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ChuckW 06-28-2019 05:50 PM

Power and torque upgrade guidance
 
3 Attachment(s)
Hello gents - New member here.

I'm looking for some suggestions on upgrading power and torque on my '04 TXT PDS (36 volt sepex) cart. The cart is in very good condition as it sits, only thing odd is that it has 5ea 2 year old Deka GC10 and 1ea 1 year old Deka CG15 batteries, which seem to be in good condition. Cart runs good but drags up grades greater than about 10-12%.

I'm planning on using the cart primarily for sporting clays, and have done all of the cosmetic and necessary mods for that use including adding a front basket, rear seat, gun rack and new 18" wheels and tires. Typically there will only be two riders, but could be up to four. Think 4 250lb men, 32lbs of shotguns, 150lbs of shells and a small cooler and you'll have an idea of load carrying requirements. Also, being in TN, we have lots of hills. I'm not interested in going 20+ mph, but I am interest in going 12-15mph and carrying that speed up a grade of 14-18%.

I've found the Carts Unlimited site and will most likely go with their product, but want to hear what you all suggest.

Chuck W

JohnnieB 06-28-2019 06:40 PM

Re: Power and torque upgrade guidance
 
2 Attachment(s)
An 18% grade is well within the 25% grade max incline for a completely stock PDS. Perhaps you are using the wrong units of measurement. (See attached)

Climbing 18 hills (about 33% grade) would need some upgrading to do comfortably.

What is the cart's top speed on level pavement?
What does it slow to on hills?

What is the measured tire height?
What is the tire's max inflation pressure?

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I suspect you have some battery issue and high current cable issues.
What is the pack voltage?
what does the pack voltage drop to on hills?

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I'd install a XCT48500-PDS controller with a MZJ400 solenoid and replace all 10 high current cables with 2Ga. (Get set for a 6 X 8V battery pack, they'll work with 6V batteries for now)

If the batteries aren't bad, drop another 6V in the space on the driver side and do 42V until they need to be replaced and then go to 48V. If the batteries are bad, go to 48V.

Or you could stay at 36V for the time being (if existing batteries are good) and go straight to 48V on their replacement.

Since you are looking for 12-15 MPH going uphill, I'd probably go with the FSIP 36V torque motor and run it at 48V. https://shop2.cartsunlimited.net/FS-...6VTORQUEEZ.htm

yurtle 06-28-2019 08:06 PM

Re: Power and torque upgrade guidance
 
Most people don't know the difference between grade and slope, though you might.

Using the chart JohnnyB posted, the easiest way is to use a four foot level (or whatever you have) and a tape measure to directly read rise/run. Or you can use a protractor, string, weight.

ChuckW 06-28-2019 09:52 PM

Re: Power and torque upgrade guidance
 
1 Attachment(s)
Thanks Johnny B

What is the cart's top speed on level pavement? - GPS Measured 15 mph with one person and 13 mph with two people

What does it slow to on hills? GPS measured 9 mph with one person, 7 mph with two

What is the measured tire height? 18 1/2"

What is the tire's max inflation pressure?
22 psi


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I suspect you have some battery issue and high current cable issues. Stock cables - see attached photo

What is the pack voltage? - 37.8v 24 hours after last charge

what does the pack voltage drop to on hills? 32.1v one person on a 15% grade - 31.5v two people on same grade.

Beginning and ending pack voltage after running 30 min up and down some pretty steep hills in the neighborhood
37.8v - 36.8
Per battery
6.45 - 6.27
6.36 - 6.19
6.31 - 6.14
6.35 - 6.21
6.22 - 6.07
6.33 - 6.19

I noticed after running it I was smelling something burning so I took some temps. Do these temps seem reasonable? Again, I was running pretty continuously on some fairly steep hills. I also found a loose nut on the + post of the battery going to the controller, so I'm sure that didn't help any.
Motor - 140 degrees
Speed control and cables to batteries - 123 degrees
Battery posts 95 to 107 degrees

yurtle 06-28-2019 10:20 PM

Re: Power and torque upgrade guidance
 
Quote:

Originally Posted by ChuckW (Post 1630543)
Thanks Johnny B

What is the cart's top speed on level pavement? - GPS Measured 15 mph with one person and 13 mph with two people

What does it slow to on hills? GPS measured 9 mph with one person, 7 mph with two

What is the measured tire height? 18 1/2"

What is the tire's max inflation pressure?
22 psi


-------------
I suspect you have some battery issue and high current cable issues. Stock cables - see attached photo

What is the pack voltage? - 37.8v 24 hours after last charge

what does the pack voltage drop to on hills? 32.1v one person on a 15% grade - 31.5v two people on same grade.

