Search found 4409 matches

by john61ct
May 30 2020 11:51am
Forum: Battery Technology
Topic: A123 26650 FIRE
Replies: 8
Views: 126

Re: A123 26650 FIRE

Yes LFP is much SAFER for thermal risks than most other LI.

But **any** high-discharge battery getting SHORTED!!!!

can basically explode, melt steel etc

not to mention just electrocute you (factors)

Be careful out there!
by john61ct
May 30 2020 8:18am
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

Well becoming familiar over time with a given pack does indeed lead to "proper monitoring", in the sense that you just know what the pack level voltages are, in order to avoid getting too far into the shoulders at the cell level. My main experience is with LFP, not the EV stuff, and let's just say i...
by john61ct
May 30 2020 6:49am
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

Okay, I see now the other post was hyperbole, since in one post 0.005 doubled to 0.010 .. "all points in their SOC" You falsely quoted that as having been written by me? here's your post https://endless-sphere.com/forums/viewtopic.php?f=14&t=106004#p1559415 Aha, mea culpa that was my quoting your #...
by john61ct
May 29 2020 1:26pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

Sorry Hummina for hijacking the thread

hope at least some of our back and forth is useful to its purpose
by john61ct
May 29 2020 1:21pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

Okay, I see now the other post was hyperbole, since in one post 0.005 doubled to 0.010 .. "all points in their SOC" You falsely quoted that as having been written by me? > throwing "mismatched capacity" into the mix Even a fresh bank from the best manufacturer, where each cell costs over $500, will...
by john61ct
May 29 2020 1:12pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

LiFePo4 does require somewhat more monitoring and periodic balancing. Again, I disagree. All LI chemistries need proper monitoring at the per-cell level. LFP needs much **less** frequent rebalancing than the other LI chemistries commonly used for propulsion so long as the usage is not abusive and t...
by john61ct
May 29 2020 1:05pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

And speaking of surface voltages, a zener diode could be perfect to bleed out any excess voltage above a certain threshold, but due to their "knee" point behaviour it's not practical. Are there more expensive zener diodes which are have a sharper knee point? 24 of these (for my 24S battery) and I n...
by john61ct
May 29 2020 12:58pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

> even 3.38V after charge is still not full False, if you mean after resting 24+ hours. If there is any **voltage** higher than even 3.35V after that, it is surface charge only, getting there only damages cells (reduces lifespan, even if only a few percentages) and does not actually result in any s...
by john61ct
May 29 2020 12:53pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

If you want both maximum range and good safety without a BMS cutoff, then balance at the bottom, and use cell level to to HVC when charging, accepting imbalance at the top. This I don't understand. Let's assume one cell has 0.4Ah less than the others. If I balance everything at the bottom, then eve...
by john61ct
May 29 2020 12:31pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

Of course this is an advantage. It makes measuring %SOC by voltage only a harder task within the 30%-90% spectrum, that is all. No, it does not. Cannot be done that way at the pack level with any accuracy anyway. Nothing to do with which style of balancing - top middle bottom - you do, the two topi...
by john61ct
May 29 2020 11:54am
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

How safe are the a123 cylindrical 26650 green B cells? I do know that if u drill through them they’ll ignite but at least won’t light the rest of the pack on fire..wasn’t me but my neighbor). But would it be possible to get them to ignite from purely electrical damage such as over charging or disch...
by john61ct
May 29 2020 11:50am
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

Avoiding wasting those tiny levels of energy is a silly goal when mains power is available. I agree that having dedicated balancers hooked up fulltime is not a good idea, but not because these balancers don't do a much better job than those built into normal BMS, they do that. Based on KISS IMO all ...
by john61ct
May 29 2020 10:54am
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

Having a midpoint balance is a "problem" with LiFe, since it's their advantage - the %SOC is extremely hard to detect in the midpoint since the voltage is at around 3.3V, and with the accuracy of voltmeters and wire resistances, you may find that even 0.05V difference in midpoint %SOC can result in...
by john61ct
May 29 2020 10:34am
Forum: Battery Technology
Topic: Any lipo checker that is not powered only from first cell?
Replies: 17
Views: 368

Re: Any lipo checker that is not powered only from first cell?

See PM for a dump of my raw notes.

