Discharging LIPO help

Paladin · Jan 10, 2015

So first real 'help' thread for me. Seems like I can figure out most issues I have just looking around ES. Thanks all, great web site.

I am looking for a way to discharge LIPO/RC batteries. Turnigy 5.0 4s batteries. edit=and LifePo4 homemade packs.
If anyone could point out threads or suggest ideas for discharging LIPO batteries, having troubles locating such.
Light bulb discharge, or capacitive resistance discharge.
Cant seem to wrap my head around it.
Layman terms would be helpful, not a rocket scientist here.

Thank you

dnmun · Jan 10, 2015

i use regular oil filled radiator type space heaters. i have one of those wire wound ceramic core radiant type too.

Ypedal · Jan 10, 2015

http://ypedal.com/Lbd.htm

mark5 · Jan 10, 2015

Re: my discharger DIY by psycholist
http://endless-sphere.com/forums/viewtopic.php?f=14&t=33637#p489415

psycholist said:
Easy lipo discharger:

Purchase a normal household 110v outlet.
Connect wattmeter between battery and screw terminals on outlet.
Plug power strip bar (4-6 outlets) into outlet.
Plug resistive load appliances (iron, quartz heater, griddle, frypan, floodlights etc.) into power strip.
Switch on appropriate # and combinations of appliances for desired amperage.

Use cellogs, battery medic, icharger (monitor mode) etc. for monitoring.

Easy battery discharge setup by jana
http://bildr.no/view/1343021

wesnewell · Jan 10, 2015

Both my chargers has a discharge mode. Even the imax B6 does.

Ypedal · Jan 10, 2015

wesnewell said:
Both my chargers has a discharge mode. Even the imax B6 does.

Good for cells.. too slow for a pack.

Paladin · Jan 10, 2015

I have been using the RC charger to discharge but its only good for .3 amps/300ma.
I wanted 2-3 amp discharge, or such, to cycle some packs that have been sitting around for a few months.
This latest charger I got my hands on, Turnigy Reaktor 2, has an 'external expanding discharge mode', sounds cool, however it makes no sense to me.

"you can expand the chargers power capacity by connecting the external capacity resistance." so the manual states...? very vague on the details.

Looks like that link Ypedal posted maybe the most simple method, with the light bulbs, and I think I have all the parts in the garage.
I will give it a go, thanks guys.

Ride on!

Paladin · Jan 13, 2015

Here is what this turned into.

SkyRC watt meter WM-010
CellLog 8 (added for space cadet'ism)
Extension cord end (female)
3-way plug
3 space heaters

Heaters hardly get warm.

Was only getting 100ma draw from the 40w light bulbs I had and not enough sockets to make it work.
3 space heaters looks like it works pretty good for 3.85a draw.

That's a lifepo4 too by the way not the Turnigy 5.0.

dnmun · Jan 13, 2015

i specifically said that you have to use the oil bath type radiator or the radiant element type of heater. you will ruin those heaters if you discharge DC current through them.

Paladin · Jan 14, 2015

dnmun said:
i specifically said that you have to use the oil bath type radiator or the radiant element type of heater. you will ruin those heaters if you discharge DC current through them.

The middle and right heaters are radiant element. Both are 15+years old so if they die I don't care. They pull less than 20w each on high setting with 12v, 1500w rated.
The one on the left side is ceramic element and the only really good one. I wont use it anymore. Swapped out for a heat gun.

dnmun · Jan 14, 2015

from looking at them they all appear to use a fan to move air through the heating element. an AC motor will not work on DC current so no air will flow over the heating element.

the heater element has a fusible link and when the heater exceeds a temperature set by the fusible link then the heater element will be open circuit.

izeman · Jan 14, 2015

Why don't you use regular car light bulbs or halogen bulbs? They come rated 55w. Which would give you around 5a discharge. Or buy one 100w type - they are not legal for street use (at least here in Europe) so they are sold as tuning/racing lights. This gives you around 8a. Pretty fast discharge.

Paladin · Jan 14, 2015

dnmun said:
from looking at them they all appear to use a fan to move air through the heating element. an AC motor will not work on DC current so no air will flow over the heating element.

the heater element has a fusible link and when the heater exceeds a temperature set by the fusible link then the heater element will be open circuit.

Added a small fan, though the elements hardly get warm.

izeman said:
Why don't you use regular car light bulbs or halogen bulbs? They come rated 55w. Which would give you around 5a discharge. Or buy one 100w type - they are not legal for street use (at least here in Europe) so they are sold as tuning/racing lights. This gives you around 8a. Pretty fast discharge.

