New England Hybrid Festival 2013
Mikes You Tube Videos
Mikes Saturday Hybrid-Solar- Electric Workshop
Insight 20 AH lithium battery system
assembling the pack core
BMS board mounting position?
Capturing the mounting boss positions
Cell tester is modified and lithium test fixture takes shape.
Charging experiments
Cleaning the cell tabs
fixing and deburring the heat spreaders
Final assembled pack core
Finishing the connection blocks
finishing the fins and end plates
First discharge graph
Getting started on the final design and build
Heat sink fins
heatsink vs no heatsink comparison
Higher thermal sensitivity look at the cell heating still shows no dents
Hot and cold cells compared.
How do the big guys do it
Is using this asking for a problem?
main I/O terminals and Heat shrink
Making the 50 insulating strips
Painted cells to increase emissivity
Punching the holes in the tabs
Same discharge with huge heat sink on one side of cell
Testing the fans and layout of the BMS boards
The Battery case starts to take shape
The case is nearly finished
the connector plate is made and mounted
The tab punch
The world in IR Cool
Grid charger Users page
Mikes Surplus Loft
Renewable energy exhibits
New England Hybrid festival 2014

Charging experiments

Charging experiments
high medium and low charge rates compared

In preparation for the second discharge I tried charging three different ways.
First I charged at 34A till the first cell hit 3.55V
On turning off the charge, the voltage immediately dropped to only slightly more than the starting voltage.
I next charged again at ~7A, and the pack voltage again rose to the 3.55 and dropped out, only to show the voltage again drop to a lower value, but higher than the first rebound.
Finally I set up two constant voltage supplies for 3.53V, and let the charger stay connected until the current drops to near zero.
After removing the charger, the voltage stayed at the 3.53V
Hi current charge gets you to the target fast, but then you have to hold the target voltage until the current drops to few ma as the cell fully charges.
Probably better to approach it more slowley, at a more moderate rate.5-8A may be a nice number.