Planes > Park Flyers / Foamies
Li Po Batteries
Ron:
PS....
Google Earth says the flying field is somewhere over there...
:lol: :lol: :lol:
Aidan:
--- Quote from: "Ron" ---I would just say however, that in general I believe it's better to use LiPos in a regular way. In other words, charge until the charger shuts off, and discharge until the controller shuts off, then immediately re-charge.
Putting LiPos on charge from a 'half charge' state can upset some chargers.
--- End quote ---
Personally, I avoid discharging the battery until the controller's low voltage cut-off (this is usually abbreviated to LVC) when I can. Occasionally I misjudge and do hit LVC but it's not hte plan! The consensus is that the lifespan of the cells is much better when you don't discharge them below about 20% on a regular basis. Still, on cells costing less than €10 it's not really worth worrying about. I'd would be very worried about any charger that get's confused by part discharged lipos! I'm inclined to think the charger is one piece of equipment that you shouldn't skimp too much on!
If you don't already have one, you should get yourself either a Multimeter (you can get pretty cheap one's in places like Maplin) or a purpose designed power meter for electric power systems. A power meter (mine's an Astro Whattmeter) will typically show you the voltage, current and power simultaneously on a screen while you run your power system and will be a big help in matching up power systems and troubleshooting. You can also use it to check the voltage of your cells or you can use a multimeter for this (a multimeter isn't suitable for checking current as they usually can't handle more than 5A or 10A).
When a lipo cell is fully charged it should not exceed 4.23V per cell and when it's fully discharged it shouldn't be below 3.7V per cell.
The "3s" in the spec of the battery pack you ordered means there are 3 cells in series in the pack. So the total discharged voltage for the pack is 3.7V x 3 = 11.1V. The max safe voltage for the pack is 12.69V. Most chargers will stop the charge around 4.15V or 4.2V per cell to be on the safe side.
The voltage will drop below 11.1V while it's in use and just after you finish using it but it should soon come back up to at least 11.1V. If not, the cell was over-discharged.
The things to be aware of with lipos are:
1. only charge with a lipo charger and make sure it's set for the correct number of cells and the correct current. If you're unsure about this don't take any chances, anyone on here will be able to point you in the right direction.
2. make sure not to short them out
3. don't over-discharge them
4. Don't use them if they've puffed up - just discharge them to zero and dispose of them per manufacturers instructions.
I mentioned the risk of fire just to give you the full picture. It's not common but it's well worth being cautious with your lipos just in case.
Aidan
Happy Days:
HHHMMMmm, pity there is no flying today Sean……..But there is a gathering of indoor fliers in Cork tomorrow :D
It is that time of year again and the Cork Model Aero Club Indoor fly-in will be held on Sunday Oct 24th 1.00pm till 6.00pm in the Hall in Middleton.
All Welcome, tea, coffee and cake will be available. A small fee if any will be charged. Helicopters, planes and freeflight welcome.
For more info contact Ralph McCarthy at 087 8322791 or rmccarthy@cit.ie
Looking forward to seeing everyone.
A lot of the indoor boys also fly gliders and, in addition all indoor models are electrically powered, so you will be able to get plenty of advise there.
See if you can make it............You'd learn a lot from them. :?:
K.
Aidan:
--- Quote from: "Happy Days" ---HHHMMMmm, pity there is no flying today Sean……..But there is a gathering of indoor fliers in Cork tomorrow :D
It is that time of year again and the Cork Model Aero Club Indoor fly-in will be held on Sunday Oct 24th 1.00pm till 6.00pm in the Hall in Middleton.
All Welcome, tea, coffee and cake will be available. A small fee if any will be charged. Helicopters, planes and freeflight welcome.
For more info contact Ralph McCarthy at 087 8322791 or rmccarthy@cit.ie
Looking forward to seeing everyone.
A lot of the indoor boys also fly gliders and, in addition all indoor models are electrically powered, so you will be able to get plenty of advise there.
See if you can make it............You'd learn a lot from them. :?:
K.
--- End quote ---
Yep, and we might manage to convince you to try indoor next!
Ron:
Hi Aidan,
Yes you are right of course.
My experience of chargers getting confused is with, probably cheap, commercial Li-Ion chargers.
And one hand power tool actually ruined a battery by letting it discharge too low.
The good ICs made for battery charge/discharge control in small battery equipment, look for the charge voltage curve rather than the absolute voltage, so it shouldn't matter what state of charge the battery is in to start with.
And, to the best of my knowledge, this is how cell balancing is done, as each cell will have a slightly different voltage at the critical point on the curve.
Anyway, yes I agree, don't skimp on the charger.
Yes the weather might make me take up indoor flying :o :o
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