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hpr_transcripts/hpr1398.txt

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+Episode: 1398
+Title: HPR1398: Batteries Part 1
+Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1398/hpr1398.mp3
+Transcribed: 2025-10-18 00:47:35
+
+---
+
+Umm...
+Hello and welcome, hacker public radio audience. My name is Mr X. Welcome to my 5th HPR
+podcast. It's been a while and I must apologise for the long interval that's passed since
+my last show. I've just started by thanking the HPR people for making all this possible.
+I would never have pulled my first podcast together without making this service available.
+It's truly a wonderful and invaluable resource on these here intertubes. If you have something
+interesting or some busting passion, why not share it with the rest of us? It really
+isn't that hard and even if you only manage one show that's fine and great. But who
+knows you might even go on to enjoy the challenge and just more shows? If I can do it anyone
+can. I plan to make this a two-part show. Hopefully you won't need to wait too long for
+the second part. The topic today is batteries. I must start by saying I am no expert. I
+really started looking at batteries in more detail when I acquired a rather expensive
+rechargeable shaver and a rechargeable battery within it failed prematurely. This compelled
+me to go searching for the truth about why batteries fail. In the process of this I found
+out about memory effect which I've heard many individuals mention and which I've seen
+written in numerous equipment packaging and in various instruction manuals. I'm here
+to tell you that there's probably not what you think it is. I'll talk more about this
+later on in the podcast. I am conscious that these days most devices do not use discrete
+batteries and perhaps to some extent it could be argued that some of this discrete battery
+stuff is redundant. When was the last time you had to open a battery compartment and replace
+a battery? Most modern devices come with a specialist battery pack, often one which is
+either difficult or even impossible to change because of this we prematurely threw more
+more stuff away. The user manual does not clearly explain how to look after your battery
+or in fact sometimes gives a bad advice which will ensure the early death of your battery.
+Either the manufacturers don't know much about the battery they are fitting or is it deployed
+to speed up the built-in obsolescence? Ask yourself would they not include a bad
+trick compartment if they wanted you to keep the devices a long time? In reality there's
+probably a variety of reasons why a bad trick compartment isn't included. You can make
+up your own mind about this. A year from now I wonder how many tablets will be confined
+to the bucket. Often conveniently for the manufacturer batteries are not covered by
+the warranty, yet they often fail to give clear instructions about how to prolong battery life.
+For these reasons I would argue that the information in this podcast is even more important
+than ever as the damn batches are so difficult and expensive to replace.
+Batches convert chemical energy into electricity and they all work in a similar way. A battery
+consists of one or more electrical chemical cells, this point is important, the multi-cell
+battery is at the heart of battery failure. A single cell battery in isolation is much more
+likely to reach old age, again all will be revealed later on in the podcast. Think of a multi-cell
+battery, it's a package of small individual batteries linked together and covered in a single
+wrapper giving the illusion of a single battery. More voltages produced by stacking multiple cells
+together. Inside each electrochemical cell are two metallic plates, called electrodes. Between
+them is a chemical bridge called an electrolyte. In a carbache the electrolyte is sulfuric acid.
+The electrolyte allows charged electrons to gather one electrode to travel to the other.
+The transfer of electrons is the basic principle all batteries use.
+Led acid batteries are typically commonly used in cars where the first kind of rechargeable batteries.
+They first started being used around 1860 but it wasn't until 2011 that we fully understood how they
+worked. The characteristics of batteries can be altered to some degree by changing the physical
+construction of the electrolyte and electrodes. However, even greater changes can be heard by using
+different materials. A lead acid cell for example, normally produces two volts. So a traditional
+carbache consists of six cells, each cell producing two volts. Six cells multiplied by two volts
+gives an 8-bit voltage of 12 volts. The cells are connected so that the positive
+electrode of one cell is connected to the negative electrode of the next cell. This is known as
+connecting the cells in series. They're connected in the exact same way that you would load
+some cylindrical batteries into a cylindrical flashlight. This is in fact all the multi-cell
+batteries. Again, think of sticking a pair of batteries together, connecting them all together
+in series, wrapping it all up in plastic, leaving only the first positive terminal on the last
+negative terminal visible. This is all the battery packers. Common arc lane cells produce a nominal
+voltage of 1.5 volts. From this you can tell that a common AA battery is a single cell battery.
+An arc lane PP3 square battery, commonly used in smoke alarms, is an example of a multi-cell
+battery because it produces nine volts. Remember an arc lane cell normally produces 1.5 volts.
+Inside a PP3 battery is a stack of six individual cells. These cells are all connected in series.
+Each cell producing 1.5 volts. Six times 1.5 equals nine.
+The nominal voltage produced by a rechargeable nickel metal hydride cell is 1.2 volts.
