Lipo battery specs.

[Jerrymac]

Is it just me, or, are lipo battery specs. just a hit and miss guess.

I have several different brands and sizes of batteries for my helis, including, Flight Power, Mega Power, and G-Force, in sizes from 3s 1500mah to 3s 3300mah and 6s 2500mah.

I generally set my TX timer so that the batteries are about 3.7 to 3.8 volts per cell after landing, which is easily within the safe range for a lipo battery.

Today, while charging all my 14 batteries to get ready for some flying tomorrow, I decided to hook my charger to an old laptop in the basement to save the charge data, as I usually pay no attention to it. Generally, when the charger beeps, I just unplug the battery and plug in the next one without looking at the display on the charger.

Many people say to use the 80% rule for charging, regarding the mah put back in. Well, what happens when you put 2700 back into a 2500mah battery?

Today, while charging and actually monitoring it, I put back ;

900 to 1000 in all my 3s 1500 packs;

2400 to 2500 in all my 3s 3300 packs;

2000 to 2200 in all my 3s 2100 packs;

and 2600 to 2700 in my 2, 6s 2500 packs.

Anybody else have strange charging results like this, or, is it just me?

[billmay]

Jerry - I don't claim to know the answer but I suspect that going by the final voltage is what's causing the problem. I believe that when most people say they are following the "80% rule" they area going by what their charger tells them has been put back in in mAh. I think, for example, there would be a pretty big difference in mAh used in going to 3.7V vs. 3.8V.

Anyway, I would go by the charger numbers and shorten my flight times for the ones that are high.

Bill

[dunkonu23]

Nor do I pretend to know the answer. I will say that my old orange Outrage packs do not kick off the ending tones at all. I have put back values as you have. I think it's because the packs are shot, but I can't prove it and I don't know how.

I can guess what caused my problem, but I doubt it will help you. My first "real" charge was an Align charger that just charged via the balance plug. I do not think it was acccurate at all other than to turn off after about an hour. Any pack that thing touched exhibits the "more put back" than capacity thing. Needless to say, that charger is in a box in basement. I'm not saying your charger is the culprit.

Scott

[Jerrymac]

Well, what is odd about it is that it seems to be only certain packs that do it. When I bought the 6s 2500mah packs I checked the cell voltage before charging them for the first time. They were basically charged to 'storage' voltage at 3.9 volts per cell when I got them.

After charging, all 6 cells were exactly 4.2 volts and I put in 2480mah on the first charge. Since the batteries are new, I like to break them in for a few flights and had my timer on 4 min. while flying the Gaui 425.

After landing they were at 3.75 volts per cell and I put back 2700, in a battery rated at 2500. Stranger yet is that when the timer went off, I did a couple of full collective punch outs before setting it down and it still had tons of power.

Oh, and none of these packs have ever puffed. Not even the 2100's that have over 50 flights on them.
One thing that I just noticed though, is that all of the packs that seem to take more than they are rated at, are all Mega-Power packs.

[dunkonu23]

Jerry,

I've always been under the impression that 3 minutes was best for break-in flights...

Scott

[Jerrymac]

Yeah, you are right Scott, but, sometimes I get in a Hurri. Unfortunately it is my nature I guess. I used to be a carpenter, and it was always a big hurry to get a new home 'under roof'. Been a truck mechanic for 2 decades, and, every driver is in a big hurry to get back on the road.

My wife says she laughs at me when she sees me out mowing the lawn as I go as fast as humanly possible around the yard.

Sometimes I feel like I will run out of 'life' before I run out of things to do. Guess that is why I fly a "Hurri".

[Jerrymac]

Here is a little update on my crazy charging stats. After flying those 6s 2500 packs for about 10 flights, they seem to take a "normal" charge now.

I fly them in my Gaui 425 and have my timer set at 4:30 minutes.

Today, after charging them I noticed that I put back 1780 in one pack and 1820 in the other, and this was using the same charger as before.

Might be able to add another 30 seconds to the timer.