Free LiPos

Looking for advise. I have an Enegitech balance charger which seems to do a good job getting
my various 2 and 3 cell LiPos charged up.

And sometimes I retreat from the field with batteries that are unused. I have a battery capacity
checker but as Klippy has pointed out to me, I should have a way to condition back to a 'storage' state.

The balance charger has no such facility so I would like folks advise on what kit
to acquire to do this.

And a suggested regime of when best to deploy capacity reduction and to what level. -Jon

I use a couple of car headlamp bulbs wired in parallel for up to 3S, and in series for 4S and upwards.
Plug your battery monitor into the balance lead, and stop the discharge at about 25%
You can also put your Wattmeter in between the battery and bulbs, if you want, so you can see the current draw, and the volts and amps dropping.
That will drop the battery level quite quickly, but without overstressing them - or taking ages and ages!
-
Careful!! The bulbs will get hot! (especially if you use quartz/halogens!)

jon
If you discharge via a bulb you will have to watch carefully to ensure the LiPo does not get over discharged or worse that one cell does.

This is where a balance discharger takes away any worry as it uses the balance lead to ensure all the cells are brought down (or up) to the desired storage voltage level and it then stops. The down side is most discharge facilities have limited discharge rates so it can take quite a long time.

As long as you are careful and the LiPo is in good condition there should be no problem discharging through a suitable car bulb. Even a partial discharge is better than leaving a LiPo fully charged for extended periods.

In last week's lawn dart I found little damage but on a later review I found that the battery had shifted forward and impacted with one of the retaining bolts for the motor. There is a ~1mm puncture on the end.

I have not explored how deep it goes. I have not attached it to anything to charge or discharge. I have kept the beastie in the battery safe.

I assume that risk is elevated and it probably needs some sort of safe disposal. I suppose I could remove the plastic sleeve to have a closer look - it might not have penetrated the actual cells. Below are a couple of images. Any suggestions? -Jon

jon
The polymer casing of a LiPO is pretty strong so it is quite possible it has not been punctured and the battery remains perfectly usable.

The only way to be sure is to very carefull remove the shink wrap around the LiPo and then the sticky tape that cover the end to inspect what samage there is to LiPo case(s). If the polymer case has punctured the electrolyte within has a very distinctive smell if you get your nose close enough! :woohoo:
If you are in anyway unsure then the battery should be discharged completely. Rigging up a 12v car light bulb is a good way to do this. Once it is fully discharged it can be disposed of in normel non recycable household waste or at a battery disposal point at a waste site.

My feeling is that if the integrity of the battery was compromised it would have self destructed. I would fill the hole with glue to stabilise it and continue to use it. Charging with great care.!

As Klippy put - it looks like the screw went between two of the cells, so you may be lucky. If it had punched into a cell, you'd have had a bonfire by now! [badass]

I have added 15-20mm of stiff fibre (heavy duty scouring pad layers) at the nose to absorb shock and well cover the bolts. That should help. Perhaps the next fuselage could also be designed to take one of those velcro tie-downs rather than just back-to-back velco. -Jon

I discharged by the expedient of attaching it to a prop and running at low speed for a few hours, occasionally checking with battery tester. It got down to ~20% - but one cell was 2V less than the others. I think that suggests it is a dead parrot. -Jon

Yes - bin it, after a total discharge to zero, OUTSIDE!! - and a dunk in water for a day or two.

Add salt to the water in a plastic bucket or similar, they will then discharge more effectively. Then as Eric says.

I got it down to the battery checker not recognising it as a battery. It is now in salt water, outside. Thanks for the advise. A scary corner of the world hopefully averted. -Jon

I finally got around to improving the safety of my battery collection by getting a newer balance charger which also does a controlled discharge (rather better than guessing about a 10W bulb to draw it down and way less risk) It also has 'storage' and 'discharge' functions.  

Granted it took a couple of YouTube searches to get it working as it kept saying there was a 'cell error'.  Ah, there was a mode of quick-clicking on the buttons which allowed you set the number of cells before the long-press to start the charging.  3rd reading of the manual got me there...

Anyway I balanced charged and then set to 'storage'  the various batteries I had.

 

jon
You probably know but if you press the INC button once whilst it is charging or discharging it will display the individual cell voltages.
This can be useful if when you start a charge it shows one cell voltage is well below the others. The charger will ensure that all brought up to the same voltage BUT it is worth noting as it could indicate a weak cell. It could mean that battery is "on the way out" or at the least should not be worked hard so risking over discharging the weak cell.

Not familiar with that charger.