72V TXT or bust....

[sportcoupe]

Of course Johnnie. The case will always be cooler then the internals. Like I mentioned, at least with the probe on the case I have an idea of whats going on inside. Subtracting 50°C is probably pretty close and that's the whole idea, just get close. Better then waiting till I smell smoke!

[JohnnieB]

Yep, I knew you did, what I wrote was for others reading thread.

[as350pilot]

this is good stuff! I was really big into Off-road RC racing. The motor temps were always the important thing there too. With them it was 180* max before they would start to show signs of damage.


sportcoupe, keep up the great work and pictures.

[48V Fanatic]

Good Luck!! Can't wait for pics!

[sportcoupe]

Currently waiting on several more batteries to finish the 72v pack. I expect some this week, hopefully I get enough.

Being the impatient person I am I plan on testing the cart at 36v and 48v to compare speed and torque increases prior to the final 72v. Speed is easy to measure, torque is just seat of the pants.

If my replacement brake cables come in today I plan on doing the 36v test today and maybe even the 48v test too.

[JohnnieB]

Originally Posted by sportcoupe

...............
Speed is easy to measure, torque is just seat of the pants.
...............

Toss an ammeter shunt in series with the pack output cable.
Amps times Volts is Watts
Watts divided by 746 is HP
HP is RPM times Torque.

I'm not sure of the exact formula for RPM vs Torque, but just straight division will give you a number for comparison.

[scottyb]

Would a timed acceleration to a fixed mph be a reliable measure of torque?

[JohnnieB]

Originally Posted by scottyb

Would a timed acceleration to a fixed mph be a reliable measure of torque?

You would have to do some number crunching to get a Torque value, but just for a relative comparison it would work without any math.
In the auto world, the 0-60 MPH time is a relative comparison of torque.

You could also do an elapsed time for acceleration over a specific distance.
In the auto world, a 1/4 mile is used, but for a cart a quarter of a football field would probable be about right.

[sportcoupe]

Originally Posted by JohnnieB

Toss an ammeter shunt in series with the pack output cable.
Amps times Volts is Watts
Watts divided by 746 is HP
HP is RPM times Torque.

I'm not sure of the exact formula for RPM vs Torque, but just straight division will give you a number for comparison.

How convenient, right next my temp gauge is a 500A shunt ammeter.

[sportcoupe]

Originally Posted by JohnnieB

...........
I didn't look all that hard, but found no mention if this is a deep cycle battery or not.
...........

Pretty sure the Enersys is a deep cycle battery. The charts I found have better curves then the trojan allowing for an even deeper discharge without effecting cycles.