48V Conversion Complete !!!!

[JohnnieB]

Originally Posted by hmcnav

I finished my 48V conversion this weekend took it up/down driveway to ensure all was working then charged it up. I have taken on simple runs to drain battery to 75% for total of 6 times so far and today was first time I put speedo on it as I know it takes time. With windscreen down, I maxed out at 35.2 but was averaging 33-34 mph. Great improvement from the original 16 mph I was running when I bought the cart a month ago.


So with 33" tires/lift , new 48V Trojans T890's , new cables all around, and Altrax 400 controller - is 35 mph what I should be getting? I already checked brakes for catching/rubbing and made sure all tires were fully inflated before run.

Either way, it has so much torque. I love it. Now to add turn signals, recover seats and get an extended roof.

If your tires are 23" tall and your differential gears are 12.44:1, your motor is spinning at 6,400 RPM at 35.2 MPH and that is probably all you can get out of your setup, or at least mighty close to it.

Road tires rather than knobbies might get you another 1 or 2 MPH, but you'll lose some off-road traction.

Basically, it doesn't sound like your cart has much of any electrical bottlenecks or mechanical drags holding it back.

On the other hand, it would be a good idea to upgrade to four-wheel disk brakes.

[vagabond]

Originally Posted by JohnnieB

Your tire height is roughly 20.5" (you need to measure them to be sure, the numbers on the sidewall are very, very approximate)
If they are in fact 20.5" tall, at 32MPH, your motor is spinning 6,527 RPM, which is reasonably safe, but don't go downhill with your accelerator pedal on the floor and then lift your foot at the bottom of the hill. (That is what I did )

just measured the tires, somewhere between 19 1/8 and 19 1/4.
The biggest hill we have here at the RV park is the boat ramp

[JohnnieB]

Originally Posted by vagabond

just measured the tires, somewhere between 19 1/8 and 19 1/4.
The biggest hill we have here at the RV park is the boat ramp

About 1.5" shorter than the numbers on the sidewall says they are, that is about the same variance I had on my tires.

They are stamped 18 X 8.50 - 8 and Carlisle listed the MTD (Mounted Tire Diameter) as 18.3", so I was pretty sure they were 18.3" and used that number to figure out motor RPM at various speeds.
Then I decided to verify it by measuring how far a mark on the tire actually traveled while I was on the cart.
It traveled 214.125" in four revolutions, so my tire height is just a whisper over 17", so my cart is 6% slower than it would be on stock height (18") tires, but has 6% more torque where the rubber meets the road.

With 19.125" tires your motor is spinning 6,997 RPM at 32 MPH and on 19.25" tires it is 6951 RPM.

That is a bit quicker than I thought, but there are several guys that frequent this loony bin that are spinning their motors over 7k.

[vagabond]

Originally Posted by JohnnieB

About 1.5" shorter than the numbers on the sidewall says they are, that is about the same variance I had on my tires.

They are stamped 18 X 8.50 - 8 and Carlisle listed the MTD (Mounted Tire Diameter) as 18.3", so I was pretty sure they were 18.3" and used that number to figure out motor RPM at various speeds.
Then I decided to verify it by measuring how far a mark on the tire actually traveled while I was on the cart.
It traveled 214.125" in four revolutions, so my tire height is just a whisper over 17", so my cart is 6% slower than it would be on stock height (18") tires, but has 6% more torque where the rubber meets the road.

With 19.125" tires your motor is spinning 6,997 RPM at 32 MPH and on 19.25" tires it is 6951 RPM.
That is a bit quicker than I thought, but there are several guys that frequent this loony bin that are spinning their motors over 7k.

after reading what happened to you I try and keep it below 27, that's usually fast enough to catch the speeders here in the park

[hmcnav]

Originally Posted by Olman

Did you mean to say 23 inch tires?

LOL!! Yes, 23". Must have been thinking of my old Jeep

[hmcnav]

After driving it all week, to / from school twice daily I can tell you I am having a blast and learned 2 critical things.

The first is that I need to upgrade brakes ASAP !!!! I really have to mash on the brakes when I am at full speed.

I wish I could tune the suspension as stability decreases at those speeds when hitting bumps and dips in the road.

I also checked the calibration on my iPhone speedometer app. I ran it in both cars at 4 speeds for about 15 sec at each speed. 20 , 25, 30 & 35 The app actually runs about a mile per hour off. I say about because I believe the cars would jump to next mph after it hits .5 vs the app tells you both rounded speed and exact speed. So I hypothetically I cold be at 35.5+. Either way, I am totally happy with speed for now and until I get brakes.

[JohnnieB]

Originally Posted by hmcnav

After driving it all week, to / from school twice daily I can tell you I am having a blast and learned 2 critical things.

1. The first is that I need to upgrade brakes ASAP !!!! I really have to mash on the brakes when I am at full speed.

2. I wish I could tune the suspension as stability decreases at those speeds when hitting bumps and dips in the road.

3. I also checked the calibration on my iPhone speedometer app. I ran it in both cars at 4 speeds for about 15 sec at each speed. 20 , 25, 30 & 35 The app actually runs about a mile per hour off. I say about because I believe the cars would jump to next mph after it hits .5 vs the app tells you both rounded speed and exact speed. So I hypothetically I cold be at 35.5+. Either way, I am totally happy with speed for now and until I get brakes.

1. Try doing the brake self adjust process a few times. It might help some.
Drive cart at speed and panic stop, but let off brake pedal before cart stops rolling.

You may have to do it several time before noticing much difference. IIRC, I had to do it something like 15 times before I could get the rear tires to lock up at 25+ MPH. Now I do a panic stop every other week or so, just to keep them properly adjusted.

2. Up the air pressure in the tires. Widen the track (spacers between hubs and wheels). Stiffer springs. Lower the cart (lower the center of gravity)

3. The GPS app on your phone is probably more accurate.

The accuracy of the speedometers in your cars varies with tire diameter and inflation pressure, while the GPS system measures distance traveled over time.