controller replacement advice needed

[thetoddjohnson]

I’ll apologize in advance for not being able to specify what model cart this is. Perhaps this information will be sufficient. The cart is a “2007 Yamaha Drive” It is a 48V cart, and the serial number is JW2-000405.

It seems the controller has gone bad and I want to replace it. (It is the stock controller JW2-H6510-00)

Some history: This cart was originally part of a golf course fleet. In 2010 it received a new set of batteries (eight 6V setup) just before I bought it. The batteries (Interstates) may or may not be in great shape. I do my best to maintain them, but the nature of how this cart is used isn’t ideal. It will sit many months not used at all, then will be used A LOT over the course of a week or a weekend, then it will sit for a while. When it is used we really use it. It is used to haul 4, sometimes 5 people a few miles; it is used to launch and retrieve a 15 foot boat that sits on a heavy galvanized trailer; etc. It is used on relatively flat land, but there are a few hills. It lives only a few hundred yards from the Atlantic Ocean on an island off the coast of NC, so the environment is about as corrosive as you can imagine.

The problem: From the day I’ve owned it there was a slightly strange behavior that I suspect has been a controller issue. It would occasionally “skip” as a bicycle would skip if a sprocket were missing a single tooth. It hasn’t been a big deal. Two weeks ago I used the cart for the first time since March. It behaved as if the batteries were going bad. It wouldn’t go as fast as it used to (about 21-23 mph with a single person and no additional cargo), and the battery charge didn’t last very long. I only used the cart for the Memorial Day Weekend, then it sat unused until 2 days ago. When I tried to use it 2 days ago it had that “skipping” feeling, not intermittently, but continuously. And the cart wouldn't go very fast. It felt like perhaps something was rubbing on one of the rear tires. That didn’t last long (only about 50 yards) and then the cart behaved like it did a few weeks ago. (Again, I suspected the batteries were going bad.) After about a mile the cart died. I waited about 10 minutes and then the cart drove again. I made it about halfway back to the house and the cart died again. Now the cart will not move at all. The solenoid clicks in both forward and reverse, but the cart will not move. I’m pretty confident that the controller has died.

The questions: Given the type of usage (lots of torque required, and a little extra speed wouldn’t hurt either) what type of controller should I put in the cart? Will a higher amp controller “burn up” the stock motor? Will an aging battery pack do harm to a new controller? Which, if any, wires would need to be upgraded? (The cables that connect the batteries to each other were upgraded when the bank was changed in 2010, but all the rest of the wiring is stock.) Essentially my question is this: Can I delay replacing the batteries and motor and only buy an upgraded controller, or is that foolish? Eventually the batteries will need to be replaced, and I’m assuming the motor will also die someday. If I am able to keep the stock motor, can I also keep the existing speed sensor, or would that need to be replaced to "match" the new controller?

Any advice would be greatly appreciated,

TJ

[scottyb]

You may have a battery problem.
Get a digital voltmeter and report the voltage of each battery.

[thetoddjohnson]

I would have measured that if I had a meter with me. I'm not on the island now, but I plan to bring a meter with me when I go on Monday.

In addition to measuring the voltages at rest, does it make sense to jack up the rear and measure "under load" even though pressing the gas pedal doesn't really apply any load?

Also, I have another 48V cart that is working fine, would it make sense for me to disconnect the dead carts batteries and use jumper cables to try to move the dead cart by powering it with the known good bank?

TJ

[thetoddjohnson]

Oops. I meant NEXT Monday.

TJ

[COURTESYCART]

I have diag several weak batteries by jacking the cart up and running it and then checking the voltages. DO both test and report back.

Have worked on several DRIVE carts, I will say the controllers are very picky. SOME will take abuse and some wont. I sold a new cart, no lift, just added rear seat and the controller died the day I delivered it. I have also lifted carts, rear seat, added extra batt for accessories and the controller worked for I know 2.5 years.

[thetoddjohnson]

Some more information:

The batteries are U2200UTL Interstate "Workaholic" batteries. The pos posts all say "9J" and below that they say "Z". (I'm not sure of the lettering convention used by Interstate, but clearly the 9 indicates the batteries aren't spring chickens.) The neg posts all say "2". (I don't know what that means.)

I plugged the (Yamaha) charger in last night before going to sleep. I don't know how long it took before the charger detected the bank to be fully charged, but I know that this morning the charger wasn't delivering any current, and the green LED indicating 100% charge was lit.

The voltages this morning after the night on the charger were as follows:

===Positive end of bank===
6.48
6.48
6.48
6.50
6.49
6.51
6.25 <-- ut oh
6.31
=== Negative end of bank ===

The specific gravity readings for all the cells were between 1295 and 1310, except those 2 batteries on the negative end of the bank. The readings were as follows:

=== Positive end of bank===
...
...
...
1300 +/-
...
...
...
1190
1235
1230
1220
1225
1210
=== Negative end of bank===


Thoughts?

TJ

[thetoddjohnson]

The plot thickens...

I figured I'd check to see if the solenoid was working properly. Using the volt meter I found that without pressing the gas pedal there is 35V between the negative end of the battery bank and the solenoid post that is connected to the controller. When I press the gas pedal that voltage jumps to 51V. When I let up the gas pedal that voltage slowing reduces back to 35V.

Wazzup wit da?

TJ

[thetoddjohnson]

Scottyb,

Do you have any comments on the voltages and specific gravity numbers posted above?

TJ

[thetoddjohnson]

I borrowed a load tester and all 8 batteries seem fine. I'm going to assume that batteries are not the issue. Aside: This exercise has inspired me to place an order for one of ScottyB's digital meters to install on the dash.

Using the DVM I discovered that there is no continuity across the armature. (The motor is a SepEx motor. model DM430-05.) I would have expected that by placing one probe on A1 and the other on A2 that my meter would have beeped. There is continuity across the field terminals. So here are my questions:

1 - Am I correct in assuming the motor is shot? Or is the simple armature continuity test only valid on series motors?

2 - Can I replace the motor with something that will give me more torque yet still use the same controller?

3 - If I need to replace the controller then I'm back to the questions in the original post.

Help is greatly appreciated,

TJ

[thetoddjohnson]

If anyone is actually reading this thread, here is an update:

I pulled the motor and discovered that all the springs that push the brushes were stuck "open". I'm optimistic that by cleaning the armature I'll be able to get the motor working again. Perhaps I don't need a controller after all.

TJ