I’ve got a 2026 Lariat Hybrid and filled it up myself for the first time about 102 miles ago, with roughly 45 of those miles being electric.

A couple days ago I noticed the fuel gauge was already down to around 3/4 tank, which seemed a little odd to me. For reference, I got about 485 miles out of the first full tank from the dealership. The truck had around 10 miles on it from test drives before I bought it, and they topped it off before delivery.

The fuel gauge itself I can probably explain away, but what’s really confusing me is the MTE. Right now it’s showing 277 miles, and over my last three ~10 mile trips it’s basically stayed locked at either 276 or 277. During a drive it might briefly drop to 276, then go right back to 277 and sit there.

Am I just overthinking this, and the truck is still “learning” my driving habits and recalculating range over time? Earlier on, right after I picked it up, the MTE showed around 525 miles on a full tank, and when I was nearly empty the MTE got down to around 55, so it does seem to adjust somewhat.

Just curious if anyone else noticed similar weirdness with the fuel gauge or MTE early on with their truck.

I realized after reading the responses to my post yesterday that I needed to do quite a bit more research and that this isn't something I can just throw together. I've fine tuned my diagram to show more specifics, and taken into account much of what was suggested. Would love a final pair of eyes before I pull the trigger.

Here's the rundown:

Current Wire Size and Fuse Plan

Solar Panel → MPPT AND MPPT → Bus Bars

Wire Size: 10 AWG
Fuse Size: 20A

Reasoning

• 10 AWG is capable of safely handling this current range with good voltage drop characteristics for the short runs I'm expecting.
• A 20A fuse protects the wire and also provides a convenient disconnect point for if I ever feel the need to service something.

Calcs (that's short for calculations btw)

Solar Panel Side

• Panel isc is 9A
• NEC 125% safety factor: 9A×1.25=11.25A

MPPT Output Side

• MPPT max output current: 15A
• Applying 125% factor: 15A×1.25=18.75A

So a 20A fuse and 10 AWG wiring should be enough on both sides.

Bus Bars → Batteries AND Bus Bars → Inverter

Wire Size: 8 AWG
Fuse Size: 30A

Reasoning

• 8 AWG provides lower voltage drop and additional overhead compared to 10 AWG.
• 30A fuse protects the wiring while remaining above expected operating current.

Inverter Calc

Expected maximum DC current draw from the inverter: 500W/24V × 1.25 ≈ 26A

So the inverter should draw approximately 26A maximum under full load including safety margin.

Battery Considerations

Thermal Safety (Unsure if this matters as much as I think it does)

The LiFePO4 batteries are rated somewhere between 0.5 - 1C continuous discharge from what I could find. Couldn't find the specifics for the batteries I have so assuming 1C.

Approximate continuous discharge capability at 1C with 2 batteries in parallel:

• Total continuous capability becomes approximately 51A
• The inverter load should split roughly evenly between batteries

Expected load per battery: 26A \ 2 ≈ 13A

So each battery would only be supplying about 13A under maximum inverter load, which is comfortably below the 8AWG rating of 40A.

Capacity Considerations

Daily Power Use

I'm assuming at worst a constant load around 25W although I'd expect much much less: 25W × 24 hours = 600Wh/day

Occasional higher load of ~75W when I'm charging a 20v battery and/or have a light on: 75W × 2 hours = 150Wh

So most days: ~600Wh/day Occasional heavier day: ~750Wh/day

Solar Production

With one 255W panel (Let's assume I'll only get 200W since it's an older panel) and ~4.5 average sun hours: 200W × 4.5 = 900Wh/day theoretical

After real-world losses from heat, MPPT conversion, wiring, panel angle, clouds, etc, I'm asuming about 80% usable: ~720Wh/day usable

So one panel should usually cover my ~600Wh/day load, and come close on the heavier days which would only come every 2 weeks or so.

Future Expansion Considerations

Adding a Second 255W Solar Panel

If I add a second nearly identical 255W panel with the same 9A isc, it looks like i'd be better off putting them in series.

The current stays the same while volts double: 9A × 1.25 = 11.25A

So the existing 10 AWG wire and 20A fuse/breaker should still be acceptable.

Cold Weather Voltage Check

Panel specifications:

• VOC at STC: 37.4V
• Temperature coefficient: -0.34% per °C (Got this from a spec sheet i found)
• Lowest expected temperature: -30°C (This has maybe happened twice since I've lived here)

I used a calculator here and got 44.39V per panel in a series.

So even at approximately -30°C (Which will never happen, except for maybe wind chill), two panels in series should remain below the MPPT’s 100V max.

Expanding Battery Bank to Four Batteries

If I add two more identical batteries:

• Total capacity: 25.6V/102.4Ah
• Total energy: ~2,621Wh

At an assumed 1C continuous discharge rating: 25.6A × 4 = 102.4A

So the full battery bank could theoretically supply ~102A continuously and with the same 500W inverter i'd get ≈26A

And an expected load per battery of 6.5A (26A / 4) so my fuses/wiring should be fine if my assumptions are correct.

Things I'm still unsure about

• Do I need to add MRBF fuses to the batteries? I don't see battery fuses in many diagrams on here, but it seems to be suggested in a few other places I've looked.
• The Victron 24|500 inverter manual talks about connecting the inverter neutral output to the chassis/ground. I doubt I need to worry about changing that since this is off-grid.

Closing thoughts

This was all quite a bit to get the hang of today but I definitely understand a bit more than I did yesterday. And if in the future some random person wants to put a few lights and a charger in their off-grid shed instead of running power from their house, I hope some of this helps. I'll try to come back and edit in what I bought and how it ended up working if/when I get to that point. Thanks for everyone's help and input.

I had on hand a Canadian Solar CS6P-255P Solar Panel and two 25.6V 25.6Ah 655Wh LiFePO4 Batteries w/BMS.

I'm in the beginning phases of planning to put them to use in my shed so I can charge a 20V battery or two for my weedwhacker, as well as a couple of lights and a little wifi security camera.
I'm mostly concerned about the wire gauges and fuses/breakers, but I'm curious if this is a viable setup.