Battery Charger Life Hack With More Detail

Ok, let's go over what we've already established:

Some of you might have devices that take longer to charge than to deplete.  For example, if you have a device that takes 4 hours for the battery to run out and 15 hours to recharge.  How do you use it non-stop?  I have the answer.  The answer is basically a modification of the duty cycle theorem on wikipedia.

But make sure that while most —devices that are charged by plugging them in rather than removing the batteries— (such as bluetooth headsets/headphones and cell phones and many other devices not listed) are safe to leave plugged in and left unattended, —BATTERIES THAT HAVE TO BE REMOVED FROM THEIR DEVICES— SHOULD NEVER BE CHARGED UNATTENDED UNLESS —THE CHARGER AND THE BATTERIES— DOCUMENTATION EXPLICITLY STATES THAT IT IS SAFE TO DO SO.

Before I continue, let me remind you that this applies to both single batteries, or groups of batteries.

Some of you may be thinking, "why don't I use multiple batteries and multiple chargers?"  That's correct.  But we need to know how many batteries and how many chargers we need.

Here's how we figure it out:

We'll use c the variable for our charge time and u as the variable for our usage time.  First we use the formula:

(c+u)/u then we round up if there is a remainder.  So in this cause c=15 and u=4 let's plug it into our formula:

(15+4)/4=4.75

We will round up 4.75 and get 5 for the amount of batteries.

Also the charger amount = (the battery amount-1).

Now as I said before will use a is the charger amount and b as the battery amount.

Now some of you might think that we only need 4 batteries in this example I will now show you what happens if we use 4 instead of 5.  Keep in mind that we will not start charging a battery until it's dead, this is so that we spend as little as possible switching, so we will log the progress of our imaginary batteries in increments of 4 hours.

So at the start (0):

Battery A is full, placing it into device
Battery B is full
Battery C is full
Battery D is full

Four hours later (1):

Battery A is dead, placed in charger 0 hours ago
Battery B is full, placing it into device
Battery C is full
Battery D is full

Four hours later (2):

Battery A is dead, placed in charger 4 hours ago
Battery B is dead, placed in charger 0 hours ago
Battery C is full, placing it into device
Battery D is full

Four hours later (3):

Battery A is dead, placed in charger 8 hours ago
Battery B is dead, placed in charger 4 hours ago
Battery C is dead, placed in charger 0 hours ago
Battery D is full, placing it into device

Four hours later (4):

Battery A is dead, placed in charger 12 hours ago
Battery B is dead, placed in charger 8 hours ago
Battery C is dead, placed in charger 4 hours ago
Battery D is dead, placed in charger 0 hours ago

Ok now we have a problem, we've reached stage 4, meaning we've depleted 4 batteries (since our first stage was stage 0) and all of our batteries are dead before our first is fully recharged.  Battery A is closest to being charged, but we need a 5th battery so that we can use our controller until then.  So let's list stage 4 again, but this time, let's add a new battery and pretend it was there all along, let's call it, Battery E.

Four hours later (4):

Battery A is dead, placed in charger 12 hours ago
Battery B is dead, placed in charger 8 hours ago
Battery C is dead, placed in charger 4 hours ago
Battery D is dead, placed in charger 0 hours ago
Battery E is full, placed into device.

So in this version of stage 4, battery E is in the device ans we still haven't run out of batteries.  Also notice that because 4 batteries were full at the beginning, 4 chargers were available until Battery D died.  This means that if Battery E was dead and started being charged at stage 0, it would've been fully charged by stage 4, since 4 stages of charging times 4 hours>15 hours of charging.  So we only need 4 chargers.

Four hours later (5):

Battery A is full, placed into device
Battery B is dead, placed in charger 12 hours ago
Battery C is dead, placed in charger 8 hours ago
Battery D is dead, placed in charger 4 hours ago
Battery E is dead, placed in charger 0 hours ago

So now we're at stage 5 and Battery A is fully charged again, so we can start using it again.  Also it's no longer in a charger so Battery E can go into the charger it was just removed from so we don't need more than 4 chargers.

Let's see if we we run out of batteries or chargers four hours later.

Four hours later (6):

Battery A is dead, placed in charger 0 hours ago
Battery B is full, placed into device
Battery C is dead, placed in charger 12 hours ago
Battery D is dead, placed in charger 8 hours ago
Battery E is dead, placed in charger 4 hours ago

So now we know that in this scenario, as soon as a battery dies, a battery becomes full or is already full and a charger becomes available.  It should also be noted that when you start using the device, not all batteries have to be fully charged; in this exampled, only one needs to be fully charged and in use, one needs to have been charged for 12 hours, another for 8, another for 4, and another has to have been just placed into the charger.

As a final note, you can keep the charged batteries in the charger until they're needed.