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Can lithium deep cycle batteries be used with powerchairs?

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  • Can lithium deep cycle batteries be used with powerchairs?

    After doing some reading I see the suggestion that using lithium batteries with powerchairs - a straight swap or add-on, would most likely cause problems with the chair's electronics. Anyone have ideas about using or adding lithium batteries for our chairs?

    Shorai LFX36A3-BS12 ( http://shoraipower.com/lfx36a3-bs12-p126 ) 36 amp hour batteries.
    Last edited by grommet; 03-29-2017, 02:21 PM.

  • #2
    Interesting that you brought this up. I have often wondered why no one talks about converting to lithium, but not having a power chair I have not looked into it. What I have been doing however off and on since getting an I-Glide is re-doing it's battery system. It came with a very weak NIMH battery which is not much better than NiCad and it seems the re branded Tailwind is still using the old technology NIMH chemistry but in a larger size that do not fit the I-glide.

    So I got busy and concerned why they did not upgrade to a lighter and better chemistry. After much research and study, I came to the conclusion that they could have used NCM Nickel Cadium Magnesium cells with a little bit of a workaround. (I'm trying that now)

    That background is to let you know what I learned on the way. You can run two lithium batteries in parallel, but they must be in equal starting charge. Full charge is easiest. And to answer your other question, you cannot mix lithium battery types and not mix them with lead acid batteries without causing long term damage to the lithium batteries. If you need it I can find the discussion on this, but that is the bottom line that I read.
    I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

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    • #3
      Wheelchairdriver.com forum for all things powerchair, especially lithium batteries. Those guys have been doing it for years.

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      • #4
        Thanks nonoise. I am doing more research and it agrees with you. I was hoping for a way to add extra capacity but it seems lithium isn't the way to go yet.

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        • #5
          Originally posted by Rustyjames View Post
          Wheelchairdriver.com forum for all things powerchair, especially lithium batteries. Those guys have been doing it for years.
          Yep, I did some reading there. A lot to understand.

          Today I did talk to the folks at Shorai, a lithium battery maker. The told me their batteries are not deep cycle and should not be used the way I was asking. They also corrected some other information for me.

          Sometimes there are shortcuts and I find them. I think with batteries for powerchairs, it's going to be lead acid for a while longer.

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          • #6
            The heavy LA batteries provide critical ballast in some power wheelchairs, especially those with seat elevators and standers. The weight keeps them from tipping over easily.
            You will find a guide to preserving shoulder function @
            http://www.rstce.pitt.edu/RSTCE_Reso...imb_Injury.pdf

            See my personal webpage @
            http://cccforum55.freehostia.com/

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            • #7
              i agree with SCIfor55yrs and would ad that i dont want to sit on top of lithium just yet. I'm a little concerned about the fire/explosion hazard still.

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              • #8
                Originally posted by SCIfor55yrs. View Post
                The heavy LA batteries provide critical ballast in some power wheelchairs, especially those with seat elevators and standers. The weight keeps them from tipping over easily.
                Yes, you're right. I completely forgot about that. My batteries are very low and my seat elevator goes 12" high. Thanks for reminding me.

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                • #9
                  Originally posted by GJ2 View Post
                  i agree with SCIfor55yrs and would ad that i dont want to sit on top of lithium just yet. I'm a little concerned about the fire/explosion hazard still.

                  Yeah I thought about the Samsung thing and how we are sitting right over our batteries. Definitely a scary thought. One article talked about that. That because chairs are medical devices the safety testing was more thorough and can take a very long time. I guess with the idea of using lightweight lithium batteries for chairs, the chairs need to be redesigned to account for the difference in weight/COG and other factors. So it may not be for a long time.

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                  • #10
                    They are already using lithium batteries in wheelchairs. I have a Smart Chair (a portable electric chair) and the battery life is awesome, also I've seen some lightweight scooters with lithium batteries and Smart Drive does too. I've not heard of any battery fire/explosions. As far as ballast, you can always add that. It's time for the makers of full size power chairs to embrace the lithium ion technology. In the space where two Group 24 batteries go you could have lithium batteries that last 3 or 4 times at long. Well that's my rant and I'm sticking to it.