+This can cause a problem when you're substituting arc lane batteries with rechargeable ones.
+Consider if you want to replace the standard batteries in your shining digital radio.
+The radio uses six standard batteries. This means the digital radio expects an nominal voltage of
+nine volts. When you substitute the batteries with rechargeable ones, you can't understand why the
+thing only runs a short time then dies. Six 1.2 cells would produce 7.2 volts. Probably the same
+voltage is six flat arc lane batteries. Your digital radio is fully to thinking the batteries are flat.
+The more cells the device use, the greater the difference between the common arc lane batteries
+and rechargeable nickel metal hydride ones. Some modern devices either ought to detect this or
+have a manual switch to get it for this situation. Memory effect was first observed on early satellites.
+It was found that the battery voltage on orbiting satellites was prematurely dropping.
+These early batteries used nickel cadmium batteries. These I believe are no longer available
+due to environmental concerns. It was found that the voltage drop was caused by the fact that
+batteries were going through an identical charge and discharge cycle on each rotation around the
+earth. After a few cycles of this, the batteries developed the memory effect, causing the voltage
+to drop off prematurely. The thing about memory effect is that it is reversible by repeating the
+charge and discharge cycle a few times. In modern satellites, the charge and discharge times are
+randomised and this stops the memory effect from being developed. Another place where memory
+effect was observed was in doctor's pages. The doctor would have his pager with him throughout the
+shift. At the end of each shift, the pager would be returned to a charging station when it was charged
+overnight. Again, the charge and discharge times were identical day after day, allowing the memory
+effect to build up. You will probably never encounter memory effect during normal day to day
+operation of battery equipment. I believe it is quite difficult to demonstrate even in a lab.
+As I said before, memory effect is reversible. Some battery charges have a discharge function on
+them to individually discharge each single cell battery. In my opinion, this facility is really
+of little benefit, since she will be very unlikely to come across memory effect in day to day use
+of your battery equipment. We now know that the premature failure of batteries is nothing to do with
+memory effect, so what in earth is going on? There is one thing above all other things that
+time after time cause batteries to fail, and I am going to let you in on the secret. It is all
+to do with linking multiple cells together in series. When a device draws current from a multi-cell
+battery, all the cells within the battery back linked together start to discharge. The problem
+is that no two cells are identical, even if they are manufactured at the same time using the same
+equipment. There will still be many differences in each cell. These differences lead to one cell
+becoming flat before all the others. The voltage from this cell collapses, and the voltage from
+the surrounding cells reverse charges the flat one. This is indeed very bad for the cell concerned.
+Reverse charging a cell is very bad, and an nickel cadmium battery causes conductive
+dendrite crystals to grow. These crystals effectively short out parts of the battery,
+are rapidly reducing the capacity of the cell. Next time you use the device, the battery pack goes
+flat more quickly, because one of the cells is damaged. It inevitably gets reverse charged again.
+This causes a death spiral of the whole battery pack. Note, only one cell in the pack is damaged,
+but this doesn't help much, as you undoubtedly won't be able to replace the individual cell,
+and it's likely you'll find it difficult and possibly expensive to find a suitable
+specialist replacement battery pack. On top of all this, you may not even be able to get into your
+device in order to replace the battery if it's something like your average tablet. If the device
+uses discrete individual batteries, you still need to locate the faulty cell. If you replace the faulty
+cell, the chances are the capacity won't match the remaining cells. This is why instruction manuals
+often say not to mix and match you chargeable batteries. The number one thing above all else
+that kills batteries is driving them flat. Imagine you're using a battery drill. As you drill,
+you start to notice that the drill is ever so slightly slowing down. At this point,
+one of the cells within the battery pack is being very quickly destroyed. Stop immediately,
+if possible, put the drill on charge. Above all else, stop drilling. Find the
+temptation with every fiber of your body. Continuing even for another minute will
+catastrophically damage the single, flat cell, causing the whole battery pack to fill within a few
+charged discharge cycles. You might imagine that your device might switch off automatically,
+and will save you from the destruction of your battery pack. I would advise you not to rely on
+this, as no matter how complex the circuitry, it cannot know the state of each individual cell within
+the battery pack. Damage can still easily occur, it is far better to stop using the device
+long before it shows any signs of being flat. Here's another common scenario, which leads to the
+same destruction of your precious battery pack. If you have a device that gradually sucks power from
+the device, imagine something like maybe a portable MP3 player, a satnav, ebook reader, or perhaps
+your favourite tablet. Go and stand by these devices draw power. My Sansa Clip MP3 player has a
+terrific battery life, but it has an internal clock within it which only came to light when I was
+running rockbox on it. I don't find the clock particularly useful, but the very fact it has one
+means the MP3 player is continually drawing a small amount of current from the battery,
+even when it is seemingly turned off. If I was to leave the MP3 player for months on end without
+charging it, then the battery of a pack would be driven flat, causing the failure of the whole
+battery pack. This is something you need to watch out for. My Sansa Clip is over four years old,
+and still has a great battery life. I recommended the same player to a colleague at work a few months
+back, or recently asked him how he was getting home with his player, and he said not too bad,
+but it tends to go flat all the time, so I tend to use my phone now. I suspect he'll let the
+thing go flat. If you're not going to use a device for a long time, and disconnect the battery,
+this will save it. Unfortunately, you can't do this with the sealed devices such as the MP3 player
+or tablet. I would imagine many of these devices will go in the bin, built in obsolescence strikes again.
