Help with fusing (and any other advice) on my camper setup.

[zacherrie]

Hi All,

Thanks to help from the people in this forum I have gotten my solar setup for my camper pretty well laid out. I have a few nagging questions on what/where fuses are necessary, what rating those fuses should be, and a few other random questions.

My planned setup, with questions is below

As mentioned above, I am curious if I need/have sized the fuses correctly at the following locations:

• fuse to camper breaker box
• fuse at inverter
• fuse at charge controller
• I didn't mention it above but I am also curious about the fuse at the solar panels (I read recently that 12V panels in series do not require fusing)

I based my 40amp fuses off the 30A capacity of the roof port, which I have configured my solar array to stay under that 30amp limit.

If anyone has any advice about wiring sizes between components, that would also be appreciated. I'll try to replicate the wire sizes that came with certain components where possible, but wouldn't mind any additional input.

One last thing, I may add one more 200W, 12 volt panel in the future, also in series. I don't think that has relevance to anything as it currently stands but want to include it just in case.

lastly, I have heard about some issues with cheap components If anyone has any opinions on that, the bus bar, fuse, and battery switch product links are below:

• Battery switch (I think this is good (Blue Sea) by brand but are the specs ok?)
  • https://www.amazon.com/dp/B00445KFZ2?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
• ANL fuse holder (I bought Blue sea, 40amp ANL fuses to replace if these go "bad" so its more of a concern with the fuse holder itself)
  • https://www.amazon.com/dp/B01LYQVTY3?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
• Bus bar (ok by specs/not too cheap?)
  • https://www.amazon.com/dp/B0D7YY6KFR?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Thanks for the help all. Excited to finally start installing after your final words of wisdom!

 

[AnarchyJet]

Fuses are matched to the wire size. BlueSea has a nice little chart Ampacity
Typically panels have 10awg wire that is good for 30 amps. If your string can't produce that then an over current situation cannot happen.
Your 2000w inverter is going to be able to pull around 175amps. Wire and fuse appropriately.
Since your SCC output is hooked to the battery, wire and fuse that circuit for its 40amp output.
What is the max continuous discharge current of the BMS in you LiTime? Wire and fuse for that.
What is the max amps your camper DC panel is going to pull. Use the proper wire and fuse to feed it.

 

[kbeefy]

Yeah, way bigger fuse for 2000w inverter.
It looks like you've got your solar input going directly to the main buss bar instead of to the solar controller.

 

[Yurtle]

I'm not an electrician, but here's my amateur opinion:

Far as I've ever heard, a "roof port" is not a device that has an amapcity rating. It's just a thing wires pass through, right? That is not something to design your system around. First step is to calculate how much power you need/want then size your system to your use.

in a low voltage system, the primary purpose of fuses and other ocp (over current protection) devices is to prevent wires and devices from catching on fire should a fault occur.
EVERY wire must be protected by an ocp device (whose size and type are determined primarily by the ampacity of the wire, with consideration for type and size of load) and should be placed at or as close as possible to the battery side of the wire.

so first you need to figure out the necessary ampacity of each leg of the system and choose wire and ocp size accordingly.

as mentioned above:
"If your string can't produce that then an over current situation cannot happen."

NOT TRUE!! of coarse your panels aren't going to send 100's of amps into the system, but your battery can! As configured in your diagram, your bus bar and everything wired to it are exposed to up to the 200A your batt fuse protects to. what would happen if any of the wires between your pos bus bar and any of your four 40A anl fuses were to short to ground? you'd have up to 200A flowing through them; that would be bad. fuses do nothing in a system that is fuctioning correctly; they're there for when you have unintended electrical contact between hot and ground (short circuit).

now say you run 2/0 copper cable from your bus bar to your inverter. 2/0 can handle 200A w/o overheating so it would be sufficently protected by the fuse at the battery.

file:///C:/Users/Computer/Desktop/Fusing%20Guidlines.pdf
"Size your fuse greater than the maximum designed for load, and less than ampacity rating of the wire."

side note: the specs on that bus bar seem highly dubious to me: "Maximum intermittent: 20A for each connection"
but 250A continuous?? doesn't seem right to me.

check this out too:

Home

WELCOME TO EXPLORIST.life We teach people how to build DIY campers. Here, we offer a wide range of resources and materials to equip you with everything you need to begin constructing your own camper.Welcome to

explorist.life

his youtube channel is gold

 

[zacherrie]

Fuses are matched to the wire size. BlueSea has a nice little chart Ampacity
Typically panels have 10awg wire that is good for 30 amps. If your string can't produce that then an over current situation cannot happen.
Your 2000w inverter is going to be able to pull around 175amps. Wire and fuse appropriately.
Since your SCC output is hooked to the battery, wire and fuse that circuit for its 40amp output.
What is the max continuous discharge current of the BMS in you LiTime? Wire and fuse for that.
What is the max amps your camper DC panel is going to pull. Use the proper wire and fuse to feed it.

Thanks for the advice.
A few follow up questions if you don’t mind:
1) So 200amp at the battery for the inverter should work then?
2) BMS is 200amp, should i change the 200amp fuse i have now at the battery then for a 250amp one? Then move the 200amp fuse to the inverter? If so is ANL fuse at the inverter fine? Or should i use a MRFB fuse?
3) so it seems like I’ll need 4 fuses then going: 250amp MRFB at battery, ANL fuse on wire going to camper DC appliances based on their specs, 40amp ANL fuse on wire from SCC to battery, 200amp fuse from inverter to battery (ANL or MRFB?)

