Why is the charger market not keeping up with increasing cell capacity?

[yo han]

We've seen a pretty good increase in cell capacity over the past few years.
However, most chargers aren't offering us higher charge currents.
It's not difficult to achieve since most hobby chargers can deliver multiple times the amount of current the "tube shape" cell chargers can.
So what's keeping them from doing this?
The latest chargers deliver around 750mA and only if you're charging 2 cells max at the time.
For 2500mAh cells this means a charge time of around 4 hours. Put 4 cells in it and it takes around 8 hours!
Charging at 0.7C (where C is the capacity of the cell) is considered standard so charging a 2500mAh cell at 1750mA is perfectly alright and won't shorten its lifespan. This means you can charge your cells more than twice as fast as most current chargers are capable of.
Ever seen the warning "Never leave batteries unattended while charging"? Well good luck staying home all day since you're charging 4 18650 cells. Such long charge times often make people decide to charge them overnight, creating an even more dangerous situation.
I really don't understand why it's so difficult for charger manufacturers to come up with a decent charger that can charge up to 2A
I'm back to using my hobby charger: it's cheaper, does balanced charging and is way quicker than all current li-Ion chargers.

 

[Baditude]

It's not so much that the chargers are limited and have not kept up with technology, but the limitations of the batteries themselves. You can only charge lithium ion batteries so fast and still keep the charging process safe for consumers. Higher (faster) charge rates could be detrimental to battery safety, health, and longivity.

Lithium battery chargers utilize multiple stages to fully charge Lithium batteries. A faster charge rate would only charge a battery to about 85%.

Charging process
Stage 1 – Quick charge algorhythm to 70% - 85% capacity
Stage 2 – Slow charge algorhythm for final 15% -30% capacity
Stage 3 – Standby mode, trickle charge​

Battery University has the technical information:

"Charge stages of lithium-ion. Li-ion is fully charged when the current drops to a set level. In lieu of trickle charge, some chargers apply a topping charge when the voltage drops.

The charge rate of an Energy Cell is between 0.5 and 1C; the complete charge time is about 2–3 hours. Manufacturers of these cells recommend charging at 0.8C or less to prolong battery life. Charge efficiency about 99 percent and the cell remains cool during charge. Some Li-ion packs may experience a temperature rise of about 5ºC (9ºF) when reaching full charge. This could be due to the protection circuit and/or elevated internal resistance. Full charge occurs when the battery reaches the voltage threshold and the current drops to three percent of the rated current. A battery is also considered fully charged if the current levels off and cannot go down further. Elevated self-discharge might be the cause of this condition.

Increasing the charge current does not hasten the full-charge state by much. Although the battery will reach the voltage peak quicker, the saturation charge will take longer accordingly. The amount of charge current applied alters the time required for each stage; Stage 1 will be shorter but the saturation Stage 2 will take longer. A high current charge will, however, quickly fill the battery to about 70 percent.

Some lower-cost consumer chargers may use the simplified “charge-and-run” method that charges a lithium-ion battery in one hour or less without going to the Stage 2 saturation charge. “Ready” appears when the battery reaches the voltage threshold at Stage 1. State-of-charge (SoC) at this point is about 85 percent, a level that may be sufficient for many users."

​

Speaking on multiple bay chargers, look for those higher end intelligent chargers that have two or four completely "independent channels" which do not split the source current between their slots for slightly faster charging, as opposed to most chargers which "share" the current source between the different battery slots by alternating a single current source between the battery slots.

Four independent charging channels, one VP4 charger is equal to four separate chargers

 

[yo han]

Thanks for your input.
I wasn't talking about excessive charge rates. All I want is a charger that can charge my 2500mAH cells at 0.7/0.8C
However, all modern day chargers (for round type Li-Ion cells) can't even do half that.
Yes, I know the final stage will take longer when upping the amps but I don't need my cells to be completely saturated all the time (in fact, it's even better not to do so). I'm just wondering why we don't get that option even though hobby chargers have been able to give us full control for such a long time already.

 

[Ryedan]

I have an Xtar charger that can output 1A which is .4C for my 2500 mAh 18650 batteries. They get noticeably warm at that charge rate so I don't do it often. I can charge my model airplane Lipo batteries at 1C if I chose to with my hobby charger but they get pretty warm when I do that.

I believe there are Li-ion chargers on the market that will do a 2A charge, but I'm not interested in them. 1A is enough for me if I occasionally run out of batteries and have to do a quick charge, but that's not something I want to be doing too often with batteries that I vape.

This is just my take on things and as always YMMV

 

[Monotremata]

Thanks for your input.
I wasn't talking about excessive charge rates. All I want is a charger that can charge my 2500mAH cells at 0.7/0.8C
However, all modern day chargers (for round type Li-Ion cells) can't even do half that.
Yes, I know the final stage will take longer when upping the amps but I don't need my cells to be completely saturated all the time (in fact, it's even better not to do so). I'm just wondering why we don't get that option even though hobby chargers have been able to give us full control for such a long time already.

