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thank you for putting this into words. i noticed this too a few months ago and my "fantastic" mother proved it. for her all tech is either magic or dumb shit you shouldn't spent time with and her phone (samsung galaxy shitthing) can't be charged fast enough. destroyed more batteries than i'd like to admit that way
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@-ANGRY-CLIENT- Well the standards are that low yes. Often the USB controllers can handle some more to account for USB hubs etc, but it depends on how the manufacturer designed it. The standard rating is a minimum that USB controllers should be able to handle while keeping a stable voltage.
As for phones, there's the battery but also the charge controller in there.. especially at the controller, engineers have to make choices between size, price and ampacity vs portability, affordability and decreased ampacity. Some other factors are accounted for as well but those are the most important ones for the controllers in phones.
There are other batteries that can deal with higher current demands, like the car batteries which are lead-acid and can handle hundreds of amps. But in the lithium technologies used in consumer electronics - lithium-ion or lithium-polymer, it's usually only a few amps. And the chemical reactions within the battery lose their effectiveness over time, thus their capacity decreases as they age. -
@oudalally RC car chargers indeed use balancers because the cells are placed in series, and just charging them at the high voltage terminals without looking at the voltage of each cell can cause them to internally short, overcharge, and cause all sorts of issues. The control circuitry involved in charging them properly does indeed cause a significant price increase.
Running the battery too low could be possible in cell phones if you really want to (by booting it up constantly even after it shut down when it noticed that the battery reached a cut-off voltage) but in normal circumstances this shouldn't be possible. The charge controllers in Androids are actually quite advanced, e.g. they fall back to 500mA when the charger isn't recognized to be able to deliver more. So when I plug my phone into the USB charge hub on my bedside table (which is powered by a 5V 5A supply) it'll take only 500mA because I only connected the VCC and ground pins while leaving the data pins unconnected. So my charging hub doesn't support some fancy fast charging protocol or anything.
But back to the RC car.. I don't think that there's any easy way out that doesn't involve taking out the cells and charging each of them with a separate charger. In case of several chargers you don't really need to worry about slightly different voltages just like you wouldn't have to when you put differently charged AA batteries in a remote. The only issue would be that whenever one cell discharges, the circuit would open regardless of the charge left in the other cells. Needless to say, taking out each cell and charging them separately would be rather unwieldy. I'd suggest investing in a proper RC charger instead :) -
I didn't know this, thank you for the info! :D I'll have to look over my charging habits.
You wouldn't happen to know any good info on wireless chargers? (Qi) I've seen a lot of confusing and contradictory information, and it's hard to tell what should and should not be trusted. :/ My impression though is that it's (maybe like the fast charging thing) honestly a bit dangerous? But I wouldn't know the exact reasons myself, I don't know much about electricity stuff. -
@oudalally Ah yes, in that case going with another NiMH wouldn't be a bad idea. However if you'd like to go with lithium nonetheless, it could be possible if you add an appropriate protection PCB on it and give the lithium cells some cushioning, it may be possible to use those and benefit from their increased energy density. Depending on the rally, custom designs may not be allowed though.. but not sure. All I know is that slightly overvolting a motor can make it go faster but will decrease its lifespan. The motors that I mentioned in an earlier rant about the desk fans were able to get overvolted from 5V all the way to 12V. I wouldn't recommend it though. Regarding the protection PCB's, some 18650 cells like the LiitoKala ones that I work with here have them slapped on their back. Those take care of cut-off in case of shorting, overcharge, overdischarge etc. I haven't yet tested the reliability of those features though.
@xewl well the load always determines the current, right? Hence why Android phones (not sure about iPhones but they should be similar) only ask for 500mA from my charging hub even though the latter can deliver up to 5A. Only if drunken fool me would decide to short VCC to ground with a 500 milliohm wire, it'd deliver the full 5 amps.
(as for why I went with a 5A supply, there's 9 ports in there that could - if all of them are connected to a load - ask for 4.5A which my supply will have to be able to deliver)
Regarding fast chargers, they speak some sort of protocol to negotiate between the phone and the wall adapter what current should be delivered. I'm sure that the data lines are used for this negotiation, but I don't know how exactly to make my charging hub speak this protocol. Not that I'd want it though, because that hub is used for overnight charging where 500mA suffices. -
@Navigatr I have actually never worked with a Qi charger. Generally I can tell that those work by delivering a high frequency AC signal to a coil within the phone, which is then rectified and regulated etc. They aren't very efficient (wireless energy transfer never is), but they should be safe to use. Every AC signal generates some background EMI, even the mains AC lines do. On an oscilloscope you can see this as a low voltage 50 or 60Hz sine wave when it's idle.
