Discharging lipos - RC-Monster Forums

jnev · **Discharging lipos -** 02.16.2009, 10:24 PM

Having never discharged a lipo before, how do you determine the amperage to discharge it at? I have always just ran the packs down, and then recharged to the storing voltage, but never discharged... any other settings I should change for discharging?

Thanks in advance.

BL_RV0 · 02.16.2009, 10:38 PM

As a rule of thumb, I discharge at 1/4 the amperage I charged with, presuming I charge at 1C.

q8-maxx · 02.16.2009, 10:59 PM

if you have storge mode in your charger you dont have to discharge anymore

lincpimp · 02.16.2009, 11:00 PM

Why would you discharge a lipo? You can store them with any charge...

jnev · 02.16.2009, 11:51 PM

This is actually for a neighbor, who has been on and off into rc. He hasn't ran the packs in about a month and a half, and has just been repeaking them and balancing them every two weeks or so. I think it would be better to just keep them at storing voltage, and recharge them when he runs them again. What do you guys think? Or just keep going with the same routine he's been doing? The charger also does not have storage mode unfortunately (Superbrain 989). Thanks BL_RVO. I'll try it out I think once I hear other's opinions on whether I should discharge the batteries or not.

BrianG · 01:42 AM

Quote:

Originally Posted by BL_RV0

As a rule of thumb, I discharge at 1/4 the amperage I charged with, presuming I charge at 1C.

Why so low? I mean you discharge them in your vehicle at way higher than 1C. Just curious.

Anyway, I usually just discharge them by running them in my vehicle, then charge them up to half the capacity. So, if they are 5Ah packs, I put 2.5Ah back into them. If this is not feasible, then I just discharge them via a resistor load until they get to ~3.7v/cell under load. Once I remove the load, they usually rebound back up to ~3.8v/cell. Of course, I have to watch this process, but I'm usually at my bench anyway...

JERRY2KONE · **Confused. -** 02.17.2009, 02:25 AM

SInce it is inherently damgerous to allow Lipos to go below 3.7V why would you need to discharge them anyway. I would think storing them at full capacity would be a better method so they will not fall below the required 3.7v level whether you store them for one month or 12 months. As long as you store them in a good fireproof container you should be good to go.

lincpimp · 02.17.2009, 02:47 AM

Quote:

Originally Posted by JERRY2KONE

SInce it is inherently damgerous to allow Lipos to go below 3.7V why would you need to discharge them anyway. I would think storing them at full capacity would be a better method so they will not fall below the required 3.7v level whether you store them for one month or 12 months. As long as you store them in a good fireproof container you should be good to go.

3v per cell, not 3.7v Jerry.....

JERRY2KONE · **Yea yea yea. -** 02.17.2009, 05:14 AM

Quote:

Originally Posted by lincpimp

3v per cell, not 3.7v Jerry.....

Yea I know James. That is what I meant. I am just saying why discharge Lipo's at all for storage? Especially if you do not know for sure when you might use them again. Just charge them up, and lock them away.

BrianG · 02.17.2009, 10:45 AM

According to many places, keeping lipos at an elevated voltage encourages corrosion inside the cell. Discharging to around 3.7-3.8v reduces this. Lipos have VERY low self-discharge, so they'll be fine at that level for months.

JERRY2KONE · **Good stuff. -** 02.17.2009, 10:49 AM

Quote:

Originally Posted by BrianG

According to many places, keeping lipos at an elevated voltage encourages corrosion inside the cell. Discharging to around 3.7-3.8v reduces this. Lipos have VERY low self-discharge, so they'll be fine at that level for months.

Its good to hear from the people in the know. Thanks for the info BG.

hoober · 02.17.2009, 01:46 PM

discharge any battery at any rate up to the max of the specific battery. Users choice.

Most of the time the discharge device will be maxxed out long before the battery is. It might be safe to use the continuos current rating divided by 2 if the pack is healthy. At times it may be ok to use the rating itself if the pack is accurately rated. If it's a used/bad/worn pack then the continuos rating divided by 5 may even be the max.