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                    • #11
                      Originally posted by wes4dbt View Post
                      They are already using lithium batteries in wheelchairs. I have a Smart Chair (a portable electric chair) and the battery life is awesome, also I've seen some lightweight scooters with lithium batteries and Smart Drive does too. I've not heard of any battery fire/explosions. As far as ballast, you can always add that. It's time for the makers of full size power chairs to embrace the lithium ion technology. In the space where two Group 24 batteries go you could have lithium batteries that last 3 or 4 times at long. Well that's my rant and I'm sticking to it.
                      I have a SmartDrive too. The lithium battery lasts a long time, never a problem. I haven't heard of a Smart Chair. We could add ballast, I thought of that, but I would rather have high capacity and light weight. Current powerchairs are designed for that ballast. I have been wondering about us getting lithium batteries especially since the electric cars began using them.

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                      • #12
                        Smartchair is another thing altogether: https://kdsmartchair.com/
                        I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

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                        • #13
                          You have to use a Li-Ion charger or the battery will become an incendiary device.

                          The Li-Ion charger listens on the 3rd terminal for events such as any cell reaching its temperature or Voltage limit and then stops charging. If it keeps on charging you will have great balls of fire.

                          The 3rd terminal will also model charging and gives the proportion of charge read out. If the Li-Ion is charged to less than 100% it will last longer.

                          Large and heavy lead-based batteries are a daft idea for power chairs and Li-Ion technology is not exactly new.
                          http://zagam.net/

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                          • #14
                            Originally posted by zagam View Post
                            You have to use a Li-Ion charger or the battery will become an incendiary device.

                            The Li-Ion charger listens on the 3rd terminal for events such as any cell reaching its temperature or Voltage limit and then stops charging. If it keeps on charging you will have great balls of fire.

                            The 3rd terminal will also model charging and gives the proportion of charge read out. If the Li-Ion is charged to less than 100% it will last longer.

                            Large and heavy lead-based batteries are a daft idea for power chairs and Li-Ion technology is not exactly new.
                            You always have to use the correct charger. What third terminal are you talking about? Do you mean the hobby Lipo packs that do not have battery management systems, (bms)? Or are you talking about the wire coming off the bms to the battery cell and calling that the third wire? I have several lithium's that use two wire chargers and should have a bms, but I am suspicious of one of them.
                            I have had periodic paralysis all my life. I lost my ability to walk in 2011 beginning with a spinal block, which was used for a hip fracture caused by periodic paralysis.

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                            • #15
                              Great balls of fire

                              Originally posted by nonoise View Post
                              You always have to use the correct charger. What third terminal are you talking about? Do you mean the hobby Lipo packs that do not have battery management systems, (bms)? Or are you talking about the wire coming off the bms to the battery cell and calling that the third wire? I have several lithium's that use two wire chargers and should have a bms, but I am suspicious of one of them.
                              There are two main terminals +Ve and -Ve that handle power. Then there is a sense terminal that talks to a microcontroller that senses Voltage and temperature of each cell and models charging. This is defined by battery manufacturer and it up to the charger to read it and obey. If for any reason the charger fails to respond the battery will fail catastrophically.

                              It is possible to have just 2 terminals and then the battery must have a switch built in to disconnect itself from the charger. A boost circuit driving a power MOSFET could be used. The substrate diode allows you drain the battery, but forward biased MOSFET can then control charging. However, if a fault occurs the MOSFET will most likely fail short circuit and will no longer be able to provide protection. A suitable fast semiconductor protection fuse to protect the MOSFET will also be required.

                              Some chargers sense the battery Voltage rather than the Voltage across each cell, but if they guess the wrong number of cells or one cell overcharges then you will have a catastrophic failure.

                              As software becomes more bloated and less efficient Li-Ion will no longer be able to run laptops. For this application Hydrogen fuel cells are being developed. Now, these will store lots of Hydrogen in an alloy and burn really well.

                              Where I work we have scary batteries on our Storage Area Network gear. Racks cubed off with millboard and fire suppression systems.

                              https://en.wikipedia.org/wiki/Wirth's_law
                              https://en.wikipedia.org/wiki/1-Wire
                              https://en.wikipedia.org/wiki/Sense_(electronics)
                              http://zagam.net/

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