Newbie fuse question

[Mikey126]

Hi
I am new to solar and DIY builds, I live in Australia so plenty of sun, I am very interested in building the 400watt system on will's video, or something bigger if possible, not an expert on amps and watts, would like some advice on breakers between, dc fuse box and the inverter also between the inverter and the mppt controller, I have purchased this invert and controller below.

Enerdrive ePOWER 2000W Pure Sine Wave Inverter | Caravan & RV | Power Inverters & Adaptors

Shop Enerdrive ePOWER 2000W pure sine wave inverter from My Generator. We provide a comprehensive range of high quality power inverters, battery chargers and generators to suit every budget!

www.mygenerator.com.au

and

Victron SmartSolar MPPT 100/50 Charge Controller

Victron SmartSolar MPPT 100/50 Charge Controller - Victron - Victron SmartSolar MPPT 100 VOC / 50A Charge Controller, 5 Year Warranty

www.mygenerator.com.au

so my question is what amp circuit breaker would I need between these two devices, also would 4 gauge wire be ok to use with this setup and 6 gauge from the controller?

Thanks in advance, for any advice
Mike

 

[HighTechLab]

The wire gauge question depends on how far apart the equipment is from the batteries. For the inverter it sounds undersized but 6 gauge is probably plenty for the solar controller. As far as the fuse block, that's a big unknown.

As far as fuse sizes, I would figure it this way:

2000 watts at 12 volts is 166 amps. Give yourself 10% headroom for surges, you now have 183 amps. Closest fuse to that size is 200 amps. I do not recommend a breaker because most that you will find online are cheap and don't actually trip at their rated current, instead much lower.

For the MPPT controller, it's rated at 50 amps, and will limit its output current to 50 amps. Technically by NEC requirements you can use a 50 amp fuse, but I prefer a little bit of headroom to prevent nuisance blown fuses/tripped breaker and would go with 60 amps, if available, but no bigger.

For your fuse box, whatever the fuse box is rated for is what I would fuse it at. E.g. 50 amp fuse block gets a 50 amp fuse.

I'm assuming you are connecting the inverter to the fuse, and then the fuse directly to the battery, that is.

That inverter looks super expensive for its specs.....

 

[Mikey126]

Thank you for that, I intend to have the battery as close as possible to the rest of the devices, what sort of gauge do you think I should be looking at? I intend to mount the devices on a board or box, like in the video that Will has done, in this sort of configuration, so I can use 4 and 6 gauge in between all devices but the two from the fuse and the inverter to the battery need to be higher than 4 gauge?

So if I use a 60amp fuse or breaker from the mppt and the inverter and a 200amp fuse or breaker, that will do it, also do you recommend any fuses or breaker to use as you said some are a bit dodge? And yes your right about the price, everything in Australia is expensive lol

Thanks again Mike

 

[mikefitz]

The high current fuses or breakers need to be at the battery end of the cables feeding the solar controller, the inverter and the camper loads fuse box. They prevent the cables from exceeding the current rating under fault conditions. Using fuses rather than breakers is recommended, even high quality breakers have a hard time at 200 A.
It seems you intend to have a 12v system using lithium batteries, so the fault currents could be very high.
The inverter needs AWG 1 or 0 depending on cable length and expected load on the inverter fused at 200A.
The solar regulator and fuse box need AWG 8 or 6 , fused at 50A or 60A.
The video did not show too clearly that a suitable fuse was needed on the battery positive cable and in error showed power feeding both the camper fuse box and inverter via the same 170A breaker. The fuse box is not rated for that current.
Rather than terminate all the positives and negatives at the inverter terminals, it would be neater and safer to use buss bars.
This is what I would do,
connect the battery negative to a negative buss bar, connect the battery positive via a Class T or MRBF fuse, rated 250 A , on or very near the battery positive, to a positive bus bar. Use AWG 0 cable.
The solar regulator, inverter and fuse box positive and negative cables are connected to the respective buss bars. In the positive cables, the inverter via a 200 A fuse, solar regulator via a 50 or 60 amp fuse, the fuse box via a 50 A fuse, the fuses and holders connected as near the bus bar as practical. The fuses could be MEGA fuses.
Cable size for positive and negative, inverter, AWG 1 or AWG 0 for long length, Victron MPPT, and fuse box AWG 8 or 6.

Note when connecting up for the first time ensure the Victron controller is powered up before connecting the solar panels to the unit, this is needed so it 'learns' the system voltage.

Buss bars




I dont know the regulations too well for Australia but for safety there should be protective circuits on the 230v output of the inverter. I note there is a version of the inverter with an RCD and transfer switch.

Is the application for a little home/shed or a mobile , RV application?

Regards (from another) Mike

 

[Mikey126]

Thank you for your detailed message, really helpful. The system I want to build down the line is to convert a van, however at the momment, I was going to install it in the shed to build and improve and understand, the only componants I have are the above charge controler and inverter, fuse box, still trying to get my head around wires and fuses, etc. dosn't help the termonalogy of wireing in Australia is different from American standard, Gauge.

