Best and fastest way to drain a battery

Thread Starter

electronewb

Joined Apr 24, 2012
260
What's the best and fastest way to drain lithium ion batteries? I have about 10 14V lithium ion batteries to fully discharged right now I'm using an halogen lamp but it takes about 2-3 hours to fully discharge. What could I use to discharge it very fast?
 

Thread Starter

electronewb

Joined Apr 24, 2012
260
I knew that question was coming!!!! ;) It's where I work we have to dispose of those batteries and apparently there's a "protocol" that we have to fully discharge the batteries before disposing of them. I know it doesn't make any sense if you dispose of a battery fully charged or discharged. BTW Those batteries don't hold their charge anymore
 

Six_Shooter

Joined Nov 10, 2012
34
The fastest way is shorting the battery, the best way is to not short the battery, but have a controlled discharge, like you are doing with the lamp.

While I will suggest this, with the preface of exercising caution, you could connect a couple lamps together in parallel to reduce the resistance of the circuit.
 

SgtWookie

Joined Jul 17, 2007
22,230
If you short the terminals of a battery or cell, you risk having a fire, explosion and/or red hot conductors. Using incandescent lamps is very good due to the resistance decreasing with a decrease of temperature; the more discharged the battery becomes, the more rapidly it gets discharged.

One oddity you'll run into is the weak cells can get charged in reverse polarity, while the remaining good cells still will have a positive charge on them. That's why a battery seems to recover after its been discharged heavily, then allowed to rest for a period of time.

If you need to guarantee that every cell within the battery has been fully discharged, you will need to open the battery pack and discharge each cell. Remember. you're getting rid of these batteries because they won't hold a charge - it's actually just one or more cells that have gone bad.
 

takao21203

Joined Apr 28, 2012
3,702
If you short the terminals of a battery or cell, you risk having a fire, explosion and/or red hot conductors. Using incandescent lamps is very good due to the resistance decreasing with a decrease of temperature; the more discharged the battery becomes, the more rapidly it gets discharged.

One oddity you'll run into is the weak cells can get charged in reverse polarity, while the remaining good cells still will have a positive charge on them. That's why a battery seems to recover after its been discharged heavily, then allowed to rest for a period of time.

If you need to guarantee that every cell within the battery has been fully discharged, you will need to open the battery pack and discharge each cell. Remember. you're getting rid of these batteries because they won't hold a charge - it's actually just one or more cells that have gone bad.
Don't short a lithium battery. It will burn the internal wires, and/or it will shut down.

Some battery chargers actually can do a controlled discharge (for instance my NiMH charger can do it).
 

bountyhunter

Joined Sep 7, 2009
2,512
What's the best and fastest way to drain lithium ion batteries? I have about 10 14V lithium ion batteries to fully discharged right now I'm using an halogen lamp but it takes about 2-3 hours to fully discharge. What could I use to discharge it very fast?
You should NEVER fully discharge a lithium battery. It ruins it.

You should also NEVER discharge them fast as that will create internal heating which could cause them to explode or catch fire.
 

bountyhunter

Joined Sep 7, 2009
2,512
I knew that question was coming!!!! ;) It's where I work we have to dispose of those batteries and apparently there's a "protocol" that we have to fully discharge the batteries before disposing of them. I know it doesn't make any sense if you dispose of a battery fully charged or discharged. BTW Those batteries don't hold their charge anymore
If these lithium cells are sealed in a pack made by any reputable manufacturer, they won't allow fully discharging. The packs contain internal protection circuitry that opens the lead when either excessive current is detected or the battery voltage gets too low.
 

Thread Starter

electronewb

Joined Apr 24, 2012
260
You should NEVER fully discharge a lithium battery. It ruins it.
That's my goal to ruin it they have to be disposed fully discharge which boggles my mind why wasting time discharging batteries that will end up in a recycling bin I tried to get an answer on the reason but I couldn't get a straight answer
 

takao21203

Joined Apr 28, 2012
3,702
That's my goal to ruin it they have to be disposed fully discharge which boggles my mind why wasting time discharging batteries that will end up in a recycling bin I tried to get an answer on the reason but I couldn't get a straight answer
I wish you good luck with that.
Consumers are not normally expected to discharge these kind of batteries before tossing them into recycling.
 

tpny

Joined May 6, 2012
220
what's the voltage on these batteries? I've let my 12V lead acid discharge thru a 50 ohm 10 watt resistor, it dropped pretty fast, but i only needed it to discharge it down to 10V. You can use a resistor size suitable to your battery voltage and current size.
 

