I would like to know what advice to give the consumer about how often they should charge the device.

I read in this answer (and various other places on the net) that MicroUSB ports are rated for about 10,000 unplug cycles.

I also read in this article and this answer that Lithium Ion batteries will last longer when you "avoid full discharges and charge the battery more often between uses."

So running the battery down is bad, but there's a limited number of times that the user can put it on the charger to keep it charged up.

How much of a charge would you need in order to justify the wear on the MicroUSB port that happens when you plug it in or unplug it.

Let's assume that neither the Li-Ion battery, nor the MicroUSB port is serviceable by the end-user/consumer, and when either one fails, the device must be sent in for repair.

The device I have in mind in this case is a cell phone, however (I would assume that) this concept should apply to any device that uses a MicroUSB port and a Li-Ion battery. If this assumption is wrong, please help me (and others) to understand why.

As @Asmyldof points out, for very light usage, it can be fine to plug the device in once or twice a day and never run out of "plug cycles," but as smartphones begin to fill roles that once were reserved for dedicated hardware devices, this can quickly change.

Think about a delivery driver who gets in and our of their car 20+ times a day, and has to keep their phone both charged and on their person so they can be reachable by the dispatcher (and maybe they need to use the GPS or listen to Pandora too.)

At 20 cycles a day, that gives you only 1.3 years of life for the port. That even assumes that each of those 10,000 cycles includes a plug-in, and an un-plug.

Then there are those who like to set their phone on a non-wireless cradle charger to prop it up and keep the screen on, then take it off each time they need to answer a call or reply to a text. The consumer may not even know that they are drastically reducing the life of the device itself in their good-faith efforts to preserve the battery.

There must be a "happy medium" somewhere inbetween where both of these components will wear uniformly, and neither one causes premature failure of the entire device.


closed as off-topic by Asmyldof, Scott Seidman, uint128_t, Daniel Grillo, brhans Apr 7 '16 at 16:14

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Asmyldof, Scott Seidman, uint128_t, Daniel Grillo, brhans
If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ Judging by the way I witness many people plug/unplug a micro-USB, 10,000 cycles seems to be very, very generous ... \$\endgroup\$ – brhans Apr 6 '16 at 20:45
  • \$\begingroup\$ 10000 cycles, let's say plugging in and out both count, charging once a day, means 5000 days. That's 13.69 years. I don't think your battery will make that, whatever you do. Plot that against a 2 to 5% difference between charging at 40% at the end of the day, or at 70% at lunch and bed time and... well... your choice. \$\endgroup\$ – Asmyldof Apr 6 '16 at 20:47
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    \$\begingroup\$ Your driver scenario precludes anyone actively trying some ideal usage pattern, as is likely with most people. If the difference is replacement every 3-5 years, does it matter. Those heavy users will probably be using corporate equipment anyway. When I was a road warrior the corp just gave me a phone, which were retired and upgraded as necessary. I think you are chasing an unnecessary ideal. \$\endgroup\$ – user65586 Apr 6 '16 at 22:02
  • \$\begingroup\$ To add, it's incredibly customary for Road bound people here to be given a new phone every year. Not when they need it. Every. Year. And those vehicles have fleet management anyway, so it's just for calling. \$\endgroup\$ – Asmyldof Apr 7 '16 at 0:05
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    \$\begingroup\$ Your life will be much better if you can somehow condition yourself to stop worrying about something like this. \$\endgroup\$ – mkeith Apr 7 '16 at 3:03

I think the simple answer here is what is cheaper. Connectors are reliable, yes, but they're also extremely cheap when we are talking about USB. I'd rather replace it twenty times over than replace the battery if I need to at all. That said, finding replacement batteries can also be a hassle, so I'm going with plug away.

  • \$\begingroup\$ Replacing a battery means unplugging and plugging in a connector, and a monkey could do it. Remounting a USB conector means SMD rework, and even an experienced person can have a bad day doing that every now and again \$\endgroup\$ – Scott Seidman Apr 7 '16 at 2:18
  • \$\begingroup\$ Here it depends on the type of phone. I agree for Nexus, but something like the iPhone they don't make it easy and honestly and handling and reseating of the battery isnt recommended for danger of short. I don't disagree with you, but maybe I'm saying you're screwed either way in some cases. \$\endgroup\$ – mcmiln Apr 7 '16 at 2:20

How about using wireless charging (also known as "Inductive Charging")?

Many phones now come standard with the power receiver built-in and it is possible to purchase add-on adapters for many other models of phone that do not come standard with wireless charging.

There are a couple of competing standards but the one that I have used successfully is the Qi system.

A quick search on eBay for "Samsung wireless charger s4" shows that there are MANY inexpensive modules and power pads available.

The receiver modules that I work with are rated at 5Vdc 1Amp and they deliver that amount of power easily.

The reason that I mention the add-on power receiver modules is that is relatively easy to find a variant that closely matches the device that you want to power.

FWIW - I spend a fair amount of time replacing micro-USB jacks on Android cell-phones. The replacement jacks are inexpensive and usually easy to source from Asian suppliers. I often upgrade the phone being repaired by adding in a Qi power receiver and supplying a matching Qi Power Pad transmitter.


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