I am wondering if i am using up more of its life by recharging my cell phone at 20% remaining or should i recharge at 50% remaining for longer lifetime.
Battery University suggests that recharging at higher discharged voltages increase the lifespan dramatically.
Ah, but think of it this way
lets use a 1000mAh (1AH) battery for simple comparison, for larger capacity multiply by actual capacity, the ratio remains the same
100% discharge (1AH per use)
300 - 500 discharges = 300-500Ah before capacity reduced to 70%
50% discharge (0.5Ah per use)
1200-1500 discharges = 600-750 Ah before capacity reduced to 70%
25% discharge (0.25Ah per use)
2000-2500 discharges = 500-625Ah before capacity reduced to 70%
10% discharge (0.1Ah per use)
3750-4700 discharges = 375-470 Ah before capacity reduced to 70%
This is not very impressive, in fact it means you should charge at 50% discharge because above or below gives you less capacity retention
Well, actually that table shows that depth of discharge makes little difference in total battery lifetime (and charging at 10% DOD can cut battery life). You get more charge cycles, but you are pulling less energy out of the pack on each discharge cycle. Total energy removed from the pack over the battery life is not much different. The largest benefit is at around 50% DOD.
That said, it is best to not totally discharge the cells.
If you really want to increase battery life, don’t fully charge the cells. If you have a hobby charger use the 4.1V setting, or charge 4.3V cells in a 4.2V charger. Charging cells to 90% capacity can extend there life by a factor of 5 to 10 times.
That is very true. I searched for an app that would stop charging my phone battery at 4.10V but I think it’s a kernel level function.
I realized my Nexus 4 charges the cell to 4.30V for a full charge to maximize battery life, but hope that doesn’t drastically cut the battery life.
Using the above chart, and the lower end of the cycle figures…
Full use of a 2000 mah battery = 600,000 mah of use
10% before recharge of same - 750,000 mah of use
50% = 1,200,000
25% = 1,000,000
Edit: How would the notes suggestion of drain rate factor in though. A fresh cell in a hot light will impact the battery more than a standard lower drain light.
mine charges to 4.35V so i assume they are using those high voltage cells
if you do find a way to limit the charge to 4.1V let me know, i have the same phone
If it is a 4.2V cell it will…
Its made by LG and if i remember correctly they build 4.35V cells
Try running the numbers at the higher end of the cycle counts…
are you getting 50% being the best from that table or from other sources?
They came up much the same. Well they reflect the same effects. The largest change was for 100% use though, with 400k more mah. Still reflects what you said, somewhere near 50% is the sweet spot.
But none of it seems to factor in the drain rate (ie: a 6amp light v a 2.5).
there are other factors as well, cell age, storage temperature and so forth, but DOD is the focus of this thread and is easier to control if there is actual data to work with
Interesting discussion
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These artificial tests tells you nothing about real aging. In real world by charging more often you only extend the time your battery spends (near) full charge and actually ages faster.
If you want to prolong your battery life charge in the morning so it doesn’t spend all night fully charged and do not let it charge fully. It is only applying topping charge after 1-2 hours anyway.
If you had a 4.3v Samsung 28A and a 4.2v Samsung 26C, and used them in the exact same conditions (discharged to the same point each time, same number of cycles, same current draw, both always charged to the same 4.2v), how much longer would the 28A last (since it's effectively being undercharged by 0.1v every time)? Would it be significant?
I was reading on this forum about pwm pulse charging being worse on a battery too. I might buy that new fruity dream charger when it comes out.
Reason is my charger is pwm pulse (I found out by reading the manual hehe). But what’s nice is it slows the pulse as it nears 4.2v and the batteries aren’t hot when they hit the goal voltage set. The voltage does spike over though during the charge and you might get 4.28v spikes on the way to 4.2v top off. I dunno just going by temp, but a constant current would heat up the battery more I’m thinking and that may be why you need to limit the charge? Heat over 45C is not good on batteries
Fwiw…
I have a few chargers that I built from spare parts that run direct DC current with no pulse with separate battery cradles.
When running at .5 or 1.5 amps the power supplies get hot enough to need cooling fans but cells that are in good shape stay cool.
I notice that cells in the one-piece commercial units seem to absorb radiant heat from proximity to the internal power supply.
I had a failed battery pack in an old Powerbook that quit holding full charge (an OWC pack maybe 7 years old);
An eBay replacement 3rd party pack never reached full charge in the computer, and gave an error blink in an external Lind charger for that model).
3rd party seller sent me another pack that worked OK; I’m guessing they had a bad batch and knew it.
Recently, over a year later, I took both of the failed battery packs apart to see what I could see.
The old OWC pack had nine Samsung cells, one of which was below 3.9v, the other eight all around 4v. I guess that rated ‘fail’ in the computer.
All nine cells charged properly as individual cells (Intellicharger I4).
The 3rd party pack — much newer — had nine no-name cells (blue shrinkwrap, bar-coded) every single one of them flat zero dead on a voltmeter.
The Intellicharger just blinks once and then turns its little yellow lights out, when given one of those cells. Dead dead dead.
I’m guessing something bad in the circuitry in the pack drained them and caused the pack never to work properly.
So anecdotally, yeah, deep discharge can do that. They’re in the metal box til I get them to safe recycling.