chekola wrote:Im not too well versed on batteries and my mathematical skills hardly help ( i suffer dyscalculia ) so I tend to struggle remembering and making sense of most number related things ( not useful skill ) but theres not much I can do about Im afraid , other than try .
I am not great with math either, though not for that reason--I just have trouble following it and often have trouble enough even with simple things, such as not always getting 5 when I add 2 and 2.
NimH always makes me think of those smalle batteries like the AA , I havent really looked into so I'll be sure to check it your thread , if its cheap and easy to wire up for use - then why not ?
If you get NiMH rated for EV use, high-current types, then they can be really good. The F-cell size is the only ones I'd really recommend for it, which typically are 13Ah, where the D size would be around 9Ah. There are potential problems with Ni chemistries as well as any other, of course, such as the fact that they get very hot during the last phase of the charging cycle, and the charger must read a thermistor that is part of the pack to tell when this happens so it can stop charging them. I wouldn't recommend charging them in an enclosure for that reason (though I am sure many people do it safely, I am leery of doing so, and actually run a fan on them at that point in the charge cycle so they don't have to stay hot for long, as heat ages all batteries faster).
NiCD is another option, and is more readily available at reputable dealers like ebikes.ca.
Both are still heavier than Li types, and may have shorter lifespans depending on usage. Both have less power density than Li, and have a lower "C rate", or ability to deliver high currents, so will take more of it to do the same thing as Li.
Looks like the typical kind of wheel you'd see in almost any personal medical equipment, like the ones I have here from various walkers and wheelchairs.
To change them out for air-filled (pneumatic) tires, you'd probably want to check out hardware stores that sell new wheels for dollys and utility carts. Many (but not all) have the same axle diameter as those wheels probably do (7/16", if they're like mine, or maybe 10mm). If you want much larger diameter wheels, you might try finding a used jogger's stroller, which typically has three bicycle type wheels on it. So far the ones I have found at thrift stores have 10mm axles, with bearings just like those in the walker/wheelchair wheels, and thus they will go right onto the axles that those came off of.
If the axles aren't long enough, well, there's a good chance that the axles on the stroller are the same thread pitch as the ones on the walker, and you may be able to swap them out, wheel, axle, bearings and all.
The catch is that now your knee walker would be several inches higher off the ground, as most of those wheels are 12" to 16".
If you can get them to answer you, Goldenmotor makes some small diameter hubmotor-wheels intended to directly power mobility scooters of various types, which may well be able to bolt right into place on your walker. Go here:http://goldenmotor.com/hubmotors/hubmotorIndex.html
and scroll down a ways. There is a 6" diameter brushed geared motor that would probably work, if the axle size is right. If not, you could make an adapter plate/bracket that would bolt to your original axle mount and clamp to the frame, that would then bolt the motor to it.
BTW ** Who exactly is TVE , I notice you mention them a lot but I didnt find any companies under that name , unless it abbrevations .
I'm sorry--I abbreviate a lot, especially with my bike names. So you will see TVE for The Velcro Eclipseviewtopic.php?f=2&t=20595&start=0
DGA for DayGlo Avengerviewtopic.php?f=2&t=15570
and CB2 for CrazyBike2viewtopic.php?f=2&t=12500
I've been fortunate enough to have most of my batteries donated to me after they were used by other people (who presumably moved on to bigger and better batteries), and the old SLA from UPSs and things. If it werent' for that I probably would still be only running lead-acid (SLA) and not getting nearly the performance that I am now.
That particular link looks fairly expensive for that battery, but it is already fully assembled into a pack with a box and switch and plugs, so it's convenient and ready to install. Making an equivalent pack from RC LiPo packs from HobbyCity/HobbyKing would probably be cheaper or the same price, and would be able to supply much higher currents when needed (like starting from a stop). And their stuff just keeps getting cheaper and cheaper, and better and better, from what I've been able to tell reading this forum the last year or so.
It looks like ebikes.ca has discontinued the only NiMH they had carried, a 36V 12Ah Nexcell NiMH, whcih was $425. Roughly equivalent price per energy unit to the one you linked. All their NiCD seems to be sold out right now, too. You might ask when or if they will get more NiMH in, if you're interested in that chemistry.
Realistically, if buying new, RC LiPo will probably get you the best deal for the longest lifespan, once you read up on the potential pitfalls of it and make sure you have a proper charger and LVC (low voltage cutoff) for it.