Marathon started struggling to go up a grade
 

My '92 Marathon, code K2892, serial 716221 has been running great for years. I replaced the batteries about 2 years ago along with all new cables and installed a new F/R switch earlier this year.

Out of nowhere, recently the cart started slowing down going up a slight grade. On the level, it's OK. With the pedal to the metal, it barely makes it up a 5% grade. The battery is fully charged. I looked at the linkage to the speed control and the linkage is all tight.

I have a factory shop manual and the tools to troubleshoot, but this seems to be a popular thread, but none of the answers seem to apply to my situation. The F/R switch worked well for 6 months before this happened.

Re: Marathon started struggling to go up a grade
 

I’d start by running it up an incline then hopping off and checking to see if anything at all was hot

Re: Marathon started struggling to go up a grade
 

And do you have a voltage meter to check the battery pack voltage while it is slowing down? That is important.

Re: Marathon started struggling to go up a grade
 

The temp is in the 40s. Took it 200 feet down the grade and turned around and immediately it was going slow, as slow as you could walk.

We started out at 36.3V. At the bottom of the grade, starting uphill, the voltage dropped at various points to 32.9 V at its lowest and varied around 33V+. At the top of the grade, at rest, the battery climbed up to 35.8V after 30 seconds. Took off the seat and felt for heat. Everything was cold except the 12 o'clock terminal of the F/R switch, I think A2 wire, which was warmer than body temp, but not burning. This goes to a controller in the back but the terminal wasn't warm there.

Re: Marathon started struggling to go up a grade
 

One note. I searched for a quality F/R switch last winter because pressing the pedal didn't move the cart. After awhile, it would go. It seemed this only happened in FWD.

I bought it from one of the popular sites, like buggies gone wild or carts unlimited, don't remember off hand. Out of the box it didn't work. It turned out that one of the micro switches wasn't the right one. It worked the opposite of what it should have been. Trying to reverse the NO and NC leads did nothing. So I had to reuse the old micro switch from the old F/R switch and it worked fine. This I found out when doing voltage tests as shown in the factory manual.

The store said the switch wasn't available and they couldn't help me.

Re: Marathon started struggling to go up a grade
 

36.3 is a mostly dead pack... fully recharge it and try it again

Sounds to me like you need to check your batteries a bit closer... that climb shouldn’t have completely killed your pack

Re: Marathon started struggling to go up a grade
 

Your cart is operating as designed. The electric motor produces it's maximum torque at minimum speed. The faster the motor turns the less torque (power) it produces. When the cart comes to a hill the motor will slow until the torque produced matches the demand (grade)
The micro switches have no influence on speed or performance

Re: Marathon started struggling to go up a grade
 

This is a quote from scottyb from an old post of scottyb

44v. If the pack does not hit this # then the problem may be the batteries and not the charger....

Is the 44V measured with the charger still attached and reading at the battery terminal? or with the charger unplugged?

I charged overnight and the charger was still on. I unplugged it and measured 38.9 at the charging plug. I put the charger on for another day. And then as scotty's post says, I'll wait 12 hours and check again.

I have a quality voltage meter in the dash which uses bars to show the charge. It was an OEM meter, but I don't remember the name just now. The meter was showing fully charged at 36.3 and stayed even when the voltage went to 33V, so maybe I can't trust the meter. We would let it run down to the lower level and then charge.

What is a meter I can trust?

Re: Marathon started struggling to go up a grade
 

44 is while finishing the charge. Right before it shuts off it can be around there.

Re: Marathon started struggling to go up a grade
 

And- bar meters are never accurate. You can get a digital voltage meter from Scotty’s website. (cartsunlimited.net.) They are far superior to the bar type.