Lets say one has purchased a new li ion powered device and wants the battery to last as long as possible and hold the most charge say after 3-5 years
This device has some draw at all times (say a phone or tablet)
Would it be better to charge to 100%, unplug charger, use and recharge when near empty or leave on charger most of the day and remove when remote operation is needed.
Leaving on charger means no cycles on the battery (less wear) while plugged in and used when plugged in, but its at 100% most of the time and likely a bit above ambient temps (more wear)
Removing from charger when full means more cycles on the battery (more wear), but the absolute and average charge level is less then 100% (less wear)
I'd say its best to keep the cells between 20 and 80% charge state. I dont remember any test on that (gotta be out there though?) but keeping it plugged in all the time will stress the cells, even "smart" chargers that let the battery discharge a little before charging again usually start recharging at 95%.
Some laptops have the possibilty to set 90% as maximum charge..
I think the big cell manufacturers publish graphs that show the relation of cycles, charge state and remaining capacity in some data sheets. Basically, dont fully charge them and they will last longer.
Having the cell fully charged at all times will kill it the fastest. Deep cycling (full discharge to full recharge) will kill it almost as fast. High ambient temperstures kills cells too. (In the Caribbean, laptop batteries typically start failing after a year and a half.)
NightCrawl said: “I’d say its best to keep the cells between 20 and 80% charge state.” I agree with this statement and can confirm that some latops charge to 80% to increase the number of cycles the battery can handle.
When LiIon cells first became available for us to use in flashlights/ mods etc, ALL the literature spoke about charging LiIon to 4.10V and no more. Even hobby chargers have different settings for LiIon (4.10V) and LiPO (4.20V) cells. The reason is that you get more cycles (battery lifetime) when you charge to a lower voltage even if you end up with a lower capacity. If I remember correctly, charging to 4.20V will give you in the range of 300 cycles and charging to 4.10V will give you closer to 1000 cycles. (If you charge a normal LiIon cell to 4.4V, you may end up with less than 10 cycles….)
It is best to use the middle range of the cell (as NightCrawl suggested). Try not to drain the battery fully. Try not to recharge fully (4.20V). Do not keep the device plugged into the charger all the time and if the cell dies, recharge as soon as possible even if it is just for a few minutes to get the voltage away from 3.00V.
Image is from batteryuniversity. (is this hotlinking?)
Unless your device has sophisticated software to control charge parameters (ThinkPad for example) then you really just have to live with the fact that the battery will eventually fail and there is precious little you can do to prevent that fact.
I set my laptop to start charging at 70% and stop charging at 90% which I feel gives a little more overall life. I'm on my second battery - the first lasted over three years and my ThinkPad gets a LOT of work.
As eebowler pointed out, high charge states, high temperatures and deep cycling are all bad for your cell. Even more so if these factors are combined.
Perhaps you need to simply find out what a replacement battery is worth. For apple products you should be able to get a quote fairly simply. Other brands can be utterly useless, telling you to send the unit in for a quote. I struck two companies recently whose "policy" prevented them from quoting on tablet battery replacement. Needless to say, they were informed that they wouldn't be getting a sale from me or anyone I know.
I think there are just so many factors that it is virtually impossible to give you a solid recommendation here, especially as you really haven't told us what device you are actually talking about. A phone's usage pattern is often quite different to a tablet. Also, many phones have user-replaceable batteries whereas many tablets do not.
Best advice I can think of is to just factor in the price of a battery every 2-3 years as a running cost. Or do like a lot of people and chuck the entire phone away for a new one every two years. Sad but true.
I wouldn’t worry too much about it. In 2-3 years you’ll have a new device most likely. And with normal use your battery will still have 70-80% capacity left.
I’ve been naughty with my netbook, leaving it plugged in all the time. Such is the price of laziness, but replacement battery packs have got cheaper too.
I do know how the batteries work, but with a cell phone you can’t choose to charge to a maximum of 80% and it has some drain whether used or not (just faster when used), hence this forced choice
New device in 2-3 years is not possible in this application and its a non replaceable battery :_(
“Non-replaceable battery” ?? If it went in, it can come out. Are you really saying this on BLF? Don’t we tear stuff up all the time in an effort to make it better, brighter, more/less colorful, or just plain for the heck of it?
