LiPO question - lil info please.

[SleepyC]

I have 3 TP 3 cell 2100 mah packs that are around 1 year old.
I'm using them with a 25 amp esc and a E flight 450 out runner,
I notice that when the Voltage cut off happens, and I charge the packs,
I'm only getting around 1300MAH into the packs..
I can charge at 2 amp, 1 amp, even .5 amp and its always between 1280 and 1330 mah...

Does this sound right or are the packs getting tired.
They pobably have around 65+ cycles on each pack.

I'm not a super electric dude, so I'm lucky that I can even charge the things right with out them blowing up.

I'm using the Triton charger on the lipo setting.
11.1 at .5, 1 and 2 amps...

any thoughts?

[MalaysianFlyer]

Might be due for balancing, assuming the packs haven't been abused. 65+ cycles should not show a large amount of degredation. It could be that one cell is lower than the others and leading to early cut-off.

[adrian]

try a very slow charge - lipos go to 80% capacity fast but the last bit takes a long time - so very slow charge right at the end - what charger?

[adrian]

ok sorry i see triton - go very slow .2 even

[SleepyC]

How do you balance cells?

[bbuzzone]

Newer TP's have a balancing pigtail on them. You use thier balancing module to do the grunt work. There may be a means to physically separate the cells to balance, but I've never gone that route.

[Marcus76]

Hey Sleepy,

I'd say a balancing may be in order, but I will not guarantee that it will revive your packs. Without balancing tabs or the TP balancer, your best bet is to charge them at as low a C rate as possible. Worst case scenario, unfortunately your packs are starting to show some wear and may be just getting tired. Other than that, you coud try propping down a bit to reduce some of the amp draw. In the air, I am pretty demanding on my Lipos, but they are always balanced and never exceed 110-120F temps. Still, I figure if I get about about 130 cycles from them before some serious performance degradation, they have served me well!! Then i start using them in lower current-draw applications. That's the cost of doing business I guess!!

Hope this helps,

Marc

[SleepyC]

THANKS!

I think since I didn't ever balance them, and have used them on some decent draw applications, perhaps they are showing a bit of wear.
Oh well.... Not the end of the world!

[MalaysianFlyer]

You can balance them by charging each cell individually with your charger set to one cell mode and connecting using crocidile clips, or by adding a balancing harness and using a balancer module. I recently added a balancing harness to my packs, its not very difficult to do, but you do need to get the correct type of solder to stick to the aluminium tabs. I used the solder paste from Solder-It, works great.

Then again, you could always get new packs, the new generation of Lipos are rated at 20C cont and 30C burst!!!! Awesome stuff

Adrian has a good idea about trying a very slow charge, that should work if your packs are not too badly out of balance. Main reason why Lipos need a balancer is due to the extremely low self discharge rate, something like 5% per year only!!!