In general wireless chargers and induction cookers etc work by.. well, induction. The EMI which all AC lines emit and is generally undesirable, is in these applications used deliberately to induce current into a nearby coil. Transformers also work this way, but those also have a ferromagnetic core to increase efficiency (because they can hold the electromagnetic fields better than air).
Fast charging isn't really dangerous except for the fact that it makes the phone heat up more and decreases the lifespan of the battery.. that is, unless you're using a Note 7 of course :P -
@Condor Note 7, wasn't that the ones that spontaneously combusted in people's pockets?
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@Condor Yeah, it's almost shitastical enough to earn them an award or something imo.
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@oudalally It should be able to handle the dust and shocks with cushioning and insulation. My biggest concern with NiMH would be its size and weight, which can decrease performance due to drag. An AM radio for control.. now that's interesting! I don't think that RC cars often use those. Are you building a custom design of your own?
Also, entry denial in those rally's is a compliment :P the ones that don't pass entry checks are always the best ones, known to win :D
I'd love to see more about it! Let me subscribe to your future rants real quick :3 -
@Condor haha yes, used it pretty correctly,this time too.
regarding your rant.
first of all, i literally made coffee for myself just to read it.
i have had a similar case, i often used to charge my phone over night,because i absolutely needed full battery in the morning. About a year and half later my phone refused to charge beyond 53-54% and i charged it more and more (i realise now how it only worsened things).
then i used my laptop to charge it and it again started charging up to 100 even with the charger.
But then i faced the same issue again and this time my "life hack" didn't work. and it got worse.
had to buy a new phone. -
@oudalally sounds cool! The battery discharge in less than a minute is really worrying though.. perhaps test the motor at a bench power supply and see how much current it takes? That way you can refine which battery you may need here. Looks like it takes a lot of current, which is expected from a high power motor.. even the small brushless DC motors in desk fans take upwards of 1 amp when the fan blades are attached. NiMH's aren't exactly known for their energy density and ampacity.. perhaps you could reconsider that if at all possible.
GreatScott! has a video about battery technologies here: https://youtube.com/watch/...
From the looks of it you need both high power and high capacity.. lead-acid provides the former (hence why it's used to crank car engines) whereas lithium provides the latter (hence why it's used in electric cars). Perhaps you could also look into the various variants of lithium batteries.. there's some other lesser known ones that have varying specs in terms of power and capacity, such as LiFePo4 which I recall is a chemistry tailored at power. I recall that there was a video on it, but I can't seem to find it anymore... -
@oudalally that'd translate to several amps (especially in the modified one which would be close to or even over 100A!) so be sure to take a battery that can handle the current! There's not a single battery in existence that likes to go beyond its current rating.. some overheat, some explode, but none of them behave nicely in those circumstances. Lithium in particular can be quite the diva. Maybe gasoline would be a more viable alternative? Not very ecofriendly but it should work. Otherwise I'd take a closer look at how Tesla powers their cars and motors.
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@oudalally That said, my knowledge about motor internals or RC car design and optimization is limited... All I can tell is that whatever battery you're using should be rated to be able to handle the load that you're putting on it. There are lithium cells out there that can handle up to 20A. They're a bit expensive but if you put 5 of those in parallel (be sure that their voltage is equalized, and put some resistors instead of wire between their positive electrodes to aid equalization), that could give you a couple of minutes of runtime.
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The Nexus 6p battery life issue has a sordid history since that model was released. There is a class-action lawsuit (I am a member) pending filing.
The original purchaser (it sounds like you got it second hand, so I don't think you could do this) can file a claim with Google support and they will replace it with a refurb 6p or Pixel xl. They replaced mine with a Pixel xl last year.
Hypothetically, ahem, I may not have actually returned my original 6p, despite their threats to charge me full price for the replacement. Because after I hypothetically ignored them long enough, they hypothetically stopped bothering me about it. It might be gathering hypothetical dust while I bide my time considering if I want to dig in & replace the battery one day.
Be careful if you decide to replace the battery yourself. Plenty of horror stories online from failed replacement attempts. I certainly wish you the best of luck. I LOVE the 6p, especially those front-facing speakers... -
I didn't read all the comments, so this might have already been brought up.
