Comments of advice?

Tim R

Solar Enthusiast
Joined
Oct 3, 2020
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37
I have received nearly everything for my build. I put this together a few weeks ago and been thinking about it. Thought I would post it here and see if anyone has any comments, advice, warnings or constructive criticism of this design. Thanks much!

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MichaelK

Photon Sorcerer
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Mar 21, 2020
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Even with enlargement, I'm having trouble reading the specifications of your equipment. First question, is your Electrodacus controller PMW, or MPPT. I could find no reference to it with a quick search. It appears that you have 4-100W panels wired in parallel, which suggests to me that the controller is PMW.

Even with 4 panels, 400W is not large enough to charge a battery that appears to be 560Ah, is that correct? I would have suggested 800W-900W as a minumum. Since grid-tie panels are cheaper per watt then 12V panels, I'd say you are already making poor choices equipment-wise. Even when paying extra for a more expensive MPPT controller, you'll start saving money once you exceed 2-3 100W panels. Double the battery later, and you should double the wattage to 1600W-1800W. 560Ah X 0.1C charge rate X 13V charging voltage X 1.25lossfactor =910W.

This is typical of unbalanced systems that have too large a battery bank, and too small a solar array to keep them charged. It would have been better if you had started asking questions before you started making purchases.
 

Tim R

Solar Enthusiast
Joined
Oct 3, 2020
Messages
37
Sorry about the drawing size. This site wouldn't allow the original.

The Electrodocus is a BMS that uses those small adapter things, (DSSR20), are PWM that control PV input. I have one on each "like" panel strings. The two panels are 100w and two are 200w, hence one per string. The SBMS0 is a really nice way to manage PV power and it's 99% efficient, beating an MPPT or PWM controller. I think its genius, has amazing support and will give you all the telemetry you could ever want or need. This setup is like having a 99% efficient Solar Charge Controller.

I have 1100 watts of panels, just didn't want to draw them all. I may even get two more 200w panels so I can set them up off rig. I plan on another 12v 560ah battery pack, which means I will have 1100w PV and 1120ah storage. That's ok because in the lower section of the drawing you will see a 80a converter charger, which will fill the storage up when shore power is available. I won't boondock without a full power pack. I didn't include it in this drawing, but I will also have a DC-DC charger using a dedicated 300 amp alt for on the move charging and emergency regen when boondocked.
 

chrisski

Solar Boondocker
Joined
Aug 14, 2020
Messages
2,694
I don’t like the 100 amp and 300 amp audio circuit breakers. I much prefer a primary battery rated ANL fuse or Class T fuse. The fuses I mentioned will perform much closer to specs.

Although others do, I don’t think a 3000 watt inverter for a 12 volt system is a wise idea, especially if the wire size is not listed. I have a 2000 watt inverter for my 12 volt system which pushes it, but I run a 700 watt 55 amp coffee maker for 3 minutes, and a 1800 watt microwave at 155 amps for 10 or 15 seconds. Any longer on the. Microwave, I plug the Generator in. For that I have a short 5’ run from the battery to busbar and 2’ run from the busbar to inverter Of 4/0 wire. That’s really thick.

I think if you’re really going to make use of a 3000 watt inverter, needs to be at 24 volts, or if it powers high wattage items a lot, then 48 volts.

With your 80 amp charger, I’d make sure it has a good profile to match your batteries. To me that looks like an RV Ac to DC converter and there’s some debate on this forum about how good the charging and maintenance profiles are.

With the distribution panel, make sure you really only need 50 amps. I have an RV build and the leveling jacks pull more than that. Most everything else in the DC side is low amperage, but most of my energy usage is also DC.
 

Tim R

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Joined
Oct 3, 2020
Messages
37
Thanks. All good points. I wasn't aware of the breakers being audio CB's. I will look at a replacement to fuses.

I got the 3kw inverter, not because I will use 3kw, but I don't want to run it too hot. I figure I will stay around 2kw for my work, but when I need to plug in my. welder, 3kw will do the trick for short periods. The cables between the batteries and Inverter and charger are 1/0 and less than 16" but I am open to 3/0, though I think the 1/0 should do the trick.

