36 Volt EZGO - add battery or buy new motor

[JohnnieB]

Originally Posted by tennesseeboy

Awesome, your answers are as educational as they are helpful man.

I found one more thing that may be contributing to my hill climbing woes. The Max Voltage that my batteries will charge to is 40 Volts. I thought I read somewhere you said that they should charge up to 44’ish volts. I’ve tried two separate chargers with the same results. Is the there something on my cart I can check with a voltmeter to see what’s up?

Thanks.


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I saw the disregard, but understanding battery voltages are akin to understanding women, and they have at least three personalities.

There are three voltage levels (personalities) that occur and you have to know which one you are dealing with to know if the voltage reading you get is a good sign or a bad sign.

1. At-Rest voltage: This is the voltage to use for SoC (State of Charge) estimations and is what is listed on the various SoC charts for the different brands of batteries. It exists when the battery has rested (nether charged nor discharged) for about 6 hours up to around 24 hours after the charger shuts off, or if the batteries have rested about an hour after use.

2. On-Charge voltage: This is the battery's voltage while it is being charged. It starts at whatever voltage the battery was discharged to and climbs to a peak voltage determined by the charger. For legacy charges the peak (for a 36V pack) is typically 45V +/-1V and for modern chargers using dV/dT technology, it might climb up to about 50V.

3. Under-Load voltage: This is the voltage the battery drops to while Amps are being drawn from it. In and of themselves, the six 6V batteries in a healthy, fully charged, 36V pack will drop about 1V/100A of current draw. The cables, connects and connections will also have a voltage drop, as will the controller.

The 3rd voltage is a major factor in your cart's uphill speed and the first two play big roles in the third one being acceptable.

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Connect a laptop to your XCT controller and you can monitor (and record for after the fact analysis.) what the battery pack voltage drops to while going up the Tennessee hills as well as what voltage is actually being applied to the motor (armature), plus many other parameters.

Record a data log, zip the raw .csv file and post the .zip file here and I'll take a look at it.

The first attachment is an edited log from my cart going up a West Virginia hill at 26.5 to 27.3 MPH before I RPM limited my cart to 25 MPH.

The second attachment is a few line of all the parameters recorded in a data log. (40 data columns plus date and time)

[tennesseeboy]

I’ll see if I have the right hookups for my laptop.

I installed scottyb’s volt meter and here’s what she’s doing after a test run:

Charging - 39V or 44V depending on the charge cycle
Full battery - 39V
Cruising - 37.5V
Floored from a dead stop - 31.5V
Rolling down hill fast - 42V (this was weird)
Top of a long steep climb - 31.5V

These are approximate but close.


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[tennesseeboy]

Misspoke on two numbers.

Cruising on flat ground - 36V
12 hrs after complete charge - 38V


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[JohnnieB]

The 42V while rolling downhill is due to regen braking, which turns motor into generator and puts energy back into the battery pack.

The cable needed to connect the XCT to a laptop is a USB-A to USB-B, the same cable that is used to connect printers. Just ask for a USB printer cable at Wal-Mart.

[tennesseeboy]

Well, looks like I waited a minute too long to get a 42V charger, there are NO 42 Volt chargers with the Powerwise connector in Amazon, eBay, nowhere. Anybody got a lead on one?


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[cgtech]

You can get any configuration you want through a DPI distributor like ScottyB (www.cartsunlimited.net)

[tennesseeboy]

Originally Posted by cgtech

You can get any configuration you want through a DPI distributor like ScottyB (www.cartsunlimited.net)

His website only has 36 and 48 volt chargers, but I will touch base with him. He can do just about anything humanly possible with a golf cart lol.


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[JohnnieB]

Originally Posted by tennesseeboy

His website only has 36 and 48 volt chargers, but I will touch base with him. He can do just about anything humanly possible with a golf cart lol.


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As I understand it, the Summit II is user programmable for various battery pack voltages and I have seen them listed on-line for 42V Western carts, so it might be just a matter of downloading the needed charge profile from Lester.

[tennesseeboy]

Can the Western Plug be swapped out for a D36 plug on the DPI Charger, or on my cart? I can find them with the notched Western plug.


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[cgtech]

It absolutely can, no issues whatsoever, as long as you have a Phillips head screwdriver. You can even use the new contacts from the new charger handle. But you would want to keep your D-plug socket on the cart, and change the handle on the charger. The "odd style" charge port probably costs real money.