Most reacted posts

  • Post in thread: Any reason why MRBF seems to be recommended over ANL so often around here?

    Thanks @HarryN for that thoroughness. It seems on this forum that if you follow every 1/1000 gotcha you quickly end up with only one solution (class T) according to the hive-think, yet, in 90% of built systems and examples, even by lithium battery manufacturers (who often show an ANL or MRBF...
  • Post in thread: MIDI-based alternative to MRBF or ANL with higher AIC

    Just sharing this fuse option for those with smaller systems considering MRBF or ANL: Littelfuse MIDI High Performance 70V (Available at waytekwire, mouser, digikey and other places for about $4). It has 2,500 AIC @ 70V (Spec sheet doesn't list lower voltages, but if it functions like all the...
  • Post in thread: 2S 12V batteries, initial balancing off grid with mppt or by putting in parallel?

    Thank you, @Vigo , it looks like I'll be doing a single 24V after all (ended up buying cells instead), but your explanation was very helpful.
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    First off, I'm off grid, so I don't have the ability to easily charge batteries besides through solar and doing a full discharge is risky because it leaves me without power if I get the weather predictions wrong. I bought 8 LF105s from ezealco (here), hooked them up to a JK BMS, set...
  • Post in thread: MIDI-based alternative to MRBF or ANL with higher AIC

    Looking closely at spec sheets just before ordering, I think your AMX find is better than the Littelfuse MIDI Hi Performance because it actually followed standard AMI/MIDI size -- it looks like the Hi Performance one has the holes spaced at 36mm instead of 30mm. The AMX one is 30mm (like all the...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    Yes perfectly flat, and the QR codes don't look to be relasered to me based on what I've seen on the forums.
  • Post in thread: Battery SG tests show ~60% SOC, but Voltage drops to 6v under load.

    I'm in the process of ordering a replacement LFP battery, but am still trying understand what is on with my FLA bank (4x 6v GC-2 215ah) which I've had for about 6 years. While I've always had voltage drop issues on my battery bank (for about the past year it has often been dropping to by 1V or...
  • Post in thread: MIDI-based alternative to MRBF or ANL with higher AIC

    This 6mm extra seems to be a thing with Littelfuse. They have a MEGA High Performance series too (as much as 2500 @ 120V!). They say in the catalogue that they are 6mm wider so that they aren't accidentally replaced with one of the standard fuses by a user (say, in an automotive application)...
  • Post in thread: Battery SG tests show ~60% SOC, but Voltage drops to 6v under load.

    Yes, I roughly understand the concept of how the batteries degrade. What I don't understand is why my batteries went from performing as poor as one would expect for degraded batteries (say, around 50% of original rated AH), to completely unable to supply power to a 500ma to an LED light without...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    Capacity tests are done at multiple temperatures (thus the included chart for temperature). This cells particular data sheet only happens to show 55c/25c/-20c lines at 1C. 13C is definitely not -20C. Sure, it's a bit under 25C (less different than 55 to 25 though). But also, I'm doing 0.35C...
  • Post in thread: Battery SG tests show ~60% SOC, but Voltage drops to 6v under load.

    Also, these batteries haven't been constantly floated. If anything they've been abused in the opposite way and failed to make it up to float half the time. But I'm not that interested in why batteries degrade, they're 6 years old and I'm ready to move on. I'm interested in the catastrophic...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    Note you can see the erratic readings from the BMS there too -- the voltmeter didn't report that much variation. Nor does the shunt have the same amperage. The BMS is way out of wack on calibration of voltage/current and a heavy load exacerbates that -- this variation isn't seen on the shunt...
  • Post in thread: LVD/BMS redundancy and apparent contradictions

    I get if there's a criticism of FETs in some specific high amp bank configurations. What I don't get is if people recommend a FET in an emergency LVD device (Victron BP) to avoid a FET in another LVD device (BMS)... or worse, the Electrodacus eschewing a reliance on FETs and then relying FULLY...
  • Post in thread: LVD/BMS redundancy and apparent contradictions

    @TacomaJoe Since those dc lighting loads are going to be low current, it seems to me that especially in that application one wouldn't be stressing the BMS very much by setting the BMS LVD in-line with your voltage safety margin you want for the other LVD. If the lights are, say, 20A (that's a...
  • Post in thread: Any reason why MRBF seems to be recommended over ANL so often around here?