The 80a charger is a Progressive Dynamics, PD9180ALV, 12V Lithium Ion Battery Converter/Charger. It is a purpose built Lithium charger and has Lithium charge profiles, thermal management, etc. Its from the same company that built the RV distro panel and while they have a replaceable charger for Lithium, I opted for an external as it has more power. I can also parallel two and get 160amps if need be.

I have wireless Happy Jacks and they do draw some current, however, they are feed from the battery box in the lower left corner of the drawing. I wanted a more consistent environment for my packs so I moved them inside under a bench seat, which is 4' from that RV distro panel.

I don't have a battery disconnect switch, which I thought might bring some notice. I didn't put one in because both the circuits are protected with breakers. That will save my SBMS from certain death if the inverter pops the breaker and opens the circuit for the PV's. The PV's will only lose battery connection if there is a serious issue with that short link. It just made sense to me.

Thanks so much for the feed back, I certainly appreciate it.
 

Dzl

Perpetual Newbie & Unofficial Forum Librarian
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Thanks. All good points. I wasn't aware of the breakers being audio CB's. I will look at a replacement to fuses.

I got the 3kw inverter, not because I will use 3kw, but I don't want to run it too hot. I figure I will stay around 2kw for my work, but when I need to plug in my. welder, 3kw will do the trick for short periods. The cables between the batteries and Inverter and charger are 1/0 and less than 16" but I am open to 3/0, though I think the 1/0 should do the trick.
I think @chrisski is on the right track with the 24V suggestion. But if not, consider stepping up to 4/0. 3000W @ 12V is nearly 300A, possibly slightly more if you factor in inefficiency or slightly lower voltage (3000W / 12V / 0.85 efficiency = 294A)

For wire safety (ampacity), distance is not a factor as far as I am aware, distance matters for voltage drop.

Here is an ampacity chart that shows you max ampacity for different wire sizes and temperature ratings (at 85*F and 120*F)
full


A couple other points that jump out at me:
  1. As has been mentioned a fuse, such as a class T fuse, rated for protection of large battery banks or lithium battery banks is worth strongly considering.
  2. I believe your positive wiring is incorrect, nothing should come between the battery and the first shunt. Loads come after the first shunt, solar (or all chargers) come after the second shunt.
  3. Question: what is at the bottom left?
 

Tim R

Solar Enthusiast
Joined
Oct 3, 2020
Messages
37
I think @chrisski is on the right track with the 24V suggestion. But if not, consider stepping up to 4/0. 3000W @ 12V is nearly 300A, possibly slightly more if you factor in inefficiency or slightly lower voltage (3000W / 12V / 0.85 efficiency = 294A)

For wire safety (ampacity), distance is not a factor as far as I am aware, distance matters for voltage drop.

Here is an ampacity chart that shows you max ampacity for different wire sizes and temperature ratings (at 85*F and 120*F)
full


A couple other points that jump out at me:
  1. As has been mentioned a fuse, such as a class T fuse, rated for protection of large battery banks or lithium battery banks is worth strongly considering.
  2. I believe your positive wiring is incorrect, nothing should come between the battery and the first shunt. Loads come after the first shunt, solar (or all chargers) come after the second shunt.
  3. Question: what is at the bottom left?
Thanks so much for the input. Very much appreciated. I spent a great deal of time thinking about 12v or 24v and the feedback was 50/50. I chose to stay with 12v because most power I use will be DC and adding a DC-DC converter is just another device to fail. The reason for 3000w inverter is, for the most part, to run a TIG welder. With a standby current approaching 2a, it won't be left on when not in use. I don't mean to weld all day, so rest assured I'm not crazy. Instead of 4/0, I think multiple cables would be my choice.

I am reviewing the fuse/breaker selection and will look closely at the T type fusing.

Yes, that is an error on my part in the wiring. All battery load should be flowing through the first shunt.. Thank you for pointing that out.

The bottom left image is the original battery compartment on my rig. I am using it as another distribution point.

Thanks again for the input.
 
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chrisski

Solar Boondocker
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The bottom left image is the original battery compartment on my rig. I am using it as another distribution point.
I did the same thing. The original wiring from the battery was 12 inches long and 6 AWG. The busbar from the new battery bank took about 5’ of wire, and I went with 2 AWG. That’s plenty big for the rigs DC usage, except for the leveling jacks which is over 50 amps, and its adequate for that with a 5% loss.
 
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