PINNED - Lithium battery conversion/info

[robint]

Thnx 10^6 BM, I have put in a request to Shirley (I should buy 2 ok?)
Will revert soonest

[Burgerman]

You NEED a handful of balance cable connectors too as these connectors are extremely scarce.
You also need the CORRECT safe high current capable 4mm banana connectors and I will give an ebay link to these at some point.
And you need an FUIM3 for each. Again, only place is shirley?

But if you decide to get one you need the software too.
dont forget to load a preset and click the advanced tick box...
Links in next post.

And you will need a bunch of my modified presets for lithium, lead, etc. As I have access to many parameters that are not visible that work better for bigger packs with some relaxed parameters that prevent errors etc.

Or you could wait and see what iCharger that some others are using looks like.

[Burgerman]

Old PL8 user manual...
Its good enough to get an idea. Many of the restrictions and safety stuff are relaxed on my own modded presets.
https://www.wheelchairdriver.com/doomed ... _Guide.pdf

Any passwords needed for the .rar files will be 123 as all mine are! Some dont need one.
https://www.wheelchairdriver.com/doomed/PL8/ rar files...

[robint]

Ok loaded s/w and d/l manual OMG 89 pages of nerdy stuff - my poor head already stuffed with tech
passed on query to Shirley
Looking at those connectors, surely those balance leads have a jst type plug? (or is it a wierd special like the jk bms)
then I could source the right 8(7?) pin plug and make up my own multicore. the power cable and banana plugs made up separately - so two sets no big deals? Or is life never that simple

NOOOOO as you were Shirley came back and said DIY not advised cables only £4 so I ordered two.

[robint]

Hi BM is this the outfit you refer to

https://www.icharger.eu/icharger-x8-110 ... p-733.html

icharger same as Junsi icharger ? confusing. Dont see any o/p to pc or s/w for graphing/controlling etc

Aimed at RC Lipo guys who want to fire up their drones quickly. I guess.

I cant see these being applicable to Wheelchair guys needs?

We need reliability and safety above all and dont do Lipo or Lion stuff (or shouldnt)

[robint]

Hi BM tell me as Im confused about chargers and overloaded with info

I see that RC guys use kit from Imax or Skyrc. It looks competent enough at first sight but they can only do up to 6 cells but a ca £30 each I could buy 2 and charge 12 banks separately (with isolated linear 10A PSUs which I have)

They appear to have USB comms to set up parms and collect data etc but I havent gone into this much yet. Attraction is no real learning, plug and play.

Shirly has quoted complete PL8 kit £200, having trouble focussing on cable needs, got your pix but what Shirley is quoting is different?

Im afraid my nitpicking attention to detail will p***s him off, but I know from bitter experience this is where you can come badly unstuck. I highlighted this problem with the JK BMS, although I am ok now as the tiny sub mini JK 1mm pitch specials havent broken (yet) but they sure look very fragile - not like the 2.5p normal jst)

[Burgerman]

You are comparing a badly programmed trabant to a ferrari.

Forget it. Been through every worthwhile bobby charger. 99% are junk. Of the ones that are not they are not flexible enough to do what you need. All have about 1 page of badly written code instead of phone books worth of highly optimised and bug fixed stuff. I spent 2 years of my life fine tuning and making the PL8 firmware alone work properly!

This is one of those cases where you are so far from knowing what you need that you are not yet capable of even understanding what it is you dont know that you dont know! Years away.

But youi can start at the begining and do that yourself if you choose!
Or be advided by someone thats got the T shirt!

[shirley_hkg]

https://www.wheelchairdriver.com/board/ ... start=6030

Collecting dust most of the time.

[robint]

I dont doubt for a moment your expertise in this type of charger technology - 2 years of your time numerous updates on a phone book of code
Trabant vs Ferrari
Q
This is one of those cases where you are so far from knowing what you need that you are not yet capable of even understanding what it is you dont know that you dont know! Years away.
UQ
Oh WOW BM This all is most intimidating for me, will I be able to take on the challenge? (any more than starting with "A Dummy's guide to Brain Surgery" or 229 pages and 12 years of development for Topic "Lithium Battery Conversion"

I am reading thru from page 200 as referred by Shirley to get some historical back ground (from 2021). Those cylindricals Headway? gave you guys some issues back then but things have improved a lot since then AFAIK

[robint]

https://www.wheelchairdriver.com/board/viewtopic.php?f=2&t=1813&start=6030

Collecting dust most of the time.

