@PlasmaHH "Macro"

I've seen "Macro X" but official SOT-103 or related

I believe "Macro" is the microsemi branding for this package, I have not found any generalized name, it seems every manufacturer has their own code for it'

good morning

hm, sot103 seems to be the "big" version, I was looking for an ~2mm version... not easy to find information on those things when you are not into rf

Is there a simple way to model a battery in LTSpice?

voltage source with series resistance?

not that simple, I'd like it to be chargeable and dischargeable. A voltage source with a cap in series gave odd results, but somehow showd that behavior

well, chargeable is a whole different thing.. anything else you were missing from your specification?

Large ideal capacitor, offset voltage source at 1/4th cell voltage, ideal zener at 1.1* cell voltage with a resistor in series parallel to that and then a series resistance

Possinbly some inductance here and there

If you want it very real-world-y you'll need further reactives to model the chemical reluctance

I think I understand your description, but I need to create that zener first

You could take a real-world-y zener for high power

But signal zeners will not flatten the curve

For a LiFePO4 I would say a Vos of 1.1V would do in series with the huge capacitor

(If you run below 2V you have poop going on anyway)

Then a zener of 3.9V-ish

With a series resistance of about 0.1V/(capacity)A

@Christoph there are libraries of tons of components for ltspice and/or standard spice

like so:

Don't have my book of spice at hand, but it might just contain some model suggestions... it's quite new

Isn't V4 already a battery?

also ltspice has a way to take an existing component and rename it, giving single properties new names

Wouldn't that have some modelled shit with current reluctance and what not

so I dont know how zeners are modelled, but if they have the voltage you can .model X ako:Y D(Vzener = 3.9)

I have never calculated anything concerning LiFePO4 modelling, so remember that the numbers I shout are blue-sky / "tumbled from the behind" kind of numbers

V4 already looks like a battery, but afaict it's just a voltage source with series resistance

Okay

I would probably not model them with a voltage source in it at all, it seems unrealistic. more like caps of thousands of F , several in parallel with different ESR

To that drawing you then add another series resistance, something in the order of 0.05V/(capacity)A and possibly a parallel resistance to the capacitor that gives t(rc) = 1 year

The offset voltage is a correction for the capacitor curve, of sorts, and if you drop below 2V with LiFePO4, your cell is going to die, so you should not care about the simulated behaviour below 1.5V

If you want to simulate LiFePO4 properly you need A LOT MORE components

Might even end up needing active components

Very likely actually

the hardest part to model realistically is the slow recovery of voltage after a big current draw

LiFe isn't too slow in that respect

But, all the more slow when you're in the last 10%

Hence the possible requirement of actives

3.6 -> 3.2V quick drop off ... stable .... stable .... stable .... stable .... 3.2V -> 1.7V quick drop off

3.2V-ish (probably drops from 3.28 to 3.17 in the 550mAh cells I stock) is at the least 70% of their capacity, if not more.

do you have a constant resistance discharge curve of them at hand?

So just capacitance will never really simulate it, but to see some battery-like behaviour anything with a resistance, capacitance and zener could do, depending on how accurate the time-based plots need to be

Nope

Can look one up from a brand though

I was wrong. it seems I can't

Although this person has some constant current-load graphs for a pack:

ka7oei.blogspot.nl/2013/05/lithium-iron-phosphate-lifepo4.html

The post then also underlines the importance of buying (or in my case building) packs with a balancing protection board

I don't know if my zener model works as intended, but the zener voltage is set to 3.9V, and the resistances are set for a 1Ah cell

maybe I should create a test for that zener first

avdweb.nl/Article_files/Solarbike/Batteries/… that graph looks useful

Only if you intend to abuse the LiFePo cells with double their rated current

Also....

ANR types are standard Li-Ion

APR (which they don't have in that size) are LiFePO

There's all kinds of wrong with that graph

No I'm wrong

i.stack.imgur.com/F388g.png that would probably near enough for my taste...

That number is LiFePO, they just never say that in the article on the website, unless you click on the other number

Which then says that the other one is LiFePO as well, and then checking the voltage that matches

Can't distinguish the line on this PC :-(

Oh hang on

Never mind

3.6V -> 3.2 doesn't go that fast on mine, nor do they jump back as much as that

But then, I do test them at 1/2C, since my cells are engineered for 1C limit (as most LiFePO cells are at the moment)

But apparently some do

I'm hungry and I need to pee... can't focus

Oh no! what to do first

ask on lifehacks.se

?

Peeing is always a more pressing issue

If not literally, then surely figuratively

bounce My new Rigol shit to play with is on its way to the Netherlands

we want part numbers

@Asmyldof this seems to work OK-ish

takes ages to simulate, though

probably because of D3

@PlasmaHH DSA815-TG + MSO1074Z-S + DP832 + DG5072 + DS4012

-s were the ones with function gen?

equally slow without D3 and V4

Yup

That's my take-along

Going to try to hack the DS4012 to become a 4052

Basically bought that one because it was discounted and I wanted to try the hacking

:-D

@Christoph hm, often the default models without specific models are causing this... try forcing double math and then lookaround if any of the voltages or currents look very jumpy in the phase where it takes so long

What's €1400 if it's a good lark >.<

the mso should be hackable too

just dont try the 500µV hack

Yeah, might do that as well

500uV hack?

