• Height = 35 inches
• Distance from rear axle to bumper = 57 inches
• Tire size = 37” (This confirms axle center height is ~18.5", but since you already gave bumper height from ground, we don’t need tire size for the calculation.)

---

Calculation:​

arctan⁡(3557)\arctan\left(\frac{35}{57}\right)arctan(5735)35÷57=0.61435 ÷ 57 = 0.61435÷57=0.614arctan⁡(0.614)≈31.6∘\arctan(0.614) ≈ 31.6^\circarctan(0.614)≈31.6∘

---

​

Your Departure Angle ≈ 31.6°

---

What That Means​

• 30°+ is solid for an expedition vehicle.

Thinking and re thinking my rear bumper mount. I originally planed it to be directly behind the truck frame rails. Even with that, is sits 7 inches below the habitat. As my habitat sits on a subframe suspended above the truck frame rails.

Cabover truck designs have 58 inches from top of truck frame to the cab roof distance to manage.