Loosing power going up hills

[SpoiledRotten]

Removed...

[turblown]

Originally Posted by uhpilot

After a charge or sitting there for a while after I drive it they are 38.3-38.4. As I drive it drops down to around 34 or so with plenty of power.

When I get to the hlls it usually drops to 32 or so. The other day it showed 34.2 as we were trying to get up one incline and it just wouldn't get up it.

I am experiencing the same voltage drop on my 2003 TXT PDS with the Steep Hill Blue Chip installed. I started with the pack charged to 38.2 volts. Driving with the multimeter connected I noticed the same drop down to around 34 volts, 32 volts going up a slight incline. I continued to drive pedal fully depressed for about 8 miles which took about 45 min. As I drove, the voltage reading with the pedal fully depressed got gradually lower. I drove it to the point that my multimeter read 36.3 volts sitting at idle thinking the batteries were 50% charged. After sitting for about 30 mins or so I checked the pack voltage and it was back up to 37.8 volts. ???

Did a controller upgrade fix the issue? Any other upgrades? Thanks.

[libertybellcdr]

The voltage is going to go down as power is drawn from the batteries to climb hills and go fast. Mine has dropped to as low as 28v when going up a steep incline. Everything is normal as long as the voltage goes back up after sitting idle for a bit. After I climb a bunch of hills, I'll sit for a few seconds and I can see the voltage go from 34 to 36 to 36.5, etc.. All the way back up.

[turblown]

If the voltage bounces back up, how do you know when you have reached the point at which the batteries need to be charged?

Doing some testing this weekend it seems like the voltage bounced back up fairly quickly in the first 30 seconds or so and then it was a slow/gradual increase. It's kind of like the microwave popcorn rule. I waited until there was more than 3 seconds between "pops" (voltage increases) and then took the voltage reading. In this case that was right around 30 seconds.

I drove the cart for about 10 miles and got to the point that I could notice a lack of power. I stopped. The voltage was at about 35 volts but was quickly increasing. I waited 30 seconds or so to the point that the voltage increase was slow/gradual and measured 36.3 volts (50%). Since I could actully feel the lack of power and the battery pack was reading 50%, I took it home.

After I got it home and let it sit for about 30 min, the pack voltage had increased to about 37.1 volts (70%). Now I know the cart was in need of a charge because it barely had enough torque to make it up the driveway.

Is the voltage that the pack eventually returns to a true representation of the state of charge? Apparently not.

I have just been using a multimeter clipped to the battery pack for the time being. I am seeing more and more the benefit of having constant indication of the pack voltage. It feels like the only way to know the true state of charge it to see what voltage the pack is at immediately (within 30 secs) of having the pedal fully depressed. I guess I need to break down and buy a load tester and eventually a voltage gauge for the cart.

I'm open to any feedback.

[scottyb]

Whether you have a multimeter duct taped to the seat or an in-dash LED voltmeter, the cart is the load tester. Take note of the voltage drops when the batteries are fully charged. That's 38.2v after 12 hrs of settling. Drops are likely 35-34v up steep hills with a 30sec recovery to 38.0 This could be used as a reference. 28v could be used as a max low voltage drop. I think the 30sec readings are correct. Your batteries may be getting old. Invest in an inexpensive needle reading hydrometer instead of the load tester. and test fully charged & fully settled batteries.