What sort of max amps do you recon i need for a positive and negetive bus bar?

Very gratefull for your advice.

Thank you again Mike

 

[mikefitz]

OK if you use metric are for wires I will change, its easier for me to work in mm squared. Wire sizes in metric and maximum current are,
6mm2 50A, 10mm2 70A, 16mm2 110A, 25mm2 170A, 35mm2 240A, 50mm2 345A.
With DC low voltage systems volt drop along the positive and negative connections are important and the cable will selected to reduce drops to an practical level rather than the max current. For example the 2000 watt inverter will take around 180 amps on full load, using this calculator,

Cable Size Calculator - Cable sizing and selection | 12 Volt Planet

Cable Size Calculator - Read our guide to selecting cable of the correct type and size for your automotive, marine or leisure wiring application. Auto and Marine Electrical Components from 12 Volt Planet

www.12voltplanet.co.uk

and assuming 1meter cable lengths and 35mm2 cable, the drop is 0.2 volts. In practice there will be additional drops at the terminations. Thus 35mm is suitable for the short cable run and is within the current rating. A volt drop of around 3% is generally accepted as a practical maximum.

So the cables in your proposed design, diagram below, the 35mm2 cable is rated at 240 A so any fusing should be lower. Standard values are 200A 225A and 250A.
Under accidental short circuit conditions the battery can deliver very high currents and the fuse has to function at these levels. If you are using lead acid batteries then the main battery terminal fuse could be MRBF type or even a Mega or ANL fuse. The MRBF may be suitable for lithium with maximum interrupt current of 10k amps at 12v although ClassT with a rating of 20k amps are recommended.

The bus bar should be rated at 200A, its not too difficult to make your own using copper or aluminum bar and SS bolts and nuts. There are also fuse distribution blocks available that simplify the connections. If you want to isolate sections of your circuit suitably rated battery isolation switches are useful.

You could use DC circuit breakers for both protection and ease of isolation, but always a master fuse at the battery positive. The problen is that the quality of many of the low cost breakers is poor with uncertain trip points and high volt drops, even the quality breakers have problems at high current.

Diagram,


Fuse distribution blocks to replace positive buss bar, Victron Mega


Mega and Midi fuse block, Midi fuses for the solar controller and fuse box, Mega for the inverter


As always with a systen ensure there can be no risk of an accidental short from any of the positive terminations to negative connections or in a van conversion the body/chassis, which is usually connected to the negative.
Its good engineering practice to limit a maximum of two large connecting cable lugs on a mounting stud.
The buss bars are useful when building the circuit as its easier to follow the wiring to the units, and you can connect one at a time and test.


Mike

 

[Mikey126]

OK if you use metric are for wires I will change, its easier for me to work in mm squared. Wire sizes in metric and maximum current are,
6mm2 50A, 10mm2 70A, 16mm2 110A, 25mm2 170A, 35mm2 240A, 50mm2 345A.
With DC low voltage systems volt drop along the positive and negative connections are important and the cable will selected to reduce drops to an practical level rather than the max current. For example the 2000 watt inverter will take around 180 amps on full load, using this calculator,

Cable Size Calculator - Cable sizing and selection | 12 Volt Planet

Cable Size Calculator - Read our guide to selecting cable of the correct type and size for your automotive, marine or leisure wiring application. Auto and Marine Electrical Components from 12 Volt Planet

www.12voltplanet.co.uk

and assuming 1meter cable lengths and 35mm2 cable, the drop is 0.2 volts. In practice there will be additional drops at the terminations. Thus 35mm is suitable for the short cable run and is within the current rating. A volt drop of around 3% is generally accepted as a practical maximum.

So the cables in your proposed design, diagram below, the 35mm2 cable is rated at 240 A so any fusing should be lower. Standard values are 200A 225A and 250A.
Under accidental short circuit conditions the battery can deliver very high currents and the fuse has to function at these levels. If you are using lead acid batteries then the main battery terminal fuse could be MRBF type or even a Mega or ANL fuse. The MRBF may be suitable for lithium with maximum interrupt current of 10k amps at 12v although ClassT with a rating of 20k amps are recommended.

The bus bar should be rated at 200A, its not too difficult to make your own using copper or aluminum bar and SS bolts and nuts. There are also fuse distribution blocks available that simplify the connections. If you want to isolate sections of your circuit suitably rated battery isolation switches are useful.

You could use DC circuit breakers for both protection and ease of isolation, but always a master fuse at the battery positive. The problen is that the quality of many of the low cost breakers is poor with uncertain trip points and high volt drops, even the quality breakers have problems at high current.

Diagram,
View attachment 29459

Fuse distribution blocks to replace positive buss bar, Victron Mega

View attachment 29461
Mega and Midi fuse block, Midi fuses for the solar controller and fuse box, Mega for the inverter
View attachment 29462

As always with a systen ensure there can be no risk of an accidental short from any of the positive terminations to negative connections or in a van conversion the body/chassis, which is usually connected to the negative.
Its good engineering practice to limit a maximum of two large connecting cable lugs on a mounting stud.
The buss bars are useful when building the circuit as its easier to follow the wiring to the units, and you can connect one at a time and test.


