https://a.aliexpress.com/_EJFeNFb
This is the stuff I’m using. Passed the salt water test and have had zero problems welding.
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Is it true that some LLT BMSs have higher idle drain rates than others?
^^ Is this BMS one of them? I’m looking for one that’s 20s+, so the links posted by Artem above aren’t applicable unfortunately…
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is this a bad bms? After connecting the unit one group shows much higher than the rest, i confirmed with a meter and there’s no pack with this voltage.
I set the pack to static balance but idk if its doing anything. I also don’t have the correct charger to give this pack some juice at the moment, can i use another charger, or does the voltage have to match even though I’m not charging to full?
I was able to manually set the correct voltage in this menu, is this a fix or will it there be issues going forward with this more than likely bad bms?
I have never used that one
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The LLT BMS I just installed is off by something like 0.15 - 0.165v per p-group, resulting in nearly 2 volts in total deviation across the entire pack. Is there a way to calibrate these things?
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I haven’t messed with it but you should be able to set offsets in the voltage calibration menu to correct for that
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That worked perfectly. I was expecting 41.92v after calibration, and got exactly that. Thanks.
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Here’s a shot of the rear of the battery. I had to use braided copper because silicone cable wouldn’t fit because the enclosure was modified by eBoosted before being shipped to me (heatsink was removed, and it was reglassed, and gel coated) in such a way that I lost several mm’s of critical headroom. I should have put the batteries in the other end of the enclosure but I wanted a nice flat surface so that I could make the most of the potential to sink heat through thermal pads into the enclosure with regard to contact area.
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yep same issue on 1 group, was able to manually change it in that screen
Looks nice and tidy bro 
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Thanks, I definitely put a lot effort into that aspect.
It’s nice to be able to adjust it so easily.
Two interesting things here
@Battery_Mooch do you think either of these things (mostly the current path lengths thing) are worth keeping in mind for our packs?
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It is definitely a measurable effect that does happen in real-world applications. It’s usually pretty small, but with a poorly optimized pack, with lots of cells in parallel and high-resistance bus bars, it can become more noticeable. Minimizing it where possible (within reason) is a good idea.
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I don’t know specifically which other things you’re referring to but minimizing and equalizing current paths through a pack will always lead to better performance and longer pack life.
Whether it’s a tiny, unnoticeable amount or a huge fundamental difference in how the pack performs and ages depends on how the pack is assembled (or could have been) and how it will be used.
Keeping all the cells at about the same temp is really important for equalizing the aging of the cells too. Though that’s about impossible with the sealed packs typical of esk8.
IMO most esk8 pack builders will prioritize convenience and pack assembly speed over pack performance as the paths are already fairly well equalized for most decently made packs and the ROI for beefing things up and adding cooling just isn’t very high.
Most builders are willing to sacrifice a bit of performance to keep the pack easier to build and to not have to add cooling (which is often impossible for the desired pack voltage/Wh).
Bottom line…it’s always good to keep the various best practices, like low interconnect resistance and good cooling, in mind but each builder needs to decide how far they will go for the resulting performance and cell life increases.
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I finished my battery builds and even though they work perfectly I cannot get them to charge through the BMS all the way to 4.2V per cell. I changed the setting in the android LLT app that considers “full” to be 4.15V, but still it stops the charge at approx 4.16-4.17V
This happens to the 4 batteries I’ve built (12S4P Samsung 40T brick packs), but I’ve only tested one charger. The charger is a YZPower 50.4V 8A BUT I’ve only seen up to 6.3A in the BMS app. Any ideas?
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Post all of your parameters settings.
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Here they are:
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I changed a parameter to 4.2 and it seemed to do the trick. I think what this does is as soon as any P group reaches 4.2v it stops charging them all to prevent overcharge. If I’m not mistaken
The setting I changed was “Overvoltage release”
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I changed it to 4.2 but it did nothing. Also the packs are very new and almost perfectly balanced, I have not seen any of the groups reach 4.2 while charging (I’ve been closely monitoring the first charge)
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