Looking for inverter/charger/MPPT, 12v/120v

Drizzt321 · March 10, 2022, 5:38pm

I am going to use something similar to that for my DC fuse/distribution for all the other bits, definitely.

For main battery protection though, blade fuses don’t have enough Ampere Interrupt current, what I’ve seen its about 1kA . Which in a short situation lithium batteries, assuming the BMS fails fused closed as well, can put out well over 1,000A.

ANL is 6kA interrupt, which is a lot better, and probably more or less OK for a single 100Ah battery.

Class T is 20kA interrupt which should be well over what a single 100Ah can manage even if the BMS fuses closed.

Breakers I’d have to look, but most of them, especially this common style seem to be a moderate range. Probably more than sufficient, honestly, for the 7-pin mount since that’s coming from the car alternator/12v lead-acid starter battery, but for the lithium side of things where Very Bad Things can happen with a short, I’m thinking I want way, WAY overspecced safety. Probably more than a bit of paranoia involved, but it’s a relatively low cost compared to the rest of the system, not even counting the trailer itself.

Really all depends on how much power your source can dump in the case of a major short, as to what the amp interrupt capabilities need to be. In most cases breakers are probably fine.

I’m thinking I might switch to ANL for the line from the 7-pin, but going to keep the Class-T on the lithium side, swap it up to 80a which is still under the max rated power draw, and a fair bit above my expected max power draw.

EDIT: So for this older (2013 video) of a Calb 180Ah grey cell, and was hitting over 2200 sustained amps from a single cell. ~12.2C, rounding to 15-20C to be paranoid, after all a spanner is probably a moderate resistance. Larger (per individual cell) than the Battleborn, true, but newer cells might very well be able to dump higher amps, even with smaller cell size. Assuming the BMS fails of course, which is unlikely, but this is a WORST case scenario, everything that can possible go wrong in the worst possible way has, is what I’m talking about.

Drizzt321 · March 15, 2022, 3:08pm

Great. Looks like I’ll be hitting supply chain issues for the class t fuses/holders. Naturally. Ugh.

Vertiginous · March 15, 2022, 3:15pm

Right, that’s… basically what I was suggesting, except to use circuit breakers instead of fuses for the batteries. Marine style circuit breakers are also disconnect switches, so you get two functions for the price and space of one, and they have the necessary interrupt rating. I am not a big fan of fuses, personally, except as a last resort, and whenever possible I prefer circuit breakers. The rig runners are fine because they’re a lot cheaper than a DC breaker panel and you can keep a tin of fuses handy, but they’re less than ideal because for some reason you always seem to run out of fuses when you’re out in the boonies somewhere and need that circuit to work and can’t steal a fuse from anything else. If I wanted to do a really nice install I’d use boat/rv compact circuit-breaker switch combos in a small panel and run dedicated circuits from that to my outlets, installed gear, lighting, etc. You’ll pay a pretty penny for it, but you’ll only do it once.

Drizzt321 · March 15, 2022, 6:16pm

I have a vague thought I might want that, but I think I’m going to stick with the Class-T on the battery side. Being extra paranoid, but if I do end up adding a 2nd battery in parallel for capacity, I’ll be getting closer to most breakers. And I’d want to check response times on the breakers too. Just simpler, for the battery, to go with the best possible thing.

As for the auto side of things, I might just relent and go for a regular ATC fuse. If it’s good enough for in the rest of the auto, should be OK for this as well. Plus it’ll match the rest of the lower current fuses/block that I’ll have.

I don’t think boat/RV breakers are all that much smaller, really. The panels themselves, maybe, but there’s only so small you can go on that and still be able to work on it.

Hmm… apparently there are blade breakers!

I probably won’t use them, but might be perfect for you.

Vertiginous · March 15, 2022, 6:33pm

Yes, I’m aware of the blade breakers, I had a couple. They’re useful, although on my setup I had a full switched panel with something like 24 or so individual switches/breakers by the end of it so didn’t need them. That’s ancient history by now, though. That said, if you do go with a rigrunner, the blade breakers are probably smart if they have the specs you need, for final distribution that’s compact. Ideal for a chart table/desk/radio station/compute centre combo.