I give you comfychair, who took a Solarforce S1100, virtually brand new, and tore it apart (albeit with some difficulty) in order to shoehorn an MT-G2 emitter into it and become one of the first to do so. Solarforce promptly came out with the S2200 having the MT-G2 already installed. This is what we do, is it not?
I, uh, (kinda hate to admit this) just yesterday, well, I removed the mini FluPIC driver from my custom made Texas Poker Titanium light and installed a custom driver. Doesn’t sound too bad on the face of it, but I had to cut the FluPIC out with a dremel tool, destroying it it in the process. Like the modes better. Point being, are we afraid of an item because it costs a lot? Because it’s difficult? Because conventional knowledge says we “can’t”?
Bah! We’re BLF’ers, we can do ANYTHING!
Use it to the max, enjoy the he out of it, fix it when it wants to bail out on ya.
Keep the battery at a storage charge level, out of the device most of the time in reasonably cool place; and run the device off of wall power?
I personally top up when down to about 40% if off a charger and leave on charger when I can - 2 years no observed wear. I will turn off before I let it go into the red zone. Never let it get hot sitting in a car or out somewhere, even with auto temp sensing and auto shut off.
My wife runs hers dead nearly every day. Capacity seems down somewhat in almost as long a time as mine, but it’s still very decent and doesn’t need replacement yet. She only uses it for data. She’s already killed a couple batteries in her voice phone from the same habits, though it is much smaller capacity to start.
I have the new HTC One. If you read the teardown on ifixit.com, its not advisable to try to change the battery at home. But on my smartphone I dont mind that much.. because if the battery gets weak within the next two years, I'll get it replaced through warranty. If it still works fine, I'll get a new phone in about 21 months because my contract will end. Or I'll get it replaced via the official repairing network of HTC for ~100€.
On smartphones, tables and so on, I dont mind about the battery. But my current to-go laptop is 7 years old because I dont want to carry my 1.000€ laptop around in public transport, university and so on. And the battery still lasts about an hour of surfing. :D
Using a cell phone for example: If for example, it takes 4 days to go completely dead from a full charge, recharge it after approximately three days. If from fully discharged it takes 3 hrs to recharge, then recharge it for approximately two hours. (Yes, I know, charge time is not exactly proportional to capacity). Your use would be something like three days use, two hrs recharge, three days use, two hrs recharge… Makes sense? I replaced an 18650 cell from friend’s bike light and gave him similar advice in order to prolong its lifetime.
Bort, BTW, I once soldered on an 18650 cell to the battery of my cell phone because I refused to spend $50US for a new battery. I put two holes in the back for the wires to go through and used double sided tape to secure the battery to the back cover. The old battey had to remain connected because of the protection/temperature circuit… It was ugly but you know what, I could go a week without recharging!!
You are going to need to stop being so cagey Bort. Tell us what device you are talking about.
DBCstm makes a valid point - if it went in, it can come out.
eebowler is on the right path perhaps. You maybe don't have to butcher it or solder 18650s but external USB packs can be had cheaply now. That is, if your device charges via USB.
Seriously dude, if you want help you need to give us more data. And if you are building Chloe's satellite for the CIA then use their think-tanks for ideas
Specifically its a cell phone, but the point of this thread is to find out generic li ion data for any device that uses the battery this way (therefore not cell specific), a netbook, laptop, cellphone, tablet, digital camera, radio transmitter, walkie, palm pilot or any device where the manufacturer doesn’t have a charge below 100% option so you must either leave at full charge to use mains power or use the battery extensively (charge/disharge) but can use below 100%
Aha. In that case you already have some good advice. Carefully monitoring and estimating when to charge and for how long is perhaps useful but would require a lot of work. The usage profiles on a cell phone can vary wildly from day to day.
Much of this data about the factors influencing cell life has been discussed in numerous threads and at batteryuniversity.com
Don't overcharge, don't draw down to a low voltage, don't store at a high state of charge, avoid high temperature, etc, etc, etc.
The reality is that the battery is considered a consumable item. Given also that marketing, technological development and economic factors combine to try to convice us that most electronic devices are due for replacement within 2 or 3 years, I doubt you will get too much help from manufacturers in terms of optimising devices for ideal charge regimes. Especially on phones and tablets where the aim is to sell newer versions ASAP.
One interesting question perhaps for the more electronically inclined....
Would it be possible to control the charge points and levels on a phone or tablet through the use of an Android app or would it specifically require additional hardware components in the charge circuitry?
