There have been a number of comments on SurvivalBlog about rechargeable batteries. The majority of these expressed the feeling that rechargeable batteries were expensive and ineffective for a long term storage plan. Before anyone gives up on rechargeable batteries I would like to share a plan that has proven effective for my family.
One day I sat down and assessed my family’s state of preparedness. Like many others, we needed more beans, bullets and band-aids. Turns out, we also needed more batteries. Before I started buying batteries, I tried to think of creative ways to minimize the number of batteries I would need. The first thing I decided to do was to go to low drain and no drain devices when possible. For example, I picked up an LED [4] conversion for my Mini Maglite that more than triples the run time of my flashlight. [JWR Adds: Such as one of these [5].] So now, I get the runtime from two batteries that used to require six batteries. An example of a no drain device is the Swiss windup alarm clock that I purchased to replace my battery powered clock. Obviously these steps only lessened my dependence but I still needed a lot of batteries. The next idea I had was to standardize my equipment so that I only needed one type of battery. This way I would not have the expense of stocking up on a bunch of different types of batteries. This also helped because I would only have to worry about rotating one type of battery in my storage. I ended up choosing to standardize with the AA battery. Not only are they cheap and readily available, I found that almost every type electrical device that I wanted came in a model that used AA batteries. For instance when it came down to an Aimpoint or a HOLOsight, I choose the HOLOsight model that was powered by AA’s. Even after standardizing I still had some devices that I purchased earlier that use other types of batteries. Instead of immediately replacing them, but in keeping with my plan, I purchased some battery adapters (from greenbatteries.com [6]). These sleeve type adapters slide over AA batteries and allow them to be used in place of C and D cell batteries. This completely solved my standardization problem and added flexibility to my plan. Runtimes are obviously much shorter when using the adapters but at least the devices will be useable should I need them.
Standardizing and going with low drain devices was only part of the solution. I was still faced the daunting task of buying a sizable number of batteries. It was at this time that I started looking at the cost of various AA batteries. I went down to the local retail store and came up with the following: 8 alkaline batteries cost $5.18 or $0.65 each, 8 lithium batteries cost $16.84 or $2.11 each and 8 NiMH [7] rechargeable batteries cost $17.87 or $2.24 each. Based on initial cost alone it would seem that alkaline would be the way to go. However if you look at cost per 500 uses, NiMH is $2.24, Alkaline it is $325 and Lithium is $1055. If you can get 1000 charges out of your NiMH battery, it will still only cost you $2.24 while the costs of the alternatives double. Although the initial cost is higher, I would only need to recharge each NiMH battery four times to break even with the cost of alkaline batteries. On paper rechargeable batteries looked good. However, I was still skeptical because my experience with rechargeable batteries has not been all good. I decided to do a little more research to see if they could be a viable long-term option.
My research revealed that rechargeable batteries have several deficiencies. To make a plan that would work I would have to overcome the following problem areas: overcharging, overheating, poor conditioning and deep discharges. The plan I came up with will require more effort to maintain than simply buying lithium batteries. However, if you are up to the challenge of making sure your batteries are properly conditioned and rotated then the monetary savings are worth it. Now let me tell you how I made the plan work for me.
The first step was buying a quality smart charger. The right charger makes all the difference in the world and helps minimize my effort by preventing overcharging, overheating and poor conditioning. The bad press about rechargeable batteries is largely to blame on older chargers sometimes called ‘dumb’ chargers. These dumb chargers are set to charge batteries for a certain time period. This time period is based on the batteries being almost totally discharged. If the batteries are not totally discharged then they can be overcharged and overheated. Smart chargers monitor the batteries charge and stop charging when full capacity has been reached. Overheating is largely prevented by not overcharging but you can also do things to prevent overheating like placing the charger on a platform that allows air to circulate. I like to use old plastic strawberry containers turned upside down. Also if the charger has a cover leave it open while it is charging or remove it completely. Overheating is not a problem limited to the charging cycle, so when the batteries are actually being used keep the device out of the sun when possible.
Poor condition occurs when the battery is used for a short time and then recharged again without being fully discharged. When this repeatedly happens a battery can lose the unused capacity. This is often referred to as memory effect. Look for a charger that comes with a conditioning cycle. The really good chargers will sense when a battery is poorly conditioned and will automatically run it through a few charge/discharge cycles to regain lost capacity. One last thing to consider in a charger is one that can be powered by both 110 volt AC and 12 volt DC. I couldn’t find the right charger locally so I got on the Internet and found a Maha MH-C204F (from Thomas Distributing [8]). This model meets all my needs and is the backbone of my plan.
