Yet Another Check My Plan thread

[Rednecktek]

OK, so I'm getting close to getting back up to camp to start working on the solar setup cleanup & expansion. Time to check my work please. There are some parts I already have that I'm going to be using, they'll be notated in the parts list.



Parts list:

Battery: 304Ah 24v

8s 304Ah Eve cells (have 4 in box already, buying 4 more soon, c'mon Amy!)
JK B2A8S20P-H with the heater function (already have)
4x 24v 15w heating pads
80a 2-pole breaker (can't find a 150a to use on the battery so I figured 2x wires in and 2x wires out, will that work?)
Isolating box penetrations
3x Noctua 120mm IP rated 12v fans
Digital thermostat for fans (to cool the box down in summer)
8u rackmount case (I'll have to find one at the local used PC shop, but
I have saws, drills, and a welder to make my own case!

Inverter Side 24v & 120v
Growatt 3Kw 24v AIO (I already have)
150a Breaker/Disconnect for 48v
40a 2-pole breaker for PV input in a DIN breaker box
Small project box with a momentary contact switch and 10w/50Ohm resistor (already have all those parts)
2AWG copper cable and 3/8" lugs (I think I have the lugs)
4-port Combiner Box ~102v @ 34a total (already have, will mount at the panels)
12x 208w panels in 3s4p (already have on site)
8AWG wire from combiner to AIO
Ground mount array of PT lumber
Lots of conduit

12v System
4x WallyWorld DC29 110Ah FLA batteries (already on site)
Weize 40a MPPT (already on site)
2x 208w panels in series (already on site)
4-lug bus bars (already on site)
150a MEGA Fuses (already on site)
4awg copper wire with 5/16 lugs
12-port DC fuse block
Utility 12awg wire
50a 2-pole breaker for MPPT to bus bars in a breaker box
8awg wire and lugs
Battery Disconnect to fuse panel (already on site)



Notes:
The battery box will be surrounded by 2" thick Mylar coated foam and will have 3x 120mm fans through the battery box to suck air through in summer.
I think I need to replace the 60a breaker in the combiner box with a 40a, yes?
Yes, the MEGA fuses are oversized but 1) I have them and 2) worst case I can still get all my loads off a single battery.
It started life as a travel trailer so I have a lot of 12v systems. I have a 60a step-down converter but I think I like the idea of keeping everything as a separate system for redundancy.

No, I'm not buying Victron.

OK y'all, how am I screwing myself over?

 

[Mattb4]

Only thing that strikes me is your PV disconnect breaker of 30a. That seems a bit low if you have 4 parallel strings with 8awg wire. But I don't see your panels ratings in the list you gave.

 

[Rednecktek]

I want to say they're about 37v and 6ish amps, but they're on the other side of the state so I can't check the data plates until I get there next week.

I'm running 8awg because it's gonna be about 50ft.

 

[Dynoman]

OK, so I'm getting close to getting back up to camp to start working on the solar setup cleanup & expansion. Time to check my work please. There are some parts I already have that I'm going to be using, they'll be notated in the parts list.

View attachment 165553

Parts list:

Battery: 304Ah 24v

8s 304Ah Eve cells (have 4 in box already, buying 4 more soon)
JK B2A8S20P-H with the heater function (already have)
3x 24v 15w heating pads
80a 2-pole breaker (can't find a 150a to use on the battery so I figured 2x wires in and 2x wires out, will that work?)
Isolating box penetrations
2x Noctua 120mm IP rated 12v fans
Digital thermostat for fans (to cool the box down in summer)
8u rackmount case (I'll have to find one at the local used PC shop, but I have saws, drills, and a welder to make my own case)

Inverter Side 24v & 120v
Growatt 3Kw 24v AIO (I already have)
150a Breaker/Disconnect for 48v
30a 2-pole breaker for PV input in a DIN breaker box
Small project box with a momentary contact switch and 10w/50Ohm resistor (already have all those parts)
2AWG copper cable and 3/8" lugs (I think I have the lugs)
4-port Combiner Box ~102v @ 34a total (already have, will mount at the panels)
12x 208w panels in 3s4p (already have on site)
8AWG wire from combiner to AIO
Ground mount array of PT lumber

12v System
4x WallyWorld DC29 110Ah FLA batteries (already on site)
Weize 40a MPPT (already on site)
2x 208w panels in series (already on site)
4-lug bus bars (already on site)
150a MEGA Fuses (already on site)
4awg copper wire with 5/16 lugs
12-port DC fuse block
Utility 12awg wire
50a 2-pole breaker for MPPT to bus bars in a breaker box
8awg wire and lugs



Notes:
The battery box will be surrounded by 2" thick Mylar coated foam and will have 2x 120mm fans through the insulation to suck air through in summer.
I think I need to replace the 60a breaker in the combiner box with a 30a, yes?
Yes, the MEGA fuses are oversized but 1) I have them and 2) worst case I can still get all my loads off a single battery.
It started life as a travel trailer so I have a lot of 12v systems. I have a 60a step-down converter but I think I like the idea of keeping everything as a separate system for redundancy.