I was trying to use available items around the house.
5amp would be about the max I would want. As the battery voltage gets low it seems as if 1 cell of 4 will get out of balance more than the rest. If I use 1amp discharge at the end of the discharge cycle it pulls the cells down more evenly.

izeman · Jan 14, 2015

Paladin said:
izeman said:

Why don't you use regular car light bulbs or halogen bulbs? They come rated 55w. Which would give you around 5a discharge. Or buy one 100w type - they are not legal for street use (at least here in Europe) so they are sold as tuning/racing lights. This gives you around 8a. Pretty fast discharge.

Click to expand...

I was trying to use available items around the house.
5amp would be about the max I would want. As the battery voltage gets low it seems as if 1 cell of 4 will get out of balance more than the rest. If I use 1amp discharge at the end of the discharge cycle it pulls the cells down more evenly.

you don't have spare bulbs for your car? or any other 12v halogen bulbs? that's bad. but they are a few $ only. and they are much smaller than the big heater park you built

down to 3.6v the cells should not be out of balance too much. and you should not discharge them below 3v anyway. they will be out of balance quite fast. so discharge to 3.5v minimum. not much juice left anyway.

dnmun · Jan 14, 2015

yep, the reason it did not melt the fuses is because the pack is so small and discharging into three heaters so it never gets hot.

but the windings in the motors may be getting a little hot since they are usually tiny tiny wires.

so an auto light bulb, 2 in series would be best to prevent overvoltage from burning out one bulb.

Paladin · Jan 14, 2015

K.I.S.S

Its not pretty, I am not trying to sell anything, nor do I plan on using this very often.
I have auto 12v bulbs, but I don't need more than 5amp discharge.
Neat thing with this is a can get 1.45a draw from each of the heaters and the heat gun is 1.05a so it is adjustable with the flip of a switch.

I opened up a space heater and felt the windings on the fan motor, it is hardly getting warm to the touch, and only is pulling 100-200ma. The heat gun is getting hot but not to the point it would burn me, with the fan pointed at it it stays fairly cool.

Only had to make the adapter plug.
The cord was some old dog chewed item so I didn't even have to sacrifice a good extension cord.

dnmun · Jan 14, 2015

i use a duplex outlet. up to 6 heaters.

sal_park · Jan 15, 2015

Paladin said:
So first real 'help' thread for me. Seems like I can figure out most issues I have just looking around ES. Thanks all, great web site.

I am looking for a way to discharge LIPO/RC batteries. Turnigy 5.0 4s batteries. To be exact.
If anyone could point out threads or suggest ideas for discharging LIPO batteries, having troubles locating such.
Light bulb discharge, or capacitive resistance discharge.
Cant seem to wrap my head around it.
Layman terms would be helpful, not a rocket scientist here.

Thank you

As someone else said above use car headlight bulbs. I used 3 in series on my 36v li-ion battery and that was good for around 4-5 amps if I remember correctly. You need to match the voltage of the bulbs with the battery voltage so if your 4s battery is 14volts (close enough to 12v) then just put one 12v bulb across the battery. If you want more discharge then put another bulb in PARALLEL with the first etc etc. Keep an eye on the temperature of the wires, if they start getting hot you need thicker wires !

Also car headlight bulbs get really really hot, but I'm sure you knew that

hth

sal_park

splitfire · Jan 15, 2015

If you have 12v-15vdc you want a quick discharge go find one car power inverter which is 12v input and has household plugin 120v and plug in whatever you want ....I use this method using electric fan or a plug in desk lamp so you can replace the bulb with 100w spot light......that will drain really quick ......
Or go find a thrift store and grab portable heater or a hair blower or anything thats heats up. Take them apart look for heating element wires and cut them of. The length of the wire will depend how much power you put in, place positive and negative to both end of the heating wires, and there you go you have quick discharger and instant heater perfect for this season....

Eclectic · Jan 15, 2015

I’m probably being very naive but couldn’t you use cheap soldering irons. I got a couple of them at the local dollar store that I use on plastic and wood.

izeman · Jan 15, 2015

those big soldering irons are normally rated between 40-100w at 110-220v. if you connect them to a 12v battery you will have only 5-10% of that wattage. so we are talking mA discharger per soldering iron.

Eclectic · Jan 15, 2015

Thought I was being naive :?

splitfire · Jan 15, 2015

You really cant use direct current to run a 120vac ...you gonna need a power inverter to drain them successfully

izeman · Jan 16, 2015

splitfire said:
You really cant use direct current to run a 120vac ...you gonna need a power inverter to drain them successfully

sure you can. but only for ohm resistive load (like bulb, some heaters etc ...)

crea2k · Jan 16, 2015

Get a battery medic, they are cheap as hell, you can set the discharge voltage, plug it and and job done.

Discharging LIPO help

100 W

1 PW

Moderator

100 kW

100 GW

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100 W

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1 PW

100 W

1 PW

1 GW

100 W

1 GW

1 PW

100 W

Attachments

1 PW

100 mW

1 W

1 kW

1 GW

1 kW

1 W

1 GW

10 kW

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