Extending battery life for battery powered devices

Extending battery life for battery powered devices by example with the Creative Labs Muvo Mp3 Player

How to modify similar products for genuine long play battery life.

music where ever you go – the reality

Executive Summary

The project takes the play time from a stock eight hours to a wonderfully economic two and half months for a single D sized battery.

The project shows the steps necessary to modify this product to take battery sizes other than those intended by the manufacturer. It does this without modifying the unit in such a way that it invalidates your warranty, so if the unit goes faulty within its warranty period you will still be able to claim.

This project doesn’t use mumbo jumbo technology that fails to deliver the results expected. It is based on the real Physics of battery life is a function of how hard the battery is discharged limits the batteries life.

In other words, a small battery made to work hard will have a shorter life than a large battery doing the same job. The large battery works less hard to discharge the same current and therefore lives longer.

Image of Creative Labs Muvo Mp3 Player

Creative Labs Muvo Mp3 Player

The Results

Advantages

The modified unit goes from only being able to run on a AAA 1.5 volt battery, to the largest available D size 1.5v cell and is able to use AA and C sized batteries too.

The manufacturer claims a play time using the AAA [Triple A] battery of around 8 hours.

Using a AA [Double A] 1.5 volt cell in the new configuration realised a play time of around four days, a doubling of battery size resulting in a four fold play time, while a D sized battery enjoyed a play time of around two and half months.

This is a vast improvement in play time, with the additional benefit that a pack of 4 AAA’s [Triple A] or a pack of two D sized cells are broadly similar in cost at the point of sale.

To put it another way, the purchaser of the two D cells will need to replenish their batteries far fewer times over the same period and when traveling where availability may also be an issue, this is a huge advantage too, not only in less demand but also the ability to use any size of 1.5 volt battery.

A further advantage to the finished unit is the ability to use any available 1.5 volt battery from AAA, AA, C and D size. Similarly a partially discharged AA, C or D cell will still be working less hard for its capacity size than a partially used AAA and will probably enjoy a longer play time, for at least “some time”.

Disadvantages

The modified unit is a far heavier unit than the stock feather light unit. However, the extra energy for a longer play time has to come from somewhere, so this is a trade off your not going to get around. To compare apples to apples, one must consider the weight penalty of carrying enough AAA batteries to provide a similar play time for a proper like for like comparison. In this regard the finished unit is still feather weight light.

In this regard there is the advantage that you do feel its weight by presence, but its far easier to loose something that you don’t feel your carrying.

The use of batteries of a smaller physical size than a D or C cell are prone to disconnect under physical knocks. For AAA or AA cells, this can be a tiny knock that’s sufficient to stop play. The Muvo unit will unfortunately revert to playing from the same spot it was first switched on, meaning the last place it was properly switched off at, and this can be an irritating consequence of interruption. The unit does support the ability to fast forward or even to jump through tracks. Unfortunately both methods of skipping forward consume far more power than playing, and so are to be avoided in low battery situations.

The sensitivity to physical knocks can be mitigated in two ways, but not completely eliminated by:

  • slightly stretching the battery spring to over come the shorter physical size of the available battery
  • providing some sort of support under the battery by way of material or cardboard to lend some support to the suspended battery between contacts
  • by positioning the unit by orientation on a surface or the fold of a coat or other soft garment that acts as a shock absorber.

There are limitations to any or all of these solutions since the next thing I usually do is forget about it and lean forward such that I give the unit a good tug from the earphone lead attached to my ears.

In summary

The modified unit demands less from your wallet giving a financial advantage. In the west we enjoy plentiful outlets selling batteries with a competative pricing structure. Where such luxury’s of commerce do not prevail, the flexibility by choice of battery size can make for a compelling purchase and a rewarding feeling for having modified the unit.

