I have both a Duratrax ICE and Astroflight charger. I notice the ICE decreases the charge amps when it gets close to fully charged. The Astrofilght pulses full amp rate as it gets close to fully charged.

I was wondering if anyone has compared battery performance between the two charging methods?

LIPO batteries are supposed to charge exclusively w/ the CC/CV charging method

Constant Current / Constant Voltage

Which to my understanding means...the amperage stays at what ever the rate set at is, until it reaches the calibrated voltage (8.40 volts for 2s) once the voltage is reached, they stay at the voltage and the amps decrease... (I haven't seen any the did different)

gfx charges at set amp rate until 8.40 than goes down until completed.

never heard of a different method?

Astrofilght has been around with their charging method long before Lipo was popular in RC cars. I would guess that 1000's have been sold to airplane guys.

CC/CV is the only safe way to charge LiPo's from what I understand. And I believe that is the only way the ICE, TC1030, CE and AstroFlight's are designed to charge them.

Different chargers may appear to perform differently but I would be surprised if you'd see any difference in performance from the battery.

And yes Hank, the airplane guys have been using the AstroFlight's for a long time.

And of course 1C constant rate delta peak is the only "official" safe way to charge NiCd and NiMh cells. Doesn't mean that is the best way to get performance from them ;)

I can assure you (doesn't appear) that the Astroflight 109 used pulses when approaching peak voltage.

Here is some info I found on Li-Ion chargers. It sounds like this is the method your charger uses. I think this method is primarily used for the Li-Ion but must work for Lipo's as well. The CC/CV method is a linear charge mode but the key to both methods is holding the voltage to the set limit at the end of the charge cycle.

Pulse Chargers
The third type of Li+ charger, the pulse charger, shares some of the advantages of both switch-mode and linear chargers. Like a switch-mode charger, a pulse charger operates efficiently. When the voltage of the battery it is charging is low, its pass transistor remains on and conducts the input source current directly to the battery. As the battery voltage reaches the battery regulation voltage, the charger pulses the input current to achieve the desired charging current, thus regulating the battery voltage at the desired voltage limit. Because the transistor does not operate in its linear region during this portion of the charge cycle, but acts like a switch and the dissipated power is much lower than that of a linear charger. Since a pulse charger doesn't require an output LC filter, it's smaller than a switch-mode charger.

Now that's one smart feller!

I'm not sure this operates as decribed in that pulse charger discription. To me it is saying it is pulsed at a high enough freq. that it is in effect a lower current rate... much like what an ESC does at part throttle.

On the Astroflight once the battery reaches 7.4v, the current turns off. If the battery falls below 7.4 volts within 5 seconds (not the exact time but that is close) it gets another pulse at the full amps for a second or so. It again stops for 5 seconds and if the battery falls below 7.4 volts, it gets another pulse. This continues until the battery does not fall below 7.4 volts within that 5 second "off state".

cliff s,

the pulse charger that you are describing is no more efficient than a linear charger since 99.9% of the charge time it is operating as a linear charger, ie the pass transistor is operated in it's linear range to limit the charge current until the pack nears full charge.

hank,
i wouldnt think that the pack charged using the astrofight pulse mode would perform any differently than any other charger since this mode is only happens once the pack reaches full charge and it is just holding the voltage at 8.4V. i would only expect a performance difference if the zero to full charge mode were different.

Any power supply or battery charger this uses a pulse mode or switching mode would be more efficient than a linear type. Less heat has to be dissipated with the switching or pulsing types. Less internal heat would mean greater efficiency. The efficiency of the chargers we use really don’t concern racers and in either case I don't think it would increase or decrease the performance of the lipo batteries.