Thnx for the tip, I am reading 20+ pages from 2021 to get more back ground and what you guys developed since then.

Its all quite intimidating I find

One question - re our pm discussions on WA given the amount of dev work and mods that went on for the PL8 will the model you propose have the latest firmware updates etc. I realise I must get the setting list from BM and also his hidden tweeks which he has kindly offered. I am not skilled in any coding languages although I can follow instructions and have dabbled with Arduino so not completely dumb.

pls advise

Robin

[shirley_hkg]

BM didn't write any code, I guess.

PL8's presets were very restricted that's unusable in wheelchair.
He talked Revolectrix over to lift some restraints, so PL8 can charge large LFE pack correctly.

Now we can use BM preset and modify it freely.

[Burgerman]

Firmware too.
You need 3.5 or 3.6 or you will have issues... Only difference between these is the current ramp up speed depending on supply so that it didnt upset petrol generators on the feild. But earlier firmwares have many of the things that I got sorted out. I have around 20 beta firmwares here! And earlier ones.

The required firmware is BUILT IN to the software I linked to. While connected to the FUIM3 and a PC just choose update.

[robint]

image_2024-08-11_153126870.png (185.93 KiB) Viewed 1043 times

Ok thanx BM, fascinating what went on over the last few years. What Trojans you all were.

I wil try and unthread all your points on LAB charging on the other topic over the next few days and send a chart to you by pm.

Would it be possible to do a similar narrative on charging Lifepo (I can be doing with Lion or Lipo after my recent experience perhaps another member may take up the challenge).
Thing Im confused about is your recommends on monitoring end of charge current with a termination value as per icharge and its %ge of charge current setting etc. JK bms doesnt have such a setting as you point out.
I thought that Lifepo didnt need an absorption phase? I may be confused with LAB

I can understand about the faff with balancing and it needs to take place when charging has stopped (or the cells volts will be misread). It also needs to within 3.450 and 3.550V, too low and it will take too long, to high and it wont work (hit against OVP of 3.600V). This can be programmed within the JK BMS

Is this your data spec?

I will try and put that all into a flow chart as well if you give me text or a link

Robin

BTW I saw a pix of your monster chair with its seat up and two big motors on the back wheels. Whats size would they be ca 0.5kW? Its no wonder you talk of pulling 250A max rule of 1kW motors = 40A but 6x at starting torque 240A. You notty guys like to lift your front wheels

[Burgerman]

Thing Im confused about is your recommends on monitoring end of charge current with a termination value as per icharge and its %ge of charge current setting etc. JK bms doesnt have such a setting as you point out.
I thought that Lifepo didnt need an absorption phase? I may be confused with LAB

The hobby type LiPo cells, can be as high as 150C so a tiny pack the size of a pack of cigarettes can start a truck. Thats 150 x a 4Ah battery...
Those are so low impedance that charge voltage is practically the same thing as charge voltage EVEN AFTER YOU REMOVE the charge current. And the charge current on a tiny pack can be 40A. Only because thats the full power of my charger! Those dont need more than a few seconds at their 4.200V charge voltage to be 100% full. So the charger algo charges, balances at 4.200V as the charger current drops away to almost zero. That charger doesent stop charging until balance is complete, plus a couple of mins to be sure all cells equally low current.

A LiFePO4 1C pack is very different. The resistance allows your charge current to pull the vltage higher than the actual cell voltage while charging. So it needs to charge untill
a) the cells are all balanced. The charger current will drop to whatever then balancer needs to NEVER exceed the coosen voltage unlike an ON/OFF bms that watches it go too high then chops off the charger repeatedly. When the current on the last cell to catch up reaches the zero balance load point, then the charger still maintains a low current at CV quite naturally until the cell stops drawing high currents. When it reaches around 320th C depending on cell brand, c rate etc the charger ends.

You want the cells all 100% saturated. But not held high too long as they dont like it. So 15 to 30 mins after balance, which you make happen by adjusting the termination current. On the PL8 you set a mA figure. That doesent change if you change charge current. So 1A to 40A and it stays at what you set. With other chargers its a % of charge current. So you need to mess around with the maths and figure it all out.

