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Small update: I talked to BigBattery and here is what they said on the topic of their products with new cells: I then asked if that meant that the products with new cells should have cells with similar internal resistance and capacity and he said

I see Will Prowse linked some BigBattery battery banks from his website...and damn if the price doesn't beat the ebay mysterymeat price for LiFePO4 batteries, even were I to DIY the whole thing myself. What do people think? Worth taking a chance on? Specifically, I'm looking at their 24 V...

Talked to Samlex this morning, they were really helpful. Thanks @Dzl I honestly didn't know I could use them as a resource, that'll be great in the future. They said that I DON'T need the breaker near the positive inverter/charger terminal because if the EVO detects a short while it's...

For what it's worth, Samlex just put the 175A breaker size in a table and didn't provide context regarding whether it was the minimum or exact size needed. Plus they had a diagram with a breaker coming off the DC positive post of the inverter/charger, and they never specified a size for that...

Thanks Dzl. Smoothjoey also responded in another thread and told me that the Victron will automatically switch ground contacts when plugged into shore power. Which is important for safety and insurance reasons in an RV, which is what I'll be using this in. So that also swayed me. But good to...

I'm reading over the Samlex EVO 2224 inverter/charger documentation. They say I should keep my battery cables together to limit inductance. Sounds good, but practically speaking there's also the positive buss bar and the negative buss bar (plus a shunt-based battery monitor and a shut off...

Thanks yall!

Thanks @MBR, that's a relief! Does that also mean that most folks here won't be using a battery enclosure unless it's something to do with temp regulation (like to keep the batteries warm enough to work on a cold night)? Do people put something over the battery contacts just to stop accidental...

Thanks, your explanation helped. I think I understand the stuff in the code box now. Or I understand it a lot more anyhow (still working through it...may need to come back to it tomorrow). At the very least I see that I was going to put the disconnect switch on the wrong side (the negative...

Oh, I should have checked that. Honestly I just looked at the color and thought "that's not copper, so it must be aluminum"

I'm trying to choose my battery and after hearing some iffyish things about Bigbattery.com batteries I'm expanding my search a little. I see that the Electric Car Parts Company is selling a 200AH 24V LiFePO4 battery for a decent price ($1,900 plus shipping)--though it won't be available for...

I bet you're right!

Good point. I guess I had avoided that route because I didn't want to babysit the connection, adding ox-gard every so often to prevent corrosion. But perhaps I should ask: Is that how it goes? Or are ox-gard/NoAlox just used the once and then I can forget them?

I have the same question as the OP. I think. For the purposes of reviving this thread (or if mods would prefer I can move this to a new thread) I'll try to state what kind of battery bank I intend to create: I will create two 100 AH, 24 V batteries (each made from eight 3.2 V cells wired in...

Oh yeah, I know.... I was trying to say that with a 24 V system I'd save not only on wires but also on the BMS.

OK, so what if there was an easier solution... What about just using two buss bars to connect the distant battery terminals? Like this: Would the fact that the "new" buss bar is close to twice as long as the old one be a problem?

Yeah, exactly. I need it to power the fan on my chinese diesel heater. But I do know that some folks do hope to heat their whole van or trailer with the magic of solar power, so I appreciate you making sure I wasn't one of those :)

I'm about to get eight of the Xuba (or whatever the replacement supplier is) 280 AH cells from the group buy thread. Hooray for that, I'll save some money! I'm trying to pick a decent BMS (and maybe a balancer?) for this setup. This unnamed BMS from Electric Car Parts Company has been...

That's really helpful @smoothJoey, I'll go with the inverter/charger then. Really glad you took the time to let me know about this stuff. Sorry to hear about the migraine and I hope it passes soon.

So what BMSs (or BMS/ battery balancer pair) should I look into if I want A) Something that'll give me 200 A of continuous discharge current capacity for my 24 V 280 AH LiFePO4 battery bank? B) Something that'll keep said bank reasonably balanced. I don't care if it's balanced actively or...

Oh, right. I was more concerned at the time with just having all the wires go to the right place. But now I've added in wire sizes, appliances, and fuse sizes for all of the appliances. One question I have right off the bat is whether I should be fusing the positive lines from the busbar to...

Definitely the former, and it wouldn't be used while I was plugged into shore power. And I should have said, this is for a mobile application. Thanks, that's kind of what I'm hoping for. Except shore power is (ideally) connected to earth ground, whereas a generator that I store in my truck...

Oh, very interesting. So if I understand him correctly, he's saying that some generators don't bond the neutral and ground lines in the generator. The bonding of those two lines in the generator (at the source of the power) would allow errant current to return to the generator via the ground...

