Design Critique Please. 24v 100A Super Compact System

[williamolyolson]

Okay, this system will be built into my tiny home(toyota rv). All components except for the panels of course will be packed into a 2foot(width) by 1.5foot(depth) by 2foot(height) cube(ish). So excluding the PV to SCC run there won't be any individual cable lengths that exceed 1 or 2 feet, most will be measured in inches.
The design parameters are to be able to supply 100A of current at 24v, with momentary surges up to 200A. Individual components have been chosen to be capable of at least 2x the power I intend to use them for thus I'm designing the system to accommodate my use case not the max capabilities of each component. So, should it work as I've designed it given those parameters or am I missing something obvious? I've been staring at this diagram for far too long.



I know all these wire sizes are well below the average recommendations, but keep in mind the compact nature of this system and the extremely short runs. Going by the ampacity charts I've been able to find, I seem to be well within the boundaries of what is recommended for my usage parameters. If I've misunderstood how that works, please let me know.
All critiques welcome! Thanks in advance!

 

[MisterSandals]

Wondering why you are using an Orion DC to DC charger to power a 12V fuse panel. I think the step down converters are the Phoenix line though I have no experience with the Phoenix.

Regarding your wire gauges, it’s impossible to evaluate wag size without a length. Have you checked the voltage drop calculators?

 

[williamolyolson]

Wondering why you are using an Orion DC to DC charger to power a 12V fuse panel. I think the step down converters are the Phoenix line though I have no experience with the Phoenix.

Regarding your wire gauges, it’s impossible to evaluate wag size without a length. Have you checked the voltage drop calculators?

Here's the DC-DC converter(not charger): https://www.victronenergy.com/dc-dc-converters/orion-dc-dc-converters-12v-24v-48v-110v
Seemed like what I needed for the job. Looks like the Phoenix line are Inverters, not dc-dc converters.

I stated in my preface the dimensions of the build and that no cable runs would exceed 2 feet (4 absolute max round trip). Except for the run from PV to SCC, which is fine as it's not going to exceed 13A.

Just checked a few calculators, I intend to keep all runs around 2 feet round trip, but even @ 4 feet round trip 8awg @ 50A is somewhere around 1% drop. I don't expect to run more than 50A via any 8awg runs. And 4 feet @ 4awg @ 100A is <1%drop, only going to exceed 100A during momentary surges, and most of the time far less than 100A will be in use. So, I don't think I'm really too worried about the wire size choices so much.

If it seems like the actual voltage drop is too much, or I find something running too hot, I'll just double up the 4awg and/or swap out the 8s for 4s.

 

[HRTKD]

The 30 amp circuit breaker on the Orion DC-DC may be too low. The max output on the Orion 24/12-70 is 85 amps. 85 amps x 12 volts = 1020 watts. 1020 watts / 24 volts = 42.5 amps. 42.5 amps * 1.25 = 53 amps. It's possible that it could draw more amps than that but I think the numbers are a fairly safe maximum. I used 12.0 and 24.0 in the calculations and that's a lowball number. Your system is likely to not be that low, in which case the amps would be lower.

Why do you have a PV meter? The MPPT device should provide enough information.

The 24v fuse panel is full of fuses, but there should be a fuse or breaker on the cable between the 24v common bus bar and the 24v fuse panel. Overcurrent protection devices protect the wire, not the device.

The 200 amp breaker on the positive wire between the battery and the 24v common bus bar is redundant. Most of us use a switch in that position.

Many of us are using a shunt, not a hall effect. The shunt goes on the negative wire, not the positive wire. Are you sure the hall effect goes on the positive wire?

 

[williamolyolson]

The 30 amp circuit breaker on the Orion DC-DC may be too low. The max output on the Orion 24/12-70 is 85 amps. 85 amps x 12 volts = 1020 watts. 1020 watts / 24 volts = 42.5 amps. 42.5 amps * 1.25 = 53 amps. It's possible that it could draw more amps than that but I think the numbers are a fairly safe maximum. I used 12.0 and 24.0 in the calculations and that's a lowball number. Your system is likely to not be that low, in which case the amps would be lower.

Yeah, I don't plan to utilize it at its capacity, most components I'm purchasing 2x capacity of my expected use. I figured under-rating the breaker would keep me honest. But I've only ordered the 1 50A breaker thus far so I've still got time to make changes.

Why do you have a PV meter? The MPPT device should provide enough information.

Likely, but it was cheap and I like gizmos and redundancy.

The 24v fuse panel is full of fuses, but there should be a fuse or breaker on the cable between the 24v common bus bar and the 24v fuse panel. Overcurrent protection devices protect the wire, not the device.

You are certainly correct, but I wasn't sure if I wanted to bother on that one because I don't expect to be using much current on the 24v panel... So I'll take another look and see what I expect to actually use and if it warrants a breaker or just a cheap inline fuse/switch combo.

The 200 amp breaker on the positive wire between the battery and the 24v common bus bar is redundant. Most of us use a switch in that position.

Yeah, I went back and forth on that one several times. Might use a switch instead, haven't ordered the breaker yet anyhow.

Many of us are using a shunt, not a hall effect. The shunt goes on the negative wire, not the positive wire. Are you sure the hall effect goes on the positive wire?

HE docs mostly say to measure on high side, though I imagine they would work on either(just flip it around). I originally ordered shunt meters, but I only got 100A shunts since I was originally planning on half this capacity so those will only work for measuring charge current(I might implement one for that). But to keep things simple I ordered some cheapo HE meters to play with. If they turn out to be crap I'll upgrade to a good shunt meter.