Not a fan of conspiracy theories by any means, but what if they do this also to force people to change their smartphones every couple of years? Might not be the sole reason to do so, afterall you can pay the service to replace even the built in batteries, but think about it. Most people I know would just get a new phone (most of the times, the +1 version of their current model). -
@DutulescuRemus sometimes there's certain shitdesigns that can't be easily serviced and thus can't be repaired either.. but in devices that can be serviced, it's usually just a matter of wear-out.
That said, this serviceability is one of the reasons why I don't like the move towards nonremovable batteries. It makes servicing the phone so much less accessible, and the mechanical connectors don't take up a whole lot of space anyway. -
@beggarboy Actually after having used my phone with its fast charger for a while, I'm not too sure about this rant anymore. There are certain chemistries that deal better with high current (like LiFePo4 which is apparently often used in power tools). Or the charge controllers in flagship phones got a lot better.. Not sure. But it looks more like the battery in this particular phone is just shit (ordered a replacement from AliExpress) and I'll replace it soon. But as the phone doesn't heat up much during charging, there shouldn't be any significant losses or anything.
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@Condor I tried to phrase it as objectively as possible since I am not to good with electronics.
But my general understanding is/was that since Chargers often have some sort of microsoftware with them the phone probably does some sort of handshake instead of just plainly accepting juice.
I would imagine it goes like this:
"Hello, I am a 📱. 👋 Who are you?"
"Me charger 🔌. Beep boop."
"Oh neato whats your max my dude?"
"5A @ 15V"
"My max is 3A @ 10V, would that be possible? 🤔"
"Sure, me also have supercharge possibilities⚡"
"Dooope, gimme that. 😍"
"Confirmed. Charging."
Long rant ahead. Should take about 2-3 minutes to read. So feel free to refill your cup of coffee and take a seat :)
It turns out that the battery in my new Nexus 6P is almost dead. Well not that I didn't expect that, the seller even explicitly put that in the product page. But it got me thinking.. why? Lithium batteries are often good for some 10k charges, meaning that they could last almost 30 years when charged every day! They'd outlive an entire generation of people!
Then I took a look at the USB-C wall charger that Huawei delivered with this thing. A 5V 3A brick. When I saw that, I immediately realized.. aah, that's why this battery crapped out after a mere 2 years.
See, while batteries are often advertised as capable of several amps (like 7A with my LiitoKala 18650 batteries that I often use in projects), that's only the current that they can safely take or deliver without blowing up. The manufacturer doesn't make this current rating with longevity in mind. It's the absolute maximum in current that a given battery can safely handle.
The longevity on the other hand directly depends on the demand that's placed on the battery. 500mA which is standard USB 2.0 rating or 1A which is standard USB 3.0 rating, no sweat. The battery will live for at least a decade of daily charges and discharges like that no problem.
But when you start shoving 3A continuous into a battery, that's when it will suffer. Imagine that your current workload is 500mA and suddenly you get shoved 6 times that work upon you. How long would you last?
Oh and not only the current is a problem, I suspect that it also overvolts the battery to maintain a constant current all the way till the end. When I charged my lithium cells with my lab bench power supply, the battery would only take a few milliamps when it got close to the supply voltage. Quick bit of knowledge: lithium cells are charged at constant current first, then when the current drops below that, it continues at constant voltage - usually 4.2 or 4.35V depending on the battery. So you'd set your lab bench power supply at 4.2V 500mA. But in that constant voltage mode, as the battery's voltage and the supply's voltage equalize, the current drops because the voltage difference becomes lower. Remember, voltage is what causes current to flow. Overvolting at the supply to stay in constant current mode all the way till the end speeds this process up but can be dangerous and requires constant monitoring of the battery voltage.
So, why does Huawei and a bunch of other manufacturers make these 3A power chargers? Well first it's because consumer demands ever more, regardless of the fact that they can just charge at 500mA for the night (8h of sleep) and charge a 4000mAh battery from 0 to 100% no problem. Secondly it's because sometimes you need that little bit of extra juice fast, like when you forgot to plug the damn thing in and you've got only 30 minutes in the morning to pour some charge into it.
But people use those damn fucking things even when they go to bed, making that 3A torture a fucking standard process!! And then they complain that their batteries go to shit?!
Hopefully this now made you realize that the fast charger shouldn't be used as a regular charger ^^
rant