Yeah Racing 5000mAh 25C HARD CASE Li-Po

[aittam]

Hello,

I have 4 packs of Yeah Racing 5000mAh 25C HARD CASE Li-Pos. I bought 2 in April and 2 in May.

After each use i put them away using the storage procedure on my charger, that charge/discharge them till the cells are 3.8v.
Before use i charge them in balance mode at 0.5C (2.5A) and they correctly stop charging at 4.2v.

The problem is that the first 2 packs i bought in April can take up to 3300mah, while the 2 packs i bought in May can take up only 2700mah.
Any idea why this happens?

I'm using them with a Mamba Max with lipo-cutoff set to 3.0v.

Thanks.
Mattia.

[peetbee]

Are these 2 cell 7.4v packs and you are referring to the individual cell voltages?

[JJ The Boat Wizzard]

I Hope Thats Not 3.0V Cutoff For The Whole Pack?? If It Is There Is Your Problem

John

[aittam]

I'm sorry i did not specify the paxks are 2s for a total of 7.4v.
The voltage i was talking about (3.8v, 4.2v and 3.0v for the cutoff) are per cell and not for the whole pack.

Mattia.

[peetbee]

I'm not sure what's causing that then, bearing in mind that each pack will have some mah in it still so you wouldn't expect to put the full 5000mah into it.
What charger do you have and have you asked someone else to try charging them to see if their charger gives different readings?

I believe that lipo don't require discharging for storage, personally I charge them fully after running and then store them fully charged.

Another question! After you've used a pack, how much charge will they take?

[aittam]

I'm using a Bantam BC6-10 charger, it's new, i bought it together with the first 2 packs of lipo.

I have never fully charged the packs after use, so i really do not know the maximum capacity i can squeeze in them.

I posted the same question on rctech.net, but so far no luck.

Mattia.

[aittam]

Is it possibile that after 5 cycles these lipo batteries lost 10min of runtime?
I'm using the same setup on the same car: tamiya ta05, mamba max 4600kv, pinion 26, spur 105.

The first time i got about 40mins of runtime.
After 5 cycles i got about 30mins of runtime.

...maybe i'm driving a little bit more aggressivly, but 10mins less are a lot...
:confused:

Mattia.

[JJ The Boat Wizzard]

I Dont Know Much About The Mamba Max System But Have You Got The Lipo Cutoff Set Correctly??

[aittam]

I set the cutoff to 2cells (6v).

Yesterday, after about 30mins, the cutoff kicked in and i stopped bashing around. Then i check the voltage of each cell and it was about 3,3v each.

Mattia.