6s batteries or 2x 3s ??

[nemorov]

I need some 6s power for my new configuration and I have quite a few 3s packs already.
Any advice on wether its better to go for proper 6s packs or wether I would get similar performance out of pairing up 3s packs to make 6s packs?

Any other pros and cons?

Thanks

gavin.

 

[ChrisViperM]

You might hear different opinons on this, but most of the time people use 2 LiPo packs to double the Amps and not so much the Volts. If you need 6S and pair 2x3S, what will happen if one pack goes "poeff"....your voltage will drop, and so will your bird.

The bird will also drop if you have one 6S pack, if this one goes "poeff"....same thing.

If you have a few 3S packs already, I would use them......just make sure that you don't use super-cheap no-name crap LiPo's.....


Here is a good vid about "linking" LiPo'S:

http://www.youtube.com/watch?v=_4KPGl1NMsg


Chris

 

[kloner]

I fly 12s on all my scale helis in pairs of 6s. Had a bitchen model, hughes md500 all done up, had been flying all day with multiple models and broke out the hughes. i did not check the voltage on my packs for some reason, felt confident that 2 i just grabbed were fresh. Well, one was fresh and the other was done...... hooked em up in series and lifted off....... got to the end of the run way and the tail got a wag, i had never seen that, right about then i made a turn for home and it LVC'd 150+ yards out and headed down...... it was far enough you couldn't hear the motor stop, but man could you see the affects. from 15 feet up and going fast and away i took her in, flared and went to survey the damage. the rotor still sat there spinning, never touched the ground, but the whole model was a total loss. bottom was flattened, ground off, inside completely destroyed.......

Moral to the story, if your gonna fly pairs of packs, you better have the patience to check each pack each flight or sooner or later theres a good chance it'll happen to you. I went three years, then "that day" Worst thing was i had it sold so it was a big hit to my brain. Made me explore multi rotors

 

[nemorov]

Thanks guys, useful advice.
When you're charging your packs would you charge them individually as 2 x 3s or would you charge them as a single 6s pack?

Thanks
gavin

 

[kloner]

i'd do 2 of them at 3s,,,,,, because this practice, you have to monitor each packs health constantly. need to know when you put more than 80% back in a charge, that's game over for a pack

 

[nemorov]

Ok thanks for that. So if I have 5000mah packs and they take more than 4000mah after use then I should retire them??
For my 6s combinations I currently have my battery alarms set around 21.5 volts, ie around 3.6v per cell on the understanding that I should never run them below 3.3v per cell.
As a 6s pack I'm putting back in around 3500mah after use. Does that sound about right or am I being to conservative?
I could use a little more flight time but don't know how close to the 3.3v per cell I should push it...
Whats do other people use as a safe margin?
Thanks
gavin

 

[kloner]

i wouldn't retire em, but i put an X on them and start looking at there internal resistance with my charger. the cells come 2-3 mv, they'll hit 10-20 in one over discharge, then there not holding what you think they are, the voltage sags more than it used to, if auto landing is enabled from low voltage, they go in where ever alot sooner than expected. if you have no way to monitor IR then i guess i would just set em aside.

I can't tell ya from volts alone, every pack is different, but on my planes, when a castle LVC's at 3.1 volts that pack is smoked, it'll usually be all 5000 mah back in that it held and it'll never bee the same. The difference between 3.3 and 3.1 volts is most likely seconds......... not minutes.