5
A123 CHG CURRENT (A) setting:
The EOS 0720iNET does NOT limit max charge rate for A123-type cells or other-brand
LiFePO4 based on capacity. For A123-Brand cylindrical Phosphate-based cells it is our position that 4C~4.3C rate is the target
MAX, as of this writing. Therefore, 9.2A~10A max for the A123 2300mAh cells
(or 20A max for “2P 2300)
, and 4.4A~5.0A for the
newer 1100mAh size. Consult battery maker documentation for other brands or later A123 types.
NiCd and NiMH:
Set BATT TYPE from MEMORY MODE screen as we did before in the LiPo example. Consult the battery
manufacturer’s documentation to determine the proper settings for VOLTAGE, CAPACITY, and CHG CURRENT.
In addition to the charge settings we have already seen in LiPo Mode, three additional settings exist for NiCd and NiMH battery
types. These are essentially “expert” settings, and should be left at defaults unless you know why you want to change them:
PEAK SENS
(peak sensitivity – delta V) – default for NiCd is 7mV/C and NiMH is 5mV/C
TRICKLE
– sets a low current at which the charger will continue to charge the pack AFTER normal charge is ended
PEAK DELAY
– Short interval after peak is detected during which the charger will continue to charge before terminating
STARTING CHARGE / SELECTING CHARGE TYPE:
After setting
MEMORY MODE
charge parameters, holding down
ENTER
takes you to a Sub-Menu with three options for NiCd/NiMH charge type. Press
ENTER
once to start the current setting flashing,
and use
DOWN
key to scroll through the three choices. Hold down the
START
button after your selection to start charging.
AUTOMATIC
– Essentially ignores your setting for CURRENT, but charges at rate determined by the internal resistance of the
battery pack. Especially useful when you don’t know what settings you should make due to lack of documentation.
LINEAR
– Charges at whatever rate you have selected from start to finish (if the charger detects no problem with settings).
NORMAL
– Charges according to your RATE setting but uses an intelligent algorithm to alter current as needed during charge.
Lead Acid Batteries:
Set Pb for BATT TYPE, correct voltage at the BATT VOLTS screen and the Ah at the BATT CAPACITY
screen, and amperage at the CHG CURRENT screen. Consult the battery manufacturer’s documentation to determine these
settings.
TCS Feature
(Terminal Capacity Selection % for Lithium battery types)
TCS has two settings: TCS CAPACITY %, and TCS END ACTION.
*
The TCS CAPACITY Setting is selected from the MEMORY screen by pressing
UP
button four times (or DOWN seven times).
TCS Capacity can be set from 50% to 100% in 5% increments (default is 100%, a full charge). The charger uses your setting
for Battery Capacity in addition to sophisticated measurements and calculations to make a close estimate for the currently
charged capacity in the pack during charging.
* TCS END ACTION can be set to CONTINUE (default) and STOP. If CONTINUE, when TCS% is reached for settings 50% to
95%, the charger will “beep” 10 times, but continue charging to 100% until stopped. If TCS ACTION is set to STOP, the charger
will stop charging at that TCS setting and - if balancing is complete – then give COMPLETE (END) Buzzer according to your
buzzer settings.
(or continue till balanced, then give End buzzer)
There are three good reasons why you might want to charge a Lithium Battery to something less than full capacity:
* The first is for long-term storage. Lithium batteries are best stored after charging to 55%~65% of nominal capacity. However,
rather than using TCS for this goal, it is easier and better to always use the STORE MODE function. STORE MODE automatically
charges or discharges as needed to reach 60% TCS, then stops.
* The second aim is to get more flight time in during a typical day at the field, by stopping the charge when the battery is 90%
to 95% full, for example. Due to the CC/CV method by which LiPo are charged, charging the last few mAh back into the pack
takes a LOT more time than the first few mAh did… So if you want to get in the air ASAP, and don’t mind a shorter flight then set
TCS at 90%~95% could save you a good bit of charge time. In this case we suggest END ACTION setting of CONTINUE, that
way the charger will sound 10 beeps when TCS is reached, so you can stop charging and fly. If you don’t catch the warning, the
charger will continue to charge to full capacity, as a safety measure in case you have forgotten that TCS is set below 100%.
* The third possibility is that evidence suggests that charging to 90%~95% can increase battery cycle life, compared to 100%
charges. So in this case set TCS ACTION to STOP.
Lithium Care
To maximize your investment in Lithium Battery packs, do the following:
* ALWAYS Store your packs at ~60% of capacity. After a day of flying, use STORE Mode to achieve this. It is especially
harmful to store lithium packs fully charged, and should be avoided for more than a few days at most.
* AVOID discharging cells beyond 90% of capacity (80% is even better). NEVER fully discharge lithium packs.
* STORE your packs in a cool, relatively dry location.
Charging Lithium Polymer in Excess of 1C Rate
(3.7v Nominal LiPo types)
Every Hyperion lithium polymer battery ever produced is capable of charging in excess of 2C.
Note: These are the charge C rates for which less than 0.3% degradation was found in Hyperion Lithium Packs:
HP CX: 3.0C, HP VX: 3.0C, HP VZ: 3.0C
(50-cycle tests completed at 1.0, 2.5, 2.75, 3.0C rates, 0.3% is within measurement error , so not significant, esp if charged at lower rate)
If 3C is possible for LiPo, Why not 3C?
2C is the sensible limit for fast charging lithium polymer. Due to the CC/CV nature of the lithium charging process, the returns
from increasing charge rate diminish very quickly after 2C. That is,
total charge time is only a couple minutes shorter
at
3C compared to 2C, yet initial charge rate has to increase 50% for that small gain. Given this, the risk/benefit equation lands
squarely on the side of 2C max rates. Additionally, since many batteries are not capable of charging reliably past 2C, chargers
which do allow 3C charging are much more likely to cause damage to batteries, or even accidents. It is simply too easy to make
a mistake with the Charge Rate setting, and there are no electronic safeguards which can be reliably employed against making
such a mistake.
If using other than Hyperion lithium packs
, consult your battery’s documentation for allowed C rates,
before exceeding 1C charge rate.
