12 Volt System DIY

I have been researching and planning my first DIY and would appreciate any suggestions. Especially the fuse and fuse location!!! And wire sizes. I may only end up with two Power Queen 12v 190Ah's but four is the max for sure.

BTW, I used someone on DIY schematic, and just replaced and moved the parts around that I wanted (the title was 2000-watt inverter schematic), so thank you very much, it really helped to be able to see it. If it looks familiar, it is! Thanks!

As one beginner to another, I can perhaps warn you off of two mistakes I made in my first build...

1. If it's a vehicle, 12v is fine. If it's a building, especially with air conditioning, 24v is a better choice, mostly to avoid the line losses a 12v system presents.

2. Ditch the switch-style circuit breakers, (unless they are super-quality,) and go with fuses. Those circuit breakers introduce way too much resistance into the wiring they protect, resulting in voltage drops across each breaker, which increases amperage in the wire which produces way too much heat, where energy is lost to heat.

I would content that circuit breakers are a better bet. It saves scrambling around for fuses. , on my boat, which is 12v solar , I have nearly removed all fuses and replaced them with breakers. Voltage drop is low as contact conductivity is high in my opinion.

I see nothing wrong with them , in vehicles and boats spaces are limited so carrying boxes of replacement fuses is not a great idea , nor is trying to find some weird fuse in the middle of nowhere.

ArkCabinMan said:

As one beginner to another, I can perhaps warn you off of two mistakes I made in my first build...

1. If it's a vehicle, 12v is fine. If it's a building, especially with air conditioning, 24v is a better choice, mostly to avoid the line losses a 12v system presents.

2. Ditch the switch-style circuit breakers, (unless they are super-quality,) and go with fuses. Those circuit breakers introduce way too much resistance into the wiring they protect, resulting in voltage drops across each breaker, which increases amperage in the wire which produces way too much heat, where energy is lost to heat.

Click to expand...

Cool, I appreciate it. It is a building! I went 12 volt because that is the only thing I knew how to do. That really makes sense. Thanks again. I had a real blind spot there! (Seems odd you don't see 24-volt stuff pop up much in my research / shopping. Can't say I have ever seen 24 panel on Renogy's website) .............ton more research.

Forgot to add, I have already purchased a few of the 12v items. I think I could use them on my first all in one solar generator and start over. (My bluetti has an alligator clip attachment that can draw about 100 watts from the power queen). Attached are the items I have already ordered / used. But its still better to at least considering starting over now that later and regretting it. Thanks again. I had run out of funds for now anyway and the research is free.

Spartaqus said:

went 12 volt because that is the only thing I knew how to do

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12V is fine up to ~2000W.
And handy with all the lighting options and RV stuff if you are off grid.

Goboatingnow said:

I would content that circuit breakers are a better bet. It saves scrambling around for fuses. , on my boat, which is 12v solar , I have nearly removed all fuses and replaced them with breakers. Voltage drop is low as contact conductivity is high in my opinion.

I see nothing wrong with them , in vehicles and boats spaces are limited so carrying boxes of replacement fuses is not a great idea , nor is trying to find some weird fuse in the middle of nowhere.

Click to expand...

I would say that's true IF you spend the money and get a good breaker. There's so many of those cheap Amazon breakers on systems you see here, and pretty much without exception, a brand-name fuse will outperform a mediocre breaker. IMHO, it would be cheaper to use fuses, but more convenient to use good quality breakers.

I spent about $5-15 each on my class-T's. The equivalent breakers go for about $40-80 each. I was able to get lots of backup fuses for less than the breakers. To be fair, if your system is designed and used properly, that fuse / breaker should never blow anyway, I've never popped a class T.

Blue Sea Systems, Carlingswitch, Fuseman-Bussman, and Ferraz Shawmut are companies that come to mind when thinking about quality overload protection. I'm sure there's others, but those are solid.

I also agree that 2000w is the upper limit for 12v systems. For 3000w, I would be looking at a 24v or 48v setup. Not saying it's not possible, but the currents required to pull 3000w from a 12v battery are beastly (250a @ 12v, 125a @ 24v, 63a @ 48v).

Spartaqus said:

Cool, I appreciate it. It is a building! I went 12 volt because that is the only thing I knew how to do. That really makes sense. Thanks again. I had a real blind spot there! (Seems odd you don't see 24-volt stuff pop up much in my research / shopping. Can't say I have ever seen 24 panel on Renogy's website) .............ton more research.

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Y'all are most welcome...!

I meant to refer you to a very informative video I found on this forum, about circuit breakers heating up and causing problems due to inappropriate internal resistance.
Here it is:

Thread 'What is the Battery Disconnect/Cut-Off Switch resistance?!' https://diysolarforum.com/threads/what-is-the-battery-disconnect-cut-off-switch-resistance.35261/

A.Justice said:

I would say that's true IF you spend the money and get a good breaker. There's so many of those cheap Amazon breakers on systems you see here, and pretty much without exception, a brand-name fuse will outperform a mediocre breaker. IMHO, it would be cheaper to use fuses, but more convenient to use good quality breakers.

I spent about $5-15 each on my class-T's. The equivalent breakers go for about $40-80 each. I was able to get lots of backup fuses for less than the breakers. To be fair, if your system is designed and used properly, that fuse / breaker should never blow anyway, I've never popped a class T.

Blue Sea Systems, Carlingswitch, Fuseman-Bussman, and Ferraz Shawmut are companies that come to mind when thinking about quality overload protection. I'm sure there's others, but those are solid.