+Recommendations
+Most devices now come with specialist batteries, such as lithium ion or lithium polymer. These
+batteries have very high energy densities, approaching that of a small hand grenade,
+because of this you need to be very careful charging them. You have no choice but to use the
+charger supplied by the manufacturer. However, if you're using a device with discrete,
+rechargeable batteries, then choose a slow trickle charger. You may find it quite difficult to
+get a slow charger, as everywhere you look, there are fast chargers boasting about how fast they
+can charge, playing the wonderful consumer numbers game. Suckering the poor consumer yet again,
+these fast chargers pulse charge batteries, which means you won't obtain the full capacity
+of your battery. The battery will also tend to fail a bit quicker. However, the failure time will
+still be nowhere near as quick as driving a battery flat, which you remember can happen just
+by leaving the device sitting unused. Just like the charger companies, the battery manufacturers
+are also playing the marketing numbers game. Just like the digital camera which must have the
+biggest megapixel count, the image may only be interplated and the crammed in megapixels count
+will undoubtedly increase image noise. The same numbers game goes on for batteries, everything
+is a trade off. The current trend for bugs on the discrete nickel metal hydrate batteries
+is to increase the capacity. Capacity is measured in amp hours. A 1 amp hour battery can theoretically
+maintain a current drain of 1 amp for 1 hour. A 4 amp hour battery can theoretically contain
+a current of 4 amps for 1 hour. Small discrete batteries use the measure milliamp hours.
+1000 milliamp hours equals 1 amp hour. I can remember my first set of nickel cadmium 80 batteries,
+having a capacity of 500 milliamps. This means these batteries could maintain a current drain
+of half an amp for 1 hour. Nickel cadmium batteries were replaced by nickel metal hydrate batteries.
+I think these started coming out with a capacity of around 700 milliamp hours. Over time these
+capacity crept up and up and I think they have now reached a whopping 2700 milliamp hours.
+This means these tiny 80 batteries can maintain a current drain of 2.7 amps for 1 hour. Incredible.
+They may think this is great, what can be wrong with continually increasing capacity.
+Well remember this numbers game is a compromise as the capacity goes up, so there's a discharge rate.
+These 2.7 amp hour batteries will be flat within a month just to think about a shelf.
+They are also more liquid to feel quickly. However, if you're using them at high
+discharge rates, like for example in a high speed remote controlled car,
+where battery is exhausted very quickly, then these batteries may be exactly what you need.
+You may also want to consider a fast charger as you may be impatient to get out with your
+model and race again. Remember if you're not using the batteries like this, then you might do
+better to get a lower capacity battery with slow charger. Again, you may think this difficult
+as everyone thinks bigger is better. 2,100 milliamp hour 80 batteries are a good compromise,
+having a decent capacity and a reasonable discharge rate, giving a reasonable charged shelf life.
+At this point I should maybe make it clear that allowing batteries to go flat,
+naturally over time with no current drawn is perfectly safe and will not destroy the batteries.
+This is because no current is flowing between the cells. Even the tiniest of currents will destroy
+cells as one collapses it is averse charged by the neighboring cell. This is why it is always
+best to remove batteries from a device if it is not going to be used for a long time.
+A descending order of importance. 1. Don't drive batteries flat.
+2. If you're not using the device, disconnect the battery. 3. Don't mix and match batteries.
+4. Where possible use a slow charger. 5. Topping up the device is not a bad thing.
+6. Leaving a device when charged for a long time is only okay if it is being trickle charged.
+5. Conclusion.
+Okay, I hope you enjoyed this podcast. That's about it for this episode. Next time in part 2,
+I'm going to try and give you real life examples of battery usage. I'll try to pull together some
+show notes for the podcast which if I do, will be available at HPR. I can be contacted at
+mrx at hpr at googlemail.com. That's mrxathtpr the at symbol googlemail.com.
+So until next time, thank you and goodbye.
+You have been listening to Hacker Public Radio. We are a community podcast network.
+The release is shows every weekday on day 3 Friday. Today's show, like all our shows,
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