The last problem I had to solve was deep discharges. If voltage drops too low you can lose performance or even kill a battery due to polarity reversal or anode oxidation. This generally isn’t a problem when using digital devices like GPS [9], FRS [10] radios and digital cameras as these devices shutdown on their own when power gets too low. You have to watch out for devices that keep pulling a charge when performance drops off. The best example of this is a flashlight that starts to get dim but is still sucking power. The solution is to immediately switch batteries in any device that starts to lose performance. Also, it is a good idea to buy a battery tester so you can check batteries in devices like this so you can be sure they are not being too deeply discharged. Deep discharges can also occur in batteries that are just sitting on the shelf. Rechargeable batteries have a higher self-discharge rate than normal batteries. Normally they lose 1% to 2% of charge each day when stored at room temperature. This means they are only good for use 3-5 weeks from their last charge. If you really procrastinate using or recharging the batteries they can eventually reach a state of deep discharge. To combat this I started storing batteries in my freezer. This slows the discharge and retains about 90% of the charge for a full month. Even if I can’t complete a full cycle of using all the batteries before they lose their charge I can slow their discharge down to the point that I can minimize the number of times the batteries have to be charged. And the fewer times they have to be charged needlessly the more times they can be charged and put to use for a necessary reason. Keep in mind that the batteries work best when they are first returned to room temperature after coming out of the freezer.
How many batteries did I buy? I made an inventory of all the electronic devices that I would conceivably use in a TEOTWAWKI [11] scenario. Let’s say I would use 12 AA batteries on my worst day. I then applied the survival rule of three and multiplied the 12 batteries by 3 and came up with 36 batteries. That allows me to have 12 batteries in use, 12 batteries that have been charged, and 12 batteries that are being charged or waiting to be charged. 36 batteries my not seem like a lot but keep in mind that I will be getting between 500 and 1000 uses out of each battery. I decided against buying additional batteries because this would make the rotation between batteries so long that some would not be used before they had to be recharged again. IMHO [12] it would be better to buy an extra smart charger or two and keep them in a sealed ammo can in the basement. This is due to the fact that smart charges are controlled by computer chips and therefore would be vulnerable to EMP [13]. You will also want additional smart chargers if the charger you choose cannot charge the required number of batteries in one work day. In the previous example the charger I picked can charge 12 batteries in less than 9 hours so the one charger has sufficient capacity for the example.
I didn’t run out and buy the batteries right away. First I looked at individual brands of batteries to see if one was better than another. I found an article on the internet titled “The Great Battery Shootout [14]”. It shows the results of a test done with digital cameras and various brands of rechargeable batteries. You can look up the results yourself but let me summarize by saying that Energizer got top marks and since my local retail store carries that brand that is what I buy. To make the plan affordable and to ensure that all my batteries don’t go bad at the same time I bought them over time. I started off with 8 batteries and kept track of how often I charged them. After 4 charges each I broke even with the cost of alkaline batteries and went out and bought 8 more batteries. Again after 4 charges each I went out and bought 8 more batteries and continued the process until I reached the required number of batteries. Once I reached the required number of batteries I actually started saving money as compared to using alkaline batteries. This money is now free to be used for other pressing needs. Eventually I will need to reinvest in some new rechargeable batteries but at my current rate of use that day is years away.
Any rechargeable battery plan is based on having a grid down power source. Ideally this power source would be your existing backup power source. If you don’t have a backup power source then you should consider investing in some portable solar panels. Otherwise, this plan will only work until the lights go out.
Summary of Plan:
-Replace battery operated devices with low drain or no drain models.
-Standardize to AA batteries (Buy battery adapters if an essential device is not AA compatible).
-Buy quality smart [AC/DC] charger(s) with enough capacity to charge your battery needs for one day.
-Buy quality rechargeable batteries (3 times the number you expect to use on your worst day).
-Rotate batteries: Charge, store in freezer, then use them on a rotating basis.
-Replace batteries when they drop below 50% capacity (roughly 500-1000 cycles for NiMH).
Note: Rechargeable batteries may not work for all situations. If you keep some supplies away from home or in your car that can’t be regularly rotated then you should probably buy some lithium batteries.