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Power bank questions

Former Member

I'm going on holiday soon and came up with an idea, I found an old laptop battery which was 10.8w and 4400mah in total there was 6 batteries inside meaning I divide the total mah by 6? which would make the 733 each? or should it be 4400mah in each one? I'm not 100% certain. Anyway since the battery holder/pack is destoryed I have no way to charge them. I was wondering if I wired them in series and added a wire to the positive in the start of the circuit and the negative at the end and wired it to a DC OUT connector would I be able to charge them like this? if so, How would I find out which charger to use? the original one from the laptop is missing that's why I used these ones. Since I'm taking it on a camping trip I was also wondering if there was a possibility to add a winding function to also charge the battery meaning if I'm that desperate I could power it and install a little voltage monitor?

 

 

I don't know much about batteries or electronics but I'd like this to be my first little project as I need a slightly portable phone charger and I'd like to use what I own to make one instead of purchasing a made one. I know there's a lot of features but I'd love to make something all in one that'll last me a life time, I did question solar power too but personally I feel it would charge too slow. although it might be feasible in the later future.

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  • There is an easy-to-read overview of Li-Ion and Li-Po cells and batteries but by the end of it hopefully you'll see that using a laptop battery is a non-trivial task and extremely dangerous to charge unless you know what you're doing - which will be hard without detailed specs and data sheet from the cell manufacturer.

    There are 'hacks' on the Internet where people pull out cells from a laptop battery and use them, but in general engineers would avoid them unless they were confident they had the manufacturer data sheet for the cells, which the laptop manufacturer will have access to. Here is an example data sheet (just for you to see the level of information that would be needed - this data sheet will be very different to the one for the cells in the laptop battery).

    Exploding batteries and fire are a very high risk. In-between the laptop mains adapter and the battery pack will be a circuit on the laptop PCB, which is the battery management circuit. Without that or a similar circuit which would have to be designed based on the cell data sheet and quite a lot of experience, the laptop's mains adapter must not be directly connected to the battery.

    It is better to just buy a power bank and choose a non-battery-charging related project to be a first electronics project.

  • in reply to shabaz

    Hi shabaz.


    I agree with this assumption (not only a warning but including the useful information you add). But as can confirm, I think as he is a great aeromodelist, it is years I see RC modelists passionate and hobbyists creating their own circuits managing batteries also of a considerable power. I think that with a sight in this direction it is possible to find projects and good and reliable advices on how to build power-banks that can work. In this case - I am not an expert - I think that they use a class of batteries almost similar or anyway of a well know standardised characteristics that can be used to power any kind or electronic circuit or project, including moving things and robots that has many things in common to the RC models.


    Respect to the use of a laptop battery usage instead I think that it is possible, and not so difficult, with a slight different approach. First of all we should assume that the battery / power side of a project, despite how much we can reduce and DIY it remain a cost to be considered seriously, also if it is very low. Then - as least in my case - I avoid the approach like "I have an old laptop so I will use its batteries" but exactly the opposite: I try to explain what I have in mind, let me know if it has sense by your point of view.


    • First of all today any kind of laptop battery (so a wide range of potentially power supplies) can be found as compatible ones. The better ways to find them at the right price IMHO it is on Amazon.
    • The choice will follow at least two criteria; the first is the power needed in the project and the second is the kind of connections on the batter as much as possible simple to hack soldering a comfortable connector for the project. Then there is the size; but thinking to a laptop battery it is almost obvious that we consider a project with a reasonable battery size to host it.

     

    At this point with the opposite approach, suppose that I decide that the right balance power / duration / size is a battery of the first models of MacBook (the 11 and 13 inches white models). This is a great battery because it includes a very good power management inside, including a led charge level button. Then it is not difficult to find on the Internet recharging circuits for this (or another of your choice) battery type. The advantage is that the battery is well-known, characteristics are clear and documented and the entire project is replicable as well.

     

    Enrico

  • in reply to screamingtiger

    Maybe that fit or not on a project, e.g. in the quadcop I see it hard to use batteries of the laptop weight; it is not rare that these are the weightiest parts of the entire device. But in some "ground" terrain project, where it is needed a lot of power (motors, servos etc.) this maybe a good solution. I prefer these kind of batteries also because are not difficult to fir in any kind of base as are usually flat.

     

    Enrico

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  • in reply to screamingtiger

    Maybe that fit or not on a project, e.g. in the quadcop I see it hard to use batteries of the laptop weight; it is not rare that these are the weightiest parts of the entire device. But in some "ground" terrain project, where it is needed a lot of power (motors, servos etc.) this maybe a good solution. I prefer these kind of batteries also because are not difficult to fir in any kind of base as are usually flat.

     

    Enrico

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