Alltrax Data - Bad Battery or Just Cheap/Weak Batteries?

[Lee0]

Batteries are approx 1 year old. Use frequently and charge after every use. Water topped up monthly.

Does this look like symptoms of a single bad battery? or just that I bought "cheap" batteries and they're weak by nature.

Costco Interstate batteries - GC8
6 x 8 volts
RC @ 56A: 110
Ah @ 20hr: 160
Item # 850984


(alltrax curves attached)

All tests performed in my neighborhood
"Test 1" - Flat slight decline
"Test 2" - Significant incline
"Test 3" - Flat slight incline

[Volt_Ampere]

Measure individual battery voltages both at rest and under load. Your total battery voltage is sagging a lot under load. Were they fully charged when you did these tests?

[scottyb]

Controller thinks it is in reverse constantly?

[Volt_Ampere]

No - that column is the key switch I believe. The headings are not aligned with the columns.

[Lee0]

Originally Posted by Volt_Ampere

Measure individual battery voltages both at rest and under load. Your total battery voltage is sagging a lot under load. Were they fully charged when you did these tests?

Gotta rig up some alligator clamps for my voltmeter and will test tomorrow.

Yeah, the drop was my concern. At the time I took the logs I wasn’t 100% fully charged. It was 100%, then I probably did 20-30 minutes of test passes to get my torque and throttle curves set the way I wanted. Then I took those log file tests. So batteries weren’t at 100%.

Resting voltage 12hrs after charge is about 51.9v. Peak charge on charger hits about 58.8v.

[Volt_Ampere]

The rest voltages sound pretty much normal. Your running voltages would have been a bit higher if you had just come off a full charge. 20 - 30 minutes of running could have been a fair amount of your available charge if you were doing it at full speed.

[Lee0]

Originally Posted by scottyb

Controller thinks it is in reverse constantly?

I don’t believe so. Scotty you helped me get everything wired and set correctly back around March via emails. I have reverse set to 50% of forward and it’s definitely noticeably reduced properly in reverse vs fwd.

[Volt_Ampere]

Originally Posted by Lee0

I don’t believe so. Scotty you helped me get everything wired and set correctly back around March via emails. I have reverse set to 50% of forward and it’s definitely noticeably reduced properly in reverse vs fwd.

I think he was confused with what column of data was the reverse signal. It looks correctly in forward to me.

[Lee0]

Originally Posted by Volt_Ampere

The rest voltages sound pretty much normal. Your running voltages would have been a bit higher if you had just come off a full charge. 20 - 30 minutes of running could have been a fair amount of your available charge if you were doing it at full speed.

I believe I was somewhere near 50.1v before hitting the accelerator to create the logs. If I’m not mistaken, that should be somewhere close to 85% charger.

In the log file I believe I dropped down to 41v-42v at one point (on my phone now so didn’t check back specifically). That seems a bit high. But maybe that’s a normal drop when starting at ~85% charge?

[Lee0]

Storming out here today so tests will have to be this weekend.

I did check a few things though. Batteries finished charging a couple days ago and my charger doesn't have a trickle so they're been sitting for ~48hrs.

Pack voltage = 51.9v
Batt 1: 8.65
Batt 2: 8.62
Batt 3: 8.67
Batt 4: 8.64
Batt 5: 8.63
Batt 6: 8.64

Tested every cell with my hydrometer. Every cell tested pretty close to 1265. It's just a cheapo one so I'm not sure how precise that reading is, but none came close to the upper 1275 or lower 1250 range so they should be well within the "good" threshold.

I'll do some load tests this weekend.