Better wheelchairs?
in [Wheelchairs]
|
Prev: driving service
Next: Wheelchair in minivan
From: Pete on 2 Jul 2008 21:01 Burgerman wrote: > "Pete" <pete(a)home.net.au> wrote in message > news:8eWdnYCBs6iFb_fVnZ2dnUVZ_obinZ2d(a)posted.internode... >> Burgerman wrote: >>> Want to know why we dont yet have lithium battery powered >>> wheelchairs? (Lighter, smaller, faster charging, better high current >>> capability etc) >>> Well in the process of building or rebuilding yet another F55 I >>> needed smaller batteries that still performed like the 55 ah stock >>> deep cycle ones. No space you see - trying to get fat off road >>> balloon tyres under a F55s by narrowing the battery compartment, >>> moving motors inwards so the fat tyres dont stick out. Well the price >>> to go lithium (because the same 55 amp hours takes up much less >>> space) continues to fall but its still far from cheap! >>> >>> http://www.greenmotorsport.com/green_motorsport/products_and_services/3,1,388,17,716.html >>> �461+Vat 24&48V, is the charger alone! (about 1k dollars for those >>> over the pond.) >>> >>> The batteries we would need to propel a wheelchair all day are >>> �1210.00 EACH! And we need 2. >>> >>> So we are looking at about 2800 pounds or 5600 dollars just for >>> batteries and charger. >>> >>> I dont think I will be bothering just yet. >> >> Have you checked these guys out Burgerman >> >> http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=1158 >> >> I'm not sure how they stack up against what you've looked at, but >> prices seem ok. > > > http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4172 > > 2 of these would give correct ish voltage and capacity. @ about 4000 > dollars. Plus special lithium charger (we dont want a fire!), @ about > 1200 dollars. Cheaper slightly but still a bit too much for batteries > every 12 months I think! In a year or three prices will fall and we can > all have fast charging 40 miles range and 20 mph powerchairs. I would have thought with being able to run these type of batteries right down, unlike lead acid, that 50ah would be enough capacity?. After all, the only reason my chair has two big heavy group 24 batteries is because they can't be run down much below 50% capacity without effecting the length of their useful life. As you say, maybe in a few years. -- Pete
From: Burgerman on 3 Jul 2008 07:37
"Pete" <pete(a)home.dud> wrote in message news:sqWdnWilEuOduPHVnZ2dnUVZ_jidnZ2d(a)posted.internode... > Burgerman wrote: >> "Pete" <pete(a)home.net.au> wrote in message >> news:8eWdnYCBs6iFb_fVnZ2dnUVZ_obinZ2d(a)posted.internode... >>> Burgerman wrote: >>>> Want to know why we dont yet have lithium battery powered wheelchairs? >>>> (Lighter, smaller, faster charging, better high current capability etc) >>>> Well in the process of building or rebuilding yet another F55 I needed >>>> smaller batteries that still performed like the 55 ah stock deep cycle >>>> ones. No space you see - trying to get fat off road balloon tyres under >>>> a F55s by narrowing the battery compartment, moving motors inwards so >>>> the fat tyres dont stick out. Well the price to go lithium (because the >>>> same 55 amp hours takes up much less space) continues to fall but its >>>> still far from cheap! >>>> >>>> http://www.greenmotorsport.com/green_motorsport/products_and_services/3,1,388,17,716.html >>>> �461+Vat 24&48V, is the charger alone! (about 1k dollars for those over >>>> the pond.) >>>> >>>> The batteries we would need to propel a wheelchair all day are �1210.00 >>>> EACH! And we need 2. >>>> >>>> So we are looking at about 2800 pounds or 5600 dollars just for >>>> batteries and charger. >>>> >>>> I dont think I will be bothering just yet. >>> >>> Have you checked these guys out Burgerman >>> >>> http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=1158 >>> >>> I'm not sure how they stack up against what you've looked at, but prices >>> seem ok. >> >> >> http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=4172 >> >> 2 of these would give correct ish voltage and capacity. @ about 4000 >> dollars. Plus special lithium charger (we dont want a fire!), @ about >> 1200 dollars. Cheaper slightly but still a bit too much for batteries >> every 12 months I think! In a year or three prices will fall and we can >> all have fast charging 40 miles range and 20 mph powerchairs. > > I would have thought with being able to run these type of batteries right > down, unlike lead acid, that 50ah would be enough capacity?. After all, > the only reason my chair has two big heavy group 24 batteries is because > they can't be run down much below 50% capacity without effecting the > length of their useful life. > > As you say, maybe in a few years. > > -- > Pete Yep they are 50 amp hour. And no, lithiums cant be run right down like nicads or NmHydrides as they then are buggered! You physically cant charge them. Oh I see what you mean. No you need the extra capacity to feed 2x 100 amps to the motors without damaging them. At least I do, I use 100 amp per channel controller and it actually takes this when turning on grass or curb climbing/wheelying etc. Lithium ions dont like big currents much. I use these things in RC helis and electric flight. There is a more expensive and lighter variant called Lithium Polymer available, In the smaller sizes and some are able to do big currents now (at silly prices) without damage. These if they were larger would be adequate for both current as well as downsizing the batteries. I couldnt go much smaller though since I regularly drain my lead acid 75 amp batteries to 80 percent discharged. I get 10 months per set of optima or hawker odyssey batteries as it is... |