Lipo discharging

[Geoff Daunt]

I am trying to be good and discharge my Lipo’s to Storage V rather than leaving them fully or partially charged.

For example l have set the discharge rate on my elderly Fusion Elysium LX60B Pro to 1.0Amp( the Max).

My 4S 3700 MAh is fully charged at 16.8 V.

when l plug in with balencer etc it starts to discharge at 0.30A and is obviously taking an age to reduce Voltage to 15.4v.

is this normal or can you discharge faster ???

It has now been running for about 1/2 hr and reading 16.578 v,  from 16.8v

Do l need a better machine or is this normal.

Thanks.

[Gary Binnie]

The LX60 is limited to  5 Watts maximum discharge, I have two.

 

Better to run the batteries down in the model that uses them.

 

The Imax B6AC charger is similar but has a storage mode, can charge up or discharge down to the storage voltage (but the discharge rate is still low).

 

In the flying season I leave them all fully charged and recharge after a flying session, round about October I run them down and charge/discharge to storage voltage. I have Lipos that are used hard from 2016 that are still performing well.

Edited May 13, 2021 by Gary Binnie

[Geoff Daunt]

Thanks Gary for the information.

l switched the discharge program off when l went to bed.

Voltage was down to 15.63, 62%full and all cells showing 3.9v.

Do l need to go that little further to get down to 15.4v & 3.85 per cell , since those are the figures l read on Lipo care.

Just not certain if it is that precise/ necessary for best protection for storage.

many thanks 

[spudsy]

Wotto Geoff,

I use an ISDT FD100 to discharge my lipo's..

A very good bit of kit, I connect 6, 2650 batteries using a balance board, and away it goes.it's limited to 80w which is enough for relatively small packs.

[Philip Lewis 3]

Chargers are notoriously inefficient at discharging and dedicated dischargers expensive, just use 12 headlight bulbs for 3 cell packs and 24 Volt 100 Watt headlight bulbs for 4 -6 cell packs. A 24 volt 100 Watt bulb will take a 5,000 mah 5 cell pack down to storage voltage in about an hour, cheap, quick, efficient and won't break the bank. 

[Martin Harris - Moderator]

Just don't get sidetracked and let them over-discharge.  While the jury may be out on the necessity of storage charging, there's universal agreement that flattening a LiPo will kill it!

[Philip Lewis 3]

14 minutes ago, Martin Harris - Moderator said:

Just don't get sidetracked and let them over-discharge.  While the jury may be out on the necessity of storage charging, there's universal agreement that flattening a LiPo will kill it!

It's a good idea to always set a timer because you WILL get distracted!

[Dickw]

Thee chargers I use allow you to put a resistor (e.g. car headlamp bulb(s)) in series with the main current connectors during discharge/storage. The discharge energy is then spread between the charger and the resistors so allowing a higher discharge rate than just the charger alone, and with the balance leads connected the charger monitors cell volts as usual and disconnects the current at the appropriate safe time.

 

I didn't think there was anything special about my chargers, so it might be worth people looking at the instructions for their chargers again or even just experimenting a bit.

 

Dick

[leccyflyer]

You have the ideal discharging device at your fingertips -it's your model -which will discharge your batteries down to storage voltage in a matter of minutes. If you put a meter on the balance leads whilst running the motor you can monitor the individual cell voltages under load, shut the throttle and see them rebound. Just make sure that you have sufficient cooling of motor, esc and battery and have the model properly restrained.

[Ron Gray]

Not sure how good these are LiPo Suction

[Gary Manuel]

32 minutes ago, Ron Gray said:

Not sure how good these are LiPo Suction

Not seen those before but they look like a great idea. Buy half a dozen at that price. Put them on several batteries and leave them somewhere safe for a day or two.

I love the name = Lipo Suction ?

 

Note that there is no Wattage or Current rating shown on the above link, but in the following link it is quoted at 500mW. Will discharge a 1300mAh battery to storage voltage in 24 hours.

https://www.flyingtech.co.uk/accessories/lipo-suction-3-6s-xt60-battery-discharger-storage-voltage

 

I also spotted this product = Lipo Killer whilst I was looking. Looks handy for fully discharging LiPos before disposal.

https://www.unmannedtechshop.co.uk/product/0v-lipo-killer-xt30-xt60/

 

[Shaun Walsh]

4 hours ago, spudsy said:

Wotto Geoff,

I use an ISDT FD100 to discharge my lipo's..

A very good bit of kit, I connect 6, 2650 batteries using a balance board, and away it goes.it's limited to 80w which is enough for relatively small packs.

I have one as well, much quicker than discharging through the charger and safer than using a headlight bulb/timer.

[Dad_flyer]

2 hours ago, Dickw said:

Thee chargers I use allow you to put a resistor (e.g. car headlamp bulb(s)) in series with the main current connectors during discharge/storage. The discharge energy is then spread between the charger and the resistors so allowing a higher discharge rate than just the charger alone, and with the balance leads connected the charger monitors cell volts as usual and disconnects the current at the appropriate safe time.

 

I didn't think there was anything special about my chargers, so it might be worth people looking at the instructions for their chargers again or even just experimenting a bit.

 

Dick

I had not thought about that being possible. I shall need to try it, it gives the best of both worlds. My charger will manage 20W which is not too bad, but an increase would be nice for my bigger batteries.

[Ron Gray]

The ISDT-FD200 looks nice

[Dickw]

5 minutes ago, Dad_flyer said:

I had not thought about that being possible. I shall need to try it, it gives the best of both worlds. My charger will manage 20W which is not too bad, but an increase would be nice for my bigger batteries.

I first saw this in the instructions for my i-Chargers, but have found it also works with my newer chargers from "Chargery".

Just quickly checked some real figures with a 6s 5000 pack, and have attached a photo of the charger screen.

At 2 amps discharge the charger is seeing a total battery volts on the main connection of 8.94V even while the individual cell volts are normal and sum to 23.17V, and the charger will safely disconnect the battery based on the individual cell volts.

 

So in the example below - total discharge of 2 x 23.17= 46watts, but only 2 x 8.94= 18watts being done by the charger. You just need to play around with the resistance values (different wattage bulbs?) to get acceptable results. I use a bank of large resistors switchable to adapt to different packs up to 10s.

 

Dick