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2021 Dodge Promaster 2500 - 159
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Discussion Starter #1 (Edited)
Hey all, I am throwing another diagram at you.

I am hoping to solidify my electric system in the next couple of weeks, so I would appreciate your feedback.
I am highly visual, so this is very image heavy, but I hope you understand whats going on.

I have a few spots marked where I am unable to figure out how to size fuses or wires... I've watched moser, read FarOutRide, dug through the forums, looked at Explorist, and it just hasn't sunk in yet.

Anyway, please be blunt if you think there are improvements to be made or guidance to be given.

Thanks!

(edited to attach negative to starter battery from DC/DC)
71244
 

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I don't see a connection to the promaster battery negative.
 

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Discussion Starter #3
I don't see a connection to the promaster battery negative.
Good catch thanks.
I will continue to research, but would the negative be able to come from the negative busbar, and be the same gauge as the positive wire from the battery?
 

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Why not the negative input terminal on the dc/DC charger?
 

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Your fuses are a bit all over the place. The simplified two rules to decide where to place fuses:

1. Always place a fuse as close as possible to a power source (charger, alternator, battery).
2. Always place a fuse at any point where wire size is reduced

There are some exceptions to each. For example, rule (1) does not apply when the power source is current limited, such as solar panels. As long as all the wires coming from your solar panels can handle the maximum possible current, there is no need to fuse. Similarly for rule (2) if the wire can handle the maximum current that might be placed on it (determined by upstream power sources and upstream fuses) then you don't need another fuse.

To select fuse size and wire sizes, consult this chart http://assets.bluesea.com/files/resources/reference/20010.pdf. Generally you can use the Single Wire, Outside Engine Room numbers for fuses unless you are bundling wires inside a conduit or similar.
 

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Discussion Starter #7
@mikemarmar thanks for these details. I really appreciate it. I have not heard the "...when the power source is current limited.." thing before, but that makes sense. Do you know if there is any risk of backfeeding to the solar panels from the charge controller?
 

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No I don't think that is a realistic concern. The victron controller should be suitably isolated/protected internally. It is fairly common to go fuseless between solar panels and a charge controller, as long as the panel wires are large enough for your cell configuration.
 

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Discussion Starter #10
Oh, also your wire to your inverter is very undersized. A 2000w inverter should use 2/0 wire
Just to learn from this experience, is it because a 2000W inverter at 12v has a current of ~166A? so according to the Blue Sea chart, for an inverter wire ~1-2ft should be 2/0?
 

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Yes exactly. A 2awg wire might not catch fire at 166A but it will cause a lot of voltage drop, wasting a lot of power. Also, a 2000w inverter can handle much larger draws for a short period (for example when starting up something with a motor), so having a larger wire gives you some leeway there.
 

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Adding to @mikemarmar post on wire sizing + fuses:

Some "conceptual" ideas about wiring.

1) Breakers (or fuses) are there to protect the wiring. So the breaker/fuse is not about the load, it is about the wire that comes out of the breaker/fuse. That being said, of course, you need wiring (and its breaker/fuse) that can handle your intended load.

2) Wire size is about 2 things - Heat generated in the wire and Voltage Drop.

2.a) Heat: If the wire is too small, the wire will heat up, eventually smoking and catching fire. This is why you have a breaker/fuse to limit the current in the wire, so it does not get too hot and thus cannot start a fire. Look into your toaster for a demonstration.

Sizing the wire for the load based on heat (current) is all you need to stress about in most cases -- check the special cases under Voltage Drop for DC below.

Since the wire safety is about heat, it is a kind idea to not bury it in insulation - maybe run it in the metal chases of the van or inside or outside the insulation, but not buried in insulation.

2b) Voltage Drop

For AC:
Fuggit about it! In a van with short runs and the light loads that our inverters and batteries can handle, AC voltage drop is not an issue. Just use wire for AC that is big enough for your load current. Some people use romex (solid) house wire. Others recommend extension cord wire which is stranded. Pro-tip: I get a heavy-duty 100' extension cord from HFT -- it is cheaper than buying the extension cord wire as wire. Also, just use GFI outlets everywhere. They are cheap, you don't need many in a van and safety.

