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Thanks. I'm still a bit stuck on why this one cell isn't balancing and I suspect the JBS BMS isn't send balancing current properly. I drained the 3 higher cells with a lightbulb, and #4 cell briefly lit up with the "B" balance icon, but since then, nothing. The other 3 cells are constantly...

you're right - 1/4" should fit m6 ok. I was thinking of another issue, oops

Exactly this. Relocate the shunt so it's reachable by both identically sized negative leads and attach both to the battery minus terminal. Then a jumper from shunt system minus to the negative busbar, just as you have it.

I'd be tempted to reconfigure the 4 banks into 2 of 6P4S. Would add stability to the runners. And still provide redundancy. (And a bunch of spare parts). Hard to tell from the pic the difficulty, though. But maybe a better approach would be to just replace the cells with new ones and sell...

Since you have two, first compare both temperatures, then extend one, and compare again to make sure they are still in sync. then do the 2nd one. That's my plan, anyway.

More thoughts on the bow battery: The advantages I’m seeing for LFP for the fore bank include: Getting 2x AGM heavy monster batteries off the bow. The thruster in its current configuration is barely supported by the AGM’s. We are supposed to only run the thruster for 4 seconds at a time to...

Good info thanks. I'm planning on a 4p4s, so I'll keep that in mind and be ready to split it into two batteries if it gets troublesome.

Seems like you are on track for success. The balancing on a JBD is super slow, so it will take days and weeks of eeking it along like that. Frustrating, too, when hitting the 3.65 cutoff voltage. I had the same issue, but have access to the cells, so just attached a capacitive active balancer...

Awesome, thanks. It's weird #4 is consistently low, but it crept up to within 0.03v after twice running through draining #1-3 and charging everything up. Now up to 14.4v, and the Vdiff range is only 0.03v, so good enough? I think I'm ready to do a pack load test and see how it performs!

good find but those are 1/4" - and it's hard to find bigger, in general. so would need to snip the rings or drill and tap the busbars - which I did anyway ? edit: you're right - 1/4" should fit m6 ok. I was thinking of another issue, oops

This is for an Island Packet 380 sailboat. It’s currently outfitted with 3x AGM’s for the house, and 2x AGM’s for the windlass/thruster. Everything is 12v. Here’s the system I’ve been sketching out: House battery: 4P4S EVE LF304Ah LFP cells Windlass/thruster battery: 1P4S EVE LF304Ah LFP cells...

[updates added here as appropriate] - Interconnect fused at both ends near batteries.

@greyghost, et al. I added a new topic that crosses over well with this thread if anyone here would care to join in :) https://diysolarforum.com/threads/lfp-system-design-with-interconnected-lfp-windlass-bank.33964/

I have a new 160Ah 4S pack and I'm using a brand new JBD-SP04S034-L4S-200A BMS for top balancing. My cell #4 has stopped balancing and is stuck around 3.38v, the other three cells active balance ok at around 3.5v. Confirmed voltages are correct with a multimeter. Tried removing and reseating...

Hey - I think I figured out a way to automate this top balancing process using only the built in balancing. First, make sure you are set to only balance when not charging. Then, under Parameter View, top two values: - set the overvoltage to 3.55v - set the overvoltage release to 3.45v The BMS...

Great info, thanks. A ring terminal with the proper wire caliber to fit the sensor would probably work very well for that. Maybe a little thermal paste + gentle compression to keep it in place.

Thanks for the color info. I am in the process of top balancing them using the BMS balancing function per Off-Grid Garage's method: I have reached the 13.8v level with balancing turned on - so why is this one cell not balancing? A user on reddit is reporting the exact same issue with the...

[de-dupe]

Thanks, I appreciate that! Super helpful to read through and make sense of it all. Great info. I did update after manually equalizing the higher cells a couple of times: And now I'm seeing Vdiff at 0.014v for the pack at 13.8v, so good enough for now, I'll say. [update after a couple of...

PSA: *never* use silicone around electrical connections - if MIL-SPEC is to be believed. It is a very effective insulator and will mess up connections like switches, etc. Again, according to MIL-SPEC.

1-2-BOTH selects source for the house load. Will be in BOTH unless a bank is down for some reason. So both banks usually share loads in parallel. Bow battery is always connected directly to the windlass/thruster via bms/contactor regardless of switch setting. From what I'm seeing, it's not a...

I have a 4s LFP in an RV. Looking for a BMS with separate charging input and low-temperature protection. Any Suggestions? [Here is my long winded legacy post:] >>> I have a DIY LFP battery made of A123 cells and a 100w solar panel in a Westie camper. I'm concerned when it gets close to...

Thanks for checking my work and watching out for well being :) No charging or balancing woes here. Yep, my power supply is an Iota DLS-30. With the plug in it tops out at 14.2v, so that's still just 3.55v/cell, which I'm calling 100% I initially top balanced it 6 months ago with a bench...

Awesome - this is for an IP 380 :) Have you looked into an external contactor for the BMS? And yea, the current draw over that distance makes for a very large conductor - that's another reason I have for two joined banks. That's going to be a large conductor for the windlass, right? The banks...

My experience with them in spring 2022 was mixed. The website was very glitchy. Email response was lacking. But eventually, everything was sorted out. Prices were good. Gear was picked up from will call, so no delivery experience here. A refund for cancelled items eventually processed. My...

Are you running both 200A BMS's actively in parallel at the [P-] outputs? Or how are you splitting the load? -thx

Cool. That's interesting that you are more towards multiple packs vs. fewer bigger packs. I know there was some chatter toward that decision, but I never saw anything compelling except for in the case of older, damaged cells that need more troubleshooting. Do you think it's plenty viable...

Thanks for this contribution, but it's hard to follow. Could you please edit your post to be more clear on what this refers to: and which 'balance voltage' is this? I think you mean 'Balance turn on voltage'? I think I like this, and would say that using 3.55 or 3.60v as the highest value...

Interesting idea. And why not just make the windlass bank tied by a bigger conductor which would allow it to supplement the house bank. Either way it would need its own BMS, so no wasted effort there. Also, if you needed to take the house bank offline the windlass bank could fill in at a...

Great to hear it's working for you! The cost difference is minimal for 304ah cells which will be identical to the house bank, so better interchangeability. Also, less risk of depleting the bank. Another bonus is that it supplements the house bank with an additional 25% capacity. But the...