[robint]

Thnx BM

On/Off type charger - I think this is what the JK BMS does as I see it switches charge on/off by itself (you also have a manual off switch to prevent charging IIRC.)

I shall look at that more closely as I didnt know why it was toggling.

There isnt a tail current setting in the bms.

Cant quite see how this second option works (preumably implemneted in the PL8?

Does the PL8 go into a CV mode after first balance start level is reach by at least one cell. Does it then limit the charge current to a low absorb level say .05C while the remaining cells gradually catch up but it does mean that the first OVP cell will begin over charge to next high level OVP. Whe this is reached it stop charge and goes into balance until all cells at < 1st OVP level. This repeats until all cells are within a preset gap of say 0.001mV and so fully charged near to 1st OVP level, still safely below 2nd OVP level but well below Full stop Level 3

This is a finer profile than the crude on/off one first mentioned ?

Have I got this right ? Can you explain?

Robin

[robint]

OBTW BM the given wisdom in solar circles is that you dont need balancing very often - maybe once per month do a top balance. grd A matched cells will normally stay quite close and only drift apart slowly.
Of course mobility EV is different cos of the rapidly varying high C loads Solar guys stick at <1C and the inverter smoothes some of the worst inrush and it all stay within 80-20%dod at most within a daily period

With chairs I assume that spikes of 5C can spread cell volts as their IRs are not identical

I seem to recall that some controllers have a ramp setting so that accel/decel times/currents will be limited - but then its all PWM so maybe the high C spikes Amps are still there just shorter width - hmm IDK

[Burgerman]

On/Off type charger - I think this is what the JK BMS does as I see it switches charge on/off by itself (you also have a manual off switch to prevent charging IIRC.)

I shall look at that more closely as I didnt know why it was toggling.

That all they can do.
Thats the problem. They are not in the correct place to balance and charge properly. So they start balancing, and they must do this over a wide range because of how the thing works. Because it tries to balance at say 1A, while the charger is happily charging at say 20 or 40A. So it adds a load of its 1A and usually much less like 50 to 100mA! and as soon as it sees a cell exceed the limit that it allows it chops off power... Then it watches the cell drop from anything from 3.7 or even higher, down to around 3.5V. Then it reconnects. And since it can only balance at a low current and the charger doesent throttle it now goes straight back up to a too high voltage again. Rinse and repeat.

There isnt a tail current setting in the bms.

No they cant do that...
They cant control power to stop a cell going over voltage either. Other than disconnecting the charger and waiting...

Cant quite see how this second option works (preumably implemneted in the PL8?

Does the PL8 go into a CV mode after first balance start level is reach by at least one cell. Does it then limit the charge current to a low absorb level say .05C while the remaining cells gradually catch up but it does mean that the first OVP cell will begin over charge to next high level OVP. Whe this is reached it stop charge and goes into balance until all cells at < 1st OVP level. This repeats until all cells are within a preset gap of say 0.001mV and so fully charged near to 1st OVP level, still safely below 2nd OVP level but well below Full stop Level 3

The PL8 watches all cells. It starts to balance at the voltage you choose, preferably choose 3.5V or above. Trying to balance lower than this can actually unbalance the pack. Causing problems. So I set balance to begin at 3.500V. It draws down the highest cells at a proportianal 0 to 1000mA. If it reaches 1000mA, then the balancer cant stop the cell voltage rising above the maximum 3.550V I choose as charge voltage. So the charger can see this, and so it proportionally reuces its output to ensure that the highest cell never exceeds the 3.550V I choose. If one cell reaches this point because of a badly balanced cell, then it might end up charging at 1000mA from this point onwards to match the balance current to keep the full cell from exceeding the correct voltage. It does this accurate to 2mV across all 8 cells.

Once the balance current reaches a 0% (no current needed) it then starts its CV time limit, or the approx 350th of capacity as a tail current and it stops when it reaches this point. Charge then ends when all cells are totally balanced, plus some CV time, and at a low tail current to ensure all cells are equally and fully charged. All stuff a BMS cant do.
As soon as any cell reaches

This is a finer profile than the crude on/off one first mentioned ?

Of course its fully proportional and can throttle the charger output and control balance current level as you charge. From 0mA to 1000mA balance, and from 5mA to 40,000mA charge current. All set to the exact voltages you tell it, the tail current you decide, the charge current and balance start point and cell chemistry and cell count you choose.