I also agree that 2000w is the upper limit for 12v systems. For 3000w, I would be looking at a 24v or 48v setup. Not saying it's not possible, but the currents required to pull 3000w from a 12v battery are beastly (250a @ 12v, 125a @ 24v, 63a @ 48v).

Click to expand...

I have a range of breakers. They cheaper ones have performed well , just like my cheap Chinese leds that all survived the lightening strike while all the expensive European gear blew up. !!

I never buy “ marine branded “ electrical gear it’s usually ordinary stuff rebranded marine and tripled in price.

Take the blue seas contactor at 180 dollars it’s actually a TE Connectivty model , made in China and costs $40 !!!

I don’t touch those marine supply chains.

E-T-A make good breakers , carling has got very expensive for what they are. I recently tested done Chinese carling look alikes. Very good it seems. This included stripping one apart.

Hey get cheaper and buy two !!

ArkCabinMan said:

I meant to refer you to a very informative video I found on this forum, about circuit breakers heating up and causing problems due to inappropriate internal resistance.
Here it is:

Thread 'What is the Battery Disconnect/Cut-Off Switch resistance?!' https://diysolarforum.com/threads/what-is-the-battery-disconnect-cut-off-switch-resistance.35261/

Click to expand...

Sure AliExpress have junk and better stuff mostly like anywhere else’s. Buying “ brand “ is no guarantee

Comments.
No details of negative feed wire to inverter.
All connections to battery positive terminal or to positive buss bar need suitable fuses or breakers as near as practical so no excessive lengths of unprotected cable exist.
Consider mounting the 300A class t fuse holder as near as practical to the battery positive post. Connect the output of this fuse to the positive buss bar and feed the inverter from this buss bar. Protect all the connections to the battery positive posts with terminal protection 'boots'.
Fit a small 1A inline fuse for the battery monitor positive cable.
Although have shown breakers in your circuit, in my view fuses are preferred. Provided the system is engineered correctly the 'resetable' action of a breaker will rarely, perhaps never, be needed.
The battery monitors shunt as shown will not monitor inverter current. Use 4/0 cable to the shunt and from shunt to negative buss bar. Connect inverter negative to negative buss bar with 4/0 cable.
Buss bars need 300 amp rating.

The high currents in a 12v system with a 3000 watt inverter will need well engineered terminations and Interconnections.

Mike

mikefitz said:

Comments.
No details of negative feed wire to inverter.
All connections to battery positive terminal or to positive buss bar need suitable fuses or breakers as near as practical so no excessive lengths of unprotected cable exist.
Consider mounting the 300A class t fuse holder as near as practical to the battery positive post. Connect the output of this fuse to the positive buss bar and feed the inverter from this buss bar. Protect all the connections to the battery positive posts with terminal protection 'boots'.
Fit a small 1A inline fuse for the battery monitor positive cable.
Although have shown breakers in your circuit, in my view fuses are preferred. Provided the system is engineered correctly the 'resetable' action of a breaker will rarely, perhaps never, be needed.
The battery monitors shunt as shown will not monitor inverter current. Use 4/0 cable to the shunt and from shunt to negative buss bar. Connect inverter negative to negative buss bar with 4/0 cable.
Buss bars need 300 amp rating.

The high currents in a 12v system with a 3000 watt inverter will need well engineered terminations and Interconnections.

Mike

Click to expand...

Well, I am going to have to read over your comments slowly and several times, I didnt get it all at first take but really like it! I really appreciate the time you took. It really helps. But after 'ArkCabinMan's comments above, I am really going to have to consider going to 24volts. That being said, from what I get, most all of your comments will apply to a 24 volt system too. Thanks again!!! btw, I totally forgot the negative wire to the inverter!

A 24 volt system with a 3000 watt inverter would be a good idea and reduce the cable and fuse size.
The 60 amp converter will need to be replaced. Consider a true battery charger or an inverter charger.

mikefitz said:

A 24 volt system with a 3000 watt inverter would be a good idea and reduce the cable and fuse size.
The 60 amp converter will need to be replaced. Consider a true battery charger or an inverter charger.

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I didn't know there was a 'true battery charger' for lithium. I got the progressive dynamics because that what I found. My use, is home use for backup up power. I would want to charge my batteries with a gas generator if needed too.

Goboatingnow said:

never buy “ marine branded “ electrical gear it’s usually ordinary stuff rebranded marine and tripled in price.

Click to expand...

Really? That’s not true. Everything from speakers to electrical wire sheathing is ‘marine’ rated and different than commodities.

12VoltInstalls said:

Really? That’s not true. Everything from speakers to electrical wire sheathing is ‘marine’ rated and different than commodities.

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When I can afford it, I prefer to use marine rated DC equipment. It's usually more corrosion, and vibration resistant, and the QC is usually better then a commodity product. I figure why not spend a few extra dollars for quality components. I've never been disappointed with marine grade stuff. I recently replaced a bunch of wire splices in my trailer, the majority of the "Amazon special" brand had some level of corrosion, and 0 of the marine grade ones did, not a single one.

Sure, I might be able to find a knock off for cheaper that works, but it's rolling the dice compared to buying a known brand. It's funny that sometimes the cheap stuff feels like decent quality until you have a real good quality version to compare it to. This is coming from the guy who pretty much had to build two systems because I cheaped out on the first one, and ended up having to rebuy most of my components.

When it comes to fuses and breakers, I don't really care about other people's opinions, I'll be using a name brand, from a trusted company as the last line of defense against a dead short and / or fire on my system. Safety is absolutely my top priority, but that's not always the case for everybody.