Beginning and ending pack voltage after running 30 min up and down some pretty steep hills in the neighborhood
37.8v - 36.8
Per battery
6.45 - 6.27
6.36 - 6.19
6.31 - 6.14
6.35 - 6.21
6.22 - 6.07
6.33 - 6.19

I noticed after running it I was smelling something burning so I took some temps. Do these temps seem reasonable? Again, I was running pretty continuously on some fairly steep hills. I also found a loose nut on the + post of the battery going to the controller, so I'm sure that didn't help any.
Motor - 140 degrees
Speed control and cables to batteries - 123 degrees
Battery posts 95 to 107 degrees

Batteries are borderline at the end of their useful life, based on age. Voltages while driving up a hill would be better.

They could stand a few equalization charges.

Smelling "burning" is never good. See if you can find the source.

Motor seems fine, but exterior temperature rises after stopping, as it has a lot of internal thermal mass, and cooling is reduced when there is no wind = parked. In other words, it could be WAY hotter inside.

How soon after your ride did you take voltages? Batteries recover after a while, so voltages may be artificially low. What was ambient temp? Some battery posts look hot. Other things also look hot. Good connections and fatter cables will help.

ChuckW 06-28-2019 11:03 PM

Re: Power and torque upgrade guidance
 
**duplicate post**

ChuckW 06-28-2019 11:05 PM

Re: Power and torque upgrade guidance
 
The pack did recover after sitting a while. Ambient temp was 88 deg. I let everything cool down for a couple of hours and checked the pack again before putting it on charge. Voltage was 37.6

I believe the burning smell was from the loose connection at the battery terminal and the cable, and plastic around the terminal post, were melting. Temp at that post was 324 degrees!! I tightened the connection and will test again tomorrow to see if that resolved the problem.

scottyb 06-28-2019 11:11 PM

Re: Power and torque upgrade guidance
 
Yikes - that's hot. A lead terminal can melt around 400. I verified this just last week using a loose connection to generate the heat. :oops:

yurtle 06-28-2019 11:16 PM

Re: Power and torque upgrade guidance
 
Quote:

Originally Posted by ChuckW (Post 1630567)
The pack did recover after sitting a while. Ambient temp was 88 deg. I let everything cool down for a couple of hours and checked the pack again before putting it on charge. Voltage was 37.6

I believe the burning smell was from the loose connection at the battery terminal and the cable, and plastic around the terminal post, were melting. Temp at that post was 324 degrees!! I tightened the connection and will test again tomorrow to see if that resolved the problem.

Sometimes too tight is worse than loose. 10 foot-pounds +/- is all a poor stud encased in lead can handle. Ratings are generally in inch-pounds.

JohnnieB 06-29-2019 03:28 PM

Re: Power and torque upgrade guidance
 
4 Attachment(s)
Your cart is running slower than normal for a PDS, but it might be in the mild hill mode. Put controller in diagnostic mode and count the beeps that sound. Text at bottom of attached PDS label tells you how to get in diagnostic mode, next chart tells you how many beeps for which mode and third chart gives speed and amount of regen braking for each mode.

I also attached a SoC chart, looks like your batteries are only being charged too about 90%SoC. Try doing some back-to-back charges and they might charge to a higher SoC.

The torque loss from the 1/2" taller than stock tires is negligible (~3%) and they are not the low pressure type, so the low speeds going uphill is very likely due to high current cables that are too small and in bad health as well as undercharged batteries.

What make/model charger are you using?

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The first upgrade I made to my cart was replacing all 10 of the OEM high current cables with 2Ga and noticed a seat of the pants increase in low end torque even though the cart was only three years old when I acquired it. Of course, the top speed remained the same because a stock PDS controller RPM limits the motor.


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