For DC: You need to calculate voltage drop through on any "heavy" runs. Specifically:
  • The run from the van battery to the DC-DC charger or inverter. This tends to be relatively high current and is also often quite long. Estimate your currents, estimate how many volts you can afford to lose, look up the wire size on the charts. Interestingly, if you are using a DC-DC battery charger, it is insensitive to the input voltage, so you could get away with smaller wire. This wire run is often buried under floor mats which allow it to heat up more for a given current, so some folks oversize the wire a notch or two to keep the temperature down.
  • The run from the battery to the inverter. Mine draws more than 200 amps at full tilt, which makes even 0000 "four-ought" wire slightly warm after some time. This run is often short -- at least it should be -- which helps reduce the voltage drop. Fair warning: My inverter came with some cables that were entirely inadequate for the job.
  • Medium loads like water pumps, furnaces, fridges and such you should do voltage drop calculations on them and make sure it is not an issue. You should be able to look up the voltage needed for each device,
All the little fiddly loads like LED lights, USB phone chargers, etc will not be sensitive to voltage drop.
 

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Before reading other comments:


- Solar on/off can be breaker instead of fuse, then fuse instead of breaker between charge controller and battery.
- Why do you have 2 fuses in the one solar line?
- 2 awg may be too small for the inverter. I have the same one (the newer model than the image you have) and it came with doubled up 4awg which equals 1awg, which I think is the minimum you’d want.
- DC wire size: use online calculator to find amp capacity and make sure the wire is larger than your loads and fuse. Also use another calculator for DC voltage drop and limit it based on the voltage your components work with.
- Fuse from battery to DC charger: The component should provide a fuse size in the specs or manual. Otherwise make the fuse 25% larger than the maximum current you expect, and 25% smaller than the capacity of the wire.

Disclaimer: I had to learn the same stuff a few months ago for my system. So on the one hand, I should know the basics cuz my system (almost identical to yours) has been working, but OTOH, I'm also a newb.
 

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Discussion Starter #14
Adding to @mikemarmar post on wire sizing + fuses:

Some "conceptual" ideas about wiring.

1) Breakers (or fuses) are there to protect the wiring. So the breaker/fuse is not about the load, it is about the wire that comes out of the breaker/fuse. That being said, of course, you need wiring (and its breaker/fuse) that can handle your intended load.

2) Wire size is about 2 things - Heat generated in the wire and Voltage Drop.

2.a) Heat: If the wire is too small, the wire will heat up, eventually smoking and catching fire. This is why you have a breaker/fuse to limit the current in the wire, so it does not get too hot and thus cannot start a fire. Look into your toaster for a demonstration.

Sizing the wire for the load based on heat (current) is all you need to stress about in most cases -- check the special cases under Voltage Drop for DC below.

Since the wire safety is about heat, it is a kind idea to not bury it in insulation - maybe run it in the metal chases of the van or inside or outside the insulation, but not buried in insulation.

2b) Voltage Drop

For AC:
Fuggit about it! In a van with short runs and the light loads that our inverters and batteries can handle, AC voltage drop is not an issue. Just use wire for AC that is big enough for your load current. Some people use romex (solid) house wire. Others recommend extension cord wire which is stranded. Pro-tip: I get a heavy-duty 100' extension cord from HFT -- it is cheaper than buying the extension cord wire as wire. Also, just use GFI outlets everywhere. They are cheap, you don't need many in a van and safety.

For DC: You need to calculate voltage drop through on any "heavy" runs. Specifically:
  • The run from the van battery to the DC-DC charger or inverter. This tends to be relatively high current and is also often quite long. Estimate your currents, estimate how many volts you can afford to lose, look up the wire size on the charts. Interestingly, if you are using a DC-DC battery charger, it is insensitive to the input voltage, so you could get away with smaller wire. This wire run is often buried under floor mats which allow it to heat up more for a given current, so some folks oversize the wire a notch or two to keep the temperature down.
  • The run from the battery to the inverter. Mine draws more than 200 amps at full tilt, which makes even 0000 "four-ought" wire slightly warm after some time. This run is often short -- at least it should be -- which helps reduce the voltage drop. Fair warning: My inverter came with some cables that were entirely inadequate for the job.
  • Medium loads like water pumps, furnaces, fridges and such you should do voltage drop calculations on them and make sure it is not an issue. You should be able to look up the voltage needed for each device,
All the little fiddly loads like LED lights, USB phone chargers, etc will not be sensitive to voltage drop.
thanks for all this insight, I really appreciate it.
 

