I may have mentioned this previously as part of another post, but I am going to cover just the rechargable batteries in this post. Namely how to make them last as long as they were designed for. Why is this important? When I handle items being recycled at an organized collection, there are often numerous battery powered devices that are not that old. Why? For many, it is because the batteries have cooked out. This is the result of leaving an item on the charger contiuously until needed. From cordless phones, cell phones, power tools, and others.
I will just mention that if you have a number of “primary cells”/ batteries, and they are not going to get used for long time- put them in your freezer inside of a sealed plastic bag to reduce the potential for them tor dry out- this will make them last a very long time until they are needed. When needed, just let them thaw out before putting them into service.
To make the batteries last their longest, charge them fully with their charger they came with before first use. If the item is not going to be used for a while, just pull the battery out once it is fully charged. The reason why to do this is memory circuits can draw a great deal of current such as the IRobot “Roomba”. It maps while it does it’s thing and that map is retained in memory. Unplugging the battery does clear the memory, the tradeoff is the battery will discharge significantly in just a few days if left plugged into the machine.
Cameras are another item. The “Everio” cameras will discharge the battery in a few weeks or less even though the memory is not needing to draw current from that main battery, it is just the parasitic load of the power standby circuit. Charging the battery and then removing it from the camera will make it last longer. The memory sticks you plug into the camera do not require power to maintain the images. This is true of many cameras.
Now there are different technologies employed in these types of batteries. Different materials and constructions: however they share the same component in their electrolyte- water. I have dismantled many battery packs and it is not uncommon to find NiCads and NiMh types to have been boiled out- indicated by the mineral salts left behind near the venting holes in the cell. Most have a design life measured in “charge cycles”- if you circumvent the original design by placing the item back on the charger immediately after use believing that the battery must be kept up like that you will be replacing battery packs quite often and needlessly. Cordless phones and cell phones are a perfect example. NiCads also exhibit a “memory” when this “short cycling” is done which reduces the amount of use you can get from it later. The memory can sometimes be undone by discharging fully and recharging fully to “recondition it a few times, but once a cell has lost a certain amount of water- it’s capacity is greatly reduced and cannot be recovered by “reconditioning” it.
The short answer to extending battery life is to charge it fully initially, then leaving the device off of the charger until the power indicator indicates a recharge is needed, or if the device shows a very degraded operation- such as a cordless drill that barely rotates. Just because a cordless drill slows slightly does not mean to throw it on a charger- use it until you need to actually rotate the screw with the screw gun itself and only then put it on charge. While it may not seem fully practical on a construction site, you need to find that balance point because I am using battery packs that are about 10 years old in some cases.
Emergency flourescent lighting systems produced by a number of companies put a continuous float charge on the Nicads used by most of them, which cooks out most of them after a year, and since most are not made in a manner that lends itself to battery cell replacements, they are effectively “disposable”. I have salvaged a number of units and modified them for use elsewhere, but they are effectively similar in principle to the cold Cathode Flourescent lighting systems used in backlit LCD panels- be they laptop computers, monitors or TV sets.
Many public schools have tried to push kids into using tablet computers or laptops- these at best are going to be a yearly expense, and a needless one for numeorus reasons, but most school boards are not known to be intelligent nor able to make intelligent decisions, or the correct decisions. A black board or a white board do not need batteries to be used effectively. One has to question if the push to technology so early is due to a lack of teaching ability or a desire to keep kids quiet? Are they truly learning anything more than they would learn by way blackboards and whiteboards and an effective teacher? Based on what I see these days the answer is clearly “No”, just look at how many misspelled words there are in many newspapers these days, or sites with free ads. In My opinion, computers should not be introduced into classrooms until 7th grade at the earliest, and even then- only for students to learn some programming or code writing. Otherwise technology should not be a requirement until Freshman year of high school- even then limited in it’s use because the technology becomes a crutch.
But the problem with technology when it is in use is that of the batteries- most of the time people do not use their laptops or pad computers untethered from their charger. This means the batteries are getting constant current to refresh them but that is also forcing water vapor or Oxygen or Hydrogen even- out of the battery cells thus “cooking them” so they will never see the full life cycle capability of the battery.
Chargers have come a long way since the initial adoption of cordless drills in industry. But the chargers are not sophisticated enough to fully shut off when charging a partially charged battery, nor are they sophisticated enough to recognize a partially charged battery and either not charge or it will charge the battery as if it were fully depleted.
Now in home power systems, the batteries are mmot likely to be Lead Acid of some variant. The byproduct of charging any of them is hydrogen as a gas. The flooded wet cell types can be desulphated or “equalized” by an application of current at a potential above the “gassing point”. Usually above 16 volts for a 12 volt battery. Sometimes this requires pulsing initially to get the process started, but once begun, it can be very effective at salvaging some flooded cell types.
The lead acid variants should never be charged at an “Equalization” point as they are designed with a finite quantity of water assuming a finite charge cycle with specific charge potential requirements with essentially a finite life expectancy. Many back up power systems use AGM types of lead acid battery which are this sort of battery. Most of the time they are on a “float charge” when not in use- this gives them a very finite life span as it still reduces water in the electrolyte to hydrogen and Oxygen. These are NOT good sources for batteries for a home power system unless one is scrapping them in order to buy new batteries. Phone systems however change out their backup batteries (usually AGM’s) on an annual basis, and those usually have some potential for use in a home power system.
With Boeing using Lithium Ion batteries now in some of it’s new airliners, it is not long before we see some made for automotive or residential uses other than in the Hybrid vehicle’s battery systems. These have rather strict charging requirements and will cause fires when incorrectly charged- or they explode. Which is why I always discussed “NOT” using any of the chargers I presented or other battery charger projects to charge Lithium types other than the chargers that were designed for them. Plus Lithium is also a very toxic metal, and while it has some use in medicine, it is in trace or small amounts only. While Lithium types have potetial for home power systems, at this time they are not going to be discussed in a home power system application due to their highly toxic nature and charging issues.
The tangential blog.
The passive solar blog- outgrowth from some projects of mine.