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Fast Lithium Power Indoor/off road Powerchair

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  • #16
    Remember that this is EXACTLY the same as connecting another discharged car battery to your running car via jump leads... And that seems to work pretty well too!


    • #17
      >>> Anyhow; most vehicles today won't sustain 100A constant draw for even an hour... At least not while not screaming down the road. They should have a much slower (20A-ish) feed option.

      Unless you have all your lights, spots, heater, air con, sterio, heated glass and mirrors on it will not need more than 20 amps when "screaming" down the road. Even if you do turn everything on there will still be some left to charge the chair. The chair does not "need" 100 amps, thats just the initial inrush current until the violtage rises a little and then the batteries naturally draw less from the supply. So after ten mins they probably only draw 20 to 30 amps anyway...

      >>> I don't need the chair to be charged in an hour if it lasts for 30+ miles on a charge. I can take it charged, and recharge it overnight or while I'm taking a break or whatever.

      The more often you give the batteries a boost, the higher the average state of charge. Deep cycling and specifically the depth of discharge is the thing that murders your deep cycle batteries. Off road, sand and hills etc rapidly depletes them even if you have 30 milers range. So its ALWAYS a good idea to keep them topped up at every oppertunity you get. Like as you drive to an airfield, on your way to the shopping centre or beach. etc.

      >>> Especially if we're out at a track or trail where a tow-truck is unlikely even able to get to me. I want my charging systems to be as protected as possible. A dead battery here can actually kill a person (which is one reason why we have at least two in all of the vehicles).

      Which the alternator has to charge? !!!
      But with your chair you have FOUR batteries. Dead truck? Start it from the powerchairs Odyssey batteries!!! Its exactly the same as fitting batteries to your truck! What part of this dont you get?

      >>> Plus, don't forget, your 100A alternator also has to run the entire vehicle, it's toys, etc. while trying to charge your chair. Some modern toyed up rigs can draw a sustained 70A or more just to run the engine, lights and the stock entertainment setup.

      My digital clamp meter says 15 engine, 5 max average for music, and about 30 with air con, fans etc running. Leaving about 50 exess to charge the chair. When after 10 mins it only draws about half that... Ohms law.

      So again not an issue. Its just the same as jump starting your truck and driving off with flat batteries...

      >>> Pulling 10-20A off the charging system at any given time is not too much for any stock system. But 10 times that very much can be. At the very least, it will drastically shorten the life of your alternator.

      An alternator rated at 130 amps, running the van and the chair will only be at full or close to full output for around ten mins. And only then if you drove your chair so far it will not move. The batteries only draw full salternator output if REALLY discharged. And then not for long. Alternator brush wear may be increased marginally. But not beyond its rated power.

      I doubt its detectable. Most alternators fail due to diodes, bearings, corrosion etc before brushes wear out anyway.

      And nobody is FORCING you to do this. You can charge it via the hyperion (lithium or lead) at any current or voltage you wish.


      • #18
        Hey still have the permobil trax?


        • #19
          Yay, I'm also into RC planes with big lithium batteries and fast chargers. I've been curious to see how long it would take for someone to build a decent power chair with lithium batteries (and brushless motors?). I personally don't need a power chair but a lot of my friends can benefit hugely. And this is just interesting to me.

          One thing i'm wandering about is how you get that amount of current to the charger while you're driving. Do you just limit the charger input to 10A or run heavy guage wires back from the car battery?

          Just to back you up:

          SirGCal.. You don't seem to understand how lead acid batteries work. A full charged 12v battery with nothing connected will sit at 12.6-12.7v. NOT 12. To charge the battery requires a CC/CV charging regime (constant currant-constant voltage). This means a flat 12v battery would take whatever currant is offered to it during the 'Bulk' phase of charge, while the voltage raises to generally 14.4V, at which point the voltage is kept constant while the current ramps down. This is the 'Absorbtion' phase. On a car usually it will just keep the voltage at 14.4V, but smart chargers will go onto a 'Float' phase which just keeps the voltage at 13.5Vish to keep the battery from self-discharging. You can go as high as 15V on most non-sealed wet batteries without damaging them, it will cause the battery to gas and loose water so you shouldn't go this high for too long, but it can be beneficial, reversing sulphation, preventing stratification and helping to ballance out the cells.

          I thought you were correct about requiring >2000rpm for the alternator to supply its rated capacity, but I've never looked into it like Buegerman has. Even if the demand exceeds the alternators rating, all that will happen is the voltage would dip and the difference in currant would be supplied by the battery. Not the end of the world because the maximum 100A demand to charge your chair is only at the start of the charge, for 15 mins or so.
          T11 Asia A after near-fatal bike crash.. Just happy to still be here

          No, I didn't loose my mind... It got scared and ran away!!