For LiFePO4 batteries typically used in off-grid applications, all the tests I have seen indicate that long term storage at full charge leads to a shorter life than storage at 50% or 80% state of charge.
Some people take that to mean you shouldn’t fully charge a battery to 100% SOC.
How the above relates to typical usage is something that I have not seen addressed properly - as typical usage of powerbanks or off-grid batteries does not involve storing for long periods in any particular state of charge.
My personal preference is to generally charge my phone to 90-something percent of charge, rather than 100%, and for my off-grid LiFePO4 battery I don’t charge to quite as high a voltage as the recommended maximum.
I’ve passed your suggestion on to our content producers. We don’t have the capacity nor budget to gather the evidence ourselves, but there are many sources that recommend tips and tricks to getting the longest life out of your battery. Here is just one example.
I now believe my comment (from two years ago!) on maintaining modern, small-scale lithium-ion batteries between 38 and 82% may be out of context for this thread. I was basing my information off prior knowledge: how decade-old, large-scale, Prius lithium-ion battery longevity was effected by charge habits. I should have put a disclaimer on this, saying it may not directly relate to mobile phone batteries.
From what I can see, there isn’t much conclusive evidence that suggests any particular habits contribute to longer life-span of your small lithium-ion batteries. I was right that modern batteries do not have a ‘memory’, but I was incorrect in saying that keeping the battery between 38 and 82% will have a positive effect.
The take aways: keep it cool, plug it in often, don’t stress.
Keep your battery (and devices) cool!
This is one of the big killers of batteries: over-heating. But, for the life of me, do not freeze your phone to increase battery performance!
You can leave your battery plugged in over night.
Plus, leaving your battery on charge is better than deep-cycling it up to 100%, down to 0%, and so on. This seems to reduce battery life. Chargers these days are smart enough to cut the power once the battery is full, so feel free to plug it in as often as you feel like to keep it topped up.
Don’t stress about ruining the battery.
These little battery lifehacks you always here make very little difference to your battery. The only things that actually affect a battery are heat and using it at all. So don’t stress if you dipped it below 5%. It’ all good. Just charge it whenever you can.
That is something new to consider, especially given the now common use of that battery technology for cordless tools and house hold appliances. All of these are typically recharged to 100%. Tradies by observation seem to use their tools from 100% battery charge until the last whimper. We’ve had 5 teams do work for us in recent years. Yes, I’ve asked the question and all still have the batteries they started with, although most have at least two or three to swap out during the day!
There is a common comment that for longer term storage and periods of low usage it is better to only part charge the batteries. I’ve also read the same in a manual somewhere.
An interesting observation follows:
I have an iPhone 4S purchased new on release in 2011.
It is still on daily and has the original battery!
Until just over a year prior it was my everyday phone. I don’t play games or typically watch video. Mainly SMS, camera and voice calls, plus email as a back up for when the laptop is not to hand.
All I’ve ever done to manage the battery is avoid fully discharging the battery. Once it drops below 50% it was charged at the next convenient opportunity, usually to 100%.
The battery now only lasts about half as long as it used to. It also seems to discharge more quickly once it drops to below 20-30% of full charge. I now get away with a charge every 2-3 days due to the lower usage.
The host of one of the more ‘extremely technologically focused’ podcasts I listen to does in fact freeze certain electronic devices. He does it carefully, and has the necessary skills to ‘do it right’ without ending up with water condensing onto the electronics. It is not something that he recommends people try at home, but is something he does to hang onto old technologies (such as half-a-dozen spares of a favourite calculator).
If you mean the CSM Its origins were as expected with such a name, but it is an old and still respected ‘paper’ that reports news. It does not tell you what you should be thinking about that ‘news’ be it technology or politics or whatever. They try to publish quality information unlike the click bait media. They are not expert in this topic (ie they are not a technical journal) but they do not follow The Sun in any respect.
Is it correct to assume the nameplate storage bank mah rating is not at the nominal 5V output? Is it actually the rating of the internal battery at approx 3.6-3.8V if lithium based?
EG one tested product.
On line the Cygnett ChargeUp Edge+ 12,000 mAh Qi Power Bank is rated at 12,000mah or 44.4Wh. This Wh energy is consistent with the internal battery voltage, and not the mah capacity at the USB standard 5V. The watt hour rating suggests with 100% energy recovery and perfect DC-DC conversion efficiency that the bank is capable of 8,880mah at the rated 5V output.
It provided a slightly greater than 8,880 mah output ‘usable capacity score’ charging the mobile on test, IE more than it is capable of by the numbers. However Choice scored it less than 100% on capacity performance.
How is this possible?
Note:
It’s self evident from the reviewed example that all battery bank products have two important sets of capacity data. They may not all be evident. The Watt hour capacity of the built in battery and the Watt hour capacity available at the 5V USB output.
