90 CC rev contactor/battery / torque questions

DIRTPIT HC

My back story is, about a year and a half ago I bought a 90 CC DS. Was lucky enough to find you guys and ScottyB before I got started on changes. Well I tore out everything but the key switch and the charging port and ordered a kit from Scotty. 700a controller, 400/1000 solenoid, HD FNR, 2g cables, Soc digital meter, DPI accusense charger, D&D high torque motor. New batteries came from local interstate dealer GC8-HD-UT. I am running 22x8-10 dirt devils on front and 22x11-10 mudlites on back. Mudlites only during hunting season then dirt devils all around. I got every thing put together and worked like a charm. No problems.

Two weeks ago I got on the cart to make a run to the sign in board at camp and heard something from under the cart. I thought it was a vine caught up in something. I pressed the go pedal a little and it seemed fine. I waited on another guy to get on and then I thought I smelled electrical wires burning. Got off and pulled the seat and smoke around the FNR. One cable on the FNR, driver side, was slightly warm. Cut the cart off and let it sit. Pushed onto the trailer that evening and brought it home. The next morning at home the cart wouldn't move in forward. Would go in reverse. Only tried a short distance. Then pushed in the garage. Hooked up the charger and went in to email Scotty. After a few emails he thought I needed the reversing contactor. I wanted one anyway so within a day or so it was on its way.

Friday the rev contactor came in and I installed it asap and nothing. Helps if you hook up the ground wire. So, second chance everything worked. Scotty was right.

I live in central MS and we have had a mild winter but by friday the temps were in upper 20's. The cart ran but didn't seem to have the torque as before. Top speed was at or close to the same as before according to my phone speed app.

I had noticed a battery a while before the break down that was down a few hundredths on my dvm. When I got the batteries I broke them in according to the break in procedure and it stays on the DPI If i'm not using it. It has never gone below 50% soc and only rarely close to that number. My SOC meter is wired to stay on all the time and I look at it quite often. After charge while floating it is 52.9-53v and settles in to 50.9v after about 24 hrs off the charger.

I did a load test in my driveway. Slight incline up, hard start, about 30', let sit until each battery was back at or close to original voltage. Here are the results.
I used an Amprobe 5xp-A dmm

Beginning voltage 50.9v
battery
1 - 8.52v sag to 7.42
2- 8.52v sag to 7.43
3- 8.52v sag to 7.44
4- 8.53v sag to 7.41
5- 8.49v sag to 7.39
6- 8.52v sag to 7.48

30 minutes after the test i checked each battery again
Pack voltage 50.7
Battery
1- 8.48
2- 8.48
3- 8.48
4- 8.48
5- 8.45
6- 8.48

Of course battery 5 is low but is that problem low?
Will the cold have that much effect on the torque? I have not noticed that before but the torque did seem better when doing load test. Temp was about 25 higher yesterday than when torque problem.
Can I charge battery 5 individually a little to bring up closer to others? I have a 12v charger that I can set to 2 amps.
Could a battery being low cause my FNR to go out? All connections were tight.

Thanks a lot for you guys help.

BGW

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scottyb

I would definitely do the 2 amp 12v boost to the low battery- be sure to monitor peak voltage and temperature while charging. I would say 20-30 minutes max then rest (cool) repeat if needed.
Here is a little info on how the cold temps effect battery capacity and power.

The performance of all batteries drops drastically at low temperatures; however the elevated internal resistance will cause some warming effect. At –20°C (–4°F) most batteries stop functioning. With lead acid there is the danger of the electrolyte freezing, which can crack the enclosure. Lead acid freezes more easily with a low charge when the specific gravity of the electrolyte is more like water than when fully charged.


Battery capacity (how many amp-hours it can hold) is reduced as temperature goes down, and increased as temperature goes up. The standard rating for batteries is at room temperature - 25 degrees C (about 77 F). At approximately -22 degrees F (-27 C), battery AH capacity drops to 50%. At freezing, capacity is reduced by 20%. Capacity is increased at higher temperatures - at 122 degrees F, battery capacity would be about 12% higher.

DIRTPIT HC

Thanks for the info Scotty. I will do the 2 amp charg on battery 5 tonight when I get home. I just bought a hf laser IR thermometer so I'll keep an eye on the battery when charging and next week be able to take some readings on some components after driving the cart. The reversing contactor works great and easy to operate. One question on the other hd fnr, could not moving the switch all the way over until it stops cause excessive heat? When I pulled it apart it didn't really look bad but the micro switch definitely smelled burnt. One other thing. I believe I have seen JB post something on batteries sagging and a point not to go below for a 48 volt cart but I can not find it again.

scottyb

Not rotating the F&R cam to the full stop position would result in partial contact and reduced conduction at the systems weak point.
Attached find a handy SOC chart

Attached Images

SOC new.jpg (84.9 KB, 0 views)

DIRTPIT HC

Ok. Not positive that is what I did just thinking that is a possibility.

I have that chart saved but have never read that bottom part. This past week end when I was cold and the torque seemed low I went to pick up a deer. Told the guys I couldn't carry anyone else. Just going up a hard packed slight incline at about half throttle it was dropping in to the high 45. V range. Above 45.5. Thanks for your help.