48v Conversion checklist for Series TXT

[scottyb]

The B1 is not faster than the stock motor. What it is is 3Xs the horsepower. So you should see less speed drop on the hills.

[noxin]

Originally Posted by scottyb

The B1 is not faster than the stock motor. What it is is 3Xs the horsepower. So you should see less speed drop on the hills.

Thanks, I imagine when I finally get around to checking my current speeds I'll probably wish I had a little more =)

Do you have another motor suggestion that will give better performance, or am I being held back too much by my drive system?

[scottyb]

I don't know what the performance goal is but site sponsor PQ does have some very fast motors.

[noxin]

Originally Posted by scottyb

I don't know what the performance goal is but site sponsor PQ does have some very fast motors.

I'd probably be pretty happy with around 20mph, maybe a little more if possible, but the slowing on hills is what gets me. I've still got stock tires as well, which I measured to be between 17-18" when inflated near upper psi levels.

[JohnnieB]

Originally Posted by noxin

I'd probably be pretty happy with around 20mph, maybe a little more if possible, but the slowing on hills is what gets me. I've still got stock tires as well, which I measured to be between 17-18" when inflated near upper psi levels.

If you were getting 15MPH with a 36V battery pack, you'll get 33.3% more speed and torque with a 48V battery pack, so that ought to put you mighty close to 20MPH already, and about 33.3% less slowing going up hills. If you were only getting 6MPH going uphill, you should now be getting 9MPH.

You can up the top speed by installing taller tires, but doing so decreases torque and you will lose some of the speed gain you've gotten on hills.

You can install tires up to about 20" tall without lifting cart and 20" equates to an 11% speed gain with a 10% torque loss. Theoretically that would give you a top speed of 22MPH and about 8MPH on the hill you now get 9MPH on.

For a motor upgrade, I'd go for one with stock speed or greater with greater than stock torque. Especially if taller than stock tires are installed.

[noxin]

Thanks Johnnie!

So I got one recommendation to check out PlumQuick from Scotty, anybody else have an opinion? Again, I'm still not sure where I'm at right now, but as you all know I'm going to want to get more out of the cart....

I don't see any reason to ever get over 25mph, though getting close would be nice since I would be on neighborhood roads. My big concern is backing up traffic on the long hills (long means a few hundred yards, though the sight lines are bad enough to prevent passing).

[noxin]

Another question about tires.... I have what I believe are stock tires -- Kendra 18x8.50x8 size.

Specs say this tire is about 17.6 inches tall, and that is about what I measured when I inflated them to near the max recommended PSI levels. Actually, the rear tires were closer to 17" and the fronts were 17.5ish.

I've read lots of info about increasing tire sizes negatively affecting torque, but I'm trying to decide if it's worth it to get a little more speed if I plan on going high-torque motor anyway. There aren't very many flat areas in my neighborhood, you're typically either going uphill or down -- only differences are how steep.

So I guess my question is, should I look at tires and motor, or just motor for now, or start with just tires on my current 48v 500A setup? I did look at the Plum Quick site and they have several options going all the way up to the Demon at "16.7 HP, Speed 28-30 mph (estimated) and added 50% more torque" for $725

[JohnnieB]

Originally Posted by noxin

Thanks Johnnie!

So I got one recommendation to check out PlumQuick from Scotty, anybody else have an opinion? Again, I'm still not sure where I'm at right now, but as you all know I'm going to want to get more out of the cart....

I don't see any reason to ever get over 25mph, though getting close would be nice since I would be on neighborhood roads. My big concern is backing up traffic on the long hills (long means a few hundred yards, though the sight lines are bad enough to prevent passing).

Originally Posted by noxin

Another question about tires.... I have what I believe are stock tires -- Kendra 18x8.50x8 size.

Specs say this tire is about 17.6 inches tall, and that is about what I measured when I inflated them to near the max recommended PSI levels. Actually, the rear tires were closer to 17" and the fronts were 17.5ish.

I've read lots of info about increasing tire sizes negatively affecting torque, but I'm trying to decide if it's worth it to get a little more speed if I plan on going high-torque motor anyway. There aren't very many flat areas in my neighborhood, you're typically either going uphill or down -- only differences are how steep.

So I guess my question is, should I look at tires and motor, or just motor for now, or start with just tires on my current 48v 500A setup? I did look at the Plum Quick site and they have several options going all the way up to the Demon at "16.7 HP, Speed 28-30 mph (estimated) and added 50% more torque" for $725

In general terms, it is better to have a top speed available that is faster than you typically drive because most motors are more efficient at a speed lower than max obtainable RPM.

Also, at 100% throttle motor amps equal battery amps while at less than 100% throttle motor amps tend to be greater than battery amps. While that sounds like you get something for nothing, it is just part of the overall system efficiency. The important part is you can see the difference on the data log you can record with a SR controller.

Tire sizes marked on the sidewall vs tire actual height leaves a lot to be desired. The metric sizing is typically closer, but not always.

Only the rear tire height effects speed and torque. I marked the Bottom Dead Center (BDC) my rear tires and and the pavement, counted the tire revolutions for 4 revolutions and divided the distance traveled from BDC to BDC by 4 to get the tire's average rolling circumference. Any number of revolutions can be used, the more the better, but 4 is all I could get between the back porch and garage. Of course a yardstick and a level is close enough for most purposes.

I have the same terrain issue, there isn't much flat land around here, so I decided to stay pretty close to stock height (18") and the specs on the new tires said they were 18.3" tall, but they turned out to be 17.0395260947761" tall when measured as described above. I ended up with an aftermarket motor that more or less had stock speed and about 30% more than stock torque, so my cart doesn't slow much on hills and will barely slow at all if I go to 48V, but quite a bit of that is due to RPM limiting my sepex motor to about 25MPH, not something that can be done with series motor and SR controller.

If your tires are in good condition with plenty of tread left, I'd stick with them and do a motor. Look for a motor with a longer than stock case length.

The turns ratio between the armature and field (stator) windings determine if it is a speed or torque motor and you can pack only so much copper wire in a given sized case. Speed motors have less torque than torque motors and torque motors have less speed than speed motors. However with more copper wire, you can increase both speed and torque. The case diameter is more or less fixed by the diameter of the mounting space on the differential, but the length is only limited by what will fit between the differential and the rear shocks, so you can find a longer case motor that has stock or greater speed with a lot more than stock torque.