Having returned to the UK the unit now does sterling service tucked into my motorcycling jacket. When commuting to work by bike I did not worry about ‘running out of battery’ on a daily basis. There has been no interruption of service while using a D cell, only accasionally when putting pressure on my jacket I may put the unit into pause, an event that used to happen when carrying the unit in my jeans while walking.

Overall my satisfaction level has been extremely high with this project, and the modification does lend itself to ANY battery powered device that demands high current – for example digital cameras or even Ipods and Smart Phones. The issue is being able to attach a larger battery pack to the unit without upsetting the units usability.

Counter claims

There are other methods to providing power. The most obvious is that of a rechargeable battery which is available as a AAA [Triple A] so why not do that?

The answer really lays within the solution. The rechargeable battery does not provide a ‘longer play’ time, only the ability to recharge the spent energy. By getting this distinction clear in your mind, it is much easier to consider the solution.

It is not until you do the modification to support a larger battery that you can now enjoy the longer play time [it is not a function of a rechargeable battery], but, for Ni Cad batteries, not with standing their higher initial purchase price and that they require the purchase of a charger that also needs to be carried by the traveler, they also self discharge over time.

So whether your using the unit or not the battery is going flat by itself. While you are using the unit with its battery, the other batteries that have been charged previously are also going flat. The longer the play time you get from the current battery, correspondingly, the longer the unused batteries have to self discharge.

This leads us on to the second issue, that of recharging. There must a controlled energy source to recharge the used batteries, and this unit needs to be carried by the traveling person. It is also a single point of failure if it is stolen or breaks while traveling rendering the rechargeable batteries near useless until a replacement is obtained. Further, the charging station needs an energy source itself with the possible complications of compatibility else a collection of plugs and sockets that also need to be carried.

The use of Li-Ion batteries if they exist at this size simply compound the problem as they also need a charger, but they require a much more specialised charger than a Ni-Cad charger, which is much less likely to be readily available in under developed regions of the world and perhaps at a prohibitively expensive price if it were.

Any type of rechargeable battery will require ‘remembering to charge the batteries’ from the operator/ owner and in some cases using a small two cell charger for compactness and ease of carrying, time may simply not be available to give them the required 16 hour charge time before you need to be somewhere else. In the same way that the rate of discharge affects the life of the battery, the same is true of ‘fast charging’ where the battery life is shortened by continual boosted charge rates.

In terms of using a Solar charger, this type of solution, variable in recharge time through the variable nature of the sun, is limited to day light hours charging only. For a small light weight solar charger the unit is at the mercy of the wind to stay put if left outside where it can see the sun, and will need to be heavier and less compact if it is weather resistant – it may still rain while your out or have forgotten about it. A spare brick or rock could be an answer but on the sorts of sailing boats I’ve been on, odd bricks and rocks laying around are in short supply. If mounted behind a window it is shielded from wind and rain and now the overhead. Therefore it needs attention throughout the day to ensure its ‘still seeing the sun’ through the window.

A less realised issue is that onboard a given boat, where I was spending my time, there may well be only one or two cigarette lighter sockets providing a DC 12 volt supply. There are other things such as VHF hand held radios, other peoples Ipods and computers that will all be competing for time spent on their umbilical cords while recharging. Clearly more sockets would be a solution, but someone has to pay and install them.

In line with having more sockets there are single cigarette lighter plug extension cables that break out into two, three or four sockets. See the problem – having a four way extension socket is not the same as having four properly installed, individually circuited cigarette lighter sockets. It is four sockets wired to one, hopefully, correctly wired and fused socket that must carry all the current demanded by the devices plugged into the four way extension socket.

But look, now we’ve added yet another thing to the stuff we’re having to carry, so we can plug in our charger for the rechargeable batteries but we’re sill left with having to manage the battery charging. One must be aware now of the ability to plug more than one or two, three or four electrical things into the cigarette socket such that we do not overload the wiring behind it, because you can be assured when two people need to charge their laptops at the same time, its going to be your multi-way adapter their going to have their eye on.