Batitude already explained it, its not safe and its also outside the limits set by the manufacturers of the batteries. If 1A current is .4C like Ryedan posted, your requested 0.7/0.8 is 2A, which is twice what any of the batteries we use are rated for. The standard charging current for just about all of the 'popular' 18650s is 1.25A. There are plenty of chargers that can do 1A charging, not sure where you arrived at the conclusion that all modern day chargers cant do it.

 

[93gc40]

FASTER CHARGED EQUALS FASTER DEAD BATTERY

Thanks for your input.
I wasn't talking about excessive charge rates. All I want is a charger that can charge my 2500mAH cells at 0.7/0.8C
However, all modern day chargers (for round type Li-Ion cells) can't even do half that.
Yes, I know the final stage will take longer when upping the amps but I don't need my cells to be completely saturated all the time (in fact, it's even better not to do so). I'm just wondering why we don't get that option even though hobby chargers have been able to give us full control for such a long time already.

I know you know it all but read what baditude posted.. The reason you can't find what you want is because what you want will ruin your batteries.

 

[zoiDman]

750mA I can Handle.

I'm still wonder why they Can't make a Charger that has a Bay that Isn't 1mm Longer than my 18650 Batteries?

 

[Steamix]

Charging/Discharging a battery is a chemical process. Speed of that process in one direction may have nothing to with the speed of the reverse process...

Ever seen something 'un-explode' at the same speed it goes off ?

 

[yo han]

Not safe? Outside the limits? Ruining batteries? No offense but I really think you guys should read up on Li-ion charging because what you just posted doesn't make much sense. Charging a Sony VTC5 at 2A is perfectly allright. Please explain the technical facts why you think it ain't.
You can double the charge cycles of any Li-ion cell by not saturating it and only charging it up to 4.10V
I choose to stop after stage 2 charging. Sure, this'll only give me 80% of its actual capacity but my cells last me much longer. I think trading 20% capacity for 100% more lifetime ain't bad.

 

[Mooch]

The "standard charge" rate for the VTC5 according to Sony is 2.5A but charging at anything below will extend cell life.

We recommend much slower charge rates than this not just to extend life though. It keeps the charger running cooler (which is good as there are lots of crappy chargers) and makes sure that even older, worn out cells (with high internal resistance) don't get charged too quickly. Lastly, it add a safety margin for things we don't know about. Could the charger be used outdoors in the sun on a August day in Arizona? While not probable, it is possible. We need to factor stuff like this in when making recommendations. For those who research the specs and understand cell safety, higher charge rates await.

 

[sonicbomb]

Please don't set fire to my toes, I'm no expert in this field.
But as I understand it, the chemistry of a battery is about optimizing certain characteristics based on priority, within the constraints of existing chemical knowledge. For example, high amp limits come at the expense of mAh. So I assume that fast charge rates are possible by tweaking the chemistry, but this would be at the expense of capacity or power output. The market as it stands puts power and longevity above short charge times, so thats how they are engineered.
I believe that fast charge times for batteries is something of a holy grail for those who work in this field, and will require a radical change in the way they are made. The mobile phone market has pushed battery technology forward at an amazing rate, and thats where I expect to see the breakthroughs in the next few years.

Future batteries, coming soon: charge in seconds, last months and power over the air - Pocket-lint

 

[Fit_Four_Life]

You can double the charge cycles of any Li-ion cell by not saturating it and only charging it up to 4.10V
I choose to stop after stage 2 charging. Sure, this'll only give me 80% of its actual capacity but my cells last me much longer. I think trading 20% capacity for 100% more lifetime ain't bad.

^^EXACTLY!

"Most Li-ions charge to 4.20V/cell and every reduction in peak charge voltage of 0.10V/cell is said to double cycle life. For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.00V/cell should deliver 1,200–2,000 and 3.90V/cell 2,400–4,000 cycles"

How to Prolong Lithium-based Batteries - Battery University

 

[yo han]

It's funny how some people think higher charge currents are automatically meant for fast charging. But remember that when battery capacity doubles, so does the standard charge current.
We've seen an increase in battery capacity, yet most of todays chargers charge at about the same current as they did 2 years ago. Like I've said before, I'm not after fast charging, I just want to be able to do a standard 0.8 C charge.

 

[Mooch]

My LUC V4 can charge two cells at 2A each, four cells at 0.5A or 1A.
That will get you your 0.8C charge for up to 2500mAh cells.

 

[yo han]

Yes, that's one of the few chargers that can do 2A. But still omly if you charge 2 cells at a time.