General Post Storage Maintenance

Harford

Active Member
I have had a break from RC helis for almost 2 years but am now focused on getting back into the hobby. I would appreciate some advice on the maintenance steps I should undertake before attempting to fly my helis. They were all in very good flying condition, with little flight time, prior to my break. Also, is there anything I should know about the Lipos, which were packed away at storage level voltage.
Many thanks
 

Smoggie

Well-Known Member
Nothing special really. Just give the heli a good check over and lubricate the swash where it slides on the shaft and also the tail slider, you should be good.

For the batteries check for any puffing and check none of the cells have lost voltage while stored (indicating a faulty cell). When you charge them make sure they balance ok.
 

Harford

Active Member
I have had an issue with an old Lipo, when attempting to put it into storage voltage level. It just would not go down to around 3.8v per cell as it normally would, but only got as low as 3.9 to 3.95v per cell. I do not think it is anything to do with the charger which usuallyy handles this type of procedure without issue. I just attached a small lamp to it and got it down to 3.8v that way. Not ideal, but it is an old battery.
 

Tony

Staff member
Another way you can do it is discharge the battery like you normally would flying, then set your charger to only charge to 3.8v per cell.
 

Harford

Active Member
Thank you for this. I will try it. I purchased the battery in March 2012 so not too distraught if it now becomes problematic.
 

Smoggie

Well-Known Member
I have had an issue with an old Lipo, when attempting to put it into storage voltage level. It just would not go down to around 3.8v per cell as it normally would, but only got as low as 3.9 to 3.95v per cell.

This indicates that the internal resistance in the battery is very high. What hapes is when you put a discharge current on the battery, due to the high resistance the voltage drops very quickly (V=I*r). The voltage hits the storage charge value (3.8V) and discharge stops. Now that there is no discharge current the voltage climbs back up again.

I'm pretty sure that you will find the battery is not usable in a heli because when you put it under load the voltage will quickly sag and hit the ESC low voltage cut-off.
 

murankar

Staff member
I Would grease the thrust bearings and check the dampers in the head and tail. Just make sure the dampers are crack free. If they have cracks i would consider replacement. I would lightly (very lightly) grease them.
 

Harford

Active Member
The battery is a 3s 2200mAh 30C. The internal resistance is 8.4, 8.0 & 7.8. Fours years ago the IR for the same battery was 6.1, 5.8 & 5.4. Using my Cellpro Powerlab 8 V2, it will only discharge to approx 3.94v per cell, or 72%. The results for an identical battery of similar age, an IR of 6.6, 6.3 & 5.9 which is only marginally worst that the IR results 4 years ago. This battery will discharge to approx 3.83v per cell, or 52%. which is consistent with the results I get when putting other Lipos into storage.
Not trying to resurrect the battery, simply curious about why it won't discharge further.

Thank you regarding the head and tail maintenance advice. Whilst the helis have had little use since being built, I am sure this is the safe thing to do.
 

Tony

Staff member
The likely cause is due to the cells resistance. The higher the resistance, the higher the voltage sag. At least that is all that is coming to mind. Not sure exactly why it is doing it as the current draw to get the pack down to storage voltage keeps decreasing, so the load keeps going down which would result in a more accurate reading...
 

Harford

Active Member
Thank you for this. I will discard the battery (after fully discharging it) . At least I have some idea of what is happening, thanks to your and Smoggie's explanation
 
Top Bottom