LHB - what is he even doing now

woah what year was that?

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the thread i was reading was 2015 i think

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6S lipo.

2015

NTM propdrive 270s, yes.

it would do about 27mph.

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just got back last night from PDX and it was fucking awesome.

the night before i got there, my 10Amp charger blew up (for my blue board) so i was stuck using a four amp charger after swapping the connectors. my board took 9 hours to charge. lol

Anyway, there has been some on-again off again discussion about batteries charging and when the green light comes on and when balancing happens, etc.

So i wanted to report that the 10Amp charger i have now is reporting its done with the green light, however, its still pumping 0.29 amps into the pack while it was green, with all cells being slightly over 4.15. It just now stopped, it did that for about 5 minutes or so. My BMS is balancing like crazy right now. So the green light definitely comes on before its completely done in some chargers.

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Someone in the Summerboard group was calling me stupid for suggesting people not pull their boards right off the charger as soon as it is green. The manual actually does say that it is imperative that it is unplugged and that damage will occur if it is left plugged in so I was kinda wrong to say…

There is something funky going on with that because I have no idea what the BMS / charger / cells could possibly do to harm the battery but there are confirmed reports of leaving a board charging ruining the battery somehow.

I am honestly just confused, the fact that Aaron the CEO was bragging that their battery has the top of the line 12S BMS chip from TI weirds me out a good bit about it all.

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i have left my packs plugged in all night on a regular basis for years with zero negative side effects. Sounds like they had some issues they couldn’t sort out and worked around them instead.

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So am I…

He said it was their top of the line chip?

TI has only one dedicated 12S BMS chip. It could arguably be their top of the line but it is expensive, hard to use, and so new there isn’t even a full datasheet for it. It’s made for very large, high voltage, functional safety-compliant EV battery packs and requires a TON of proper software testing to get to that level of safety.

Using it for an esk8 pack would be a spectacular waste of time IMO and significantly raise its price. Getting the software certified to be compliant with the safety standards the chip was designed for would be a long and frightfully expensive process too. It’s worth it for the major EV manufacturers (the intended customers) but a high hurdle for smaller companies to get over.

Using this chip and not taking the time and money to create an “ASIL-D compliant” (very safe) pack would be silly.

Perhaps he’s using one of their other great BMS chips that is capable of handling a 12S pack as several work with a range of voltages that include 12S. They’re all just as good as the other, just different to handle different requirements for the pack. There’s no “top of the line”.

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Li-ion cells really hate being left charging all the time. If the charger does not turn off the voltage to the cells, and lets them settle down to their resting voltage, then the cells can be damaged. The more often and longer they are forced to stay at the full charging voltage (because the charger never stopped) the worse the damage.

IMO if charging isn’t stopped automatically then they’re not using a charger, they’re just using a power supply and (maybe) hoping that the BMS stops the charge.

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They also don’t like being left fully charged all the time. This is one reason I have been experimenting with having my BMSs all programmed to balance all the time, constantly and slowly bleeding off the top cells in hopes of achieving perfect balance when it never really can.

of course i may be skewing my results by riding every single day but overall my packs are always balanced reducing the risk of over discharging any individual pgroup.

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Flexi has a setting to discharge to a specified voltage after a specified time. I set mine to 72 hr and 3.8v.
It’s really slow, but an injury allowed me to test it back in July. Pretty damn slick if ya ask me.

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I’m down to two Superflux GTSs now.

An old evolve mod customer who is not on this forum walked in and paid cash for one. I made sure he got an esk8.news t-shirt as well as one of mine and told him to get on the forum.

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Damn bro sucks about that superflux that was stolen, at least you can write it off…

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Stolen?!!! Whaaaaat!?!!!

Fuck thieves.

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just call brian. hell take their hands.

I enjoyed our lunch time tech talk at CarvePDX. After hearing that you programmed your SmartBMS to be balancing all the time, I decided to do the same with all my boards. Genius! I don’t see any reason why this shouldn’t be the standard for all builds with a SmartBMS.

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I currently do this and don’t ride all my boards. It seems fine. It’s helping that century stay more in line. Ish

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This can actually unbalance the pack (if balancing at lower voltages), forcing the BMS to do even more work at the higher voltages when charging and possibly extending the charging time.

Once top balanced there’s no need to try to account for the differences in how the cells discharge. These differences, that manifest themselves as the cell voltages drop, will disappear once the pack is recharged. The cell-to-cell voltage differences during discharge don’t mean anything and are expected.

Using an always-balancing method, to try to extend pack run time, could only work if a charge-transfer balancing method was used anyway as passive balancing (which bleeds off charge as heat) just discharges the pack down, actually reducing your ride time.

There is just no need to balance except when nearing full charge, once the charge current has started tapering off and the limited balancing current levels can have a bigger effect. Previously top-balanced cells that discharge down to different voltages recharge back up to a balanced state if no cell damage has occurred and the cells weren’t left partially charged for a long time (where the differing leakage current levels can unbalance the cells).

Balancing before a pack nears the end of the charge is just the same as adding a parasitic load to the pack that only drains certain cells.

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If riding every day then this will have a minimal effect except to discharge your packs down, reducing run time.

There’s just no advantage in trying to compensate for differing cell self-discharge rates if recharging fairly often. There’s just no imbalance being created. You can do “normal” top balancing which stops soon and let the cells settle and start self-discharging. The differences in charge lost over the next day, or several days, will be minimal unless the cells are damaged or old.

This leaves more charge in your pack and the cells will still only require little to no balancing if being recharged fairly often.

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what happened? stolen?

Yes. For a fee, I allow my products to be stolen from my house. It’s simply all the rage these days.

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