Let us know what more you learn please
by john61ct
May 28 2020 5:12pm
Forum: E-Bike General Discussion
Topic: Want to build something comfortable, but issues with local bike path 'style'
Replies: 26
Views: 376

Re: Want to build something comfortable, but issues with local bike path 'style'

One of the puzzling things about US market bikes is the "comfort bike", which is intended for a similar purpose to that of a Dutch bike, but set up badly for it, with a handlebar height and seat tube angle that are at odds with each other. https://cdn.shopify.com/s/files/1/0799/5585/products/7bbbde...
by john61ct
May 28 2020 7:48am
Forum: Battery Technology
Topic: 30Ah 28s LiPo from 7s bricks
Replies: 29
Views: 2113

Re: 30Ah 28s LiPo from 7s bricks

So there aren't any ready to go master CAN controllers people sell to work with their modules?

Would seem pretty easy to get an MCU programmed to handle that. . .
by john61ct
May 28 2020 7:38am
Forum: E-Bike Technical
Topic: Reducing controller's current
Replies: 4
Views: 102

Re: Reducing controller's current

The controller should have limiting settings.

A CAv3 can give you that if not.

Or just go to a less powerful motor!
by john61ct
May 27 2020 10:54pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

I don't take LFP CV past 3.45Vpc, any higher is no point as you say no useful energy stored there. Resting 3.33-3.35Vpc is Full. Also as stated the balancing point can be at midpoint, or bottom, no reason to balance at the top, many reasons not to. Nothing to do with any advances true for nearly a d...
by john61ct
May 27 2020 5:33pm
Forum: Battery Technology
Topic: 40T, neodymium magnets, plasti dip cycle test
Replies: 88
Views: 1563

Re: 40T, neodymium magnets, plasti dip cycle test

And of course the kind of vibration / shock something fixed to bike experiences is many orders of magnitude higher than tremors passed through the ground
by john61ct
May 27 2020 5:31pm
Forum: Battery Technology
Topic: 40T, neodymium magnets, plasti dip cycle test
Replies: 88
Views: 1563

Re: 40T, neodymium magnets, plasti dip cycle test

While actually measuring resistance, would be interested.

Weighted pull tests are how you establish milspec rating for gas-tight crimps, but there, the full conductivity remains right up to where the physical connection tears open.
by john61ct
May 27 2020 5:24pm
Forum: Battery Technology
Topic: Creative Cooling Ideas?
Replies: 44
Views: 888

Re: Creative Cooling Ideas?

Generic data loggers Logomatic from Sparkfun https://www.sparkfun.com/products/12772 decent analog logger (8 channels) for $60, and can log to an SD card. https://endless-sphere.com/forums/viewtopic.php?p=1525900#p1525900 txt log files, open in spreadsheet to graph https://forums.adafruit.com/viewto...
by john61ct
May 27 2020 4:48pm
Forum: Battery Technology
Topic: Any lipo checker that is not powered only from first cell?
Replies: 17
Views: 368

Re: Any lipo checker that is not powered only from first cell?

For one hour, it would only draw 50MaHr of pack capacity. For a 10AH pack, it would take 200 hours to deplete pack (10,000Mahr/50MaHr = 200). For a one hour ride, you would use about 1/2 percent of pack. Is it possible to calculate the voltage difference that would result between the first cell (po...
by john61ct
May 27 2020 2:43pm
Forum: E-Bike Technical
Topic: Bike Throttle Replacement Search
Replies: 7
Views: 243

Re: Bike Throttle Replacement Search

Yes apparently the box arrived (thank you!), but I may not get back to that location for a few weeks
by john61ct
May 27 2020 2:40pm
Forum: General Discussion
Topic: Thoughts? Ebike ticketed/conviction upheld (Canada)
Replies: 142
Views: 2524

Re: Thoughts? Ebike ticketed/conviction upheld (Canada)

NYC is my city, and I very rarely go anywhere near it these days. I understand NYPD is very draconian about confiscating bikes that violate their crazy-conservative regs - plus big fines and now have millions of dollars' worth in city warehouse waiting to get auctioned off or scrapped or whatever th...
by john61ct
May 27 2020 2:33pm
Forum: Battery Technology
Topic: looking for the simplest balancing circuit
Replies: 42
Views: 1065

Re: looking for the simplest balancing circuit

There are literally dozens of different types all over eBay and Ali etc, seen also on Amazon priced higher. called "non protective BMS" or equalizers but I prefer calling them dedicated balncers. Better ones go for hundred$ at high amp balance rates, high voltage S-counts like 24S, ability to balanc...