Burgerman wrote:I think that a mobility controller can just about cope with a wheelchair on flat ground with casters so it turns easily. And anything with tracks is a (huge) step too far for any mobility controller. In order to make it turn in place at all, they have reduced its speed to 4mph. And so forwards and backwards will be fine, any attempt to turn will max out amps and roll back power and it may or may not turn. When it fails it will rapidly roll back power to say 50A and then wont turn at all and will barely move.
Take a test ride. Turn in place just 20 degrees. And then back. Reapeat a few times. Try it on dry clean road and on grass. When it stops moving and turning at all, thats the thermal rollback kicking in so it doesent burn out the controller.
Test and then tell me I am wrong.
martin007 wrote:How much does the lowest model cost?
What is the lifespan of the tracks?
Burgerman wrote:Remember that all those seatin opions add around 100 kg to an already inadequately powered chair. Be careful what you choose.
swalker wrote:I have mostly seen videos of track chairs on flat ground without significant obstructions. I believe there is a reason for this.
First, as you already know, they are under powered. I don't know of a single commercial off the shelf solution that has adequate power. You will essentially be building a custom wheelchair.
Next, when crossing an obstacle such as a downed (small diameter) tree, the track chair climbs up it until the balance point is reached and then tips down the other side. In practice, it cannot overcome much of such an obstacle because of its short wheelbase.
In contrast, my four wheel drive wheelchair can approach an obstacle so that only 1 wheel starts over it. I have made it over some surprising obstacles this way.
Next, consider how you will transport the track chair. The ones I looked at were too wide to fit on the lift in my wheelchair van. I would have needed to get a trailer or a pickup truck with a hoist to put the track chair in the bed.
After considering all this, I abandoned my search for a track chair and went with a four wheel drive chair. My four wheel drive chair certainly has limitations, but has allowed me to get into the woods (primarily on trails).
Steve
Burgerman wrote:If I was going to use an off road chair I would go with something like that. Be aware that as mentioned trying to turn on a dry clean road for e.g will suck every amp possible and heat up motors and controller in rapid time and it may or may not actually turn depending on weight and conditions. They could have gone with 4mph motors in place of 6 and gained 50% extra torque and much less heating and battery drain at the same time. So 6mph motors a bad choice.
Burgerman wrote:If I was going to use an off road chair I would go with something like that. Be aware that as mentioned trying to turn on a dry clean road for e.g will suck every amp possible and heat up motors and controller in rapid time and it may or may not actually turn depending on weight and conditions. They could have gone with 4mph motors in place of 6 and gained 50% extra torque and much less heating and battery drain at the same time. So 6mph motors a bad choice.
Burgerman wrote:As you say, I wouldnt. Theres no good solution. So whatever you try would be no better than the stuff already available. And theres hundreds of supposed "off road wheelchairs" most of which are not wheelchairs at all. And so useless indoors or impossible. And those are OK if you really want to drive about in muck and crap. But you will need a trailer, and something to store them in. At which point why mess around with useless heavy batteries at all.
fishinjunky wrote:Which 4x4 chair do you have? Is it the x8 whats your thoughts any recommendations? I need something for really rough terrain and can go through around 12" of water or mud?
martin007 wrote:I have a question.
What do you have to do in your powerchair going through mud and water?
I'd rather be away from the mud.
swalker wrote:fishinjunky wrote:Which 4x4 chair do you have? Is it the x8 whats your thoughts any recommendations? I need something for really rough terrain and can go through around 12" of water or mud?
I have a Magic Mobility X4, which was the predecessor to the X8.
My X4 uses a Dynamic Controls 80 amp DX power module that is rated to put out 80 amps to each side of the chair (and, of course, there are two motors on each side).
It is a reasonable wheelchair, but the 80 amp DX power module is quite limiting. I encounter thermal rollback quite often. I added a fan to keep the power module a bit cooler and that has really helped. A 120 amp RNet setup would be far superior, but may not be sufficient for some of the trails I would like to do.
I often do a 9.5 mile ride (total of out and back) that gains 1,000 feet in elevation. The chair can often do that without thermal rollback on a cold day. However, on even a moderately warm day of 70 F, thermal rollback was assured before I put in the fan. I have never had a thermal rollback on that ride since I put the fan in.
I have looked very seriously at getting an X8. They cost about $30,000 new and am just not willing to pay that much when the X4 is good enough.
I have looked for used X8 wheelchairs over the last 5 years and have found a couple for less than $10,000, but those did not have the 120 Amp RNet system on them. I am unwilling to pay $12,000 to $15,000 for a used X8, which seems like the current market price.
The US distributor of Magic Mobility wheelchairs used to be Innovation In Motion. However, Sunrise bought Magic Mobility a few years ago and the US distribution deal with Innovation In Motion expired in October of this year. When that happened, Innovation In Motion cleared out their demo wheelchairs for around $10,000 each. Unfortunately, none of those demo wheelchairs were configured appropriately for my needs and getting the seating changed on them would have added many thousands (perhaps well over $10,000). Again, that was a price I was unwilling to pay for a used X8.
I have used a demo X8 and like most things about it better than the X4. The only thing I did not like as well is that the X4 has removable leg canes while the X8 (at least the one I was in) does not. Being able to remove those is essential to getting the X4 to fit into my wheelchair van. I have a full size wheelchair van with a Braun Vangater II lift. The X4 just barely fits on the lift. It will not go on that lift with the leg canes in place.
Also, the X4 cannot make it onto my local buses with the leg canes in place. If I remove the leg canes, I can get the X4 onto any of the local buses, but just barely.
Steve
Burgerman wrote:Theres much much more to this than just understanding the roboteq manual... Maybe 30x more. Read the full pinned thread at the top before considering it.
Burgerman wrote:The point of the roboteq is that it allows twice the volts. And that means you can keep the slow/6mph speed the same. And have MUCH SHORTER GEARING instead (say intended for 3mph@24V) and still keep the same 6MPH speed as before. With DOUBLE the torque due to shorter gearing, and half the battery drain. So half the motor heat/load too.
In fact you gain more torque still. Because roboteq is 150A rather than 120A and doesent roll back power easily due to 32 mosfets instead of just 16 in a mobility controller. (half the resistance). So you also gain another 20+% on top of that already doubled torque.
All provided top speed remains the same as before.
The Roboteq we've been using can handle 150 Amps for two minutes - 25% more torque for a much longer time and that may be a worthwhile difference even without changing gearcase and voltage.
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