Battery charge tests - running a battery to 0 frequently - checking re-charge times

When a person makes a mistake like that, if you dislike them, it's annoying, but if you like them, it's cute.

On the other hand, if you prefer speed x while driving and someone zooms by at 2 x, they're an idiot but someone in front of you at 1/2 x is a jerk.

Yes, my phone does say it will end charging by alarm time.

Actually, my night charger does so at "1 load unit", and does the job just fine.

Well, I have been slow charging my previous phone during 4 years, and battery life is almost the same as when I bought it. There was a decrease or impact the first year or two, then none.

nospam is wrong of course™.

You can charge at the very low rate by not letting the charger see the resistors on the data pins.

There's no upside to charging at 100mA, just as there is no upside to charging at 500mA or 1A, versus higher rate charging, but not everything anyone does is necessarily based on actual data. You still have people doing 3000 mile oil changes on new cars, not because they are necessary, but because it makes them feel good.

by not seeing the resistors (or actual negotiation), the 'very low rate' is 100ma, as per the usb spec, which is insufficient to charge a phone battery.

some devices will even say not charging:

because it's too low to actually do anything.

yes there is. the upside for charging at 500ma-1a versus faster rates is longer battery life.

you being the prime example of that.

Don't be that absolute. When you do that, you deserve getting the «nospam is wrong of course™» response.

Some phones may not charge at that rate, others do.

I have one such cable with just two wires, and all of my devices (with micro-usb connectors) can charge with it, except an old Samsung Galaxy Mini 2 phone. That cable came with a BT headphone, probably with the purpose of forcing slow, low rate, charging.

I have a charger with eight outputs. 2 of them are "1 load unit", same as an old computer. They can charge all my phones, tablets, headsets, cameras, etc. All of those with USB connection, that is. Except one, that old Samsung phone.

So I intentionally use those two outputs to charge my phone while I sleep, or other devices that I'm likely to forget I left charging.

I have been doing that to my previous phone for four years, the battery is just fine.

Ah, an iPad. :-P

...

Lead-acid could be fast charged. They do that some times with cars on garages. It is dangerous, the battery must be disconnected from the car first, or the electronics can be destroyed (overvoltage). Happened to me.

it can, but also reduces the life of the battery, depending on how fast it is.

they do, because they want to move onto the next customer.

only if improperly done.

the battery doesn't need to be disconnected.

modern car battery chargers initially supply a constant current until the battery voltage rises to ~14.4v (bulk charge), at which point it switches to constant voltage to top it off (absorption charge) until the current draw is minimal, and then switches to trickle charging (aka float).

when the vehicle is running, the voltage is ~13.8v with a fully charged battery (higher if it's not).

chargers that do not limit voltage and/or current can destroy all sorts of things, including the battery. do not use.

the usb spec is absolute, as are other specs.

the usb spec *requires* that a device initially source 100ma, with higher rates only after negotiation. originally, that required a request, but that was not practical for a simple charger, which is why resistors were added to the spec.

if you disagree, take it up with the usb consortium.

the rate is defined by the usb spec.

non-compliant devices do exist, however, they should be avoided. there is no guarantee what they will do.

compliance not only guarantees expected functionality and compatibility between manufacturers, but also a level of safety.

any cable with only two wires is non-compliant with the usb spec, and if it came with a bt headphone, then that too is non-compliant.

you have a lot of non-compliant devices. that's unfortunate.

nospam is wrong of course™

You can charge a phone, albeit very slowly, at 100mA.

There's no good reason to do this, but someone else was concerned that when you plug a phone into a fast charger there is no way to force it charge at a lower rate. For an iPhone there is two ways a) turn off the phone, b) use a power-only USB cable or a device that prevents the data lines from being seen.

nospam, don't talk of things you don't understand

Fast charging a lead acid battery means supplying it with a high voltage, maybe 20 or 30 volts, much more than what the battery can absorb. If the car is not disconnected, that voltage reaches the car itself.

What you say now is trash:

extremely slowly (as in days), and it needs to be powered off because idle power consumption is higher than 100ma.

if it's powered on, it won't actually charge, which is what causes the no charging indicator to be shown on the display. link in another post.

except that the phone will turn on when connected to a charger (android partly boots, iphone fully boots) and then will charge at whatever rate the charger supports and negotiates with the device.

that won't work. see above.

the correct way to charge at a slow rate is use a 2.5w (500ma) or 5w charger (1a).

take your own advice.

i'm *very* familiar with battery chargers for various battery chemistries. you clearly are not.

that is flat out false. where did you get that bogus information?

applying 20-30v to a 12v lead acid car battery will destroy it.

fast charging is a function of the *current*, not the voltage. see below, and the initial charge phase is constant current, while the battery voltage rises to a particular threshold. see below for specifics.

it isn't.

here's an example of a ctek car battery charger and its various phases. other brands are similar.

I've never heard of high-voltage charging of lead-acid batteries, at least not beyond 2.5 volts per cell (14.8V for a six cell car battery).

The exception is the "pulse chargers" that attempt to remove sulfation in lead-acid batteries by using high-voltage, high-frequency pulses, and in that case it would make sense to disconnect the battery from the vehicle prior to attempting this.

There is no conclusive proof that pulse charging has any positive effect, only some limited empirical evidence. There are ways to remove sulfation from non-sealed lead-acid batteries, but not with pulsed charging.

pulse chargers are nowhere near 20-30v.

for ctek, it's 15.8v for the initial (and mostly useless) desulfation phase, which will not destroy a vehicle's electronics.

true.

none that reliably work.

You're ignorance is showing.

Not likely, since the phones need to be on in order to charge, and they use more than 100mA to be on. You will not charge the phone at 100mA, you will very slightly slow the phones discharge.

Of course not, since it will not charge the phone.

No iPhone will not charge at all when off.

Funny thing, my wife's iPhone 13, and the two before that charged just fine when off.

Jimmy Neutron is proud of itself! All this BS, stupidity and absolute crap over nothing whatsoever of substance!

Peter Wieck Melrose Park, PA

Yep. Not only will all phones charge when off, they often charge faster when off although not dramatically so.