Opti-power fully charged at 4.18v per cell

[Stuart]

Sounds positive i think maybe once Andy has concluded his testing within environmentally controlled conditions. This data maywell help abit. Though i suspect maybe you could find some minor variances across all brands some may hold charges or discharge quicker or slower than others. I am presuming that Andys data is only going to refer to Optipower packs as to give comparible data across various brands could just make.the whole thing more confusing lol.

[Guest]

Well guys all very interesting stuff. I have been beavering away to try and locate/hire a suitable environmental cabinet in which can do some testing, I think I might have found one in High Wycombe. All we need to do is sort out the testing criteria find some time (and money), then get the testing done.

We will report as soon as we have more factual data probably a month or so depending on work schedules, equipment availability etc. The data will of course relate to OPTIPOWER cells but I suspect the rules will generally apply assuming chemistries are similar.

Andy

[NEAGRON]

Andy,that's good news,so hopefully we can expect to see your results before xmas,and a general chart of good practice in chargeing and the maintenence of our lipo's,i for one will definately be using optipower cell's though only 3s-2200 at the moment,hopefully next year i will be able to go back to600 size helis,health permitting,i do use a PL8 wounderfull piece of kit,once again many thank's,your's Marty.

p/s Ashley thank's for your input.

[cjcj1949]

I've measured the change in volts on a 3S lipo and found no change in voltage from 22C to 12C. That's on a meter reading to 1mv. Not a fully charged lipo. Voltage was 11.683. There was certainly no major obvious change as there is with internal resistance and temperature.

As far as best practice goes there is no argument. Charge and usage as close to 30 degrees C as possible. Storage at storage voltage 3.85V and temperature around 10 degrees C.

There is disagreement on what you can get away with and exactly what makes a lipo fail. Cold charging at the field is not best practice and neither is charging in the warm and using in the cold. Last Winter I kept the lipos in a cool box with a milk bottle full of warm water. They stayed between 15 and 20 Degrees.

[Mark_T]

I've measured the change in volts on a 3S lipo and found no change in voltage from 22C to 12C. That's on a meter reading to 1mv. Not a fully charged lipo. Voltage was 11.683. There was certainly no major obvious change as there is with internal resistance and temperature.

By a strange coincidence I conducted a similar test today

I also found no variation in voltage when using a pack with individual cells at 3.91V

I then repeated the test with a fully charged pack and was able to observe a very small drop in voltage which then returned as the pack warmed up.

I'll be interested in Andy's results using rather more repeatable methods than mine.

[cjcj1949]

They certainly are very tricky things. Never seem to do what you expect. They cool down when you charge them and every few months they bring out a new version that is better than the one before. They used to be useless in the cold, but the newer packs aren't so bad. Still much better when warm. I was sure the volts would go down. And the lipos are big capacitors as well. They mentioned 4F in the simulation program. Next years lipos will be even better as well.