diy solar

diy solar

Crude at this point, but my design needs scrutiny please

Solar panels, the link has examples.
Duh, for some reason I was thinking power distribution panel....(slapping forehead)

The specs I have say the panels are rated a 5.56a at optimum operating current and says there is a temp range of -40 to176f. Does say max series fuse rating is 15A. I don't know if that helps answer your question.
I'd write/call them and ask then. If they're speccing a 300A fuse that means they expect there can be 300A on it, in which case the wire gauge might be off.
I wrote the dealer who is Battle Born as Victron doesn't want direct contact it seems. I also sent the diagram to see if they will comment.
Not sure... possibly those ratings are the maximum ratings rather than the continuous ones?
Worse of all, could be some kind of peak rating that it could produce for a nano second.

Still need to know what kind of wire to use under the TT floor between power center and battery center...

Thanks..
 
Duh, for some reason I was thinking power distribution panel....(slapping forehead)
I do both of those all the time.

Still need to know what kind of wire to use under the TT floor between power center and battery center...
I know nada about trailer wiring. Hopefully someone's about for that. What's it most subject to? temperature, abrasion, vibration, water, chemicals, squirrels??

Oh, here's a thought.... any wires down there with writing on them that tell you the wire classification for that application?
 
I do both of those all the time.


I know nada about trailer wiring. Hopefully someone's about for that. What's it most subject to? temperature, abrasion, vibration, water, chemicals, squirrels??

Oh, here's a thought.... any wires down there with writing on them that tell you the wire classification for that application?
Most of the TT's wiring is in the ceiling and walls as it easier during the build. I don't remember seeing any wires under the trailer once you got past the hitch wiring. Since I will have 10ga going in both directions and I will have another 8ga wire to run in there, plus the UTP cable, perhaps a conduit big enough for everything. I know it is probably breaking 10 codes to run all this stuff together, but the alternative of every wire running separate seems excessive.
 
OK....heard back from the Battle Born tech regarding the 300A fuse. I framed the question regarding the suggested 1/0 cable although in my case I am intending to use 2/0.

"The current carrying capacity of 1/0 wire will depend on the quality of the wire itself. If you opt to use some high strand pure copper wire, like welding wire, you may have the ability to carry upwards of 285 amps continuous. If you are using a 3,000 watt, 12 volt inverter then you can only pull a maximum continuous current of 250 amps. The 300 amp quick blow fuse should work fine as we want to account for a small spike or surge over the max current that can transmit through the system."

Think his answer was a bit off focus, as he says 12 volt when I was asking about 24 volt.

Will write him back as his answer for 24V should change. Their manual suggests 400A fuse for the 12v version of the inverter.

I had him look at my wiring diagram and he noticed a goof. It showed the negative from the SCC going to the battery side of the shunt.
 
OK, heard back from Battle Born regarding 24V vs. there initial response regarding 12V.

"The manual is correct in the 300 amp fuse spec. We would take 3000 and divide it by 24 volts for the maximum continuous current the unit can carry. This gets us to 125 amps. Based on wire gauge and a spike/surge rating of at least 50% it gets us to 187.5 amps. Typically we would round up to the next largest fuse available. In this case a 200 amp fuse is suitable, but we also size fuses based on wire size. For a 1/0 AWG wire it has the capability to carry a higher continuous current so in theory using the 300 amp fuse will protect both the inverter and wire for danger.

For the 12 volt we use the same principle and divide the 3000 by 12 volts which gives a higher continuous current. We will typically suggest 2/0 wire resulting in the need for a larger 400 amp fuse."
 
Hi guys....if anyone has been following what I am up to, I have 8 more cells and a BMS coming in. This will make another battery to add to the one I have now. in the current configuration, the negative from the BMS goes to the 500A shunt that goes to the BMV712 and then on to the inverter. Can the negative from the second BMS connect to the same shunt such that the shunt is reading the combined output?
I assume the second battery can connect to the same busses and all is well? It is just whether I need the second shunt or not?

Thanks so much, you guys have been great!
 
