Endless Sphere

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...

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 discha...

I just got a bunch of lifepo4 cells and am wondering what you mean when you say this: “ Lifepo4 can be in balance and still reflect +/- 0.05V differences between series groups, so it's impossible to know their status without balancing regularly.“ Are you saying lifepo4 cells are different than other...

john61ct wrote: ↑

May 12 2020 9:35pm

A shorted cell does not usefully store any Ah at all.

right you are, and then it wouldnt be a battery would it, and i wouldnt be trying to get accurate amp hour measurements from it.

i see youve bombed me with nothing related.

i have a theory based on solely ohm's law yes. i was given the impression there were other variables and that i was being told about them but i wasnt taking. maybe there are no other variables.

as far as i understand dentrites dont effect capacity, no?

That’s why I say hypothetically. The point is to discover what the other variables would be. IF running two identical resistance and temp cells through the same simple resistance till discharged what would other variables be that world effect the time till total discharged. Assuming there are other...

i didn't post a theory. i posted a THEORETICAL question. If you where to ask what would happen if the sky were yellow....that sounds like an interesting question to me as well. No one is "trying to help me by "telling" me what the other variables are" as no variables were presented. Am i wrong? if p...

That’s why I say hypothetically. The point is to discover what the other variables would be. IF running two identical resistance and temp cells through the same simple resistance till discharged what would other variables be that world effect the time till total discharged. Assuming there are other...

> What u mean broken in properly. Commissioning, break-in period, battery pack’s capacity will be activated to its full capacity after X cycles. Best to keep C-rates low before then. See SEI formation. > And what u mean esir internal resistance, GIYF > what would be a variable in determining the ca...

What u mean broken in properly. I’ve never heard of that for lithium batteries. And what u mean esir what would be a variable in determining the capacity of two cells in relation to each other if both are of the same model, temp, and resistance and both are put to the same resistance to discharge un...

I meant if hypothetically the cells’ resistances and temp were all the same what other variable would alter the current drawn when connected to a simple resistor thereby ruining a capacity comparison.

Resistance will vary the current according to many variables, so not enough consistency. There are little 3-bulb testers, put a pot/dimmer on it watching an ammeter might get pretty close. With just using a resistor to discharge the cell the current will be dropping as the cell voltage drops of cou...

Thanks for all the info and I haven’t gone through it all even yet but wanted to get your thoughts on possibly using just a simple resistance as the dummy load. Ideal would be a load that kept the current consistent but in the interest of keeping it simple and cheap I figured I could time a cell I k...

I looked up cel test and nothing related came up I think ur over thinking it. If possible to get a very accurate and consistent current, let’s say 1 amp continuously, (maybe hard to do as the cell voltage will be dropping) and measure the time discharging that current from an exact top voltage to an...

I’d like to do like 40 cells at once. I Got 2000.

I want it accurate to within maybe 1-2%. Is that doable @hillhater.

I imagine would be a simple circuit and just requires precision current draw and voltage cut off. And a timer added of some sort would be ideal

battery resistance testers such as this: https://www.amazon.com/gp/aw/d/B07W3TCRYL/ref=psdcmw_14244451_t1_B0716ZL1SM#aw-udpv3-customer-reviews_feature_div aren’t a good revealer of capacity or cycles left and I’m looking for an easy and cheap test rig I could assemble for multiple cells at once. The...

That would be ideal electrically. The design compromises electrical equality in the p group for an ideal mechanical design where the cells being perpendicular allows unrestricted flex of the pcb and no cells touching or straining the nickel connections and safe. One day ill take the p groups apart a...

Ultimately wanted to get the balancers put on the pcb but decided that’s too risky with how brittle components are and the flexing of a pcb on a skateboard. Did add a balance plug. If anyone is interested in (36) 26650 A123 cells put on here I’ll sell them for 250$ From batteryhookup. I forget how m...

i ended up just adding balance traces so a balancer can be plugged in. enough trouble getting my step files converted to gerber as is without adding even a single bit on the board thanks for your thoughts. if any of you is good at designing boards and are interested in getting a battery built with a...

i had some pcbs made that i attached to cylindrical cells with a spot welder and nickel between and it was good. then I wanted to design it with balance traces to attach a bms. Now i want to just integrate the simplest and most reliable balance circuit on the board where i was fitting traces before ...

Everyone uses their vehicle differently and has a different battery but hoping someone has some advice: I have a battery I mostly use maybe only 1/4 of its capacity before recharging and wondering what’s the best voltage to be using that 1/4 to have the most cycles. They’re 30Q cells. To keep it sim...

What temp you figure is too high for cells to get when charging and can you just look to the cell temp as a guide to what deterioration is happening? What’s the best cell temp to start charging? I imagine there’s a lot of trade offs and you could go all out with cooling jackets but with cells being ...

Justin has measured saturation on a number of motors, there's an old thread on the subject. http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=14494 It's hard to saturate a motor instantly due to the inductance of the winding, unless you have infinite voltage to drive it with. Justin found it...

I was just saying if ur battery wires are long enough it’s worth adding caps to protect the esc. Ron’s guide here, the foreign Ron, is the most thorough guide I’ve seen. The foreign Ron is a powerhouse of knowledge hard to be compared to favorably.

Found it: https://www.rcgroups.com/forums/showthread.php?952523-too-long-battery-wires-will-kill-ESC-over-time-precautions-solutions-workarounds https://www.rcgroups.com/forums/showthread.php?952523-too-long-battery-wires-will-kill-ESC-over-time-precautions-solutions-workarounds/page58&pp=10#post24...