I've read that active balancing is really more helpful if you'll be topping up your batteries instead of charging to 90%. So would I be ok with the 35 mA of balancing that the electrical car parts company BMS offers if I just wanted to do "passive" balancing?

Huh. I'm not sure I understand. I thought the two protessive dynamics chargers would be...like I set them up and plug them in when I want a charge, simple as that. Is it not that simple? (I want to use the progressive dynamics chargers because they're meant for LiFePO4 batteries)

Oh, ok. So FET vs relays/contacts are just two ways that BMS' cut off the battery from the rest of the system when certain conditions are met. And probably it doesn't matter to me except that it might be hard to find certain sizes of the FET-based one. The chargery you mentioned looks good...

@Steve_S I know it's been a bit--been dealing with getting booted out of the campground I was going to spend winter in because of a lockdown--but now I'm back to the project, and I've got a follow up question: Any reason not to use the Chargery 5008B Balance Charger instead of the QNBBM active...

Would you mind linking to the other thread? There are so many threads that mention "group buy" in the title I'm not sure where to look.

One final thing: @Steve_S I'm looking at the chargery store and I see the options for the DCC um, add-on I guess. I found your thread on the topic but some of it is still greek to me. But I gather that it's good to have because it protects from surge currents? Does that mean I don't need a...

Thanks @smoothJoey, just what I needed! I'm thinking I'll use a 30 A buck converter, though at this point I'd only ever need maybe 16 A maximum of 12 V--and that's on startup power for two devices, if they ever came on at once. The 30 A is just in case I want to add more stuff later. I'm...

OK....just saw that for large cells passive balancing may not be enough (just because the current offered for passive balancing by the BMS is often sized for a smaller cell), and many people find it needs active balancing. So if the consensus is that that's the smart thing to do then maybe I'll...

Hopefully this is a simple question: What size mounting bar do I need for the MRBF fuse I'm going to mount to my inverter's positive lead? The hardware: 1) Samlex EVO 2224 inverter/charger. Here's a picture of the back. I've circled the part that connects to battery negative (actually...

And wouldn't the same be true about the fuse between the positive busbar and the multiplus? As in: the fuse is sized to protect 1 gauge wire, and that's the wire I'm using to connect not only the battery to the busbar but to connect the busbar to the multiplus. Or is it more that the...

Once again, this is just great. Thanks for the link (which you shared earlier but I missed) @smoothJoey, I've bookmarked it. I didn't realize that smallish or undersized wires could cause voltage to drop. And thanks in particular for this quote @Hedges I was just wondering about this...

Thanks @Dzl that makes sense. OK, so I'll bring my fuses a bit little under what the perfect temp rating of the wire is to make sure they blow first. And of course I'll make sure the fuses stay above 125% of the expected load. Great!

Hah, maybe it does for you. I'm a klutz. Thanks, I'll wrap it in electrical tape and be as mindful as I can.

Hi Yall Encouraged by some excellent help with my last question, I've decided to look into not only wiring up my own system, but putting together my own LiFePO4 battery by getting cells from Ebay (rather than getting something from, say, Battleborn). I see what look like some pretty great...

Interesting, they don't allow soldering at all, or they don't allow soldering of connections in the 120V side of things?

Thanks @Steve_S Hmm... -I don't need bluetooth monitoring. Just need to be able to plug something in. -Hah, I don't even understand the purpose of the relay. Is that the thing that would let me shut down the inverter/charger if the BMS shuts down so that way I can plug the inverter/charger...

Interesting. That looks pretty handy for a mobile application...

Thanks, that's really good info.

Thanks @Hedges So just to make sure I've understood what you're saying...does this line up with what you said?: 1) The Midnite surge protectors will protect my electronics from shore power surges as well as, hopefully, near lightning strikes (which is what I see them advertised for, so I'm...

So in your setup, does the battery function as a surge protector of sorts? Is your outlet strip placed between the shore power source and your charger, or between your inverter and your devices?

Hah, I did catch that right after I posted, and edited the post to fix it ;). But that was going to be my next question: The Samlex document doesn't mention a fuse on the inverter/charger, but I was told...I think by @smoothJoey, that because it's an inverter/CHARGER it will function as a...

My batteries will be LiFePO4, if that makes a difference.

My apologies.

Thanks for posting this, that's my situation--well, the part about using two smaller busbars per terminal is--and I hadn't realized I had to clean off the tin oxide on the side where I smoosh the two busbars together. Would I be ok using a metal file to get this off? Or would that leave the...

Thanks for the recommendation @Zil Can you explain the benefit of using a DPST vs a SPST circuit breaker in your situation? Or is it even something that I should be worrying about at this point?