    A bit confused. I keep reading a generality that MRBF fuses have higher current interrupting capacity than ANL (usually from posts asking about class T alternatives), but I keep finding the opposite in spec sheets. Apples to apples: BlueSea MRBF 5000A @ 32V vs BlueSea ANL 6000A @ 32V. Spec...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    I'm highly doubtful there's anything wrong with the QR codes. The phone somehow blurred or couldn't capture one in the corner. Definitely working way up to being sure of a full charge. But it will take days with the weather. I drained them to disconnect and am instead counting amp hours on the...
  • Post in thread: Any reason why MRBF seems to be recommended over ANL so often around here?

    I understand that ANL is specifically not rated for 32V max. Beyond that, though, I can't see anything other than a form factor preference (or a preference to ANL for price and slightly higher IAC). While at the higher voltage, the ANL wont work, at the lower voltage, it appears to extinguish...
  • Post in thread: Any tear downs or experience with RoyPow 24v 80ah metal case?

    I'm looking at this battery by RoyPow: https://www.18650batterystore.com/products/roypow-24v-80ah-lithium-battery-s2480-a-heated-ip67 https://www.amazon.com/Lithium-Rechargeable-Scrubber-Trolling-Electric/dp/B09SYZCYDS Strangely full of higher end features for the price (and priced much lower...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    Ok, so here's the update. On the charging, I had to push my SCC almost all the way up to 3.65VPC to get the shunt to report up to 105Ah. The JK BMS itself has terrible current estimation. It's low resolution, unsteady, and jumps all over the place -- plus it seem consistently off by a good...
  • Post in thread: MIDI-based alternative to MRBF or ANL with higher AIC

    @740GLE - Fortunately all these products have spec sheets. Simply look up your chosen MEGA fuse and compare AIC. Most MEGA fuses I've seen are 2,000A @ 32V. So yes, these should be much better since they are 2,500A @ 70V (which is absolutely better, but, in theory, it should come out to at least...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    Note that the unusually low voltage relative to SOC and the final cut off voltage under load was verified at the cells themselves, so while there could be voltage drop issues in the system as a whole, that variable should be eliminated from the test results. Voltage at cells was steady and...
  • Post in thread: 2S 12V batteries, initial balancing off grid with mppt or by putting in parallel?

    I'm redesigning my system and switching to LFP. I need a 24V 50ah or possibly 100ah (depending on price-value ratio). It seems that the market provides better prices and better features on average if I do 2x12Vs than if I try to get a single 24V. Plus, I'd have a bit of resilience in the event...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    That's a weird jpeg encoding problem or something with my phone. Bizarre looking.
  • Post in thread: LVD/BMS redundancy and apparent contradictions

    I'm a bit confused why there's a universal recommendation for an LVD in a LFP bank with a BMS. The only argument I hear repeated over and over is in the form of a truism: "your BMS *should* be the last resort for protection." But, what exactly is the technical reason for this? As far as I can...
  • Post in thread: Fusing Panels

    I'm going to be wiring some new Hyundai 305W panels (9.86 Isc) in 2S2P. I believe the fusing/wire is rated by Imax which is calculated by Isc * 1.56, so that's 15.3 per series string/panel. These appear to have 12AWG. The spec sheet says maximum reverse current 20A. Since two strings...
  • Post in thread: Fusing Panels

    This is news to me. Can you point me towards an explanation. I'm assuming this is some nuance I don't understand about the max current the panels will experience, but I'm not quite understanding what that would have to do with the limits on the cabling/connectors.
  • Post in thread: Fusing Panels

    My understanding is that Isc will multiply in parallel, and that wiring/connections and therefore fusing should be based on Isc * 1.25 * 1.25 (or Isc * 1.56). So in this case, with two strings, that comes out to 30.76A. That 30.76A appears to be particularly annoying. The MC-4, and the...
  • Post in thread: Fusing Panels

    @pvgirl - I'm thinking to just fuse it at 30A. What's the worst that could happen, the fuse blows? Then I'll know I need to address the problem. My suspicion is that the 0.76A will never occur sine the 1.56 represents multiple safety factors (1.25 for extreme irradiance and a 1.25 safety factor...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    Curious if there's some chance that the cells were never fully charged -- I've been doing an absorb at 27.6v (3.45vpc) for 30m (one day though the victron charge controller got stuck on absorb for hours though). Is it possible that I need to take the volts closer towards 3.65V initially to be...
  • Post in thread: New LF105 cells seem to have a sudden drop in capacity, bad cells? Something else?

    @Partimewages On one day by accident it was held at 3.45 for a few hours. But, in general, I was following off-grid garage and other conservative values that indicated 3.45 for 15m up to 1hr was plenty to ensure balancing, and that going over 3.45vpc served no purpose other than to trigger...
Back
Top