Li-Ion troubles

[Ivan]

I have a 7.4v 2400mAh pack that I am running through a Fromeco reg.

I have been noticing that I only get about 2-3 flights through the pack then the checker (Fromeco 8 ball) says no fly since it load tests at less than 7V.

This seemed peculiar to me, so I started to investigate. I thought maybe it was the pack its self (MPI Maxx) so I load tested it just the pack. This time I got 7.5V at 1.5A. So, says I, it must be the switch. I tried three other switches and they all drop the same. With the voltage drops I am seeing over the switch, it figures to be somewhere around 5 ohms, which on this low of a voltage circuit is unacceptable. Are the switches (Airtronics, JR, Futaba, HiTech) just not cut out to handle the LiIon setup? Or is there something else I am missing. I would sure like to get the extra 2 flights out of the pack.

Ivan

[Phaedrus]

Are you sure you are testing the battery itself BEFORE the regulator?? You need to do your voltage test on the orange lead make "CHK" Putting the load tester anywhere else will not read the actual pack voltage and that is what you are interested in.

Where is the switch you refer to?? This regulator has a built in switch and you do not need another switch anywhere. It is a failsafe "ON" switch. You can use their pin switch set up or a simple shorting plug. Either way they connect to the lead marked SW. You can even connect a regular switch to this plug and one way turns the regulator on the other way turns it off. But you CANNOT check the battery voltage or charge through the lead marked SW.

[Ivan]

This is only a regulator, not the switch regulator combo. The regulator is between the switch and the reciever, and I check at the charging jack, so the battery is connected directly to the charger, through the switch. The voltage gets regulated between the switch and the reciever.

I have tried a few JR heavy Duty Switches, an Airtronics switch, a Futaba and a Hitech, and they all give the same voltage drop.

I took apart one of the Heavy Duty switches and it looks as if it should be able to handle 1.5A without getting a big voltage drop.

I will meditate on it, and see what I come up with.

[Phaedrus]

Sorry, I misunderstood what type of regulator you had.

That said, I have several giant scale planes set up with Fromeco packs and regulators. These are planes with 10 to 14 large digital servos. The sustained draw is around 3 amps with spikes up to 20 amps. All these planes have had either the Cermark or JR heavy duty switches. I have never observed a problem with these switches.

Beats me what the problem is.