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Insulated Cutters
Forum: General
Last Post: johnyradio
01-19-2018, 10:33 PM
» Replies: 6
» Views: 52
Books that teach pack bui...
Forum: General
Last Post: Ryan Martin
01-19-2018, 09:47 PM
» Replies: 2
» Views: 9
Boxes for storing loose 2...
Forum: General
Last Post: johnyradio
01-19-2018, 08:59 PM
» Replies: 1
» Views: 9
Test setups thread
Forum: General
Last Post: Ryan Martin
01-16-2018, 09:44 PM
» Replies: 1
» Views: 31
Refurbishing The Original...
Forum: General
Last Post: johnyradio
01-12-2018, 11:55 PM
» Replies: 0
» Views: 17
Wrong eBay board
Forum: General
Last Post: ahalekelly
01-12-2018, 08:18 AM
» Replies: 1
» Views: 29
DIY Automated Bulk Cell T...
Forum: General
Last Post: ahalekelly
01-12-2018, 12:10 AM
» Replies: 0
» Views: 21
Reverse Engineering the A...
Forum: General
Last Post: ahalekelly
01-11-2018, 11:55 PM
» Replies: 0
» Views: 22

 
  Books that teach pack building
Posted by: bob - 01-19-2018, 09:33 PM - Forum: General - Replies (2)

[Image: 51WaEhb6KjL._SX384_BO1,204,203,200_.jpg]

Micah Toll's book on building lithium battery packs is a great place to start. 
Find it at your favorite bookseller. 
ISBN 9780989906708

Micah is well respected in the e-bike and battery communities. The book is clear and concise. I recommend a copy for everyone in this group.


  Boxes for storing loose 26650 cells
Posted by: bob - 01-19-2018, 04:11 AM - Forum: General - Replies (1)

Here is the cut file to make cardboard dividers to store 26650 cells. 

Hmmm... Cannot attach DXF files. 

So here it is inside a Zip file.



Attached Files
.zip   26650_dividers.zip (Size: 9.81 KB / Downloads: 1)

  Insulated Cutters
Posted by: johnyradio - 01-18-2018, 07:07 PM - Forum: General - Replies (6)

a bit sloppy, but safer than exposed metal

   


  Refurbishing The Original Packs
Posted by: johnyradio - 01-12-2018, 11:55 PM - Forum: General - No Replies

is this a good idea, or even possible? 
if a pack contains a bad cell, how feasible to replace that one bad cell?
seems building new packs makes more sense, since this particular voltage, current, might not suit most needs anyway.


  Wrong eBay board
Posted by: johnyradio - 01-12-2018, 12:19 AM - Forum: General - Replies (1)

this board lists 3.6V in title, but 4.3V in description. 
i can't tell if it's a balancer, charger, or just over-voltage protection, 
but either ways seems like it would not work for these cells. 
https://www.ebay.com/itm/182092400192


  DIY Automated Bulk Cell Tester
Posted by: ahalekelly - 01-12-2018, 12:10 AM - Forum: General - No Replies

I'm starting to design an automated tester for testing cells in bulk, probably 10 or 12 at a time. The idea is to charge the cell, discharge and measure the capacity, and then recharge to half charged for storage, and log the whole thing to a computer for analysis. These are the parts I'm thinking about so far:

Arduino Pro Micro because it has 12 5V ADCs
26650 Cell Holders
TP5000 3.6V Chargers

The TP5000 doesn't have a enable/disable pin, so I need to use a MOSFET to disconnect the power either between the power supply and charger, or the charger and battery. And then another MOSFET and a power resistor to do the discharging, and probably some temperature sensors for safety. The idea is to stream all the data over USB serial to a computer or Raspberry Pi, which would then display the capacity of each cell so you know which ones to keep.


  Test setups thread
Posted by: ahalekelly - 01-11-2018, 11:58 PM - Forum: General - Replies (1)

Show me what you got! Here's a thread for everyone to post photos and details of their testing setups.


  Reverse Engineering the A123 BMS
Posted by: ahalekelly - 01-11-2018, 11:55 PM - Forum: General - No Replies

x and I started working on reverse engineering the Battery Management System board that comes on the A123 packs. It seems to be based around a PIC microcontroller, with a bunch of voltage dividers to read the cell voltages, shunt resistors and MOSFETs to balance the cells, and an serial port isolator to allow it to communicate with the next battery pack up, allowing the BMS boards to be daisy chained via the 5 pin connector.

Current list of identified chips:
Microchip dsPIC30F5011 TQFP-64 microcontroller
ADUM2401 Quad-Channel Digital Isolator
ISL21009BFB841Z 4.096V Voltage Reference
Crystal marked ECSR7.3EX, unknown
24LC1025 EEPROM
LM2937 5V LDO Regulator
LT3437 Switching Regulator

In order to use this as a BMS, we need to figure out the pinout for the connectors, then either figure out all the serial commands they use to control it, or write our own firmware for the PIC. I contacted the project lead for this BMS, we'll see if he can share any details on the protocol, but I wouldn't bet on it.

As this board is too big to fit in any of my projects for these cells, I'm mostly interested in it for testing the cells. But I think a lot of DIY Powerwall people would like to use this board for it's intended application.