Simple and cheap lipo discharger?

[rcboosted]

My chargers don't have a discharge function and we have had some bad weather here recently. Normally I would not have cared if my lipos sit fully charged for a week, but recently this is happening more often than I am comfortable with. Forecast is saying this coming weekend will be rained out as well. If I let it sit, that will be 2 weeks with the lipos fully charged. So how do I discharge my lipos down to a reasonable level? I have a logger so I can monitor the voltage, and I also have lipo alarm that can warn me when I've reached a low voltage. I tried hooking up a 55watt automotive light bulb, but it barely draws 0.1A! (55watts on 4S should be drawing almost 4A, I have no idea why my logger is showing such a low draw.) Ideas for a discharger?

[Pinecone]

Hook up more light bulbs in parallel.

Or go to electronics store and buy a large, low ohm power resistor. 1 ohm will discharge your pack at about 15 amps.

[rcboosted]

I thought about the 1 ohm resistor after I posted. So:

V=IR, 14.8v = I (1). So that means it'll discharge at 14.8A
P=VI, 14.8 x 14.8 = 219.04 watts

So the 1 ohm resister will have to withstand over 200watts!! The 1 ohm resistor I can find at radioshack are rated at 10watts, so I'll need 20 of those! $1.99 for a 2-pack, I'll need 10 of those. Hmm, maybe I'll just find a wire long enough that will have 1 ohm of resistance.

[piwko4]

how bout you put the pack in the heli and spool it up 4 a little while. I have a model setup on my DX7 for dischargeing. I just made all the Throttle curves linear upto about 60% and all the pitch curves flat at about -2deg pitch. dont have to wory about it taking off and the battery gets discharged at about the same rate as easy flying. I figured it be better for the battery to see the same kind of discharge all the time. You could increase the load and or throttle curve by giveing more neg pitch or higher hs.

[Pinecone]

And the problem is, if you parallel them, you woul dneed to recalculate the R value to get 1 ohm.

But remember, that power rating is based on still air. Use a fan or even better, immerse it in oil. I do have radio and have a 50 ohm, 1500 watt load. 1 gallon paint can, 50 ohm wire wound resistor, and a gallon of mineral oil. The oil allows a reasonable amount of power time without burning up the resistor.

But let's see, a reasonable 5 x 2 pack ($10). that would be 10 in parallel, so 100 watts easily. So you need 2 ohms. So get 20 ohm resistors. 10 in parallel would be equal to 2 ohms.

[rcboosted]

I took 5 long power cords and daisy chained all 3 wires inside together (so it's the length of 15 power cords) and finally got over 1ohm of resistence. Tried it out using a puffed lipo and it seems to work. But the wire heats up quite a bit and for some reason my logger's lcd screen keeps fading out for some reason. Seems too risky for my liking, I might just have to use the heli to discharge it. But I have 9 lipos, at 5 min each 3200rpm to discharge them, it'll take 45min just to drain all lipo without counting the lipo changing time. I also don't have a safe place to do that indoors. Maybe I need a cheap commercial solution.

[widower]

Has anyone tried an old curling iron element, toaster element, or even a bunch of lightbulbs?

[Helifarns]

Any other ideas?

[istandalone]

i'd just spool it up in the basement or garage front porch wherever. keep it at 70% throttle and -2 pitch. that's probly easier then jerry-rigging a discharger.

[mkoutnik]

i'd just spool it up in the basement or garage front porch wherever. keep it at 70% throttle and -2 pitch. that's probly easier then jerry-rigging a discharger.

Just make sure if you do this take the main blades off....trust me, I speak from a bad experience.