EZGO Series Cart - New Batteries - Horrible range

[branson]

you mentioned you are careful not to bring the batteries below 50 percent state of charge which is good.
you also mentioned that you have brand new batteries. brand new batteries should not be brought down to 50 percent state of charge. they should only be brought down to 75 percent for the first 20 charge cycles. this is a break in. And as you go thru it you will notice the batteries get stronger and last longer

[JohnnieB]

Originally Posted by Exchangegeek

..............Based on the questions you guys have it sounds like you want to rule out the batteries before you start thinking about the other components. Is that because it is rare for a motor and/or controller to be radically inefficient? I agree with your assessment which is why I spent $600 on new batteries. When we bought the cart, the range was terrible and one battery would not fully charge and so I bought 6 new ones from SAM's. I did my normal voltmeter checks and was shocked by how quickly the batteries discharge with normal use..............

You more or less hit the nail on the head.
There are a lot of things that waste energy (inefficiencies), including controllers, motors, cables, F/R switch, solenoid, and mechanical issues such as tire height & type, dragging brake shoes, stiff bearings and the thickness of oil in differential to name a few, but the starting place is always the storage capacity of the battery pack and whether it is being fully charged or not.

Sounds like you essentially have a stock cart with a series wound motor and a new set of 215AH batteries. That is about 4.4% less storage capacity than the standard 225AH batteries, but close enough to give you decent range and performance, so the problem isn't the batteries themselves. but could be a charging issue.

New batteries only have about 75% of their rated capacity until they are broken in, but even so, you ought to be getting more than just 5 miles. Ny guess us that is about half of what it ought be now and about a third of what it ought to be when the batteries reach the full capacity. I take it your other two carts are sepex (PDS) drives. A series drive is a bit less efficient than a sepex drive, so the new cart won't quite have as much range, but it ought to be fairly close using the same make/model batteries. (Taller tires take more amps to turn, but travel further with each revolution, so it more or less cancels out)

As for pushing, it takes some effort to get them moving, but once they are moving, it doesn't take much to keep them moving on a flat hard surface. There should be no grinding or running sounds.

Next time you take the cart out for a spin, feel the high current cables, connections and components when you get back. Any heat felt is lost energy. The motor may get fairly hot and the controller might get warm, but nothing else should.

The differential oil probably hasn't been changed, so changing it would be a good idea. I prefer 75W-90 or 75W-140 gear oil rather that the 30 weight motor oil EZGO puts in them. The 75W gear oil is actually thinner, but designed for gears, they are rated on different scales.

There is a range problem, but to find it, we will probably have to eliminate the possibilities.

[Exchangegeek]

OK, I am back and have hooked up a voltmeter to the batteries. The cart has been charging for a while and my volt meter shows the batteries to be charged probably more than they should.

Overall Pack - 41.5 Volts
Battery 1 : 6.97v
Battery 2 : 6.95v
Battery 3 : 6.97v
Battery 4 : 6.96v
Battery 5 : 6.97v
Battery 6 : 6.94v

Going to run to the store and back (about two miles) and I will record the overall charge again.

Tires are at correct tire pressure, only a single driver, stock tires, wheels, height, etc.

[JohnnieB]

Originally Posted by Exchangegeek

OK, I am back and have hooked up a voltmeter to the batteries. The cart has been charging for a while and my volt meter shows the batteries to be charged probably more than they should.

Overall Pack - 41.5 Volts
Battery 1 : 6.97v
Battery 2 : 6.95v
Battery 3 : 6.97v
Battery 4 : 6.96v
Battery 5 : 6.97v
Battery 6 : 6.94v

Going to run to the store and back (about two miles) and I will record the overall charge again.

Tires are at correct tire pressure, only a single driver, stock tires, wheels, height, etc.

The are Duracell batteries , so I think the have about the same At-Rest voltage vs SoC (State of Charge)
Here is a SoC table for Trojan batteries.

Notice that I said At-Rest voltage.

At-Rest voltages are measured about 12 hours after the battery charging stops, or it will be erroneously high. (Like the voltages posted )

To get a accurate At-Rest after the cart has been driven, you only have to wait about half an hour. (Otherwise is is erroneously low)

If you can give me the voltage about half an hour after you get back and the distance traveled, (down to 1/10 mile), I can estimated the carts range.

