Looking for MP 170amp breaker for inverter to 24V LiFePO4 bank

[erik.calco]

Updated diagram.



Here is a copy and paste of section with links, since I couldn't paste or attach the diagram as an SVG file with the links.

• 4/0 battery cable between battery terminals
• 300A MRBF fuse on (+) terminal
• 2 * 6 AWG cable to inverter
• 150A surface mount circuit breaker / shutoff
• 12V Lion Energy UT1200 90Ah LiFePO4

All DC connection poles are M8 (5/16").

I just know when checking out someone's design, I wish it had links to the parts.

 

[Rider]

Hahaha for the record, I put that disclaimer on our listing for MRBF holders because people kept asking if they could drill out the holder's M8 hole to fit around their regular battery terminal (by which I mean, the clamping post) which, obviously, no. I got tired of answering the question so I added the disclaimer

Here's a pic of one installed on my test bench setup, showing how it attaches to a standard M8 (threaded insert in this case).

I just retrofitted my in-line fuses for a pair of these @150A each. Much nicer to work with.

 

[Justin Laureltec]

• 4/0 battery cable between battery terminals
• 2 * 6 AWG cable to inverter

Man, what the... I wonder how those guys can make their cables that cheap, we can't even begin to compete with that... Good for you! The lugs are definitely dinkier than the FTZs we use, but that's not a huge deal... and the lugs aren't the source of the price discrepancy either. Well, good on them - let us know, once you get them, if they seem like good cables.
In re to the diagram, one thing I'd personally recommend is a shutoff on the PV input side so that you can isolate your controller if needed without either waiting until dark or climbing around covering your panels. PV shutoffs are tricky because of the high voltage, but I always recommend the MidNite Solar MNEPV-series breakers (sized according to the amperage of your panels). They're rated to 150vDC or you can series-wire them to get 300vDC.
Personally I consider it a necessity to be able to easily isolate any power source, so I always recommend these on the PV input side (the 187s are great for that as well if you just have a couple panels running less than 48VOC, but it looks like you have a decent-sized array). Just my two cents!

 

[erik.calco]

Man, what the... I wonder how those guys can make their cables that cheap, we can't even begin to compete with that... Good for you! The lugs are definitely dinkier than the FTZs we use, but that's not a huge deal... and the lugs aren't the source of the price discrepancy either. Well, good on them - let us know, once you get them, if they seem like good cables.
In re to the diagram, one thing I'd personally recommend is a shutoff on the PV input side so that you can isolate your controller if needed without either waiting until dark or climbing around covering your panels. PV shutoffs are tricky because of the high voltage, but I always recommend the MidNite Solar MNEPV-series breakers (sized according to the amperage of your panels). They're rated to 150vDC or you can series-wire them to get 300vDC.
Personally I consider it a necessity to be able to easily isolate any power source, so I always recommend these on the PV input side (the 187s are great for that as well if you just have a couple panels running less than 48VOC, but it looks like you have a decent-sized array). Just my two cents!

Great advice. I put a link in my plan document (not diagram) to this post, so I read it when I'm ready. I haven't spec'd the PV side, yet. Goal is to get it from Battery to AC as a UPS, then add PV. Reasons I'm doing PV last include: it's freezing here in the NE, taking a long time to settle on a PV mounting plan, and I have a giant pine that needs to come down before PV will produce a lot. I'm also doing testing on the PV side of various sorts. But, it will be nice to just focus entirely on the PV side and have the battery to AC parts done.

PV could end up being its own diagram with branches, fuses, diodes, combining, breakers, grounding, conduit, panels, etc,... not to mention structural design for mounting / tilting.

I added a little disclaimer :

 

[Justin Laureltec]

Nice... I approve of the plan; I see that sort of thing a lot, where the UPS/backup comes first and solar gets added in later down the line. Also f*** a whole big old bunch of being out in the freezing cold trying to mount panels.
In re to the MNEPV breakers, it's worth noting that they're DIN-mount breakers, so you can either fabricate a DIN rail to mount them to when you get to that point, or you can buy MidNite Solar's cute little BabyBox enclosure for them.

 

[erik.calco]

Nice... I approve of the plan; I see that sort of thing a lot, where the UPS/backup comes first and solar gets added in later down the line. Also f*** a whole big old bunch of being out in the freezing cold trying to mount panels.
In re to the MNEPV breakers, it's worth noting that they're DIN-mount breakers, so you can either fabricate a DIN rail to mount them to when you get to that point, or you can buy MidNite Solar's cute little BabyBox enclosure for them.

I really want to see someone here create videos on DIN or other DC breaker distribution DIY. I realized I was not ready to include a DC breaker box when I saw a shunt for the negative bus bar. I haven't really tried to see what's on YT on this, yet, though. There could be good videos and blogs out there.

The thing about DINs is their limit of 100A. I suppose that makes them a great fit for the PV side. But, not a good fit on the battery DC distribution side. I'd like to come up with a better plan for branching access to the battery bank (adding 24V load circuits). But, it wasn't critical to complete in this phase. Just having a 24V circuit would be a plus, though. I'd like to understand potential options for adding / combining inverters, too. I understand MPP Solar paralleling. But, I'd want to one day understand options for extending the bank with batteries that are not a perfect match, or adding a different vendor's inverter to a bank. I realize both introduce issues. But, that doesn't mean they are unsolvable challenges. This all fits in the umbrella of the potential for extensibility and integrating changes in market options over time.

 

[erik.calco]

That got a little less cute when I saw the price for one box! I figured it'd be cheaper.

LOL that really is the entry price for those.. thus "baby".

It will look cheap when you look at the high amp DC breakers lol. Not DINs cuz they stop at 100A. But the 1.5" ones that go over 120A. You'll wish they were the cost of a BabyBox. @Steve_S alluded to it earlier in this thread.

 

[erik.calco]

Ha. That's the problem I'm having with being on this forum. I'm getting a lot of good ideas off the members and all of them are starting to add up FAST. $$$$$$

It's cheaper than heroine.... I think.

 

[erik.calco]

The first step is admitting:

 

[erik.calco]

And you want an expensive addiction... try skydiving! My addict friends have two jobs to help pay for it and max their credit cards.

 

[Supervstech]

It's cheaper than heroine.... I think.

... was the misspelling intentional? As in... drugs/women?

 

[erik.calco]

... was the misspelling intentional? As in... drugs/women?

Women are only expensive if you marry them, unless you can find that Playboy centerfold CEO you always dreamed about.