Syonyk · March 15, 2022, 8:57pm

Why?

They’ll pop soon enough under sufficient overcurrent, and generally don’t trip the moment you go slightly over the rating.

Midnite demonstrated you can push 10,000A through 12AWG with their surge suppressors, if the pulse is brief enough. Though apparently at that point it tend to “ignore corners in the wire and just keep going straight.”

Use NEC wire gauges for your amperages, temperature derate if you want to be extra cautious, but it’s just not likely to be a real problem.

Drizzt321 · March 18, 2022, 4:36pm

Well… I have $2K worth of battery and chargers and such sitting in my living room now.

And have to return that 2nd DC-DC charger that somehow made it into the cart facepalm. At least returning it is easy.

Syonyk · March 18, 2022, 5:50pm

What’s the spare DC-DC charger, exactly, and how much was it? Those come in useful often enough.

Drizzt321 · March 18, 2022, 6:30pm

It’s the Orion-Tr Smart DC-DC Isolated charger, 12v to 12v, 18a. It’s one of the parts that’s expensive enough that I don’t feel I need 2, even though it is pretty flexible within the 12v in to 12v out battery, flexible with setting up the charging settings, etc.

It’s ~$180, so as I said, expensive enough I don’t need a spare around. If it was 50, I’d probably just keep it around cause it could be handy.

Drizzt321 · April 11, 2022, 1:21am

Ok, after being gone a while, have things allllllmost ready for installation into the trailer. And naturally I forgot some bits, so need to wait for the right size ring lugs for the shunt. Hopefully tomorrow, probably Tues. I do so living right near McMaster!

Pictures and info below, relevant comments, suggestions, critiques encouraged. Although unless it’s actually a hazard I probably don’t have the time to change much of anything around before I leave on Sat for the local regional burn campout.

So here’s the electronics, breakers, bus-bar, etc. All wired up, except obviously what’s going to be coming from/going to elsewhere. Some plexi front/protection held on with 1/4" bolts, T nuts on the back of the plywood, all the nuts have Blue thread locker on, all the wiring has ferrules/lugs depending. I don’t think I’ve got too much strain on anything, needed to keep things fairly compact for obvious reasons. The flap to lift up for the breakers/distribution access has 2 printed things to hold it up, with magnets glued underneath, and into the flap, to help hold it in place.

The battery platform is nearly ready. Forgot about the extra lug for the temperature/monitor power, so in the middle of printing up another cover for the Pos terminal. The big thing in the middle is the Class-T 80a 10k AIC 300v fuse, as my last resort protection. Although technically I suppose the battery BMS is, but I don’t anticipate getting anything close to 80a, expectation of 30-40a at my most, and that’ll be during the day when I have solar going.

The other thing is the shunt, which I was concentrating on the rest of the system so much I completely forgot to figure out what size lugs I needed. facepalm But tomorrow straight after work, so I’ll have sufficient light, I’ll head to the trailer to get the battery tray and electronics installed, hopefully the wiring run, and ready for new lugs I need to arrive. Also ordered some spares of the kind I already have used, since I stupidly ordered exactly the number I needed. Good to have some spares around! Despite them costing a fair bit, but worth it to get a known quality product for this.

I’m hoping I won’t have to drill/bolt through the bottom, going to try to avoid that, but I suspect I’ll have to do it in 2-4 places to help hold the battery platform down securely.

Also not pictured is the battery strap and J hooks, although you can see 1 eye lag installed on this side, and one on the other.

I’m just using some 1/4" plywood and 1.5x1.5 (so 2x2 nominal I think?) redwood that I just had laying around. No other reason than I had it laying around, and using the plywood to help hold it all together/hold it down in the trailer because I’m so very close to the max height that I have available. I might even have to trim the J hook threads down a bit with my rotary tool to make it work.

And since I apparently have the time before installation (tonight/tomorrow day), I’m thinking I probably should 3D print up some kind of cover for the shunt as well, for no other reason than I can and just in case. And I’m being paranoid about it.