Download Battery Charger Test Results

Photovoltaic Harvesting Team: Battery Charger
The battery charger is responsible for regulating power to the lithium ion batteries. These batteries are a
potential hazard when over charged or when charged too rapidly. The LTC4006 Standalone Li-Ion
Battery Charger is capable of charging 2, 3, or 4 cell stacks of batteries safely and efficiently. Lithium ion
batteries should be trickle charged when below 10% charge or above 90% and receive max current
otherwise. What is unique about this battery charger is the ability to divert power around the charging
circuitry to the load. This feature allows the energy from the photovoltaics to drive the load when
needed and support larger currents.
Equipment Needed:
1. DC power source
2. LCT demonstration board
3. Lithium ion battery stack
Start Date:
March 16, 2012
Finish Date: March 16, 2012
Engineer set-up experiment: Mike Grolling
Assistant:
Test Plan:
Test #
Component / System
Tested
Description
Engineering
Spec
Pass/Fail
Criteria
1
Lithium ion batteries
Batteries energy storage capability
6
~ 5 A-H
2
LCT4006
Proper charging of lithium ion batteries.
N/A
See Figure 1
Figure 1: Example Charging Curve for Lithium Ion Batteries
Test Results:
Test #
Measured Result
Pass/Fail?
Comments
1
N/A
N/A
This requirement is an energy rating of the battery stack.
2
See Figures
Pass
In agreement with the charge curve for lithium ion
batteries
Figure 2: Charging Curve
Figure 3: Switch Event from Trickle to Full Charge Rate
Comments/Observations:
The requirement for 5-Amp hours (spec6) will be met by the 4-cell battery stack. Testing was performed
on a 2 cell stack. As shown in Figure 2 the control circuitry of the LTC4006 never allows the voltage on
the battery to rise above the maximum allowable voltage which is 8.4 V for this battery stack.