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Electric EZGO Electric EZ GO Marathon, Medalist, TXT and RXV. |
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11-09-2011, 10:14 PM | #1 |
Not Yet Wild
Join Date: Oct 2011
Posts: 7
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'89 marathon loses power after a few seconds.
I have a feeling it's a speed controller issue. Batteries are 4 months old, 37-38 volts.
The cart runs nice and strong for a few seconds, but then instantly loses power. It doesn't fade away like I would expect if the batteries were to blame, it's there one second, the next time I hit the pedal it has half power. It stays like that (low power) until I push it back to the garage and let it sit for a while. I searched for troubleshooting tips on this model and didn't come up with much, sorry if I'm repeating a common question! Any tips will be appreciated. |
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11-10-2011, 08:44 AM | #2 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: '89 marathon loses power after a few seconds.
Welcome to BGW.
New batteries can and do go bad, but need to do some troubleshooting to find out for sure if it is a battery, a controller problem, or something else. First, what is the battery pack voltage? 37-38 volts only tells us they are someplace between 65% and 95% charged. A fully charged 36V battery pack will measure about 38.2V 6-12 hrs after charger shuts off automatically. Attached is a chart showing terminal voltage versus State of Charge. To check the battery pack, attach a DVM to the BL+ and BL- terminals (The ones with cables going to controller and motor) and monitor the voltage while driving. It'll drop a bit when you start moving, but be on the lookout for a sudden drop that coincides with the drop in performance. If that happens, monitor the individual battery voltages one at a time to find out which one(s) is failing under load. Also, make sure all the connections are clean and tight (about 100 in/lb), and all the cables are in good condition. Next, monitor the voltage between BL- at the battery pack and the big solenoid terminal whose cable goes to the controller. (Might be a bad Solenoid contact getting worse when it heats up) If the batteries, connections, cables and solenoid contacts are good, chances are it's the controller. |
11-21-2011, 09:27 PM | #3 |
Not Yet Wild
Join Date: Oct 2011
Posts: 7
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Re: '89 marathon loses power after a few seconds.
So...
A buddy had a spare controller from who-knows-where. I put it in, and it was dead. I put the original back in and took it for a 5 minute ride (in the rain) and everything seems ok. I'm still not sold. I will do a few more laps when its not raining. Voltage at the batteries was 37.5 when I got it back together, has not been charged in weeks. Volts dropped to 34.5 under load on a slight grade. I didn't do the voltage at the controller yet, more info to come. |
11-21-2011, 09:51 PM | #4 |
Happy Carting
Join Date: Dec 2007
Location: Southern California
Posts: 73,358
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Re: '89 marathon loses power after a few seconds.
Recharge then try again.
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11-22-2011, 07:51 AM | #5 | |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: '89 marathon loses power after a few seconds.
Quote:
I'm not sold either. The last line in my reply was, "If the batteries, connections, cables and solenoid contacts are good, chances are it's the controller.", and I'll repeat it here, but I'll add the F/R switch before the controller. So far you've proved your buddy's "spare controller from who-knows-where" is bad and still need to prove if your Batteries and/or Connections and/or Cables and/or F/R Switch and/or Solenoid Contacts and/or Controller is/are causing your cart's problem(s). How on Earth do you expect to find out if your "New" batteries are good or bad if you don't charge them?????? It might be a good idea for you to go to Scotty's website and read everything in the top left menu that contains the word "Battery" before going any further. http://www.cartsunlimited.net/ |
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11-24-2011, 11:48 AM | #6 |
Not Yet Wild
Join Date: Oct 2011
Posts: 7
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Re: '89 marathon loses power after a few seconds.
Batteries are on charge right now. My charger isn't automatic, so i'm a little concerned about overcharging.
They were at 37.5 again this morning. (I need to dig up my specific gravity battery tester i guess?) I monitored volts at the batteries again today as I drove. 36.9 at rest after i drove a few hundred feet, 32.9 pulling a pretty decent hill in the grass, everything "felt" normal to the seat-of-the-pants meter. After a few minutes it instantly lost power again. Now the batteries read 36.9 at rest, and dropped to 36 at full throttle, but the cart BARELY had any pull at all. I then connected the meter to the controller side of the solenoid, 36 volts there as well. In my mind it seems like something is heating up and either loosing connection or limiting current. I think its happening in the controller or the motor. Would either of them have any type of overload protection? |
11-24-2011, 12:37 PM | #7 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: '89 marathon loses power after a few seconds.
Measure the individual battery voltages. They should all be within 0.1V of each other.
I don't know which manual charger you have, but most of the early golf cart charger are basically the same as the later automatic ones except for the automatic turn-on/turn-off circuit, so all you have to do is monitor the pack voltage to know when to terminate the charge. If the battery voltages are all within about 0.1v of each other, put them on charge and let them stay on charge until the battery pack voltage reaches 45V. (An automatic 36V charger shuts of between 44V and 46V) If the batteries have never been fully charged before, this may take 12 to 16 hours. Monitor individual voltages and temperatures while charging. No battery should exceed 7.5V or 120 degrees F. Personally, I suspect you have one or more sick batteries. Your cart may have other problems, but let's eliminate batteries from the list before trying to chase them down. |
11-24-2011, 12:53 PM | #8 | |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: '89 marathon loses power after a few seconds.
Quote:
A bad (loose, burnt, corroded, etc.) contact in the solenoid or F/R control could cause the symptoms described. Put a voltmeter across the big terminals on the solenoid and monitor. Should be zero volts, or mighty close to it. If it jumps up to a a volt or more, the solenoid needs to be replaced. Same technique will work with F/R control. (And any other suspected bad cable or connection) |
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11-24-2011, 09:28 PM | #9 |
Not Yet Wild
Join Date: Oct 2011
Posts: 7
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Re: '89 marathon loses power after a few seconds.
The voltage actually "bogged down" more when it was running right. There was very little drop when it was acting up, so either the motor wasn't asking for the current, or the controller wasn't willing to give it up!
Thanks for the info. What did we do before the internet? |
11-24-2011, 09:35 PM | #10 |
Not Yet Wild
Join Date: Oct 2011
Posts: 7
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Re: '89 marathon loses power after a few seconds.
Here's some pics of my buddy's gas ezgo. We did the 36'' limo stretch, lift, air ride, motor swap and some other fabrication in my garage. 30'' Dub floaters, 27 HP Kawasaki v twin.
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