There are losses in the conversion of stored energy (Wh) to the USB output, prior to any further losses in the device being charged. Choices mobile phone charging test steps nicely around all the differences to produce a simplified number of to 80% re-charging cycles as a product guide. I get that.
The capacity performance score in percent might be also be a reliable measure for each power bank, however the actual base line data is not in the tables? The results vary from 69% up to 92% excluding two notable exceptions. Clear as mud and is this comparing Watt hrs to Watt hrs?
Still using my Moki. That 71% I referenced earlier was wrong. It seems to be a number that appears in its little LED screen for no apparent reason (clearly more depleted than it was showing) and its why It took forever to recharge itself. However, the phone was twice charged so I remain pretty happy with it.
More recently it kept my ipad and iphone charged during a blackout which lasted 24 hours.
Actually, the Wh capacity should be the same, it’s the Amp hour capacity that will be different at the different voltages. Low V at higher Ah, higher V at lower Ah. Assuming of course a near 100% voltage conversion
18.5Wh in the internal battery becomes 15Wh at the USB port. IE 81% efficiency before any further losses in the device being charged.
I think the Choice reviews do a good job of comparatively ranking or rating the capabilities of each power bank. The tests are not a repeated test over time to assess durability or quality of the product. The absolute efficiency of each option might be a guide.
I’m hoping for a little more explanation of the other test results and how they relate, perhaps sufficient to clarify the inconsistency noted, between what I read relates to the 5V USB measured capacities of each power bank and the mobile phone charging capacity scores.
I read the load discharge capacity test is independent of cycling each power bank with a real mobile phone. Perhaps this is not correct. The variation in scores suggest they are independent.
P.S.
I can get nearly two full charges of an iPhone 8 out of the above PB.
Boosting the voltage from 3.7 to 5V is as you say 81% efficient, and I think not really the best way to do it.
I have seen a battery with 12V output as well as the 5V USB output, and I suspect this could be a more efficient way to do it, if they have some sort of MPPT circuitry included. Much the same as MPPT solar charge controllers are significantly more efficient (>95%) that PWM type charge controllers, which vary depending on PV panel and battery voltage.
Article by Peter Zaluzny…
Just a comment regarding power capacity chapter in the article:
Capacity is measured by WH (watt/hour) and not AMP - unless you know the voltage.
Most Airlines for example, will nominate the max capacity for carry on batteries in WH which is the AMP/H x Voltage for example a power tool battery of 5A/18V have a capacity of 90WH (5x18) and is quite close to the max. capacity allowed on board (usually 100WH).
Most branded power banks are showing the AMP/H (or mAH) measured on 3.7V but unless the WH is stated, they can always claim that the AMP/H has been tested on much lower voltage…
This is the reason you can see many unbranded batteries online with ridicules claims like 200,000mAH.
I understand the reason behind your decision to nominate the AH as capacity, since most power banks are doing the same, but this explanation should be included so buyers will understand that suppliers are not necessarily lying when claiming high AH capacity, but being a bit deceiving.
Although the Wh capacity indicated is relative to the output power. This is not misleading relative to the output capacity. It is misleading in respect of the true internal battery capacity, and requires multiplying the nominal internal battery voltage 3.7V by 5000mAh to get 18.5Wh capacity. Not an issue for carry on board in this example.
Not likely a concern given the relatively generous carry on allowances for battery capacity. Total carry on weight might be more of a concern if travelling in a low cost fare?
In the tables included in the reviews it was interesting to note that the Choice reviewers were for some products unable to clarify the battery technology used, internal battery voltage or nominal capacity. The test results are all a consumer has to rely on.
Well…AH does not tell you the capacity unless you know the voltage WH does tell you the capacity.
Quick search on ebay (where many unbranded batteries are available will show you many batteries with huge mA/h claim without the voltage - WH would be the only true indicator.
With many trying to find the best and cheapest deal on the internet, buying unknown brands of powerbank with extraordinary claims is a recipe for disappointment…and being shammed…
Now, as is the case with products like this that are sold in the UK, I liaise with UK trading standards officers to get products like this removed from sale.
Does the UK have something we don’t?
Although the prospect our Aussie Government has any interest or the capacity to do seems unlikely?
Note:
A National levy on all marketing and advertising spend of 10% might be the go. Passed on to someone more responsible than the average advertise or platform, IE Choice, to produce fact checking adverts that must be run at the end of every advert or promotion, 20% of the space or 15seconds duration. Advertiser beware! If there is a Latin translation it might even be one law.
) on maintaining modern, small-scale lithium-ion batteries between 38 and 82% may be out of context for this thread. I was basing my information off prior knowledge: how decade-old, large-scale, Prius lithium-ion battery longevity was effected by charge habits. I should have put a disclaimer on this, saying it may not directly relate to mobile phone batteries.
