No, you have a good grasp of rechargeable lithium longevity. But there are some people that feel cheated if their battery won’t go the whole distance and the charger won’t get them there. This forum is positively loaded with them.
gaus163 - I get that history. But, within that history it is normal for 3.6v nominal to mean 4.1v full. That charger is using it to mean 3.6 > 4.2. They are mashing the different conventions together. It’s not a big deal, but it is somewhat confusing.
The LiIon manufacturers has not learned that, some cells are specified 3.6V nominal and 4.2V charge.
That’s pretty scary that some LiIon manufacturers don’t fully understand their basics of their power storage device.
We desire it simply because it can be done basically. I actually charge my batteries to 4.1-4.15v the majority of the time unless they are laptop pulls, then I give them a full charge and let them sit to see how they self dischrage.
Or if I am going for a peak output in a light, then it gets a full 4.2V charge.
All that said I don’t really care what they charge to as long as it is NOT over 4.20 volts. We do not use batteries enough to wear them out by usage, you would have to run your batteries down and recharge them every night to make a noticeable difference is capacity within 2 years time.
Since most of us go weeks/months between charges simply because we can’t use the lights that much. The batteries will simply become outdated before they wear out.
In 5+ years I am positive they will have some better batteries out that we all simply must have. I saw somewhere that the 18650 form factor should be able to reach 6000-7000mA before they have exhausted the lithium technology.
Yes, kind of gives you pause if they don’t even get that. OTOH, a BIG problem is in the technical writing and marketing arena. The engineers probably get it, they likely don’t/can’t/won’t talk to the marketing and writing dept. and those people tend to be pretty poor at translations. We make fun of the Chinglish but it’s a fact of life for this kind of device. Their manuals tend to be mediocre to awful.
Eh, some chemisties are a bit differnt in how they deliver power. Nominal simply means average voltage. Some have a higher or lower average voltage during discharge then others. Plus they want to keep things fairly standard which is why you don’t see things like 3.654v nominal.
The nominal voltage really means nothing to us though, all we care about is peak charge voltage and min discharge voltage.
Exactly. Saying all batteries today are 3.7V nominal is wrong.
I have seen a few datasheet (Maybe only one) with two digits after the decimal point for nominal voltage.
Well, to the consumer. It actually is the natural voltage of the materials interacting with each other, no charge or discharge applied. This is the voltage they come from the factory at. It’s the best voltage for storage, because the materials are both in their fully natural/relaxed state. Factories don’t take the time to charge each cell to 50%, it’s just natural, and called the nominal voltage.
The Sanyo NCR18650GA has a 3.6V nominal rating and if you calculate the average voltage during a 0.2C discharge .my guess would be that the result is very close to 3.6V.
Because I only discharge to 2.8V I could not verify that. The average voltage I got at 0.5A was about 3.65V and 3.63V at 1A (0.2C is 0.67A).
Of course, but i was referring to the discharge graphs.
They show a steep voltage decline from 4.2 to 4.0 Volts, which is not because of the internal resistance, because then it would be immediate, not a decline over a short amount of time.
Or am i wrong?
Those graphs didn’t ‘speak to me’ earlier, but now i see (better).
Still, there’s a ‘knee’ there, but it’s around 4.1 Volts.
I’m not sure about the recovery after charging cuts off, but i usually measure 4.15 V on a freshly charged cell, but that could be my charger…
This has to sink in yet somehow… (in my mind that is…)
But thanks for explaining so far.
Would you guys like to see the same cell capacity tested from 4.1 to 3.1 and then 4.2 to 3.0 on this charger?
If you really want full control of your new charger look into the Cheali Charger firmware
I talked about it in this thread, I love it: Serious battery charging station setups on a budget
I don’t know that that is made for the version 2 charger.
If it has the Atmega MCU it should work, thats the only sure fire way to know.
Nope, a look at the Google group says in the V2 charger “the chip is megawin MA84G564”
Well, I guess that is your answer. You could get a basic version of the Imax and flash it, I keep thinking I should order another one while I can get them just to have around.
What are the benefits of that firmware?
Full control for one thing, you can also calibrate it to be exact, much more accurate, the ability to use external “probe” to sense actual voltage after the wire voltage drop allowing for internal resistant measurements that actually work and better charging. Plus just general improvements.
It is not a must have but if you like full control over all the details of your batteries charging, then it is lightyears better.
I like having full control lol.
If you guys are curious to know - I had charged the batteries from my old laptop to only 4.1v out of caution many days ago. Today I decided I wanted 4.2 or flames. Each cell took another 110 mAh.