There are many reasons why you want to discharge LiPo batteries. Maybe you have fully charged LiPo left from a flight session, or maybe you just want to discharge them completely for disposal. I will show you the options for discharging LiPo batteries.
You may use your LiPo chargers to discharge batteries too, as most modern smart chargers have discharging function. However they are not very powerful and it can take a very long time to discharge, therefore I am recommending other more efficient ways.
Further Reading: How to dispose LiPo batteries?
Table of Contents
Cheap 3in1 Battery Discharger
You can get this 3in1 discharger from:
- Banggood: http://bit.ly/2mlYPN2
- Amazon: https://amzn.to/3x9xSiX
It is perhaps one of the cheapest dischargers you can find, and it’s pretty powerful too. At 150W, it can discharge most FPV drone batteries in a matter of minutes.
With this discharger, you can either discharge the battery completely, or set a voltage to stop the discharge (e.g. 3.80-3.85V per cell for storage). It is simple to use and even keeps all the cells balanced during the process.
One thing to watch out for is that the bulbs get really hot. It’s important that you keep them away from anything that can melt or burn.
DIY Light Bulb Discharger
Check out the tutorial: How to build a DIY halogen bulb discharger
I have been using this to discharge batteries for disposal. It’s not expensive and easy to make, and it’s a lot faster than using resistors of similar cost.
These halogen light bulbs are rated at 12V, so in theory you can only discharge up to 3S batteries. However if you connect two bulbs in series you can do up to 6S, and by connecting three in parallel you get triple the power, and this is what I did in mine.
DIY Resistor Discharger
Check out the tutorial: How to build a DIY resistor discharger.
Using these power resistors is a handy method for discharging old or damaged batteries. It’s cheap and easy to make. Perhaps a bit slower due to the low power, but it’s safer for emptying damaged batteries for disposal, because it won’t build up too much heat in the battery due to the slow rate, and you can just leave it outside and let it do its thing.
Reverse Charging
If you have a LiPo charger that can be powered by a battery, you can do reverse charging :)
You can hook up your fully charged LiPo as the power source of the charger, and charge your empty LiPo’s (or storage charge). You can even connected multiple fully charged packs on a parallel charging board to speed up the process.
You can set a minimum input voltage on the charger, 15V for 4S and 23V for 6S, so it stops discharging automatically (at roughly 3.8V per cell).
This is my go-to way to discharge full LiPo that I don’t fly on the day, it’s fast and hassle free, and no electricity is wasted.
Make sure you check the cell voltages though with a lipo checker, to make sure they are not out of balance just to be safe.
Getting a Smart Discharger
A smart discharger allows you to set a voltage to stop the discharging, so you don’t have to check it constantly. Most of these dedicated lipo dischargers have decent power so discharging is relatively faster compared to the DIY solutions, or discharging from a LiPo battery charger.
The iSDT FD200 is a 200W wireless discharger and you can monitor and control it from your smartphone, which is really convenient to use.
- AliExpress: https://s.click.aliexpress.com/e/_AgdK3h
- Banggood: https://oscarliang.com/product-1l1u
Edit History
- Jul 2018 – article created
- Mar 2019 – added reverse charging
- Apr 2021 – added dedicated discharger option
11 comments
Does the ISDT balance the cells during discharging?
Strange that there are only that few options for balanced discharging on the market.
Pretty much any chargers I’ve reviewed on this blog with discharging capability can do balancing during discharging, as the discharging stops when individual cell voltages reaches certain level.
If charging and discharging aren’t balancing the cell voltages, it’s something I’d definitely point out in my review as it’s not safe.
Hi Oscar
Thanks for your website. Lots of great info here!
I’m trying to fully discharge an 1800 mah LiFe battery which is seriously puffed up. Since I don’t have the halogen light bulbs on hand, I thought I would try discharging them via a 100 watt incandescent bulb. When I started, the pack read less than 4 volts. Well below 3v/cell So I figured I would be safe discharging this way. It has been discharging this way overnight and now reads 11.4 mV.
I figure the resistance in the incandescent bulb is preventing the discharge to go any faster.
At this point can I safely short out the two battery leads?
Or is this low enough to put in the trash?
Or should I leave it discharging like this until it reads 0.0 v?
Thanks in advance for your expertise.
Albert
Always short the leads no matter what before disposal, this ensure the cells are at zero volt.
If the cells are at 11.4mV that’s low enough to short the leads. just keep your fingers away from the contact, wear protective gear for extra safety :)
Thanks Oscar
what sort of resistor should be used in the case of 1s lipos?
Awesome, thanks Oscar!
Heyo! Big fan.
Anywho, about this section here “Make sure to set minimum input voltage to 3.8V per cell, for a 4S that’s 15.2V, for a 6S that’s 22.8V.” How do I do this exactly? I want to safely field charge off a 10,000mah 4s and then reverse charge back into afterwards. How do i set a minimum input voltage?
just hold down the scroll button to enter system settings where you can set the minimal input voltage.
Hey I got the 3in1 Discharger you linked from Banggood, but I can´t find out how to fully discharge the Lipo may you please help me :D
Best to go for the DIY resistor discharger if you plan to discharge them completely :)