Lithium or AC Conversion opinions

[somfas]

Hey. I have an older TXT converted to 72V about 7 years ago. It has a 7 year old custom high torque series D&D motor, 7 year old Trojans, and a 1 year old 500a Alltrax controller.

Since I need batteries, I am checking on opinions and costs of a few options.

1) Just get new batteries and try a custom tune on the controller hoping it will do better on the hills in the future. I have not done any programming to the controller but have heard it would help my speed. I am fine with the speed on the flats (about 27mph), but it slows down quite a bit on the hills (it is a 6 seater).

2) Convert to lithium batteries (would the cart still slow down on hills?) I have heard that it would not, and that these batteries basically last forever and don't need maintenance. But cost $3k - $5k

3) Convert the cart to AC. How much would this cost and what all would need to be replaced?

I only use the cart in a paved road golf cart community with some decent hills. I like all the RXVs that just cruise right up the hill.

Thanks for any input!!

[JohnnieB]

Originally Posted by somfas

1) Just get new batteries and try a custom tune on the controller hoping it will do better on the hills in the future. I have not done any programming to the controller but have heard it would help my speed. I am fine with the speed on the flats (about 27mph), but it slows down quite a bit on the hills (it is a 6 seater).

2) Convert to lithium batteries (would the cart still slow down on hills?) I have heard that it would not, and that these batteries basically last forever and don't need maintenance. But cost $3k - $5k

The faster an electric motor spins, the fewer amps it is capable of drawing, so its top speed is the maximum RPM at which the amps it is capable of drawing produces an amount to torque equal to the mechanical load it is working against.

When the mechanical load is increased, (IE: going uphill), the motor slows until once again the amps it is capable of drawing produces an amount of torque equal to the new mechanical load imposed on it.

In addition to the laws of physics paraphrased above, the voltage of a battery drops when amps are drawn from it. The voltage drop per amp drawn for lead-acid batteries is far greater than it is for lithium batteries, so the same cart with lithium batteries won't slow quite as much on the same inclines as it would with lead acid batteries.

[bronsonj]

I have lithium and for me the cart (basically) doesn't slow on hills. Caveat is I live in a pretty flat part of the country... So what I call a hill you'd call a bump.

But the lithium doesn't sag much at all. The weight loss and lack of sag will cause a lot less slowing. But you will still slow a little, because of all that physics stuff JohnnieB likes to talk about :)

AC is a very cool drive system, but I have no idea the conversion costs.

For Lithium an 18S pack at 4.2vpc gets 75.6V max (though you'd want to stay somewhat lower than max to make the pack last). 19S charged to 4.15vpc gets you to 78.85V. Given that you are a six seater you'll likely need a 2P (maybe 3P pack). Then the BMS system and possibly a charger depending on the BMS you use. Your Alltrax can be programmed for different max and min voltages. You will want to change your min voltage to make sure you don't drain your pack too far. 3.0 vpc is considered the minimum for my lithium chemistry so I set 45.5V as my controller stop point for low voltage. If all the cells are perfectly balanced, that would be 3.25vpc on my pack, but as you get lower you will find not all the cells are balanced and some will drop dangerously low. So margins of safety are your friend.

[Buggieman18]

Originally Posted by somfas

Hey. I have an older TXT converted to 72V about 7 years ago. It has a 7 year old custom high torque series D&D motor, 7 year old Trojans, and a 1 year old 500a Alltrax controller.

Since I need batteries, I am checking on opinions and costs of a few options.

1) Just get new batteries and try a custom tune on the controller hoping it will do better on the hills in the future. I have not done any programming to the controller but have heard it would help my speed. I am fine with the speed on the flats (about 27mph), but it slows down quite a bit on the hills (it is a 6 seater).

2) Convert to lithium batteries (would the cart still slow down on hills?) I have heard that it would not, and that these batteries basically last forever and don't need maintenance. But cost $3k - $5k

3) Convert the cart to AC. How much would this cost and what all would need to be replaced?

I only use the cart in a paved road golf cart community with some decent hills. I like all the RXVs that just cruise right up the hill.

Thanks for any input!!

Just sell the TXT and/or get an RXV and spare yourself all the trouble. The TXT will always be a TXT and will not perform uphill climbs like an RXV. If you have the time and money to tinker with lithium, put lithium in an RXV and you'll have a scream machine!

[yurtle]

Originally Posted by somfas

1) Just get new batteries and try a custom tune on the controller hoping it will do better on the hills in the future. I have not done any programming to the controller but have heard it would help my speed.

You wouldn't by chance be thinking "someone" on this board could work magic with your controller, to unleash power that the OEM deliberately tuned down, would you?

[PingEye3]

Originally Posted by somfas

Hey. I have an older TXT converted to 72V about 7 years ago. It has a 7 year old custom high torque series D&D motor, 7 year old Trojans, and a 1 year old 500a Alltrax controller.

Since I need batteries, I am checking on opinions and costs of a few options.

1) Just get new batteries and try a custom tune on the controller hoping it will do better on the hills in the future. I have not done any programming to the controller but have heard it would help my speed. I am fine with the speed on the flats (about 27mph), but it slows down quite a bit on the hills (it is a 6 seater).

2) Convert to lithium batteries (would the cart still slow down on hills?) I have heard that it would not, and that these batteries basically last forever and don't need maintenance. But cost $3k - $5k

3) Convert the cart to AC. How much would this cost and what all would need to be replaced?

I only use the cart in a paved road golf cart community with some decent hills. I like all the RXVs that just cruise right up the hill.

Thanks for any input!!

Go to 10 leaf modules for a total of 84V (83.4V) fully charged, the Alltrax XCT72500 will operate on 84V just fine. It will accelerate up hills with the weight loss.

[somfas]

Thank you for all the input. Thanks JohnnieB, that makes sense. I think I will look into a way to do the lithium batteries, if I can find a way to do it on somewhat of a budget.