It will be easy in such a situation to overload the wiring behind the socket or blow the fuse, assuming one has actually been fitted, and now we’ve moved the problem to that of a fire risk or having a stock of the right fuses. Finally we have to ensure that people do as they are told, to not overload the wiring. A situation now far removed from the desire simply to have music where ever we go.

This type of solution hasn’t solved the problem at all, its just moved it further down the line requiring more and more other things until eventually we’ve got other problems. With all this stuff waiting to be unleashed from your rucksack, how will you feel when you arrive to be told there is just one cigarette lighter socket on board, and it doesn’t work.

We can only live with what we find.

The rechargeable solution in all its guise are solutions that I profess to being biased against because usually the people who suggest these solutions haven’t actually lived with them, them selves, for real. Especially when compared against the ease of use of the disposable Alkaline battery,  these solutions only offer greater expense, greater complexity, more wires, more things to go wrong, more compatability issues and finally, they still demand your time and attention as well.

This apparently simple project throws up several solutions to the issue, disposable batteries, rechargeable Ni-cads, Lithium batteries, Li-ion batteries, solar chargers, even wind power if you want to go there, simply to play an Mp3 player where ever you go.

The reality is, there is only one viable solution when considering the investment in equipment, portability, compatibility and availability. This example really illustrates that ‘less is more’.

To the beginner there are many possible solutions.

To the expert there are but few.

Image of The fully modded Creative Muvo Mp3 Player - Months of music play

The fully modded Creative Muvo Mp3 Player - Months of music play

 

The project for the long play Muvo

Here we have the Creative Muvo dismantled as a normal person would dismantle it. There is no need to go any further than this since our modification is to bring out the battery terminals which we do by making up a plug.

Image of The Creative Muvo to user level dismantled

The Creative Muvo to user level dismantled

Our first modification is drilling the plastic battery door. The hole made is about 1/8th in diameter. The plastic is quite thin. Patience with a sharp drill bit twisted by hand will drill through the plastic or use a power drill with a speed control.

It won’t be hard to find the drill cutting through well before your ‘ready for it’ with the result that the plastic door will whizz around on the drill bit. If this happens you do not want to try stopping it as it spins as its just too easy for the door prong to catch on your hand or somewhere and snap off.

If this does happen it will be nearly impossible to keep the battery door secured to the unit. Without the battery door in place there is no support to the main Mp3 player and this will inevitably result in  the USB connector becoming strained to eventual component failure.

If you have a Creative Muvo that has succumbed to this battery door securing problem but the unit is still working, you could always use this modification and having satisfied yourself that your new plug battery is working, simply glue up the battery door permantly using a hot glue gun or other sealing method since there is no longer any need to get access to the battery compartment once its been modded.

With regard to the placement of the hole, please become familiar with photo later showing how the new plug lays into the compartment. The wires from the plug need to clear, and fit within the gap between the plug body and the sides of the battery compartment. If using a slightly thicker wire than I had on hand, you may find if you’ve placed the hole over where the body of the plug is that there isn’t sufficient room to lead the wires up neatly to the hole. In other words you want the hole to be somewhere over where the prong of the plug is going to be as there is physically more room for the wires to approach the hole. Also, just be aware that that battery door needs to slide into place.

Image of Modifying the Muvo battery door

Modifying the Muvo battery door

The card in the picture shows the Maplins code for the banana plug is L23BH. The plug was chosen because its diameter was close but on the small side compared to the diameter of the AAA battery it was replacing.

The overall length of the plug is longer than the battery and needs to be shortened. This is a trivial task to remove around 5mm of the plastic plug body with a junior hacksaw.

Image of The Banana plug compared to the AAA battery

The Banana plug compared to the AAA battery

Having removed the small screw securing the plastic body to the plug, the red wire is soldered to the plug tip in the usual manner. However, I realise now the picture is misleading. I have used the 1/8th drill bit shown in the picture to drill a hole in to the plastic body. It is from this hole that the red wire is emerging. It is not ‘just laying there’.

