2013-11-03 08.41.37

Pack Re-Assembly

Just finished testing the last of the cell groups that had cells replaced. Here is a summary of my findings. Since there are six 10 Ahr cells in each group the original capacity¬† when the cells were new was 60 Ahr. The “Starting Capacity” column shows the capacity of a group before cells were replaced.…

Cell_Group_Test

Pack Evaluation

The rear pack is still out of the 240SX and I’m now in the process of getting the pack back together and back into the car. The overall result of my testing is complete and it’s not all that good. The lowest cell group in the pack is now at 42 Ahr, down 30% from…

TestCart1

Faster Charging

My charge setup uses a Vicor MegaPac with a 5V 40A module. A JLD404 Intelligent Ammeter is used to track the energy into the battery and cutoff the MegaPac charger once the voltage reaches 3.65 Volts.

DischargeTester1

Faster Discharge Testing

Discharging a Lithium battery is actually quite simple. Put a load on the cell and wait until the cell voltage drops to 2.5 Volts then stop discharging. The load should be between 0.5C and 1C and you probably need a way to measure the amount of energy you have removed from the cell. I decided…

CBA_II

Battery Testing

Testing batteries is the most boring process imaginable. After 3 or 4 manual tests I decided some automation was necessary. In my case that means it’s time to build something. After reviewing the BMS logs I came up with 4 cells that seemed to be the weak links in the pack. They were the ones…

RearPackRemoval

Pack Capacity Problems

You never really know the true range of an electric vehicle until you try and push the limits. The 240SX pack has lost almost 40% of it’s capacity in under 4 years. Not so good, but probably due to the hear here is S. FL. My 240SX is my only car. I rely on it…

Headway Cell Refinishing

Talk about tedious work. I refinished 3 packs worth of cells (96) in a week. the refinishing process goes as follows: Disassembly Preparation Treat De-prep For the fist packs-worth of batteries I prepped the cells by applying masking tape to the top 1/4 of the cell side then adding a rubber-backed metal washer to protect…

Still no word from Headway

Well, it has been a month and still no word from Headway. Not all that surprising. I’m going to have to restore each of the cells on my own. The process I’m considering is as follows: 1) Remove all cells from packs. 2) Polish contact ends and attach a steel backed rubber washer to the…

DCF 1.0

LiFePo4 Upgrade – Headway

I purchased a set of LiFepo4 batteries from Headway Battery in China. http://www.headway-cn.com/ I have 512 of the the 38120-S cells. These are 10Ahr cells with an operating Voltage of 2.5V-3.65V Dimensions 38 (mm) x146 (mm), Weight 307g Max continuous discharge 5C Max pulse discharge 15C At my request they were arranged into 16, 32…