My two battteries will be connected to a busbar and then the shunt. THe shunt will monitor total system output. I can get individual battery output from the BMSs.

I avoid putting two lugs on one end of a shunt.
 
Can I suggest some improvements? :)

- Use Class T fuses or better NT or NH fuses. ANL fuse is not enough for LFP.
- Disconnect both + and - (like with a fuseholder for NT or NH)
- If you want a switch or breaker then NOARK
- fuse every parallel battery bank separately
 
My two battteries will be connected to a busbar and then the shunt. THe shunt will monitor total system output. I can get individual battery output from the BMSs.

I avoid putting two lugs on one end of a shunt.
Thanks Chris, I changed my diagram to do it that way.
 
Can I suggest some improvements? :)

- Use Class T fuses or better NT or NH fuses. ANL fuse is not enough for LFP.
- Disconnect both + and - (like with a fuseholder for NT or NH)
- If you want a switch or breaker then NOARK
- fuse every parallel battery bank separately
I love suggestions.

Every diagram I have seen, including several straight from Victron, they all have ANL fuses on the batteries. In the attached example, they are using a MEGA fuse on the inverter. I haven't seen a diagram with a class T fuse but I have heard them mentioned before. I found a nice comparison chart at Blue Sea and they too suggest class T for inverters. Since I am adding the second battery, I can use the ANL I bought to one of the batteries, buy another 300A ANL for the other battery, and buy a 300A class T for the inverter. How does that sound?
victron dual lithium.jpg
 
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I love suggestions.

Every diagram I have seen, including several straight from Victron, they all have ANL fuses on the batteries. In the attached example, they are using a MEGA fuse on the inverter. I haven't seen a diagram with a class T fuse but I have heard them mentioned before. I found a nice comparison chart at Blue Sea and they too suggest class T for inverters. Since I am adding the second battery, I can use the ANL I bought to one of the batteries, buy another 300A ANL for the other battery, and buy a 300A class T for the inverter. How does that sound?

Interrupting Capacity is the main problem. It is not enough if the fuse blows, it has to stop the arch too.
This big LFP cells can deliver ... nobody knows exactly, some made some calculations ... but it can be near 10-30.000A short circuit current.
Class T fuse can block 20.000A at max.
Google NT and NH fuses. That are a bit more robust fuses, filled with sand to block arching.
 
Since I am adding the second battery, I can use the ANL I bought to one of the batteries, buy another 300A ANL for the other battery, and buy a 300A class T for the inverter. How does that sound?
I am considering the very same thing. Or, two class T fuses for each battery and an ANL (or MBRF) fuse for the rest.

The only drawback to an ANL for each battery and a Class T fuse is if something before the Class T fuse shorts to ground, like a tool dropped across the bus bar to a ground, now the potential is there for the ANL fuse/fuses that blows to arc across. Because this tool made the circuit is complete before Class T, the potential is there for a "self Sustaining" arc.

I feel, and I don't know the code and am not an engineer, that a Class T fuses by the battery would be the only place requiring a class T fuse. You have to draw the line somewhere or after the Class T-Fused Battery comes the busbar and this may go to my 24 1 amp lights, and I don't want to put a class T fuse on all the lines out of a busbar. Each line fused after the busbar yes; each line does not need a class T fuse.

There's a few fuses I need to add. I'm considering MBRF fuses between 30 and 300 amps. The Blue Sea one I'm looking at is designed for to attach to a 3/8 busbar and accepts 5/16 studs. https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A
 
I am considering the very same thing. Or, two class T fuses for each battery and an ANL (or MBRF) fuse for the rest.

The only drawback to an ANL for each battery and a Class T fuse is if something before the Class T fuse shorts to ground, like a tool dropped across the bus bar to a ground, now the potential is there for the ANL fuse/fuses that blows to arc across. Because this tool made the circuit is complete before Class T, the potential is there for a "self Sustaining" arc.