Thanks again for the help!

 

[time2roll]

Stick with 200 MRBF at the battery. 2/0 wire from battery to bus and bus to inverter. Skip the switch and second fuse to inverter. My 12v inverter pulls about 130 amps running the full size Dometic microwave and that is about max load. I have not disconnected my inverter in close to five years. Extra fuse and switch is just more resistance and potential fail points.

Yes the smaller wires off the bus need a smaller fuse. 40A/50A is fine with #8 or #6 wire. These smaller fuses need to be close to the bus.

LiTime with four outlets is interesting. Verify full 2000w is available at any outlet. Seen some where power is split with a lower limit per pair.

 

[zacherrie]

Stick with 200 MRBF at the battery. 2/0 wire from battery to bus and bus to inverter. Skip the switch and second fuse to inverter. My 12v inverter pulls about 130 amps running the full size Dometic microwave and that is about max load. I have not disconnected my inverter in close to five years. Extra fuse and switch is just more resistance and potential fail points.

Yes the smaller wires off the bus need a smaller fuse. 40A/50A is fine with #8 or #6 wire. These smaller fuses need to be close to the bus.

LiTime with four outlets is interesting. Verify full 2000w is available at any outlet. Seen some where power is split with a lower limit per pair.

Thanks! I was planning on wiring the 120V AC wire straight to the inverter, rather than use any of the outlets. I assume that would give the full 2000W? either way I'll give that a check. Thanks for the advice

 

[zacherrie]

I'm not an electrician, but here's my amateur opinion:

Far as I've ever heard, a "roof port" is not a device that has an amapcity rating. It's just a thing wires pass through, right? That is not something to design your system around. First step is to calculate how much power you need/want then size your system to your use.

in a low voltage system, the primary purpose of fuses and other ocp (over current protection) devices is to prevent wires and devices from catching on fire should a fault occur.
EVERY wire must be protected by an ocp device (whose size and type are determined primarily by the ampacity of the wire, with consideration for type and size of load) and should be placed at or as close as possible to the battery side of the wire.

so first you need to figure out the necessary ampacity of each leg of the system and choose wire and ocp size accordingly.

as mentioned above:
"If your string can't produce that then an over current situation cannot happen."

NOT TRUE!! of coarse your panels aren't going to send 100's of amps into the system, but your battery can! As configured in your diagram, your bus bar and everything wired to it are exposed to up to the 200A your batt fuse protects to. what would happen if any of the wires between your pos bus bar and any of your four 40A anl fuses were to short to ground? you'd have up to 200A flowing through them; that would be bad. fuses do nothing in a system that is fuctioning correctly; they're there for when you have unintended electrical contact between hot and ground (short circuit).

now say you run 2/0 copper cable from your bus bar to your inverter. 2/0 can handle 200A w/o overheating so it would be sufficently protected by the fuse at the battery.

file:///C:/Users/Computer/Desktop/Fusing%20Guidlines.pdf
"Size your fuse greater than the maximum designed for load, and less than ampacity rating of the wire."

side note: the specs on that bus bar seem highly dubious to me: "Maximum intermittent: 20A for each connection"
but 250A continuous?? doesn't seem right to me.

check this out too:

Home

WELCOME TO EXPLORIST.life We teach people how to build DIY campers. Here, we offer a wide range of resources and materials to equip you with everything you need to begin constructing your own camper.Welcome to

explorist.life

his youtube channel is gold

Thanks for advice! Found I diagram on the Explorist site that basically shows what I'm trying to do, looks like a great guide to follow

 

[time2roll]

Thanks! I was planning on wiring the 120V AC wire straight to the inverter, rather than use any of the outlets. I assume that would give the full 2000W? either way I'll give that a check. Thanks for the advice

Yes if there is a hardwire provision the circuit should have full power.

 

[MisterSandals]

I assume that would give the full 2000W?

2000W / .85 inverter efficiency / 11V ? inverter cutoff = 214A

If you're going to pull 2000W, you may need to fuse and wire for 250A

 

[HarryN]

Suggest finding an alternative solar charge controller to the renogy rover. Pretty much anything is better.

Consider to do the project in 24 volt instead of 12 volt - much more viable.

 

[MisterSandals]

Suggest finding an alternative solar charge controller to the renogy rover. Pretty much anything is better.

Agreed!

Consider to do the project in 24 volt instead of 12 volt - much more viable.

I could not bring myself to go 24V in either of my RVs. I have a 2000W Magnum (standard equipment) and added a 2200W Giandel dedicated to the A/C and thats been great. Manageable with reasonable wires and fuses.

Discarding 12V equipment, especially if quality, standard equipment is MIGHTY hard to do!

I have 800W solar and 620Ah of lithium (206Ah standard, added my self built 412Ah 2P4S LiFePO4 battery).

 

[HarryN]

Agreed!

I could not bring myself to go 24V in either of my RVs. I have a 2000W Magnum (standard equipment) and added a 2200W Giandel dedicated to the A/C and thats been great. Manageable with reasonable wires and fuses.

Discarding 12V equipment, especially if quality, standard equipment is MIGHTY hard to do!

I have 800W solar and 620Ah of lithium (206Ah standard, added my self built 412Ah 2P4S LiFePO4 battery).

Agree - but it does not look like the OP has much with that list shown.

There are reasonably priced 24 - 12 volt converters for the couple of items that are historical 12 volt.