How is range measured??

[wbhess]

Last weekend I wanted to test the range of my golf cart. Starting voltage was full charge 44.59v (42v setup- xct48500/admiral motb2). Outside temp was 32F, and 475lbs of ppl in the cart. Trip was 5 miles one way and 5 miles back with occasional rolling hills (nothing that slowed the cart to less than 14mph). I did not check the pack when I got back but waited 10hrs later. Pack voltage was 42.7 and all batteries were roughly the same (approx 55% SoC).

US Batteries less than 2yrs old (almost a full year of no use)

Is range measured by total miles running the cart until its dead or running it down to the 50% soc voltage? I remember reading that people were getting 25-30 miles on a charge....wondering if my batteries are getting worn..

-20" a/t tires on 12" aluminum wheels 22psi
-stopped for about 5 minutes at turnaround point
-full windshield

A couple questions-

-Is it bad for the batteries/controller/motor to drive long distances without any stops?

-Do cold temps cause extra strain on batteries/components?

-Does regen braking hurt battery life?

[JohnnieB]

Electric golf cart range is measured the same way as the range of a vehicle powered by an internal combustion engine. Distance traveled vs fuel used vs size of fuel tank.

Distance traveled can be measured with GPS
Fuel used is the starting SoC (State of Charge) less the ending SoC. (Getting these two numbers is tricky - explained below)
Size of fuel tank is the AH capacity of the battery.

When I do a range estimate for my cart, I travel over a route of mixed terrain (Paved, gravel and dirt roads, plus cross country with mild to steep hills, very little is level around here, and over ten miles in length as measured to a 1/10th of a mile with a GPS.

Getting the SoC is tricky since the batteries have to be at-rest about 12 hours after the charger shuts off or about an hour after the last discharge (Cart movement). Easiest way is to start first thing in the morning after an overnight charge and call it 100% SoC.

Battery voltage drops as amps are drawn, and it takes about an hour for the battery voltage to fully recover after amps have been drawn, but the recovery rate in non-linear and most of it occurs in the first half hour, so I typically take the voltage for my end SoC half an hour or so after I get back to the house, which is the end of my test route.

Subtract the end SoC from the start Soc and divide that number by the miles traveled to get %SoC used per mile.

You don't want to discharge your batteries below 50%, so divide 50% by the %SoC used per mile to get a estimate of your cart's range.

Weight affects range.
Tire height affects range.
Tire pressure affects range.
Speed affects range.
Terrain affects range.
Windshield up/down affects range.
Battery temperature affects battery capacity, which in turn affects range.
Battery age affects battery capacity, which in turn affects range.

Attached is a spreadsheet that calculates range when you plug your numbers in the yellow boxes.

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Answers to your questions:

Your sepex drive shouldn't be driven slowly (walking speed or less) for great distances or driven at max speed for great distances, but will cruise at about 80% to 90% of max speed for as long as the battery lasts.

Other than reducing the battery's capacity, cold has little effect on the cart. How the cart driver reacts to frigid temperatures is another story.

Regen braking extends both range and the batteries' cradle to grave lifespan.

[cgtech]

Here's a general idea of what Temperature does to your capacity/range.

[john fox]

I sure wish I could open the attachment!
JohnnieB could you post in a different format?

[JohnnieB]

Originally Posted by john fox

I sure wish I could open the attachment!
JohnnieB could you post in a different format?

What spreadsheet program are you using?


I can save in most of the popular formats, just have to know which one.


(I have to decontaminate my hard drives when I save in a Micro$oft format. )

[JohnnieB]

Here it is in a Excel 97 format. Every spreadsheet program coded after 1997 ought to be able to open it.

[john fox]

thanks JohnnieB
I couldn't get back before this morning.
I use libreoffice suite and ubuntu the attachment works fine with it.
very interesting, I'm gonna play with it.
thanks again JohnnieB
john