Here are the chargers I'm talking about, they're the ones Prowse links on his website: https://battlebornbatteries.com/product/progressive-dynamics-12v-45-amp-lifepo4-battery-charger/ https://battlebornbatteries.com/product/progressive-dynamics-12v-60-amp-lifepo4-battery-charger/

Oh, that's really interesting. If they are cycled down to 3kWh usable capacity, should I expect them to have as many cycles as a "new" 3kWh LiFePO4 battery?

Ooh. I'll do that. Then I can coat the handles on some other tools too while I'm at it. So funny to think that all these insulated tools are SO much money, but I can insulate a whole batch of my own tools for $5-20.

Hi Yall It's come to my attention that I should have a surge protector for the electrical system for my cargo trailer conversion. However there seem to be a dizzying array of these things, and because at least some of them seem to work by sending excess voltage to ground, I'm not 100% clear...

My current system design, if that helps:

Oh interesting. How did you get the screws to grip the insides of the 1/4" aluminum sheet? I didn't think metal would accommodate something like that :unsure:

Interesting. Any idea why it did that? And other than "being quick about it" is there a way to avoid this? Like, I don't know, using a disconnect switch?

Here's the one I'm considering. Honestly I have no idea if it's considered to be a cheap one ?...looked better than some though. Is it mystery meat or is it hamburger (I'm guessing it's not prime rib)? Ah, I see. In case my buck converter is considered to be "good," would it still be...

OK, thanks again. So to make sure I understand...are you saying that we want to measure the voltage difference between the DC neutral bussbar and the ground wire of the AC system (when it's connected)?

Fantastic! That's probably more humidity than mine will deal with most of the time...

Oh...so I'm removing the oxidized layer of tin but not the tin itself? Did I understand that correctly? Or are you saying I should be careful not to remove the oxidized layer on the outside of the new bussbar sandwich?

Bumping this. I'm still very definitely confused :) @smoothJoey or anyone else?

Hi Yall It's come to my attention that I should have a surge protector for the electrical system for my cargo trailer conversion. However there seem to be a dizzying array of these things, and because at least some of them seem to work by sending excess voltage to ground, I'm not 100% clear...

Huh, that's good to know, guess I'll have to call Progressive dynamics and find out what's going on. Thanks for the heads up!

Sorry, just realized I posted this in the wrong section. Here is a link to the post in the right place. Mods: Please remove this thread. Sorry about that!

I imagine I'd zip tie it to the...well, to the board or the box where I'm attaching most of the other components.

...and on the page with all their manuals, the link doesn't work to the manual for the PD9145L or any of the others in that series of lithium battery chargers. Sigh.

Thanks Steve, I guess I'll ask Jason about the Balance Charger. Hopefully he'll get back more quickly than he did last time (it took a month)!

Thank you @Zil, that's the answer I've been looking for for a day and half! It does seem like a good idea. Should I be concerned that the inverter I'm looking at--which is the one that Prowse recommends--doesn't have GFCI integrated into it? Edit: And if it is a problem, could I plug one of...

Right, but the numbers don't match up with that in any way I can see. Other than that the value given does get larger in proportion to the actual dimensions. For example, a 1/2" wide and 1/8" thick buss bar has a cross section of 0.5" X 0.125" = 0.0625 square inches. Converted to square cm...

I'm in Colorado.

As I design my system I've realized that my negative bussbar will have more connections than it has posts. The situation: I was going to use a Maxibus buss bar with six posts. The connections it needs to make: 1) Ground Wire (From Victron Multiplus) 2) DC Negative (From Victron Multiplus)...

So I called BattleBorn and they confirmed that the battery charger I was looking at is indeed a dumb battery charger that just puts out a constant voltage but which is supposed to work for lithium ion batteries in conjunction with SOME BMS's, including the BattleBorn BMS. I've contacted...

My system diagram, such as it is:

Is it any different from a disconnect switch? I'll have a big bluesea 300A disconnect switch between the battery and the positive buss bar.

I'm willing to spend a bit more money for the right bussbar...but all the bussbars I've seen either have smaller connections (like with a screw) or not enough posts. Am I missing something?

@efficientPV thank you, that is very helpful! Actually, I think the most useful bit may be the chart I found in the paper where your center image came from: So if I understand this correctly, with the panels hooked up directly (without charge controller/battery/inverter) to a resistance...

Hah, ok... I admit, I'm not a programmer or at all familliar with the syntax of this code. I understand the legend well enough but I don't understand what the } and { are supposed to be telling me, partularly when combined with the upstream and downstream descriptors. Where should I be...

Part of my confusion is that if upstream { pos neg } means that something is upstream of the battery on both the positive and negative sides...that confuses me since there is some stuff between that and the battery, the BMS at least.

Thanks for the info on your Samlex EVO @Steve_S . If I can get away with the cheaper not-combined inverter/charger I probably will...but it's good info and appreciate your time!