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The run from the battery to the inverter. Mine draws more than 200 amps at full tilt, which makes even 0000 "four-ought" wire slightly warm after some time. This run is often short -- at least it should be -- which helps reduce the voltage drop. Fair warning: My inverter came with some cables that were entirely inadequate for the job.
Ok now I'm confused. My inverter is 2000 watts, shipped with double 4awg wires. I recall reading that they used to ship with too small wires (single 4 awg) so I assumed they doubled the wires for proper current rating. So I calculated that double 4 awg is the same area as 1awg, checked some online tables, and turned out blue sea recommends 1awg for 150A and 2/0 for 200A. Assuming this is the continuous rating, and 2000W continuous is 167A discharging at ~12V. Other charts show current rating for 1awg at 210 amps. The blue sea chart shows 4awg current rating at 100 amps, so double 4awg would be 200 amps. But double 4awg is the same size as single 1awg. Perhaps 2 wires dissipate heat better than one?

I just checked several charts, and they consistently list 1awg at far lower amps than double the 4awg rating. Looks like 2x 4awg is good for 200-260 amps depending on the chart, and 1awg is only good for 150-180.
 

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Perhaps 2 wires dissipate heat better than one?
Two wires will definitely dissipate heat better than one as long as they aren't bundled. There is much more surface area to radiate/conduct heat away with two wires. Voltage drop however is not affected by 2 small vs 1 larger wire. as the total cross section of copper remains the same.
 

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Two wires will definitely dissipate heat better than one as long as they aren't bundled. There is much more surface area to radiate/conduct heat away with two wires. Voltage drop however is not affected by 2 small vs 1 larger wire. as the total cross section of copper remains the same.
Yes but voltage drop isn't the governing factor for such a short run, the online calculators indicate less than 1% drop for 1awg 2 ft each way, and 200A. 2% for 5 ft each way.
 

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Discussion Starter #19
Updated wire diagram (Feb12)
I am closer to buying... looking for help in flushing out details.

notes:
  • we are trying to notrely on shore power other than battery top offs and charges before a weekend camping trip.
    • The noco outlet seemed nice, just in case we want to bring along a small heater or something similar.
  • not sure if the BEP on/off is a good idea pre MPPT, or if I should get a breaker.
  • i am hoping to consolidate some wiring, but I entered values that I got from the Blue Sea Circuit Wizard
  • I have been reading endlessly about isolated v. non-isolated DCDC chargers... I think I set this up in a reasonable manner.
@Baxsie: thanks for all the tips... the below hasn't fully considered voltage drop, just what I got from circuit wizard... I will double-check.
@aaronmcd: thanks for your tips as well. I will for sure eval the inverter cables...again the circuit wizard says 2awg is fine.. but is there any harm in oversizing?
@shreddagorge: appreciate the insight on the battery selector... is there a risk in the attached diagram to not having a switch for the 30a shore charger?

Thank you all, I appreciate all the eyes on this.
Ver 2:
van-things-electrical-victron build-v02.jpg

71420
 

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If you have the "MBRF terminal fuse - 200A" at the battery, and the cable does not get smaller on the way to the inverter then the Fuse-MEGA 200A is redundant.

I think you could replace "MBRF terminal fuse - 200A" and "BEP on/off" and with a single, quality, 200 amp breaker (and delete the Fuse-MEGA 200A ) so three components become one.

Keep the high-current lines (your 2/0 ) as short as possible. Since you only have one high current into and one high current out of the BUS bars, I would consider getting rid of them and just stacking the small AWG wires on the inverter or shunt lugs (there is some debate about this).

Looking good otherwise, IMHO.
 
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