Controlled, correct charge. Without bouncing it all on/off... And ending at the correct point. So you dont end up with cooced cells etc.

[Burgerman]

If you buy a decent EV like a tesla it does the same.
You connect AC or high power DC to the car. Its on board "pl8" - a custom charge computer does the same as the PL8 does but its a little more complex Its still refered to as a BMS but it works like the PL8 does. In that it doesent just keep turning the charge current on/off it CONTROLS it as needed.

Whats more they do not run the cells down to empty, always allowing around 10% reserve and never charge to above 85% either. But thats because the lithium ion cells they use have only around 500 cycles if 100% of capacity is used. They last 10x this however if you avoid the higher 4.200V end, and the lower end below 3.6V. This is how they "unlocked" a shit load of extra range during a tornado a few years back to help users.

But you CAN balance lithium ion at any voltage. You cant balance LiFePO4 below about 95% full. Anything below 3.45V actively ruins the balance! Its quite possible with LiFePO4 that discharge in a pack by say 20% can INCREASE voltage a few mV. So a balaner would actually be balancing voltages while UNBALANCING capacity - the opposite to what you need. And some BMS do this nonsense all day long - active balancers. Run away!

[Burgerman]

after spendng so much time on numpty EV or electric bike and solar forums I bet your head is now spinning! Try and forget all the garbage you "learned" from these experts!

[Superchunk]

I was wondering, does anyone here have a failsafe for 12A R-net XLR charging? Like a charge-only BMS?

I am just wondering what will happen if I don't have a BMS, and one of my carers forgets and plugs the XLR charger in the joystick?

[Burgerman]

What will happen is that the first cell to become full will shoot past the safe voltage and do it some damage.

If it worries you put a sticker or something over the charge port.

[robint]

after spendng so much time on numpty EV or electric bike and solar forums I bet your head is now spinning! Try and forget all the garbage you "learned" from these experts!

Quite right Prof BM, I sure am confabulated by the Solar brigade who have an army of old blowhards shovelling bigoted horse dung at you.

So I am trying to reset my technical compass and this
Anything below 3.45V actively ruins the balance! Its quite possible with LiFePO4 that discharge in a pack by say 20% can INCREASE voltage a few mV. So a balancer would actually be balancing voltages while UNBALANCING capacity
is something they dont tell you

So pls bear with me - stoopid boy Pike its going to be a painful relearning path for me.

OBTW I came across this chip CN3058E that is a dedicated Lifepo4 single cell 1A charger chip (ca 50p ea 10 off). It seems to contain all the normal charge protection feature associated with the well know TP4056 Lion chip used in every cheap charger. It has termination current detection built in as well as UVP lockout and temp stuff

Unfortunately Ive not found it in Module board form https://pdf1.alldatasheet.com/datasheet ... 3058E.html. In fact I havent found any dedicated Lifepo4 module boards.
You could see how this could be a clip on kit for individual cell boost (instead of manually prodding another full cell on top which is a techie bodge)

Just some passing interest.

Robin

OBTW thanx for that tip about Tesla cars dirty tricks - well thats Musk for you. I laughed when he got trashed over his acquisition of Twitter - really taken to the cleaners for $4billion . Its been all the way downhill for his rebranded X ever since, Its barely worth half what he paid for it and dropping fast. I think they call it Hubris

Have you seen the way BYD is racing ahead trying to invade EU and already have a Lifepo model out with their blade cells https://www.batterydesign.net/byd-blade/. Their PHEV design looks ready to sweep the board as a hybrid and is definitely not a mickey mouse outfit. IMHO
I have a businessman palwho has a dozen or so Reps on the road using Teslas. They all hate the EV especially in the 9 months of cold weather we get when you have to use electric power, headlights, wipers, windscreen heaters, passenger heating makes a nonesense out of mileage expectancy and a constant anxiety about find charging station that work or have available slots. A Phev will solve all that.

[Burgerman]

Twitter is the only available place now that isnt sensoring everything to please the left. So regardless of what he paid for it its the only refuge from mainstream media and all the woke left wing nonsense from all the rest.