Mike

Thank you again for your time and detailed feedback, really appreciated! I'm just waiting for components and other gear to get delivered, I will update, when they arrive, I ordered the mega fuses, 60amp 200amp and 250, got a bonus! The inverter i ordered above, they said is a long term out of stock, so they are sending the one with the rcd, built in, so that was a win, just hard in Australia to get this gear, its crazy when you think how much sun we get, anyway I will update you when I see what comes in the post, thank you again for your help?also found a source for wire, there is a chain of electrical retailers over here called jaycar, think I can get the wire from them.

Jaycar.com.au

 

[Mikey126]

Starting to get my gear together, the 2000w inverter they sent was the one with the rcd and ac transfer switch, so that was nice, for the same over priced one I ordered, it came with a 250amp fuse, 4.8a usb charger and 16a iec c19 output socket for wiring to ac distribution circuits(male iec c20 plug supplied) I take it the rcd is for the front socket.

In the manual it recommends 250adc fuse and 70mm wire to the dc source, recommended cable lenghth 1.5m

Enerdrive ePOWER 2000W 12V Pure Sine Wave Inverter with RCD & AC Transfer Switch

www.mygenerator.com.au

The mppt controller victron smartsolar controller,

Victron SmartSolar MPPT 100/50 Charge Controller

Victron SmartSolar MPPT 100/50 Charge Controller - Victron - Victron SmartSolar MPPT 100 VOC / 50A Charge Controller, 5 Year Warranty

www.mygenerator.com.au

Fuse box from Amazon

I guess I'm wanting to have a battery and panels that would best match the performance of this hardware, also still not sure about wiring, so any advice would be great.??

 

[Zil]

You need one of these fuse holders for Class-T https://www.bluesea.com/products/5502/Class_T_Fuse_Block_with_Insulating_Cover_-_225_to_400A

 

[Mikey126]

OK if you use metric are for wires I will change, its easier for me to work in mm squared. Wire sizes in metric and maximum current are,
6mm2 50A, 10mm2 70A, 16mm2 110A, 25mm2 170A, 35mm2 240A, 50mm2 345A.
With DC low voltage systems volt drop along the positive and negative connections are important and the cable will selected to reduce drops to an practical level rather than the max current. For example the 2000 watt inverter will take around 180 amps on full load, using this calculator,

Cable Size Calculator - Cable sizing and selection | 12 Volt Planet

Cable Size Calculator - Read our guide to selecting cable of the correct type and size for your automotive, marine or leisure wiring application. Auto and Marine Electrical Components from 12 Volt Planet

www.12voltplanet.co.uk

and assuming 1meter cable lengths and 35mm2 cable, the drop is 0.2 volts. In practice there will be additional drops at the terminations. Thus 35mm is suitable for the short cable run and is within the current rating. A volt drop of around 3% is generally accepted as a practical maximum.

So the cables in your proposed design, diagram below, the 35mm2 cable is rated at 240 A so any fusing should be lower. Standard values are 200A 225A and 250A.
Under accidental short circuit conditions the battery can deliver very high currents and the fuse has to function at these levels. If you are using lead acid batteries then the main battery terminal fuse could be MRBF type or even a Mega or ANL fuse. The MRBF may be suitable for lithium with maximum interrupt current of 10k amps at 12v although ClassT with a rating of 20k amps are recommended.

The bus bar should be rated at 200A, its not too difficult to make your own using copper or aluminum bar and SS bolts and nuts. There are also fuse distribution blocks available that simplify the connections. If you want to isolate sections of your circuit suitably rated battery isolation switches are useful.

You could use DC circuit breakers for both protection and ease of isolation, but always a master fuse at the battery positive. The problen is that the quality of many of the low cost breakers is poor with uncertain trip points and high volt drops, even the quality breakers have problems at high current.

Diagram,
View attachment 29459

Fuse distribution blocks to replace positive buss bar, Victron Mega

View attachment 29461
Mega and Midi fuse block, Midi fuses for the solar controller and fuse box, Mega for the inverter
View attachment 29462

As always with a systen ensure there can be no risk of an accidental short from any of the positive terminations to negative connections or in a van conversion the body/chassis, which is usually connected to the negative.
Its good engineering practice to limit a maximum of two large connecting cable lugs on a mounting stud.
The buss bars are useful when building the circuit as its easier to follow the wiring to the units, and you can connect one at a time and test.


Mike

Hi
Just to clarify, in your diagram I only need 35mm2 cable and 10mm2 cable between the devices on the board, I have got 2m of 6 awg (16mm2) wire would that be ok as that's what it said in the Victron charge controller manual for the connections, as in your earlier post you stated larger grade wire to use, is that because you did not know my controller or inverter stats? I'm really thankful for your help, also what fuses would you put in the holders in the diagrams you sent, as you said earlier the breakers are not great, so I have got 3x mega fuse holders and mega fuses 60amp 200amp and 250amp.

Regards Mike