[Exchangegeek]

Thanks. So I just got back and I drove 2.66 miles with an average speed of 9.9 MPH on paved golf cart trails. The LED meter dropped 3-4 bars so glancing at the meter I would say we are at 60-70% remaining power. I will wait 30 minutes and then will measure the batteries with a volt-meter and post the numbers.

Thanks again for your help.

-Steve

[Exchangegeek]

After the 2.66 mile drive, here are the numbers

Overall Pack - 38.1 Volts
Battery 1 : 6.35v
Battery 2 : 6.35v
Battery 3 : 6.35v
Battery 4 : 6.34v
Battery 5 : 6.35v
Battery 6 : 6.36v

Based on my voltmeter's numbers this would imply that my batteries went from 110% charged to 100% charged. Also, my LED battery meter dropped from 100% to 60-70%.

This leads me to believe that either:

1) My handheld voltmeter is faulty (reading high) and my cart is very inefficient
2) My cart is not as inefficient as I thought and my LED battery status meter is crap

I guess I need to borrow someone's volt meter to check mine and then I need to monitor the battery levels as we continue to break in the batteries. I can also change the gear fluid, ensure my tires are maintained and continue to monitor.

[kernal]

For the time being I would disregard the dash mounted LED meter and only go by the hand held digital volt meter. Put a new battery in the hand held to rule out misleading readings.

My series cart would do 20 miles easily on paved cart paths before reaching 50% of battery capacity (225ah batteries). The fact that this is a series cart is not the problem.

[Exchangegeek]

New batteries in my handheld and I get the same numbers. I want to track the battery usage but I am not sure how to do it since my handheld seems to report high numbers.

If I am to monitor usage manually, what number would we call 50% ? The "book" says 6.1v is considered 50% and 6.3 is 100%. My voltmeter indicates I have 6.35v after a 2.6 mile trip. It also reports voltage as high as 6.97 after a full charge. I just checked my PDS cart batteries and they report 6.65V. (That cart just came back from a 6 mile trip)

Either these Duracel batteries have more voltage than the Trojans or my handheld voltmeter is crap!

[kernal]

Rule of thumb. Never trust what the dash mounted LED bar state of charge (SOC) meters are telling you until they are verified to be reasonably accurate and then use them as a guide or to monitor trends.

To determine true, repeatable and comparable results:

1. Use the chart from post #14 by JohnnieB.

2. Charge the batteries completely and check the pack voltage 12 hours AFTER the charger shuts off. The charger takes the batteries to about 45v for a 36v pack before it shuts off. It takes awhile for the voltage to stabilize hence the 12 hour wait otherwise you get an artificially ( and misleading) high reading.

3. Drive the cart for some distance. Lets say 8 miles but around the block is not far enough. Wait 30 minutes and take voltage again. Compare it to the chart to find how much capacity you used for the miles driven.

Time consuming I know but you only have to do this to establish a base line and then maybe some time in the future if you suspect a problem.

Taking the voltage too soon after a charge gives inflated readings and too soon after use gives misleading low readings.

[JohnnieB]

The voltage at the start of the trip is far too high to get a ballpark range estimate, and the trip is too short also.

Try doing this.
Either wait about 12 hours after the batteries come off charge to get the "Start" voltage reading. OR, drive the cart about a mile or so and wait about half an hour to get the Start voltage. (That should deplete the surface charge, which is what the 41.5V reading is.)

Drive cart at least 5 mile, the longer the trip the better.

Wait half an hour after the cart stops and measure the "After" Voltage.

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Don't trust that LED battery meter for anything. They lie more than politicians.

As kernal suggested, put a new battery in you DVM, some of them do read high when the battery gets low.

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You've got new 215AH batteries that are not broken in yet, so you range will be about 5% less than it would be with 225AH batteries, and they are someplace between 75% and 100% of their full storage capacity depending on how far the have been broken in so far, which means they are somewhere above 160AH, but less than 215AH at the moment.

My guess is that you ought to be getting around 15 miles of range now and it will improve some as the batteries get broken in.

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You are only getting 9.9 MPH and should be getting about 14, so there are some other issues. Are any of the cables or components getting hot?