Lipo Woes - please Help...

[chopperboy]

Gents,


maybe this is just the minefield of Lipo's but maybe some comments would help.

I have the following battreies: -

2*Flightpower 2170 Evo25
1*Flightpower 2500 EVO Lite
2* 1800 15c Electrolite
2* 2200 Revo 25C
1* Align 2100 20C


Recently I placed athread on here about cold weather flying as I kept getting LVC and had to land the heli. (TREX 450SE V2 (Standard).

I keep the batteries in a foam box and warm in my pockets before flying but have had issues gain today with one Flightpower 2170 pack and both of the Electrolite packs.

Soon after takeoff or virtually immediately, the tail starts to wag and I have to land the heli. I have tried gentle hovering first to warm up the cells a bit more, this does not help.

it was only 3 Degrees C today so not that warm, but my revo cells performed fine. My Flightpower 2500 pack only lasted 4 minutes and one of the 2170's only lasted 3 minutes before the tail started to wag......

I am flying sport and gentle aerobatics not 3D.


I have a Cellpro 10S charger but admitetly didnt see any of these issues when using a cheap Century balance charger when the weather was warmer.

is this just the cold giving me grief, i only fly for 4-5 minutes per battery but sometimes get to the LCV on the ESC if it surprises me.

any help would be greatly appreaciated.

P.S. is it ok to store LIpo's for 1 week once charged?

ta



Chopperboy...

[MrB]

Hi- If the revo's were fine then I'd suggest the others may well be coming to the end, lipos last a certain amount of cycles. Going on my own experience Flightpower/TP etc do not give the same ammount of cycles as the Revo's, and thats probably the widley held thought on here.

With the 10s it gives you an internal resistance measurement that'll tell you the state of the packs and possibly what cell is playing up, what sort of reading are you getting.

edit- No problem with full charge storage for a few weeks-




Mark.

[chopperboy]

All of the batteries are less that 3 months old though and only 20 clycles or so?
I will have a look at the resistance - on the P.C I gather?

ta

[daren]

My six flightpower 10s1p did less than 10 flights each in a logo 14 before i started having problems, even had one swell sat on the table for no reason,
flightpower may say they are the best but they are also the the most fragile.

[chopperboy]

Daren,


did you get these replaced?

ta

[rceccleston]

When discharging the batteries, are you staying with the 80/20 rule.

If you were to repeatedly run over the 80/20 rule, the batteries would become weak and may show strange characteristics.

I would recommend running an LED/speaker Li-Po monitor on your battery balancer connector. In my experience, the monitor shows a safe low voltage before the ESC, so saving the Li-Po. These can be found on a well known auction site.

Me and my mate have been running our heli's with these for over 6 months without any issues.

[chopperboy]

Removed due to stupidity

[chopperboy]

ok, the Flightpower pack reads 18.5 to 19.3 mOhms per cell. Is that Normal?

[chopperboy]

bump to the top

[Sieze2]

ok, the Flightpower pack reads 18.5 to 19.3 mOhms per cell. Is that Normal?

Put it this way my new 30C packs are 3-4 mOhms per cell and my packs with 180 flights or so are about 10 mOhms per cell. Lower is obviously better when it comes to internal reistance, so I would say your pack is finished matey.