What are the effects of voltage increase on cart performance? - Lithium battery pack

[JaxPilot]

So, I know we have debated Lithium packs ad nauseam, but I've got to order batteries and I am suffering from Analysis Paralysis!
Looking at lithium options, there are a wide range of voltages available; Average - max - min, in all AH configurations. In hopes of codifying and clarifying some info, I want to present a scenario and various options for debate and discussion.

Scenario - 1999 TXT DCS, 36v originally. Alltrax XCT 500A controller, HD solenoid, 2 GA cables, lifted with 22" high pressure (20 psi) tires. BUT, with the original fleet speed motor.

I know that AH are what will give extended run times, and the options out there seem to be 45, 47, 50, 52, 54, 60, 62. Then paralleling these values (modules) give you multiples. I also think that while there is some dissent, most folks are of the opinion that most use cases call for a multiple of these, with 90 - 108 AH being desirable, and 120-200 considered top tier.

I think it has also been said repeatedly that voltage = speed and amps = torque, generally speaking. I've read and reread several posts (many by JohnnieB) about calculating range and runtime from WattHours.

So given all that, I'm trying to determine what I should expect from various voltages on my cart. I'm looking at several options and trying to keep prices down, but here is where I get lost.

1. What would be the effects of these voltage values on performance, if any?
2. Will I see much difference between 38.0 volts and 54 volts?
3. Does it matter some have a MAX - MIN voltage range of 10v, while some have 16 volts difference between MAX and MIN?
4. Is AH king of consideration, and voltage irrelevant on a stock motor?
5. What about an upgraded Admiral Torque motor - what effect will voltage have on it?

Vavg - Vmax - Vmin
53.0 - 58.00 - 47.00
54.0 - 58.80 - 42.00
46.0 - 50.00 - 40.00
38.0 - 42.00 - 30.00

Thanks in advance for helping me gather the last bit of data to synthesize into useful information so I can make a freaking decision, already.

[cgtech]

It's linear. A 10% increase in voltage will get a potential 10% increase in torque & speed. The word "potential" is included because drag like wind & tire resistance goes up exponentially with speed. It takes a real good increase in power to increase your top speed from 200 mph to 230mph at Bonneville.

[JaxPilot]

Originally Posted by cgtech

It's linear. A 10% increase in voltage will get a potential 10% increase in torque & speed.

Well, hell, that was easy!

[scottyb]

And a 100% decrease in the weight of your purse

[JaxPilot]

Originally Posted by scottyb

And a 100% decrease in the weight of your purse

Well, hell, that hurts!

[JaxPilot]

So, then, to see if I have the math correct.

FLA Batteries at 38.22 volts only got me about 13 MPH. Is this "theoretically" correct?

42v = +10% = 14.3 MPH
46v = +20% = 15.6 MPH
54v = +41% = 18.4 MPH

And, does that then mean that fully charged, 58.8v is a 54% increase, and should result in 20 MPH, slowly decreasing to 54v nominal, at 18.4 MPH?

Good grief, I have a headache!

[agpfl]

I know its a struggle to justify the added expense of lithium, but after a couple months the sting fades and the smile remains.

Figure out how far and how fast you want to go and work from there.

I only needed 5-10 miles so was looking at a smaller pack that would get me 15 miles. I have a 2005 PDS and was already running 23 Mph so speed was not a concern, and I knew losing 350lbs of lead would increase torque.

I narrowed it down to a 36v pack with 60Ah batteries for a total of 2300Wh and a 43v with 82Ah batteries for 3750Wh. I decided on the larger pack based on the incremental price difference vs gained performance and distance.

As it turns out I stumbled into an awesome voltage of 43v. The voltage is high enough with my stock PDS motor and Alltrax controller to get me fast without being too fast. I also see the B's constantly singing the 42v praises.

I can run 31 Mph with Alltrax set for max RPMs of 6000. One day I will bump it up to 6500 just to see what it can do. No way to accurately measure toque, but its now very strong. Had to get used to the concept of having a light foot on the go pedal.

Voltage is a little different from FLA as well. For the Leaf modules 8.4v (4.2 per cell) is the max voltage and is stated to run down to as little as 6.7v. The discharge is very linear in this range. After a lot of testing, I have found my pack to run 49.5v-34v. At 40v, I know to get home because I only have a couple miles left and start to see a sharp decline in voltage. At 34v it just drops through the floor. As the voltage drops so does the speed.

Hope this helps.

[SouthCo]

You'll get a little more too speed and some torque. The reduction in weight helps too. My cart dropped nearly 300lbs. The initial cost is worth it. No bulky charger, no worrying about water level, less wiring, quick charge times... so many benefits. My series cart saw about a 4mph increase. Fully charged my lithium pack is just above 58v. Just had it at a 300+ acre campground. Only charged every other day and would still be north of 54v after the second day of running when I decided to charge again.

[cgtech]

Only thing I left out (for the speed/acceleration junkies) is the fact of "voltage sag". The old style lead batteries sag in voltage when you "mash it". The lithiums (bigger packs, can't say for these little lithium packs suggested here), have very little sag in voltage when at full throttle. A pack of "good" golf cart 12v batteries drop a lot when at full draw. The lithiums I build sag very little when at full draw. Keeping the voltage higher during peak load is great for torque. I can't say with experience how that goes with these smaller lithium packs suggested here. But it also is a consideration. I notice it.... Haha, dropping weight in the triple digits can't hurt that either. The first time I tested it & saw voltage stay above 48 even during full load brought a smile to my face (computer nerd grin , I love good numbers). Never made a 36v version, only "48v" carts. Principles are the same, only cell count is different.

[teecro]

Originally Posted by cgtech

Only thing I left out (for the speed/acceleration junkies) is the fact of "voltage sag". The old style lead batteries sag in voltage when you "mash it". The lithiums (bigger packs, can't say for these little lithium packs suggested here), have very little sag in voltage when at full throttle. A pack of "good" golf cart 12v batteries drop a lot when at full draw. The lithiums I build sag very little when at full draw. Keeping the voltage higher during peak load is great for torque. I can't say with experience how that goes with these smaller lithium packs suggested here. But it also is a consideration. I notice it.... Haha, dropping weight in the triple digits can't hurt that either. The first time I tested it & saw voltage stay above 48 even during full load brought a smile to my face (computer nerd grin , I love good numbers). Never made a 36v version, only "48v" carts. Principles are the same, only cell count is different.

If the prices continue to drop on Lithium when the times comes for me to replace the battery pack in my cart in another couple of years if I still feel interested in keeping an electric cart I will make the switch...