Bad Battery? Please help me confirm

[AtlantaVIP]

Originally Posted by cgtech

The fact that your voltages are dropping so low tells that you have a battery problem, or another major restriction in the power delivery system. Like a really bad cable, or solenoid. If you drive it around for a bit, then check all the cable ends & solenoid for high heat, you could eliminate them as a major problem. If you have clips for your meter ends, clip them to each battery one by one & monitor for which one drops the most during a driving test.

Originally Posted by JohnnieB

Not everybody uses Excel.

Zip the *.csv file and post the zipped file.

Thank you for your response! I'll check each individual battery under load and start from there. By under load should I check while going up the steep hill in my neighborhood or on flat ground?

[hunt365]

I would fully charge the pack. Wait 12 hrs. Record each battery voltage. Should be around 6.3. Then check individually on the hill. It should show up under load if one is bad.

[cgtech]

Originally Posted by hunt365

I would fully charge the pack. Wait 12 hrs. Record each battery voltage. Should be around 6.3. Then check individually on the hill. It should show up under load if one is bad.

Yep, that will show you the weakest battery.

[JohnnieB]

Originally Posted by hunt365

I would fully charge the pack. Wait 12 hrs. Record each battery voltage. Should be around 6.3. Then check individually on the hill. It should show up under load if one is bad.

It is good to record the all individual battery at-rest voltages after 12 hours, but for this type of load testing you want to record the voltage of each battery immediately prior to going up the hill.

The resting voltage of each battery will decrease some after each trip up the hill, so the start voltage for the sixth battery tested will be lower than the start voltage for the first battery tested.

The significant information isn't the start voltage or the lowest voltage dropped to, it is the difference between the two points.

A FLA battery's internal resistance increases as the battery is discharged, so
the drop will increase slightly with each test, but all six drops ought to be with 5% or so of the preceding ones.

FWIW: I use a DVM with a Min/Max function. Makes it a lot easier.

[cgtech]

While that is true, here we are looking for any battery Significantly worse than the rest. 5% isn't going to meaningfully skew the results.

[yurtle]

So my multiposition switch connected to my Ex-Ray isn't overkill, as i can switch to each and every battery while climbing a hill?

[AtlantaVIP]

Originally Posted by JohnnieB

It is good to record the all individual battery at-rest voltages after 12 hours, but for this type of load testing you want to record the voltage of each battery immediately prior to going up the hill.

The resting voltage of each battery will decrease some after each trip up the hill, so the start voltage for the sixth battery tested will be lower than the start voltage for the first battery tested.

The significant information isn't the start voltage or the lowest voltage dropped to, it is the difference between the two points.

A FLA battery's internal resistance increases as the battery is discharged, so
the drop will increase slightly with each test, but all six drops ought to be with 5% or so of the preceding ones.

FWIW: I use a DVM with a Min/Max function. Makes it a lot easier.

Originally Posted by cgtech

While that is true, here we are looking for any battery Significantly worse than the rest. 5% isn't going to meaningfully skew the results.

Thank you for the suggestions and possible solutions! I will try to get this done as soon as Georgia stops flooding! We have a great week coming up until Friday so I will get it done and report back.

[AtlantaVIP]

Originally Posted by yurtle

So my multiposition switch connected to my Ex-Ray isn't overkill, as i can switch to each and every battery while climbing a hill?

Lol not overkill when you're in a predicament like myself. I wish I would have just bought an Ex-ray instead of my current voltage meter. But $30 vs $200 isn't too bad... although I will most likely purchase an Ex-Ray by the end of the year since Scotty has set me up to go 25+ mph!!!

[yurtle]

Originally Posted by AtlantaVIP

Lol not overkill when you're in a predicament like myself. I wish I would have just bought an Ex-ray instead of my current voltage meter. But $30 vs $200 isn't too bad... although I will most likely purchase an Ex-Ray by the end of the year since Scotty has set me up to go 25+ mph!!!

You don't need an Ex-Ray, just nine fuses, nine wires, and a Mil-spec 1 through 12 position rotary switch. Off, Pack, battery 1 - 8, and aux battery if you have one.