But he bought it for that reason. Not to make a profit. Mostly as a place that free speech doesent die. Many of the intolerant losers on the left have stopped using twitter which if fine by me and it really pisses off the stupid marxist labout party who think they can control the internet, who think free speech is great as long as its THEIR speech, and same with bidens lot and the green idiots too.

Anyway...

That chip...
Accurate to 1.5% isnt good enough.
That means 3.654V if high, and equally under 3.54x volts if low... A huge spread. And not one you would want.
A difference of over 100mV in fact. And 50x less accurate than the PL8 for e.g at 2mV.
And the next problem is that you would need all of these on seperate isolated power supplies or all the negatives would be tied to 0V.

So maybe OK for a laptop chip.

Tesla isnt using dirty tricks. That is the way all EV manufacturers and anyone that has any sense gets a 10 year lifespan from a more energy dense lithium ion cell. That gets it from 500 cycles up to around 2500 instead. While still beating LiFePO4 for weight/size per Ah. I do the same 10% minimum and 85% charge on my laptops. These dells allow this config in the bios. That way I wont be buying new batteries every 2 years... Maybe every 10 to 15. Phones batteries lose capacity fast because they use 100% of the capacity. Mine needs a new battery already. Its down to 80% of its original capacity. How do I know? PL8 measures that too. You cant do that with a powerchair as if it decides its a firework you cant get off it fast enough or charge it safely next to your bed. And 200Ah plus isnt a laptop with 3 cells, but a huge bomb! An EV can be safely parked and charged outdoors.

[robint]

That chip...
Accurate to 1.5% isnt good enough.
That means 3.654V if high, and equally under 3.54x volts if low... A huge spread. And not one you would want.
A difference of over 100mV in fact. And 50x less accurate than the PL8 for e.g at 2mV.
And the next problem is that you would need all of these on seperate isolated power supplies or all the negatives would be tied to 0V.

Yes very surgically perceptive

Now I thought about all those separate supplies and I have a large torroid xformer on my bench and it occured to me that 8 separate 5V windings are quite possible and could power each of 8 chips via Usb type psu modules. so each cell has its own dedicated charge with the lifepo profile/protection etc to go with it. Of course this is just a superficial treatment but maybe overcomes the balancing issues passive vs active and interactions etc already mentioned. Afterall isnt this what is done inside laptops? with dreaded Lion chemistry? Thankfully laptops bursting into flames is very rare today AFAIK

Anyway just some passing observation

Robin

[Burgerman]

Afterall isnt this what is done inside laptops?

If youdont mind the fire risk the traditinal BMS works OK in a laptop. And with lithium ion cells generally as they dont have that super flat, even reversed, discharge curve. And so can be balanced regardless of state of charge. But in a laptop there are many methods used. My dells each have 2 batteries with individual control of everything in bios so that I can keep them away from the extremes and make them last. OR I can choose to do as the do in a phone and get maximal capacity. I do both. Mostly its plugged in, so sits at 80 to 85%. If I am taking it out with me, I charge to 100% before leaving.

This is what tesla and other DECENT EV manufactuers do. If they just fit a smaller back, and give the same range, then your battery will not last. Like many early ones such as the toyota prius, volt etc. They do several things wrong. Not least the pack is too small and so worked too hard as well.

Lithium is a SYSTEM not a battery or fuel tank. You need to understand how it will be used, and deterioration/reliability and safety over time. LiFePO4 isnt well suited to a simple BMS. The BMS manufacturers just think its the same as lithium ion with a different voltage. Hence issues...

Both my laptop packs are sat at 85% bottom right...

[robint]

Good point I must go and check my laptops to see what charge settings are.
I have one Lenovo W 8.1 that is on 24/7 as its used to put Windows OS on my LG big screen via HDMI rather than the annoying LG OS. I wondered whether this 24/7 usage is hurting the Lenovo?

I did the same with my Acer Aspire 10" Notebooks with W XP sp3 . These still work well after 20 years and are needed for some data logging gear I have that only works on XP (Hantek 356a ca £50 - BTW good kit for what it is and can do ca 9000pts up to 100s intervals ie a months logging)
Worked a treat - little gem.

Robin

[robint]

Here is another one I found (ca £1.50 x 10 off) MCP 73123

https://ww1.microchip.com/downloads/en/ ... 22191E.pdf

Seems a much higher spec? 3.582 - 3.618V ie +/- 18mV but maybe sufficient?

