Hello Patriots.

Rechargeable batteries are an important part of preparedness.  Having undamaged, fully charged batteries in the event of a power failure is critical.

You want to avoid the following situation:  The grid fails.  You are without power and communications.  Fortunately you had batteries in your communications gear and lighting systems.  All is well.

Wrong!

After using your radio for only a few minutes it stops working.  “Strange,” you say to yourself.   Your radio’s batteries have been charging up until the power failure.  Why did this happen at the worst possible moment?  The batteries were charged.  Why did this happen?

First, the investigation:  When you measure each battery with a multi-meter you discover that all of the batteries indicate 1.2 volts — except one.

The battery capacity was mismatched.  Capacity on batteries is measured in milliamp hours (mAh).  In our radio example, four batteries were used.

  1. 2000 mAh
  2. 2000 mAh
  3. 1200 mAh
  4. 2000 mAh

In this example, battery number three has a capacity of 1200 mAh.  All of the others are 2000 mAh.  As the radio was used, the 1200 mAh battery discharged.  After it discharged, current from the other batteries flowed into this battery.  The resulting reverse current will damage that cell and others.  The result is one very dead battery and three possibly damaged batteries. Oops!

Example 2: Using old and new batteries, resulting in capacity mismatch.

Here is an old and new battery example:

  1. 2000 mAh (2014 manufacture date with 1975 mAh measured capacity)
  2. 2000 mAh (2014 manufacture date with 1980 mAh measured capacity)
  3. 2000 mAh (2003 manufacture date with 900 mAh measured capacity)
  4. 2000 mAh (2014 manufacture date with 1995 mAh measured capacity)

In this case.  All of the batteries are labeled with the same capacity.  One of the batteries is significantly older than the others.  Over time, battery capacity drops due to use and the number of charge cycles.  The older battery has a measured capacity of 900 mAh.  This is less than half of the stated capacity.  The same situation develops.  Greatly reducing the time that the device can be powered, likely resulting in battery damage.

This same situation can develop if you use batteries of differing manufacturers or different chemistries.  Do not mix Nickel Metal Hydride (NiMH), Nickel Cadmium (NiCad) or Lithium Ion (LiON) batteries.

Using rechargeable and and non-rechargeable batteries is also not a good idea.  The voltage is slightly different between the two.  The voltage level remains constant over time with rechargeable batteries.  With non-rechargeable batteries, the voltage declines slowly over time.  The difference in voltage drop rates can result in damage to the batteries.

What should you do?

The best advice I can give anyone, is the following.

  • Use a smart charger. A good smart charger will allow you to charge cells independently of each other (one cell at a time if needed).
  • The charger should also have a way to adjust the charging rate. You need to be able to adjust the charging rate according to the capacity of the battery.
  • I usually charge at 50% of the battery’s stated capacity.
  • A 2000 mAh battery should be charged at 1000 mAh.
  • The discharge rate (for testing) of a 2000 mAh battery should be 500 mAh.
  • The charger should also have a way to measure capacity of a battery (discharge fully, rest, recharge).
  • A charger that can be powered from a 12 volt system, is a plus. A 12 volt powered charger will allow you to use your car or a solar panel to charge your batteries.
  • Any batteries that are performing less than 80% of their stated capacity on a consistent basis should be retired.
  • Avoid 15, 30 and 60 minute chargers. These chargers may work in a pinch, but they will overheat your batteries. Fast charge cycles and overheating will cause your batteries to fail much sooner.

Capacity matching (in a nutshell)

Here is a technique that can really help.

Determine the capacity of your batteries using a smart charger.

Keep an inventory of your batteries.

Pair up batteries by measured capacity for your devices.

Details of the inventory system (paper or in a file)

Assign each battery a unique number. Write the number and the measured capacity on the battery with a permanent marker. It is best to write the measured capacity next to the labeled capacity printed on the battery.

Record the unique number, stated capacity, measured capacity and the date that the battery went into use for the first time. You can also record what device is currently using the battery.

When you need to power a device, look at the measured capacity on the batteries that you have in storage. Choose the batteries that have the closest measured capacity for your device.

Once I started using this system, my batteries lasted a lot longer.

Personally I use two chargers. Both are excellent and I highly recommend them.

Well, thank you for reading my post. I hope this information suites your needs. Best Regards.

— Keep those batteries safe.

Lima-06

P.S.

Here is an example of a recording system that I use to inventory my batteries:

Battery Number

Measured Capacity

Label Capacity

Cell Health

Date in Use

Manufacture Date

Device

1

2180

2000

109%

8/11/2013

1/1/2013

Garmin GPS V

2

2160

2000

108%

8/11/2013

1/1/2013

Garmin GPS V

3

2190

2000

110%

8/11/2013

1/1/2013

Garmin GPS V

4

2170

2000

109%

8/11/2013

1/1/2013

Garmin GPS V

27

2131

2300

93%

Old

Sony Shortwave Receiver

28

2139

2300

93%

Old

Sony Shortwave Receiver

29

2117

2300

92%

Old

Sony Shortwave Receiver

30

2108

2300

92%

Old

Sony Shortwave Receiver