95 Medalist loss of power after trailering problem?

MPrimeaux

Ok, I noticed something a couple of days ago that I was hoping you experts could shed some light on. I recently rebuilt my first cart from the frame up and changed just about everything on it except the motor. I have a DCS 36v medalist with a 500a alltrax controller, batteries are less than a year old (they are "inexpensive" duracells from Sams), 2 awg cables all around, 6" lift, 22" tires. I took it in the woods the other day for the first time to fill up deer feeders and trim shooting lanes and it did great! I was really surprised at the way it handled the hills and terrain. After being sweated down from working all day, I rode it up and down an old railroad track bed that runs through my hunting club while enjoying an adult beverage and cooling off a little before loading up to come home. Again, it did great. I noticed the cooling fan did run a good bit from putting around at half throttle as I expected. Motor was warm, but not unreasonably so. After I cooled off, I loaded it up on the trailer with no trouble and batteries were still good and strong. Total ride time that day may have been 30-45 mins at half throttle....give or take. After trailering it 2 hours back home, I unloaded it and hooked my trailer up to the cart to go park it (my normal practice) and I noticed that I had to go full throttle to move the trailer. when backing the trailer up into it's "parking spot" which is slightly up hill, the cart wouldn't move the trailer in reverse. I had to kind of rock it to get it going in reverse to get everything moving to make it up the hill. Ok, those are the details for you troubleshooters. My question is why did I have seemingly strong batteries when loading it up and weak batteries after trailering for 2 hours? I am sure that everything was turned off while trailering. Any ideas?

BGW

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orangeman6

I’m not one of the experts, but did you happen to check the pack voltage when you got it home? I know you said new batteries, but if you were going up a bunch of hills, and maybe you were carrying gear and another rider, you may have just ran your pack down.

cgtech

Try disabling half-speed reverse in the software. Seems you will need full power up the hill in reverse.

MPrimeaux

No i didn't. I just didn't think of it for some reason. I thought about it the next morning after charging and thought that maybe I had a shorted cell or two, but all batteries measured 6.4-6.5 VDC charged. As far as gear and such, I was by myself, but I did have 150 lbs of corn with me. The thing that gets me is the cart was still strong when I loaded it up on the trailer. I remember specifically because I was paying attention to it being the first real outing. I didn't know what kind of range I would get, so I was surprised that it seemed just as strong when I loaded it up as when I unloaded it. When I got it home, it was a much different story. Noticeably weaker. Just has me a little puzzled.

MPrimeaux

I will surely be doing that. It is set at 50% in R right now, but it was sluggish even in F after I unloaded it at home.

orangeman6

http://www.cartsunlimited.net/battery-meters.html

Might as well have one of these in the dash, if you don’t already. Then you can see at a glance what the pack is reading the next time it bogs down and even when you’re on your hunting travels.

JohnnieB

You might have a battery failing under load. Bad batteries will often have normal voltage at rest and the bottom drops out when amps are being drawn.

What does the pack voltage drop to (fully charged to start with) when going uphill?

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Could be a bad cable connection, or motor brushes, or throttle, or some other stuff also.

If possible, connect a laptop to the XCT and save a data log while driving around and going up hills. All sorts of good info in the data log, battery voltage (at the controller) and amps, motor voltage and amps, field amps, throttle % and controller temperature to name a few.

The saved file will be in .csv (comma separated values) format, which cannot be attached to a BGW post, but all you have to do is zip it and the resulting .zip file can be attached.

WalterM6

Is there a run/tow switch on your cart. I'm thinking that the rocking motion of the ride home was kicking the roll away brake on and off. Enough to run your batteries down.

MPrimeaux

I will connect laptop to see what's going on as soon as I can. I ran it today and everything seemed ok, but I didn't run it for long. As far as the amps dropping out under load, I realize that that is a phenomenon, but it didn't have ANY trouble until I got it back home. I will definitely check all of the things that you've mentioned though. Thanks a bunch for the input!

MPrimeaux

Now that's something I didn't think about and would make sense. I did have the parking brake on while on the trailer and I put my front tires on the front rail of my trailer and ratchet strap it forward. Not sure how much rocking it takes for the brake to engage, but I did NOT have it in tow mode while trailering. Thanks! I'll see what I can do to check it out. Going to be hard to test.