One of those on each cell can push out 1A for trimming cells after bulk charge?

Just musing

BTW I assume the PL8 is a resistive passive balancer? 2mV impressive for a hobby charger originally?

Robin

[Burgerman]

Yes. But you shouldnt need much balancing if the pack is healthy and built properly. A few mins.

The same passive resistors that do the balancing also allows 100 watts or 10A internal discharge when testing batteries or cells too.
And if you connect it to a battery or add a big resistor, it can do regenerative discharge testing at up to 40A and 1340 watts.

But since we need a 20H discharge on lead to get an accurate figure the 12 or 24V battery can be tested using its internal discharge testing. And be set to charge correctly, discharge to the correct figure at the correct rate, then recharge again. And graph the result like your tester.

But it can do the same with lithium on all 8 cells and do CC/CV or constant current only, and stop when 1st cell reaches set lower voltage etc. Or 16, 24, 32 cells etc if you connect the PL8s together as on my bench. I have a 13S LiFePO4 pack so use a pair of them as one charger. Remember I dont just do chairs as I have dozens of things here using lithium from cameras, lighting, tools to hobby stuff etc. I need to be able to find remaining safe capacity on quadcopters for e.g. They dont glide very well.

[shirley_hkg]

Once the balance current reaches a 0% (no current needed) it then starts its CV time limit, or the approx 350th of capacity as a tail current and it stops when it reaches this point. Charge then ends when all cells are totally balanced, plus some CV time, and at a low tail current to ensure all cells are equally and fully charged. .

From my observation, CV timer starts clicking when the first cell hits the charge voltage (OVP as you named it). PL8 swap from CC to CV, and drains 999mA from the cell / cells.

The cell is not full, so PL8 throttles bit by bit, as long as no cell exceeds OVP. (soaking)
PL8 seems to do it 5mV lower deliberately, and raise it 5mV higher(for a short while) when all cells reached the charge volt. I think it wants to finish soaking faster.

PL8 will stop when the residual current reached the termination value OR timer expired.

It is possible that the balance has not completed, say a very unbalanced pack. Usually in the initial charge, cells come with different SOC.

[Burgerman]

No because:

IF SET CORRECTLY
Then the timer only starts when the TOTAL charge voltage reaches the preset value. So for e.g 3.550V per cell x 8 = 28.400V which is where the CV times begins.
That means that any cell that is below 3.550 drags the total below 28.400V and so no end, no start of CV timer either.

In addition, theres a setting that says dont end unless all cells = balanced. And that means with a very low or zero drain bypass current - averaged over around 10 seconds.

So again charge cannot end until:
1. ALL cells are balanced.
2. CV Total voltage is at the CV voltage.
3. And after the termination current YOU CHOOSE is reached. Or the CV timer YOU CHOOSE has expired. But once you have determined a safe termination current, that actually gives a 15 to 30 minute balance + CV then this should be set to none as in the screenshot below. A 8 hour limit is great for lead, not needed on lithium. Other than for safety on a LiPo... Those things like to set fire to your house. But the termination current SHOULD be the thing that ends charge. If theres a cell "brake" of 1A on a charged cell, then the termination curent will never be reached anyway. So thats when a faulty cell may need a set CV time for safety.

If its a new unbalanced pack, I set this to off (none.) Because it may take a day to balance!
If its a sorted pack, in use, that ends correcty at around 30 mins after balance, and CV begins, then I would set that to say 4 hours just in case it has a faulty cell. It shouldnt ever reach that point.

Set to always balance fully etc as below in the termination tab.

REQUIRE ALL TO BE AT THE CV VOLTAGE.
REQUIRE ALL TO BE BALANCED.
SET TERMINATION CURRENT initially to around 320th C and correct to match your pack so that you get around a 20 to 30 minute CV after balance ends. This varies a lot so dont worry about adjusting the end tail current.

This require balance done prevents ending unless they are.
The require charge V means each one will be at your chooses 3.550V per cell before it can end.
So it will balance fully, to within 2mV, and all cells at exactly 3.550V per cell, while charge current drops to 320mA or less.

In the safety tab there is a 16 hour limit that will kick in if all else fails. Mostly because if its taken 16 hours to balance or charge then theres bigger problems!
It can discharge for 4 days. You may not see allof these settings. I have a registry hack that allows me beta testing and developer options.