EZGO PDS limp mode

[Hole-in-one]

I wonder if anyone on the forum can help me understand limp mode in an EZGO TXT PDS 36v golf car. By limp (safe) mode, I mean where the golf car's maximum speed and power are drastically reduced, typically to around 6 km/hr.

On my golf car, this is a sporadic thing that sometimes happens, sometimes not. The batteries are in good condition, measuring 89% on the discharge test. Other than limp mode, nothing else is an issue, and there is no history of problems.

As an electrical engineer, I'm hoping to get some insight into this problem and what causes it.

[JohnnieB]

Welcome to BGW!

The label on the controller cover list four conditions (Error Codes) that will cause the cart to run slowly. It might be one of those.

Put the controller in diagnostic mode (Text at bottom of attached label tells how to do it) and listen for any error codes (Beep sequences).

What is the pack voltage when the cart is misbehaving?

Also, what is the ambient temperature? It is summer in the southern hemisphere, so heat may be an issue.

------
I'm a retired Clinical Engineer and have the PDS controller fairly well figured out, so I can probably answer most of your specific questions about how they work.

[Hole-in-one]

Originally Posted by JohnnieB

Welcome to BGW!

What is the pack voltage when the cart is misbehaving?

Between 36.0v out of the charging shed and 34.0v on the 18th

Originally Posted by JohnnieB

Also, what is the ambient temperature? It is summer in the southern hemisphere, so heat may be an issue.

Typically between 24C and 32C. Have not seen any correlation between limp and OAT.

Originally Posted by JohnnieB

I'm a retired Clinical Engineer and have the PDS controller fairly well figured out, so I can probably answer most of your specific questions about how they work.

Thanks for your response, Johnnie. Given the above, here's my burning question, then. What is the interval between the controller checking the voltage difference between Batt and B1? or does it check every time the solenoid opens?

[Hole-in-one]

I meant between Batt and B+ on the controller !

[JohnnieB]

Originally Posted by Hole-in-one

1. Between 36.0v out of the charging shed and 34.0v on the 18th

2. Typically between 24C and 32C. Have not seen any correlation between limp and OAT.

3. Given the above, here's my burning question, then. What is the interval between the controller checking the voltage difference between Batt and B1? or does it check every time the solenoid opens?

1. Low pack voltage is the problem. A fully charged 36V pack reads about 38.2V (See attached chart)
36.0V is less than 50% SoC (State of Charge) and 34.0V is less than 10% SoC.

2. Please ship me some of that, it was -7°C here this morning.

3. It is looking for an increase in the voltage on the controller's B+ terminal every time the solenoid closes. The full pack voltage is applied to J1 Pin-5 all the time and when the solenoid contacts are open, the voltage on the B+ terminal goes through a 250 Ohm resistor, so it is a few volts less than the full pack voltage. The controller energizes the solenoid, so it knows when the contacts close.

It also monitors pack voltage while the cart is moving, but it beeps and stops if the voltage drops too low.

Sounds like you have some battery or battery charging issues.

What charger are you using? (Make & Model - there are a bunch of different ones out there)

BTW: You can downloads the Owner, the Service and the Parts manuals here: http://www.buggiesgonewild.com/elect...g-manuals.html
They are the three *.pdf files near the top.

[Hole-in-one]

Thanks for this in-depth information, JohnnieB - the picture is very much clearer now.

[sxecrew]

I had a cart going in/out of limp mode..
I kept getting a 3-2 code (welded solenoid) but i knew the solenoid was good

my problem was 1 of two things, never did figure out...

1. Loose battery connection from last battery in pack to the controller (the crimp connection was bad) - Batt and B+
2. the resistor across the solenoid.. (my buddy had said sometimes this goes bad)

Once i fixed/replaced both of these issues, i haven't had the problem since..

One trick to use, if the cart goes into limp mode, far from home is:
As the cart is rolling, turn key off, and back on (making sure the cart doesn't stop) and the cart will go back to full speed, until you let off the gas again

[JohnnieB]

Originally Posted by sxecrew

I had a cart going in/out of limp mode..
I kept getting a 3-2 code (welded solenoid) but i knew the solenoid was good

my problem was 1 of two things, never did figure out...

1. Loose battery connection from last battery in pack to the controller (the crimp connection was bad) - Batt and B+
2. the resistor across the solenoid.. (my buddy had said sometimes this goes bad)

Once i fixed/replaced both of these issues, i haven't had the problem since..

One trick to use, if the cart goes into limp mode, far from home is:
As the cart is rolling, turn key off, and back on (making sure the cart doesn't stop) and the cart will go back to full speed, until you let off the gas again

It was the bad cable.
The controller runs normally with or without the resistor.

[skgreen2001]

Hi to all you good folks on this forum,

Just a note to say thank you for sharing your experiences here.

With regards to this thread, I had the exact same issue - cart was going into limp mode.

Found the problem was the positive lead from the positive side of the battery pack had come loose in the crimp.

I have a EZGO 36v, lift kit, alltrax dcx 400 controller and D&D motor upgrade for high torque and 400 amp solenoid.

I actually bought a set of 2 guage battery cables for automobile and bingo, off and running.

Next purchase will be 2 guage cable set complete.

One question, any creative ideas about how to clean up and properly cover the controller? Factory cover no longer fits with upgraded solenoid.

Maybe a picture or two would be ideal.

Thank you again to all you golf cart 'guru's'!

Stevo

[kgsc]

Usually you can cut off the lower half of the original cover and use some longer bolts up to cover it all up.