Audioguru

Joined Dec 20, 2007
11,248
Lithium batteries are not "recycled" because they are hazzardous waste and might blow up or catch on fire. I think they are sealed in concrete then buried.

I have some LiPo cells that are swollen and might blow up. I cut one in half with a shovel (woopee!) and it smoked but did not blow up nor catch on fire.
I store them in a tin can that also might blow up before I take them to the hazzardous waste dump.
 

Thread Starter

electronewb

Joined Apr 24, 2012
260
By recycling I meant those orange bins. I was thinking about a 5W resistor but wouldn't higher the resistance the faster it would discharge? For real those batteries are burried in concrete? If that's the case I don't see why we have to drain them!!!
 

davebee

Joined Oct 22, 2008
540
If you don't drain them, and they are holding a good amount of charge, they could catch fire or explode in the face of someone who accidentally shorted them in the recycling center.
 

crutschow

Joined Mar 14, 2008
34,281
What's the best and fastest way to drain lithium ion batteries? I have about 10 14V lithium ion batteries to fully discharged right now I'm using an halogen lamp but it takes about 2-3 hours to fully discharge. What could I use to discharge it very fast?
As SgtWookie noted, an incandescent bulb is a good way to discharge a battery since their resistance reduces as the voltage drops, tending to maintain the discharge current. Just use more lamps or a larger lamp to obtain a faster discharge. But don"t exceed the batteries maximum current rating (not necessarily determined by the AH rating).
 

BillO

Joined Nov 24, 2008
999
As has already been said, most modern LiPo battery packs have internal circuitry to prevent them from discharging to a point where the cell would be damaged. However, this achieves your goal. Just discharge them at about C/10 until they do not pass anymore current. So if they are a 5Ahr battery, discharge them at 500 mA until they go dead. C/10 should be a same rate for most battery packs

The concern is that if you try to dispose of them while they have power, they may short an overheat causing the release of undesirable chemicals or even fire. Although this is only a real danger with older or poorly designed packs.
 

bountyhunter

Joined Sep 7, 2009
2,512
If you don't drain them, and they are holding a good amount of charge, they could catch fire or explode in the face of someone who accidentally shorted them in the recycling center.
FYI: in the first generation of Lithium Ion batteries, allowing them to discharge too far caused formation of internal shorts and extreme heating...... as in law suits where some guy's family jewels got fried by his laptop computer.

In the case of first gen Li-Poly batteries, similar problem: discharge too far and they short internally and cook and melt whatever they are in. Was not good because Valence Technology's first contract for their Li Poly cells was to the ARMY for their night vision goggles. They were not happy when they were cooking on their face.:eek:

Don't screw around trying to "fully discharge" Li cells.

It's the same reason I don't give razor blades to children: while I can't predict exactly what will happen, I know for sure that it is almost certainly going to be bad.:p
 

JSWilsonX

Joined May 26, 2021
1
That's my goal to ruin it they have to be disposed fully discharge which boggles my mind why wasting time discharging batteries that will end up in a recycling bin I tried to get an answer on the reason but I couldn't get a straight answer
I would imagine that if you short a charged battery it could catch on fire or explode. So you wouldn't want it in a recycle bin charged.
 

Ya’akov

Joined Jan 27, 2019
9,069
FYI: in the first generation of Lithium Ion batteries, allowing them to discharge too far caused formation of internal shorts and extreme heating...... as in law suits where some guy's family jewels got fried by his laptop computer.

In the case of first gen Li-Poly batteries, similar problem: discharge too far and they short internally and cook and melt whatever they are in. Was not good because Valence Technology's first contract for their Li Poly cells was to the ARMY for their night vision goggles. They were not happy when they were cooking on their face.:eek:

Don't screw around trying to "fully discharge" Li cells.

It's the same reason I don't give razor blades to children: while I can't predict exactly what will happen, I know for sure that it is almost certainly going to be bad.:p
Dendrite formation is a problem if you try to charge a shorted battery. If you intend to dispose of a Lithium chemistry battery there is no danger in discharging it as completely as you can manage. The only danger would be overheating the battery while doing it, but that is easy to avoid.

Lithium cells are dangerous when charged and when charging but if they are discharged they can’t be a problem since they have little or no energy.
 
Top