I ran sort of a stress test on my new build. Speed,dist,heat, etc. how does it look?

Jeffreynmandy

I've been making a few posts about my build. I got a pile of parts for super cheap and decided to bulid a cart for speed.

Now that it's all together and running good, am I getting all I can from my setup? I strongly suspect I am. And are my stats from my stress test within the norm, and looking good? I'm new to golf carts in general, especially high speed motors and controllers.

Here is what data I collected after a 8 mile street drive. I went as fast as I could, several spots of hilly terrain, only stopping at stop signs.


Distance- 8.46 miles
Average speed - 24.3
Max speed- 37.3 (downhill, foot off accelrator) scary!

Temps measured with a wireless RadioShack temp gun.

Motor temp -163F
Solenoid temp -120F
Controller temp- 100F
Outside ambient temp- around 80F
Tires. 30psi 21" tall 205/40/14

6 New trojan t-875
Voltage before ride 54
Voltage after ride 50.2

Golf cart specs-
95 ezgo txt
650 amp alltrax axe controller
emp 2 stage 36v motor(wired for speed setting)
2awg welding cables throughout
48v upgrade with 6, 8v,
TEMPORARY- standard 36v solenoid and F/R switch. Beefed up coming soon.

BGW

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Revolution

Looks good to me!

MattFX4

So you are close to 90% charge after your run? What do you think your total range would be?

Jeffreynmandy

I'm not sure yet, my normal starting voltage is 52.2. It may have just came off the charger I don't remember.


My father in law has a stock Ezgo marathon. When he put new t-105's in his cart, he drove 30 miles in a day. We have a lot of area to ride around here.


I'm hoping to get 20-25.

Sir Nuke

My main concern would/will be temps.....as that's indicative for voltage/amperage running through everything. so as long as the temps are low/in the ballpark, you are good to go. and yours are good!

JohnnieB

If your tires actually measure 21" tall, the motor was spinning at 7,500 RPM when the cart was going 37.3 MPH.
That is spinning the motor about 1000 RPM faster than it probably ought to be spun.

At 163°F, your motor is running relatively cool. 239°F is the max recommended case temperature for a Class-H motor.

As for the range. Assuming you started at 100% Soc and let the battery pack rest at least half an hour before measuring the after voltage, you ended up at 84.4% SoC. If you discharged the pack to 50% SoC, at 80°F your estimated range is 27.1 Miles. (In cooler weather, the range is less and in warmer weather it is greater.)

If your batteries aren't fully broken in yet, it take about two dozen charge cycles before new batteries reach their rated storage capacity, your range will increase a bit.


Other than spinning the motor too fast, everything else looks good.

Josh61513

How do you like the EMP 2-speed motor? I don't seem to read much about it on the forum, but the flexibility is appealing.

Thanks,
Josh

Jeffreynmandy

Thank you for your input. I'll try to not go over 33mph, that should be about 6500 rpm. I really don't see how it hit that fast. That section of the road was bumpy, so I couldn't watch my phone. If I hit 37 it was for only a second or two max. I remember slowing it down.

Thorectically, what would be the next step needed to reach 40mph while keeping all the components in their safe operating range?

Get a strictly speed/race motor and give up more torque? I kind of have the best of both worlds right now. I'd basically be throwing money away to go 40, I'm kinda scared of it at 30+.

But I would be able to say my cart can go 40mph!

Jeffreynmandy

I like it a lot. It is a 36v version running on 48. If you call them they won't recommend it.

I have moderate hills in places near me, and it will pull 4 passengers uphill at 17-20mph. This is with it only wired for speed with no switch.


From the reviews I can find, people say the switch only makes a small difference in torque. It will go down a few mph and add more torque.

Maybe I have no problems with torque since I have a 650 amp controller. It may be more useful with lower amp controllers.

JohnnieB

1.

2. It might not have reached 37+ MPH. A GPS measures the time between two horizontal points and calculates the speed for it, so going downhill shortens the horizontal distance between two points on an incline, which would calculate to a slower speed. On the other hand, the accuracy of the horizontal location of each point is about 10' at best and could be 30' or more, so the apparent speed from point to point could vary greatly.

Most GPS receivers average the elapsed time over several points and toss out the outlying ones, so the speed displayed is typically more accurate than most car's speedometers, but I'm not so sure about the max speed.

I use a Garmin Nuvi 255 to check my cart speed and distance traveled and have a program that downloads the raw trip data from it and I have seen point to point speeds over 100MPH in cart trip data, but the highest max cart speed I've ever seen it display was about 33 MPH.

When I check top speed on level ground, I don't trust the GPS speed unless it is repeatable, or at least stays constant for several seconds.

3. First, buy a good life insurance policy. Going 40 MPH on a golf cart is ludicrous and on a lifted cart, it is insane.

Unless the motor is specifically rated for over 6500 RPM, that ought to be as fast as you spin it. If you can hit 6500 RPM on level ground now, the only option open to you is the final drive ratio. (Tire height and gear ratio)

Going to taller tires or numerically lower gears loses torque to gain speed, so you may end up with a fast cart that won't have much acceleration off the line and will slow down a lot on hills.

4. If you cannot hit 6500 RPM on level ground, you have the options of higher pack voltage and/or a different motor.

5. Bragging rights can get expensive and dangerous.