I feel, and I don't know the code and am not an engineer, that a Class T fuses by the battery would be the only place requiring a class T fuse. You have to draw the line somewhere or after the Class T-Fused Battery comes the busbar and this may go to my 24 1 amp lights, and I don't want to put a class T fuse on all the lines out of a busbar. Each line fused after the busbar yes; each line does not need a class T fuse.

There's a few fuses I need to add. I'm considering MBRF fuses between 30 and 300 amps. The Blue Sea one I'm looking at is designed for to attach to a 3/8 busbar and accepts 5/16 studs. https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A
If you look at that Blue Sea chart, they specifically single out the Class T as for inverters. The Victron drawing has a Mega instead, but does have ANL on the bats so I am going that way. I just checked another forum topic on this same point and they too loved class T. I think if I add the one class T before the inverter hopefully the world won't go poof.

New diagram for you guys to molest :)
trailer solar wiring diagram_j.jpg
 
Design hasn't changed but I have gotten my second set of 8 batteries in from Basen. Charging one now to do a capacity test on it. If I am not mistaken, I have gotten all my components in now for the build other than the roof rack material for the solar panels. Given the change to two sets of batteries I hope I have enough cable :(
 
I'm going to disagree with your design. Some is nit picky, some not.

The battery switch needs to be able to cut off all power into and out of the battery. You don't have that, at least not with a single point.

Battery (pos) -> Class T Fuse -> Battery Switch -> Common Bus Bar (pos) <- all load and charge connections

Most installs are using a circuit breaker, instead of a fuse, between the common bus bar and the inverter. A 300 amp fuse is too high I think. 3000 watts / 24v / .85 inverter efficiency * 1.25 fudge factor = 183 amps. Rounding up, a 200 amp circuit breaker would work. 200 amp is the largest breaker that Blue Sea Systems makes.

With the assumption that your inverter could pull 200 amps, putting 300 amp fuses on each battery may be too high. Maybe 200 amp fuses? Maybe go a little bigger to 225 amps with the thought that one battery could be taken offline and the other could still run "most" of the loads.

You really need a set of common bus bars. The power from the solar charge controller needs to be on the same side of the shunt as the inverter. Otherwise, your state of charge is going to be completely wrong. Same problem with the step down converter.

Given that we put in breakers and fuses to protect the wire, it could be argued that a breaker on the output side of the step down converter is warranted. I don't have a breaker or fuse on the output side of my AC-DC converter. I probably should. I may address that soon with an MRBF fuse.
 
If you look at that Blue Sea chart, they specifically single out the Class T as for inverters. The Victron drawing has a Mega instead, but does have ANL on the bats so I am going that way. I just checked another forum topic on this same point and they too loved class T. I think if I add the one class T before the inverter hopefully the world won't go poof.

New diagram for you guys to molest :)
View attachment 61343
Coming to this late, but I did notice a couple of things.

-The negative from your SCC should be on the other side of the shunt if you intend to measure current going into the batteries.
-You only need a single pole breaker from the panels to the SCC. The ground leg does not need to go thru a breaker.
-You do not show a ground leg from your 24>12 converter, but it needs to be on the "not-battery-side" of the shunt as well.
 
The battery switch needs to be able to cut off all power into and out of the battery. You don't have that, at least not with a single point.
I might have been inept at making my drawing, but there in most cases, I am designing based on Victron's guideline or sample. Did you look at the segment of their design I posted above? I address most of the points there you brought up here. They clearly go from the batteries, through the ANL fuses to the main switch through the MEGA fuse (where I have my T) and then to the inverter.

Battery (pos) -> Class T Fuse -> Battery Switch -> Common Bus Bar (pos) <- all load and charge connections

Most installs are using a circuit breaker, instead of a fuse, between the common bus bar and the inverter. A 300 amp fuse is too high I think. 3000 watts / 24v / .85 inverter efficiency * 1.25 fudge factor = 183 amps. Rounding up, a 200 amp circuit breaker would work. 200 amp is the largest breaker that Blue Sea Systems makes.