Haven't read the topic fully yet

Just know it's there

yeah, some rigols have 500µV/div capabilities, and there is a code that enables all options, including thta one

but since hardware and calibration are not there for the 1000Z series, it fails miserably.

so edit in all the options one by one

I'm also going to try if the MSO has enough room for battery powered, as Dave said in his DS1054Z teardown

without the 500µV

Ah

But it does work okay for the 4012?

Of course prefer having a working one :-D

I dont have a 4000 series but I think it should, they have official 500µV options

See if I can chuck 3 or 4 10Ah LiFePO cells into the MSO with a buck/boost board

Would be fun

yeah it doesnt need much power, but I would be worried a bit about thermal issues. its not really cold inside there either

Should be fine. Can always add a floating metal deflector with thermally regulated 30mm fan

Going to make it an assembly that screws in place of the original PSU, so that I can always "undo"

If I were to modify it, I would probably add some connector so that you can add some battery pack, or maybe a car adaptor etc.

Original PSU is too complex to hack for single voltage in. Will need to add electronic voltage management myself.

And then modifying that for all rails that it can be paralleled... meh

Best to just use a LiFe-BMS that has single rail chg/dischg and put a 10 ~ 18V to all that are needed board behind it, then add a 13.5V 5A non-universal plug input with a power supply

Or whatever current is needed to charge in 3 hours while turned on

what I always wondered is if you can modify the AC trigger to be an external trigger ... and I wonder what the AC trigger would do if you ran it from battery

Be as accurate as the 50Hz that I generate, I'd suspect

Might be tollerant for 10 to 100

tolerant*

But, since it has an internal F-gen, that's not really very important for this one

MAximum power consumption 50W

3cell battery pack, about 95Wh

I say: Perfect!

I can't really simulate a usage cycle (fast-charge, float, remove solar power, and so on) but when I set the "battery" to different initial voltages it is charged or discharged as I would expect. Thanks @Asmyldof

It's never going to be perfect, but just fiddling around with what you know to "fake" a simulation often works well enough for batteries

anyone has experience with fridge bimetal switches? could it be that one is failing to properly function because of increased contact resistance => heating up => shifting switch point?

Hey guys, just a question of opinion: Would you prefer to use a ST Microelectronics STM32F based ARM MCU or an Atmel SAM4 based ARM MCU for a device which needs to do multi-channel fast current shunt ADC measurements, while displaying to some form of simple graphical/LED display and some simple button style user interface?

Has anyone worked with both SAM4 or SAM3 and the STM Cortex M3/4 equivalents and have an opinion/preference, and why?

@PlasmaHH Sounds potentially possible, but can;t say I have ever seen it happen

Rip it out and replace it with a uC!

Also: Know of any risks in hacking a DP832 ?

@KyranF As to internal ADC I cannot say, only worked with SAM3 on that point. As to my choice it'd be the SAM. 65% because I use Atmel a lot, 35% because ST has gone off the deep end with the IDE/Toolchain as far as I'm concerned. Round the same time Code Red went to NXP-Exclusively I think

Currently working on extending a previous project using a SAM4D with external ADCs for 24 channel simultaneous <4&mu;s conversion

Ahw, didn't work.. well 4 microseconds

Fancy Pantsy!

sorry, I felt I hadn't used it enough yet

@Asmyldof would love to, but its not mine, belongs to the landlord

@PlasmaHH Tell landlord to rip it out and put in a uC

@Asmyldof landlord is as dumb as a piece of aldi bread

hey @Asmyldof are you around?

I'm still not convinced about that pixel thinghy

the photodiode works in the photovoltaic region thus is a costant current source thus voltage should increase linearily.

is this really just a matter of parasitic resistances?

@Asmyldof I agree that the Atmel Studio IDE is probably a better (more stable, useful, no fees) IDE than all the random stuff the other IC companies have partnered up with. I have experience only with SAM chips as well, in the ARM Cortex world.

@VladimirCravero was locked away in the lab.

I was thinking the same thing while microscoping, haven't figured it out yet.

But the graph is clear as day

Although, isn't it true that the photo diode will decrease the response as a function of its voltage, since it charges the gate, that could explain it maybe?

shrugh

@KyranF I have worked with ST

Not a fan

Mystery datasheets, complex read this then that procedure to understanding what actually happens

And they seem to want to be in the middle of the range exclusively.

And many more reasons that I can't think of for lack of daylight, food and other stuff

@PlasmaHH Then rip out his brain and replace it with a uC

Going home now