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Could someone take a look at my 24V camper van electrical schematic? (Using all-in-one solar system)

rboothe

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Hello! Newbie poster here. (Please be kind but all assistance is greatly appreciated.)

Can someone please look over my wiring schematic for this 24V system for my camper van? It uses BigBattery's battery power bank and connects it to an all-in-one Growatt unit. There's a DC-DC step down converter attached for my 12V appliances.

This is my first attempt and I'm still worried if (1) it will even work and (2) if I'm missing fuses or my wiring is going to blow something up.

I have attached a PDF with links to all the products I'm looking at if you need more information.

Thank you!!
 

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Hello! Newbie poster here. (Please be kind but all assistance is greatly appreciated.)

Can someone please look over my wiring schematic for this 24V system for my camper van? It uses BigBattery's battery power bank and connects it to an all-in-one Growatt unit. There's a DC-DC step down converter attached for my 12V appliances.

This is my first attempt and I'm still worried if (1) it will even work and (2) if I'm missing fuses or my wiring is going to blow something up.

I have attached a PDF with links to all the products I'm looking at if you need more information.

Thank you!!
Seems like 6 awg from battery is thin/small for 3kW inverter.
 
The things that immediately jump out at me after a quick glance:

  • 6 AWG is likely too small for main battery wires (particularly considering that you use 4AWG elsewhere in your system). Even 4AWG may be on the small side, there is a link in my signature called 'circuit wizard' it helps you calculate wiring and fuses
  • 300A Fuse is massively oversized for 12 AWG wire and a 40A converter. The main job of a fuse is to protect the wire, it has to be smaller than the wire it protects or it can't protect it adequately
  • 12AWG is too small for a 100A DC fuse block (unless you will only ever use a small fraction of the rated current.
  • I don't see a main battery fuse or inverter fuse, does the battery have one built in? If not you should include on as close to the B+ terminal as reasonable. Class T, ANL or MRBF are good choices. Sized to protect the wire and handle the full power of the inverter (the inverter manual will reccomend a size).
 
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The things that immediately jump out at me after a quick glance:

  • 6 AWG is likely too small for main battery wires (particularly considering that you use 4AWG elsewhere in your system). Even 4AWG may be on the small side, there is a link in my signature called 'circuit wizard' it helps you calculate wiring and fuses
  • 300A Fuse is massively oversized for 12 AWG wire and a 40A converter. The main job of a fuse is to protect the wire, it has to be smaller than the wire it protects or it can't protect it adequately
  • 12AWG is too small for a 100A DC fuse block (unless you will only even use a small fraction of the rated current.
  • I don't see a main battery fuse or inverter fuse, does the battery have one built in? If not you should include on as close to the B+ terminal as reasonable. Class T, ANL or MRBF are good choices. Sized to protect the wire and handle the full power of the inverter (the inverter manual will reccomend a size).
Thanks so much! I will adjust for your first three points. To the last one: The main battery has a built in BMS with over and undercurrent protection up to 300A. The all-in-one inverter Growatt system has internal circuit breakers. Would the battery and Growatt still need fuses??
 
Thanks so much! I will adjust for your first three points. To the last one: The main battery has a built in BMS with over and undercurrent protection up to 300A. The all-in-one inverter Growatt system has internal circuit breakers. Would the battery and Growatt still need fuses??
Even then, from what I've learned, a proper fuse is a good idea, much more reliable as a safety device. Fuses if properly sized and rated will fail safe, whereas a BMS might fail shorted, at least this is what I have heard. A fuse also has the advantage of simplicity.
 
Even then, from what I've learned, a proper fuse is a good idea, much more reliable as a safety device. Fuses if properly sized and rated will fail safe, whereas a BMS might fail shorted, at least this is what I have heard. A fuse also has the advantage of simplicity.
I'm not sure why BigBattery suggests the 6AWG Anderson plug to rings cable. Would I be better off making my own super short 1AWG Anderson plug to fuse (on the B+ side), then continue 1AWG to the bus bars, and continue to the Growatt?

Also, would I have to run that 1AWG to the DC to DC fuse, then again to the Step Down? What size wiring would you suggest I use after the Step Down to the 12V Fuse Block?
 
