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Home Forums Technical Discussion Why not recycle li-ion batteries and use them for OTG systems?

This topic contains 8 replies, has 4 voices, and was last updated by  Dustoffer 4 years, 11 months ago.

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  • #37155

    erFiodena
    Participant

    Hi everyone,

    I read that almost everyone that lives off the grid uses lead acid batteries. They have been proven to be safe and reliable for off the grid systems.

    I do not live off the grid, but one day I would like to.

    Batteries and electric mobility are my hobbies. I recently started to recycle “dead” and/or not working laptop batteries and I made a reliable li-ion battery for my electric bicycle.

    The process is time consuming but I found out that many batteries (50-70%) that are discarded are still good. The process to build the battery is time consuming due to the tests that I performed in order to be sure I had reliable cells.

    Why not use those cells for off the grid solar/wind systems? Of course the way the battery is “managed” is different from lead system but I believe it can be done.

    I have used this battery on my bicycle for over 3 months and it still performs the same as the beginning.

    Here is a video where I explain how it’s done: http://youtu.be/jHV8n8CVEZ0

    What do you think?

    #42918

    WrethaOffGrid
    Keymaster

    Looks interesting… :) thanks for sharing

    What else can you tell us about your setup? The bike? What got you interested in doing this?

    Wretha

    #42919

    erFiodena
    Participant

    The bike has a 500W motor. On a flat road the motor uses 200-500W, with peaks of 1200W during stop & go and on steep hills.

    More on the bike here: http://jacklithium.wordpress.com/my-electric-bicycle/

    More on the battery here: http://jacklithium.wordpress.com/2012/05/17/transform-dead-laptop-batteries-into-a-reliable-e-bike-battery/

    I become interested in electric vehicles about ten years ago and I owned several. I grew up among batteries and cables so it easily became an hobby for me.

    Back on topic the main advantages compared to lead batteries are:

    * weight and size less than 1/2-1/3 for the same energy “quantity”.

    * more efficient.

    * unknown cycle life (can be very long if treated properly IMHO)

    * can be recharged at 1C (while lead has to be recharged around 1/10C to avoid damage or shorten life)

    * no Peukert’s effect.

    * Good for the environment as we can recycle most of those cells.

    disadvantages:

    * Need a BMS (battery management system) unless you know how to monitor them (I don’t use one)

    * Cannot be dischaged more than 1C or will start to produce heat and get damaged

    * Cannot be mistreated (charge/discharge must stay within voltage limit to not damage the cells) this is why a bms is needed

    * Time consuming to recover

    Other than this I consider this technology safe, as it has been been used for a lot of years in laptop and other electronic devices.

    The battery I made suit my bike perfectly but It’s possible to build a battery of virtually any capacity depending on the need.

    #43036

    elnav
    Member

    For limited current applications this would work but most OTG home need more power (amps) so this increases cost. Recycling AA size battery is not practical in most applications

    #43037

    erFiodena
    Participant

    These are not AA size batteries. The size is 18650.

    The battery pack can be built in any size, so If you need more amps just build a bigger pack.

    I was just curious if somebody was interested in trying building a stand alone solar system with those batteries.

    I would do it but at the moment I can’t have solar panels in the house where I am living.

    #43042

    elnav
    Member

    you are still talking about many cell interconnections made by hand if your description is understood correctly. Whole house systems typically require battery banks far larger than what you propose. Yes I am aware you can add to or extend your system in theory but in practical terms there are going to be limitations. Adding more connections will reduce mean time between failures to the point you would always be trouble shooting for problematic connections.

    Good systems should be capable of running months if not years between failures.

    #43109

    Dustoffer
    Participant

    Yes, the 18650 battery is similar to AA but slightly larger and higher voltage. AA is 14.4mm x 50.5mm and 1.5 vdc. The 18650 is 18.6mm x 65.2mm and 3.7vdc, and 2200 to 3400 milliamp/hrs. and average is greater than 1000 cycles of charge. The L16 is around 2,900 cycles of charge.

    The closest you could come to a viable solar electric is hooking 7 of them + to – for 25.9vdc and 130 of these sets – to -, + to + for around 390 amp hours, and of a voltage that could be charged by a 24 volt charge controller and driving a 24vdc to 110 vac inverter. It would be equivalent to 4 6vdc L16S batteries with a total of 6 connections vs 3,640 connections.

    Cost without the connective wiring is around $940 for the 4 L16s, and $910 plus shipping or so direct from China. Obviously, the connections would cost a lot more.

    For a 12vdc nominal, the closest is 130 sets of 4 18650 batteries with 1,040 connections for 14.8vdc, which would drive a 12vdc to 110vac inverter. However the voltage is too high for most 12vdc charge controllers to be very effective. It would be close to equivalent of 2 L16s for $470+, while the 18650s would be $520 plus connections and shipping from China.

    With the fact that they are less than 1/2 as good for cycles and so many connections, it is highly impractical, as treasuregift said, for any alternative energy system.

    #43110

    erFiodena
    Participant

    Hi Dustoffer,

    Where do you get the 390Amp hours number?

    It’s true that a lot of interconnections between cells are needed, but It’s also true that those cells can be discharged at 1C continuous, something that is not suggested for lead acid batteries.

    I am willing to make a prototype, at my cost and based on my specifications, experience and ideas for people that live off the grid and are interested in this technology and that can provide me real feedback data on the behaviour of the prototype.

    As I stated before I cannot have solar panels where I live at the moment but from the test I have been running I am pretty optimistic.

    Those cells can always be used as a backup or emergency. 24v battery pack of discrete capacity ( 1 kWh for example) can be transported/moved easily compared to one of the same capacity made of lead acid batteries.

    I am just sharing ideas..I didn’t expect to encounter so many walls…

    #43111

    Dustoffer
    Participant

    390 amp hours is the rating of my L16 battery. I have two banks of 4 batteries each for my main system to run twin DR2424 inverters com linked for 180 degree out of phase 232VAC to my standard electric box. Split with only the well pump on 232VAC (actual), and the rest on 116VAC. Each bank is 5472 sq. in. in volume and the corresponding Li-ion 18650s would take 3434 sq. in. both without the extra room for connections.

    The best are the nickel iron batteries which are larger than the L-16 lead acid type, which can be discharged even more, last three times longer for 2 1/2 times the price.

    The Li-ion are just over a third the number of cycles or life of the lead acid.

    Rather than using a whole bunch of laptop batteries, I would think the manufacturers would make some that are already at the common 6vdc and 12vdc sizes, and in the amp hour ranges of the L-16 and the more variable nickel iron, and increase performance cycles to similar, too.

    NiMH, too. Both are used in electric vehicle batteries, but at different voltages. My Mercury Mariner is over 3 years old and guaranteed for 7 on its big NiMH battery.

    I think no maintenance Li-ion or NiMH rechargeables in similar performance voltages, amp hours and cycles, and styles of the L-16, golf cart, and nickel iron types that are compatible with solar and wind charge controller outputs for recharging, and in smaller and lighter packages, would be something well received in the off-grid community.

    I think the labor and connections expense of putting 910 #18650 Li-ion batteries into a 24VDC nominal package that lasts less than half as long as the L-16 type, would not be cost effective.

    It is not a wall, but physical reality and real world economics, that have to be considered. Battery bank amp hour sizing is for not only large loads, but days without sun for charging.

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