Meanwhile the black lead looks like it is going into the plug body, but it isn’t. Its passing underneath the plug and isn’t actually connected to anything as it stands. I have stripped a long length off the wire, as shown on the right hand side, since this is what I am going to use as the negative terminal as shown in the following pictures.

The following pictures in this series will make it clearer what I’ve done, so check those out as I am sure you will before you start doing something anyhow.

Image of Modifying the Banana plug for two wires

Modifying the Banana plug for two wires - one each end

The length of bared wire on the negative is formed into a loop. The inner most ring was pushed through slightly to make a cone shape in the windings. That’s a cone shape, not a spring.

In other words the windings are still touching each other, or almost. They were not pulled further apart making a spring like spiral. This too much spacing and minimizes the contact area for the battery terminals. Its a slight depression/ cone shape your after, as shown shortly.

The winding is soldered up to give it electromechanical strength. The opening in the smallest winding ideally should not be filled with solder as this gives a bonding point for the Chemical Metal filler. Chemical Metal was used because it was to hand, but otherwise some sort of 5 minute epoxy, though do note epoxy does not bond well to plastics, could have been used. A hot glue gun would probably do too, with the glue being dripped into the rear aperture of the plug. With hot glue do be careful to ensure it does not melt the plastic. Its more distortion that’s the concern since applying too much glue in one go may raise the temperature of the plastic body where it could go ‘barrel shaped’ and thus be a problem for fitting the compartment.

Just give it go with what you have to hand, otherwise you’ll not make the project. Whats the worst that can happen? Its all solved by using another plug and starting over with two bits of wire. Trivial.

Image of Creating the Negative terminal on the Banana plug

Creating the Negative terminal on the Banana plug

The plug body is filled, or packed up with in my case Chemical Metal. The hole that was made earlier in the plug body can clearly be seen as the lead out point for the wires. This is the bit of confusion i was trying to clear up in the earlier photo… I hope this illustrates what’s required so the confusion can just be forgotten.

Notice I have wrapped the negative wire around the plug pin. This was to stop the movement of the cone shaped negative terminal from moving as the Chemical Metal set. Rather than going by the manufacturers instructions of leaving it for 10 minutes, it was probably left over night. When sanding the chemical result, if its not set properly hard the material will bead up and clog the sandpaper and it may even dislodge the terminal – now we do have a problem. Patience is a virtue and all that.

Image of The lead out wires from the body of the Banana plug

The lead out wires from the body of the Banana plug

The picture below shows the completed assembly. Clearly visible is the dimple impression of the negative terminal. This allows the pins/ springs in the Muvo unit to have something to ‘get into’ thus giving mechanical strength to the connection while the solder thats currently hidden under the mess of the Chemical Metal will be lightly sanded and cleaned up to reveal a first class contact that is electrically and mechanically durable.

Image of Characteristics of the Negative terminal end

Characteristics of the Negative terminal end prior to clean up

The homeward run.

The new plug battery is laid into place with in the battery compartment. The wires are tucked into the gap between the rounded plug body and the wall of the battery compartment.

If you remember from the beginning with the comments about where to drill the hole in the battery door, this picture illustrates how far along the plastic jacket of the plug extends. With the hole drilled somewhere over the pin end of the plug there is clearly going to be more space to lead the wires comfortably out through the hole.

Image of Banana plug battery in place with extension wires

Banana plug battery in place with extension wires

The battery holder is a D cell single battery holder. It was chosen because not only does it accommodate the larges 1.5v cell, but as luck would have it, it is also a very close match to the size of the Muvo. A single C cell could also be used, resulting in less weight together with less overall play time. If thats what you have to hand, want to use, then go for it.

Regretfully the camera flash has bleached out the colour of the red wire that happens now to be the grey looking wire to the left of the picture, while the black wire is the almost invisible blur in the left middle of the picture.

