View Single Post
Old 03-06-2012, 05:13 AM   #5
JoelWisman OP
Beastly Adventurer
 
JoelWisman's Avatar
 
Joined: Apr 2009
Location: STL, MO, USA
Oddometer: 1,392
Houston we have a problem.

I haven't even begun tests yet, and already 2 issues are revealed.

1: Take a look at the BMS receptacle.

Shorai left 2 pins on BMS receptacle!

From the left, pin 2 is bent to almost touching pin 1. Based on how discolored pin 1 and 2 are, they did touch! There is a pin sized slit melted in the receptacle cover, so it can be surmised what happened. It looks like this cover needs to be pressed straight in, not angled shut as one might tend to do since the cover is hinged on the left side.

I doubt the owner of this battery did this as I don't think he has a fancy charger to plug into this port.

No harm as the pins straightened easily, but from the meltage factor, I suspect these pins are unfused and not current limited. Had this short been prolonged, I wonder what would have happened?

The thing that is handy about having a BMS receptacle is, we can measure individual cell voltages as well as the total battery voltage.

I will have to find out more details on this batteries life because these readings are alarming. At the least, it has been sitting on my book shelf for a week, and in transit for a few days before that, but that wouldn't be relevant to a lead / acid battery let alone a LiFePo4 battery.

Total resting battery voltage is 13.149 volts, so between 60 and 70% full. Hmm, wonder why it's not 100% charged? Owner details may clarify and it is certainly not harmful for a lithium battery to be 60% charged. Lithiums actually prefer to be at a 60-80% charge when left standing which is why good lithium chargers have a store mode to keep the battery at other then fully charged, but since the owner does not have one of these fancy chargers........

Next up is the truly alarming part..... From left to right on the BMS receptacle, we can measure individual cell voltages.

Pins 1 and 2 show cell one voltage which is " 3.2965 volts " or about just over 70% charged

Shorai Cell 1

Pins 2 and 3 show cell two voltage which is: " 3.2962 volts " Also just above 70% charged.

Shorai Cell 2

Pins 3 and 4 show cell three voltage which is: " 3.2938 volts " also just above 70% charged but slightly imbalanced.

Shorai Cell 3

Pins 4 and 5 chow cell four voltage which is: " 3.2633 volts " Hello! whats this? between 30 and 40% charged.

Shorai Cell 4

I measured it again, even using my other meter and its real. P.S. the last digit on the meter in the picture is funky cause it decided to settle out from a 4 to a 3 as the shutter was open. 3.2633 IS the #4 cells resting voltage. That's a HUGE imbalance in a lithium battery.

This has a meaning that I will iterate tomorrow, if no one else beats me to it, but for now, I'm torn.

Stuff it in the Capo and see if it will start it?

See if I can induce an F8 rider over here and see if it will start that?

Load the battery and see what that cell does compared to others?

See if the Capos hot charging system will balance the cell voltages back out?

See if the F8's anemic charging voltage WONT balance the cell voltages back out?

Balance the cell voltages manually and commence testing like this was never there?

The last option I am reluctant to do. Many techs first inclination is to beat on or replace something to fix it. To me a problem is like a mystery novel. I want to play detective and know the why as the why is far more significant then the what that fixed it because the whys have a habit of reappearing again and again.

This may be a battery defect, or it may be that tolerances are what they are and an F8 charging voltage isn't enough to keep the cells of a Shorai in balance.

Alright, interview owner tomorrow, r today, but much later after a couple hours of sleep.

After that, not sure. Suggestions and comments from LiFePo4 aficionados welcome and desired
__________________
Owned to date. Honda Aero 50, Honda Elite 80, Honda Elite 250x2, Suzuki Katana, Suzuki RF600, Yamaha YZF1000R, Kymco Xciting 500, Suzuki GS500, Suzuki Burgman 650, BMW F800GSx2, BMW S1000RR, Aprilia Scarabeo 200, Aprilia Caponord, Aprilia Sportcity 250
I love and miss you Jeneca and I'm sorry.

JoelWisman screwed with this post 03-06-2012 at 05:25 AM
JoelWisman is offline   Reply With Quote