At least I couldn't find any of this info in the sticky threads. I also did some searches... Anyway, I'm pretty new to this hobby, and I have a 2100mAh 2S1P Li Poly by Thunder Power.

I have been reading on what to do and what not to do with these batteries. I know that some people say that the voltages should not be below 6.0 volts, and others (manufacturer) say that it should not go below 6.6v (3.3v per cell) Also on the charging end it should not go above 8.35v. So with that said, I assume these voltages are measured with a multimeter and the battery at rest.....

Well, my charger shows voltages much different than my multimeter. Which one of these do I rely on?

The multimeter seems to have about a .4 volt difference (high) than my charger. I think that's a huge difference, and so much I'm afraid of starting a fire. I'm taking the reading with my multimeter and the battery at rest. I'm taking the reading with my charger just as I plug the battery into it. At that point in time, it's usually charging at less than 50ma.

The charger I have is a Schulze isl 6-330d, and the multimeter I have is a no name $15 meter I bought at like Target or Wal-Mart. I would like to not just assume that my cheap multimeter is wrong, but would rather know exactly how I can check the accuracy of both of these devices. Is there a way to calibrate? Or maybe, because I don't know what I'm doing, and I shouldn't be checking voltages of my pack with my charger...

I notice the voltage of my pack increases in relation to the number of amps it's being charged at, but my multimeter still reads higher than my charger anyway.

I have never discharged my pack below 7.4 volts (I don't know the voltage while at full throttle so I try to keep it safe), and I have never charged it above 8.3 volts. These measurements were taken on my charger while still charging at a low current. I have never peaked my pack, and have always disconnected the pack from the charger before it reaches 8.35 volts ( again, this measurement is taken while the pack is being charged at .6 amps) Oh, and I never charge above .6amps.

Also, how long can I safely store this particular pack fully charged?

Any info on this will be greatly appreciated, and I give thanks in advance!!

If I were you, I'd go to your local electronic repair shop and ask them to compare your multimeter to one of thier high end units. They shouldn't charge you anything and you'd have a good answer in about 15 seconds. Alternatly you could measure a brand new 9volt battery (non rechargeable) with your multimeter and then compare how others on this board measure the same brand battery in new condition.

To your other questions. 3.0 volts per cell is where you should be stopping at 3.3 volts per cell leaves a LOT of capacity in your battery, especially at high discharge rates. You should charge your batteries to 4.2 volts per cell. 4.175 is fine as well, you won't notice much difference.

I wouldn't store your batteries fully charged for much more than a week. It's not good on the cells, so take a little extra time and take about 1/2 the capacity out if you don't plan on flying for a while.

-Jim

Originally Posted by Jim McPherson

I wouldn't store your batteries fully charged for much more than a week. It's not good on the cells, so take a little extra time and take about 1/2 the capacity out if you don't plan on flying for a while.

Jim,

First time I've heard of not storing LiPo's fully charged ... and what's the ball park for "a while"

TIA!

Jim-

Thanks for the most helpful info. It has eased my mind quite a bit, and I appreciate the help.

You say that long term storage for packs should be at about half capacity. Does this mean half capacity is 3.6 volts per cell?

Also, if i find out that my multimeter is correct plus or minus a hundredth of a volt, does this mean my charger is messed up? Any way to test my charger other than sending it back to the manufacturer?

Thanks again!!