Thanks @Hedges, good information! I'm so happy I have the folks here to tell me about little details like wiggling the stranded cable around a bit to make sure it settles. OK, so it sounds like I can probably combine the DC ground, Chassis Bond, and Surge Protector all together. Since none...

I...thought GFCI was just the way to go? It protects us from electrocution by cutting power more quickly than a breaker does, is what I read. Is there some other alternative I should be considering? Does the panel provide extra protection that I'm not understanding? Like I said, I would...

So if I'm understanding this correctly, you're saying that while you don't have a fuse on the inverter/charger's DC positive, you do have a breaker on the positive line between the inverter/charger and the positive buss bar. So what would the problem be with putting one of my MRBF fuses on...

I'm curious if you were suggesting I use de-ox as a way to remove oxidation or as a way to treat the metal to prevent further oxidation?

@smoothJoey if I got the Victron but only wanted to wire up a single outlet for AC (because that's all I'd ever use) then could I just use a simple 15 A breaker between the Victron and the outlet? And if so, would something like this work?

Huh, that's what I was wondering...the tinned copper seems really hard to find. What's the difference between the two, do you know?

Follow-up question: So I'm looking at the Samlex EVO wiring diagram and I see that in addition to the breaker between the EVO and the positive buss bar it suggests there be TWO breakers between the positive buss bar and the battery. I'm scratching my head about that. Why on earth would we...

Thanks @smoothJoey for your input! What's a "pita"? The shunt-based battery monitor is a good point, I'll add that to the general list. The problem with the "make two battery" thing is that if I get the 280 AH cells, I'd have to get a BMS made for 6.4 V batteries in order to have two...

You know, I looked for one and didn't really find one that ticked off all the points on...I think it was Prowse's checklist....that I'd want with a good inverter, but which also had GFCI sockets.

Ah, so this would be why when I double the cross-sectional area of the bar by increasing the lesser of the dimensions (say increasing a 1"X1/8" bar to a 1"X1/4" bar) the ampacity increases but doesn't double! Always great when stuff makes sense.

Oh, when I talked about "measuring" the difference between the DC neutral bussbar and the AC ground wire, that was in the context of the surge protector "measuring" those differences. Which is guess is the wrong way to talk about it, it doesn't measure the difference, it just kicks in if there...

After reading this article about Lithium battery fires, I came away with the impression that LiFePO4 batteries should be encased in some sort of fire-resistant enclosure. Honestly I'm kind of fuzzy on this, they had a picture of some kind of bag. I gather there's also the issue of protecting...

Ah, that makes sense. The flow direction reverses! That's what I was missing...

Oh, I didn't know that...and I've already bought the Eaton MRBF fuse, I thought I was fine since the Samlex manual specifically said they were ok! Could you explain a bit more about this? I looked up the interrupt capacity for the MRBF fuses, it seems to be 5000 A @ 32V (my system is 24 V...

OK, so I'm sure this conversation has been had before but...I just watched the Prowse Video where he says "don't use an active balancer" unless and then he lists a few situations where it might matter, including if the cells are mismatched (because you didn't buy the highest grade of cells) and...

Thanks Chrisski. That's a really interesting table...but now that I'm trying to use it, I admit that I'm a bit confused. What does it mean by "cross-section area"? It doesn't seem to be a reference to the bar's cross section...or at least a bar that's 1/2" wide and 1/8" thick does not have a...

@smoothJoey another follow up: If I get the victron multiplus inverter/charger, will the battery monitoring software on that be as good as the shunt-based battery monitor you mentioned? In other words, would I still need to get the shunt-based battery monitor if I get the multiplus (with...

Well I want to join the extrapolation fun! Here's a chart from batterblog.ca, which I've never heard of before (not that I would have heard of anything...I'm pretty new at this): But if this holds true then the capacity does indeed fall of a cliff (or at least roll down an increasingly steep...

OK, good to know. If that's how it's generally done then maybe I shouldn't try to reinvent the wheel. And it seems like a breaker will only cost me $30 or so, so compared to to the rest of the system, it's not breaking the bank.

On the other hand this offering from Big Battery says it's using NEW cells. Makes a big deal about that. Do we know anything about Model 3 2170 cells?

I do understand this, it's just that the only reason I'd go 12 V instead of 24 V is that the 280 AH battery packs can be a lot cheaper per AH than, say, 135 AH battery packs. If the cost were similar I'd probably move to 24 V rather than make two 12 volt batteries out of the 135 AH battery...

When I size fuses for these wires should I assume that the fuses will also lose ampacity in the heat? For example I've got a water pump which claims that although it's a 24 V device, it'll need 4 amps. Seems like a lot but whatever. The wire run (there and back) will be 40 feet, so according...