With the assumption that your inverter could pull 200 amps, putting 300 amp fuses on each battery may be too high. Maybe 200 amp fuses? Maybe go a little bigger to 225 amps with the thought that one battery could be taken offline and the other could still run "most" of the loads.

I also think I mentioned elsewhere, if not in this string, that the designated amperage for the fuse is right in the manual, 300A. I also mentioned where the value was confirmed by Battle Born's tech.
You really need a set of common bus bars. The power from the solar charge controller needs to be on the same side of the shunt as the inverter. Otherwise, your state of charge is going to be completely wrong. Same problem with the step down converter.
My drawing is poor, but the little squares are the busbar...I made my drawing from bits and pieces, modifications, and doesn't reflect how it would look if drawn now from scratch. Regarding the shunt, in the Victron drawing above, it shows batteries > shunt> busbar and the SCC negative connects to the same common busbar.

I apologize for my drawing, but I don't see a distinction between my diagram and the Victron diagram. If you look at my diagram and their diagram and see that I haven't followed their guideline, otherwise I assume they are the authoritative source when installing their hardware, including them insisting on a 300A fuse.
Given that we put in breakers and fuses to protect the wire, it could be argued that a breaker on the output side of the step down converter is warranted. I don't have a breaker or fuse on the output side of my AC-DC converter. I probably should. I may address that soon with an MRBF fuse.
I didn't have a breaker between the bus and the converter and it was highly suggested by many people. As far as the output side of the step down, the DC panel has it's own breakers and fuses.

Thanks!
 
Coming to this late, but I did notice a couple of things.

-The negative from your SCC should be on the other side of the shunt if you intend to measure current going into the batteries.
-You only need a single pole breaker from the panels to the SCC. The ground leg does not need to go thru a breaker.
-You do not show a ground leg from your 24>12 converter, but it needs to be on the "not-battery-side" of the shunt as well.
Just addressed the first point in my response above. Unless I can't read a diagram, my shunt is where Victron put their shunt?

I agree on the single pole breaker, however, when I had only one breaker there, I was told it isn't code. Further, I was told you don't need a breaker or fuse at all, other than to turn off the power to the controller. I was told the fuse or breaker would never blow, but it was NEC to have a breaker on both legs.

I used a purple line for the converter to indicate it wasn't the "real" wiring connection. I only have a single wire shown for the input and output and it is just showing that it connects, but not the exact wiring.

As an aside, they show a "earth" ground on their common negative busbar. I haven't indicated a chassis ground in my diagram but presumably, there should be a chassis ground from the negative busbar and nowhere else.

Thanks
 
It's your drawing that is throwing us off. I also based much of my design off of a Victron drawing. The one I used has all positive connections for loads and chargers downstream of the switch, except for the solar charge controller. Most of us on the forum would likely say that even the solar charge controller should be on the common bus bar and not bypass the switch. The circuit breaker on the cable from the solar charge controller (in the drawing below) can be used to shut off power to the battery, but you have to remember to flip it. A big red switch that is the single point of entry to the battery is safer.

Here's a link to that drawing.
 
It's your drawing that is throwing us off. I also based much of my design off of a Victron drawing. The one I used has all positive connections for loads and chargers downstream of the switch, except for the solar charge controller. Most of us on the forum would likely say that even the solar charge controller should be on the common bus bar and not bypass the switch. The circuit breaker on the cable from the solar charge controller (in the drawing below) can be used to shut off power to the battery, but you have to remember to flip it. A big red switch that is the single point of entry to the battery is safer.

Here's a link to that drawing.
That drawing, although AGM vs L, shows the same config. Batteries to an ANL to the switch to the MEGA fuse to the inverter. They have a second switch for the load side.

In my design, the "power", i.e. batteries and SCC are on a common side of the switch, so with the switch off, there is no power going to the inverter.

In my layout the only charger is the charger in the Multiplus so there isn't any additional connections for a charger. All of my loads come off the existing power center other than the converter connected to the busbars.

I also noticed in the drawing, in response to 100 proof, they have dual breakers for the panels.

Thanks
 
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