No, I'm not buying Victron.

OK y'all, how am I screwing myself over?

My understanding a Class T fuse is needed between the LiFePO4 battery and the AIO/Inverter. Don't see the need for the 80 amp double pole breaker with the Class T fuse. I use the Class T fuse with a Blue Sea 9003e battery disconnect switch. With that combo on the positive wire no need for breakers. Picked up Blue Seas Class T Fuse and fuse block at Home Depot a while back and was the best price.

I just use a 50W 25 ohm resistor with a couple of alligator clips wired to it for pre-charge and jumper the Blue Sea Battery switch (when off) for 30 seconds or so before turning on the switch and have had no problems with my 2 LiFePO4 271AH 24 volt battery banks.

For the Solar Panels Disconnect a IMO switch along with an ANL fuse is a good way to go. See link & product brochure attached.

IMO DC Disconnect Rooftop Isolator Switch

IEC 60364-7-712, dc disconnect, imo, ul listed, DC AC, DC DISC

signaturesolar.com

Be weary of inexpensive circuit breaker switches. Some have been known to cause problems.

 

[Rednecktek]

Don't see the need for the 80 amp double pole breaker with the Class T fuse.

That breaker in there is one I'm planning on mounting inside the battery box for a main disconnect. I was hoping I could use a double 80a and just have 2 wires between the battery terminal inside, split it at the breaker, then bring them back together at the terminal of the case. I'm having a nightmare of a time finding a 150a DC breaker anywhere.

EDIT: Just tried ordering some, we'll see if they actually get here.

I just use a 50W 25 ohm resistor with a couple of alligator clips wired to it for pre-charge and jumper the Blue Sea Battery switch (when off) for 30 seconds or so before turning on the switch and have had no problems with my 2 LiFePO4 271AH 24 volt battery banks.

I'm building this system to be as simple to turn on and off as possible so it will come down to:
Step 1: Turn on battery
Step 2: Hold down Precharge button for 30 seconds
Step 3: Turn on inverter breaker
Step 4: Turn on Solar Panels breaker

My nephews are jocks and too old to be retrained. ? Plus the instruction manual is designed for anyone who finds themselves up there so it's gotta be super simple. The label maker will be working hard.

Be weary of inexpensive circuit breaker switches. Some have been known to cause problems.

Oh yeah! I've smoked a few but the T-Tocas have always behaved well. I'm searching for other options but single pole in 150a is a real pain to find if I still want a kidney and all of my liver.

My understanding a Class T fuse is needed between the LiFePO4 battery and the AIO/Inverter.

Oops! I knew I forgot something. What are the odds I can even get one? Last time I tried to track one down I had 3 orders cancelled and 1 is still pending from almost 2 years ago. 150a seems to be the size difference in holders too from what I'm seeing, right?

I'm also thinking about mounting a shunt inside the battery box while I've got it open between the P- of the BMS and the negative terminal bolt. I think it'd be handy. Yes, I know it's not going to track anything on the 12v bus but I just want to be able to see it at a glance

 

[Rednecktek]

So I'm finding that the Seplos 24v DIY battery case is going to cost me $680 plus shipping and then I need the fancy cables that snap in with it.

Well... I have a welder, hole saws, jigsaws, drills, and screwdrivers so I figure I gotta be able to build a case cheaper than that! I already have a good BMS for it, it even supports heating pads. I can weld plates and drill holes and rhino-line everything. Throw some 1" L-brackets on the lid (8 of them) to hold it on. Mount some 120mm Noctuas in the back, plan for vent holes, mount everything to everything and call it a project!

Thoughts?



Yes, I know, it's a krappy MS paint, but it's color coded and has the measurements I'll need.

 

[Rednecktek]

System drawings updated. Added heaters and side plates to batteries and correct fuse & breakers to system design.

 

[Kenny_]

Definitely DIY....fitting of this forum!

 

[featherlite]

What model BMS will you use?

 

[Rednecktek]

What model BMS will you use?

The JK listed in the parts list at the top. I've got a relay coming to turn the pads on & off as the 3a limit on the heating switch is jjuuussttt too small for me to risk it.

And before anyone asks, no, I'm not going to build one for @Will Prowse to review. ? This is likely to be another "Did it! Never Again!" projects.

 

[Rednecktek]

Updated the battery box drawing. I'll install a Class-T inside between the breaker and terminal, updated the steel list for my shopping trip Tuesday, scooted the shunt lower to make space for the fuse. I measured my cells and dropped the interior wall heights 2" to allow for clearance space above everything to feed the fans.

Any other things I'm missing?

 

[Rednecktek]

The battery is almost complete! Heading up to the camp with multiple totes of stuff on the 23rd!