[iggymo]

Hi All,

Scratchin my head here....just installed a new set of Interstate 8volt GC8-HD-UTL batteries (9) and have about 500 miles on them. I originally had a range of about 25 miles, but this last week it has dipped to about 8 miles, which is luckily my total commute, but barely made it home. I have noticed a lack of 'punch' when accelerating, and am curious as to why.

Here are some specs:

1992 Festiva
72 volt system with Alltrax 7245 controller
D&D Motors ES-15A Series DC motor
Quick Charge - Select-a-charge 20amp automatic on-board charger

when charged, the batteries are at about 1275 on Hydrometer guage

Battery water levels are good, I have been topping them off with distilled water when needed. (Have I put too much in? if so, how do I fix it?)

The charger says it is giving a 100% charge, and the pack voltage and individual battery voltages are withing expected range (about 81 volts for pack and about 9.0volts per battery when fully charged)

When driving, I typically pull anywhere from 40 to 200 Amps (300 max) (According to controller software)

Can I be overtaxing the batteries? Have I damaged them?
Can I be charging them too fast?


Also am having toruble telling if motor is binding to transmission, seems tight, and some squeaks at slow RPMs, difficult to tell if it is aligned or not.

Any ideas? I am not sure why this is happening. Pretty dissapointed if the batteries are going south. Any suggestions? I would really appreciate any help that you are willing to give...

Thanks in advance,

Steve (Iggymo)

 

[Newbiee]

Did the weather get really cold where you live? what is the temperature? This is the only thing i can think of that could be causing loss of that much range just suddenly. Because i would think a slow but steady decrease in range happens as the batteries get older. If the cold is causing your range to drop i have read about people who live in cold climates using battery heater pads to keep the batteries warm.

 

[Newbiee]

oh yea also if its not the batteries that is the problem you might try checking the battery terminal connections? If the batteries have been spilling out water from overfilling them then you could have lost some acid, that would take some capacity away i think. It sounds like you take care of the batteries though. And if there is a sudden alignment problem with a sudden loss of range i would think you would notice the car pulling more amps than usual for the same speeds? But that is just a guess sorry.

 

[Ziggythewiz]

The important thing is what do the batteries read at the end of the commute? You might just have one bad one that's cutting out or in cell reversal due to a shorted cell.

 

[iggymo]

Hi Guys,

Well, it has not been too cold here (50's to 70's daytime), and the car is garaged overnight so I do not think temps are an issue yet. However, it will be getting cold and if I plan on driving this in the winter, my reserve batt capacity I was planning on for cold weather is now gone, making the car unusable in the winter months. I have been pretty careful with battery maintenance and have not spilled (much) water or acid out of the cells. I service the batteries while in the car so they are not tipped or sloshed around. All caps are kept tight when in use too....

I will make a run tonight and let the car sit for an hour after coming back and then test each battery for voltage and specific gravity, I wll do before and after testing and log all the data...I will keep you informed!

Thanks for the input, the more brains the better! Isn't the internet wonderful?

-Steve (Iggymo)

 

[Ziggythewiz]

Don't let them sit before testing voltage. Don't know why anyone recommends that. You want to know what voltage is available to you at the end of your commute. Not after sitting for 1 or 48 hours as some people recommend.

 

[iggymo]

Hey Ziggy,

I did both actually, I measured voltages right after and then waited about 1.5 hours for a second set of measurements. Here is what I got:

Before: Pack=82.6v (immediately off charger) 80.9v just before test. Each cell measured 8.9v.

Immediately After 10.5 mile test run: Pack=75.1v batteries 1,2,4,5,6 = 8.2v bateries 3,7,8,9 = 8.3v

1.5 hours after test run: Pack=76.3 batteries 2,4,5,6 = 8.3v batteries 1,3,7,8,9 = 8.4v

From these voltages, it looks to me that the pack is fine, I need to look for some points of resistance. I recently installed new rear brake shoes, but the wheels turned pretty free afterwards. I just ordered new wheel bearings for the rear, maybe that will help. I also need to re-align my motor to the transmission as it seems to slow down too quick, it does not "coast" very long in neutral when I rev the motor and let it spoin down.
The other thing is the transmission; I may need to flush it and get some better lube in it. It call for Ford automatic transmission fluid, but would I be better off with a synthetic oil of some sort? I am hoping a bearing is not going out in the tranny. I did replace the output bearings and the halfshafts right after I got the car and ran it several hundred miles with the ICE...hoping all of it would wear in a bit.

Any other ideas?

Thanks!

Steve (Iggymo)

 

[Ziggythewiz]

Were you getting a lot of sag at the end of the 10.5 run, or previous runs? Also, do you know how low was normal when the batteries were fresh? 8.2 does seem pretty low, but maybe not as they are so consistent. My 12's are functionally dead when they get down to 12.2, but that's the few worst, with most around 12.4-5 and fresh ones at 12.7-8. (fully charged is 13.2)

I know a lot of people recommend synthetic ATF, I think redline or somethin. Should be an easy search.