I'm not sure why BigBattery suggests the 6AWG Anderson plug to rings cable. Would I be better off making my own super short 1AWG Anderson plug to fuse (on the B+ side), then continue 1AWG to the bus bars, and continue to the Growatt?

Also, would I have to run that 1AWG to the DC to DC fuse, then again to the Step Down? What size wiring would you suggest I use after the Step Down to the 12V Fuse Block?
Basically there are two factors to consider when sizing wire,

Ampacity: How much current the wire can safely carry. You need to consider (1) wire gauge (2) wire insulation temperature rating (3) ambient temperature

Voltage drop: how much voltage is lost due to wire resistance (and by extension how much power is lost). The factors are (1) wire gauge (2) round trip distance, (3) Voltage

Calculators like the one in my signature ("circuit wizard") will help you calculate both.

Or you can use tables like this:
Ampacity:
https://diysolarforum.com/media/condensed-and-modified-abyc-single.34/full


Voltage Drop (lower table, 24V):
https://diysolarforum.com/media/abyc-3-voltage-drop-table.5/full
 
I'm not sure why BigBattery suggests the 6AWG Anderson plug to rings cable.
Yeah, I'm not sure either, that is pretty skimpy for a main battery cable

with 105*C insulation (common for marine grade wire, higher than most household wiring), 6 AWG is good up to 120A in temps up to 85*F, your inverter could draw substantially more than that.
Would I be better off making my own super short 1AWG Anderson plug to fuse (on the B+ side), then continue 1AWG to the bus bars, and continue to the Growatt?
Probably yes, but the question is can you easily replace all the 6AWG or is some of it internal and not user replaceable?

Also, would I have to run that 1AWG to the DC to DC fuse, then again to the Step Down? What size wiring would you suggest I use after the Step Down to the 12V Fuse Block?
Off the top of my head 6 AWG, 105*C wire would probably be a good match for a 100A fuse block, but double check with a calculator as the answer partially depends on distance.
 
Have you finished out this build and updated your pdf schematic? This is the exact build I was wanting to do in my Ram Promaster 2500 that I'm just now starting on. Also, is it possible to add a second battery of the same kind?
Thanks for any help
 
Hey there! I actually have not updated it yet but I’m about to! They came out with a 12v larger MPP all-in-one that I’m adjusting my entire schematic so that it runs off a 12v system bc I heard the losses from the DC to DC step down can actually be quite a lot (20%- even if it says it’s 96% efficient). I’ll keep you posted!
 
Have you finished out this build and updated your pdf schematic? This is the exact build I was wanting to do in my Ram Promaster 2500 that I'm just now starting on. Also, is it possible to add a second battery of the same kind?
Thanks for any help

Hey there! I actually have not updated it yet but I’m about to! They came out with a 12v larger MPP all-in-one that I’m adjusting my entire schematic so that it runs off a 12v system bc I heard the losses from the DC to DC step down can actually be quite a lot (20%- even if it says it’s 96% efficient). I’ll keep you posted!
 
Hey there! I actually have not updated it yet but I’m about to! They came out with a 12v larger MPP all-in-one that I’m adjusting my entire schematic so that it runs off a 12v system bc I heard the losses from the DC to DC step down can actually be quite a lot (20%- even if it says it’s 96% efficient). I’ll keep you posted!
@seanski I decided against my original plan to use 24V and an all-in-one unit to instead go with a 12V system. My reasoning for doing so is because I do not have that many 120v AC loads, but more importantly, I'm using this in my camper van and planning on having the alternator help charge the battery bank. By doing so, it's best if I stick with the vehicle's battery voltage of 12V. Also, the losses in the step down are just too great. Best of luck to you.
 
@seanski that is funny! I was planning on going with Big Battery but they raised all their prices recently so kudos if you got in before that! Also, I'm still a bit unsure on their terminals. For the amount of amps going through the 12V if you hook up more than one in parallel it seems like you would need a much thicker cable, meaning you'd have to make your own to an Anderson connector. Is that what you're planning on doing? How many aH total are you planning on doing for your battery bank?
 
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