We only need now to solder the wires to the battery holder ensuring we solder red to positive and black to negative. In my effort the wires were just trimmed to size, booted with heat shrink sleeving and soldered into place.

An improved method would be to drill a small hole into the back of the battery holder inline with the exit hole from the battery compartment. A further couple of holes, drilled into the bottom corner of each of the end plates of the battery holder would then facilitate the wires being run in this space created by a round cylinder in an oblong box.  The wires would then emerge at the end plates where they would be booted with a couple of layers of heat shrink tubing. This latter may be more of a dream than a reality as there is so little space that it will be hard to not to shrink the heat shrink tubing as you solder the joint thus making it next to impossible to position the two layers of tubing over the terminal.

The effect of the heat shrink tubing is only lend to a level of mechanical protection to the wires.

Image of Battery door in place, ready to mount the battery holder, towards final wiring up

Battery door in place, ready to mount the battery holder, towards final wiring up

The completed unit complete with D cell, after around four years of use and many thousands of miles traveled.

About being ‘Green’

Our great leaders tell of the urgent need for addressing the industrial output of Greenhouse Gases. Funny enough the whole method is wrapped up in a trading system of ‘pollutant credits’ that can be traded on the open market.

To me it doesn’t take much to see what happens to ‘index’s that are know as indices’ when the great money men get behind them trading futures like they do for grain, wheat, copper and gold. Its just another new market for them to trade bundled up as Co2 vouchers.

Anyhow, having revealed alittle about my skeptical view point on the whole ‘green’ affair, while we’re being told its industry that is producing all these gases, could you agree here that we seem to have found  a huge ‘industrial waste and consumer’ driven market here as a function of product design.

In other words for the slight addition of another piece of plastic facilitating a much larger battery than the manufacturer originally supplied, approximately four D cell batteries would give us 10 months of play time from this unit. Conversely an unmodified unit would require around 290 triple A batteries to give the same play time.

That is 72.5 packs of four to a pack of triple A batteries would need to be purchased, after they have been manufactured of course, at an approximate cost to the consumer of £290 based on £4 per pack of four batteries.

Compared to the D cell, sold as a pack of two, two packs required also £4 per pack, resulting in £16 for approximately a 10 month play time.

The consumption has been designed into this product, and I often hark on about commercially designed products, it is designed to fail through normal wear and tear so you will eventually go out and buy something else. The what ever else you buy suffers the same design problems.

What I am saying here its not the electronics that I expect to fail. Its that damned battery door clip. Once that’s gone, there is little support for the USB stick and I can see if your not careful with the unit, it is only a matter of time before the USB begins to be strained in its socket leading to a premature breakdown for the whole unit. As small as it is, its probably beyond economical repair so off it goes to landfill. Off you go to the shops to get something else.

Meanwhile the battery manufacturers are turning up production for batteries.

I’ve no idea how many of these Muvo’s have been produced around the world, but I begin to hazard a guess the waste output of dead batteries could be more of ‘green’ Co2 issue because of the thousands of Muvo’s that must be around in the field and their consumption of batteries probably outweigh the volume of Co2 production created by Creative Labs for Muvo manufacturing.

Sure the battery manufacturers Co2 output must be higher to reflect the higher demand, but the real problem lays squarely at the product design stage, not with some index of interchangeable and sell-able Co2 production quota vouchers.

I’m sure a politician would say this bureaucratic process would indeed lead to manufacturers re-thinking their product line because it will reduce the cost to them for Co2 production.

From my position here I don’t see it, since Creative are only interest in producing the products, not their battery consumption, while the battery manufacturers are only interested in meeting demand for batteries, not crappy product designs that reduce considerably the demand for their products.

Do you see my point?

It falls between two stalls and the proposed solution by the politicians doesn’t get close to solving the real issue – Capitalism. Capitalism requires Consumerism. Things that are built to last don’t fit too well with Consumerism.

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