MM input voltage.

[Robert]

I've just built myself a 9cell pack. Fully charged it's 13.95 volts. I know the MM says it will handle 12 cells or 3s lipo. 3s lipo is only 11.1 volts. Am I going to cook my MM?

[BrianG]

Actually, 3s lipo is as high as 12.6v (4.2v/cell), but that's beside the point.

That 13.95v on 9 cells is 1.55v/cell. But I bet if you let the cells sit for a little bit, they'll drop to something around 12.5v (~1.4v/cell), and even then, the cells don't stay there very long when you start running. Even at 1.4v/cell (typical "peak" voltage for NiMHs), a 12 cell pack will be around 16.8v (which, incidentally, is the same max voltage for 4s lipo). You should be perfectly fine. The components on the MM are rated for at least 25v, but some of that is for a little "headroom".

You may have trouble if you decide to try 14 cells, but even then the MM would simple not arm (won't blow anything).

[Robert]

Thank you for the info Brian.

[Arct1k]

But i would say use an UBEC such as the castle bec for anything 3s or higher...

[BrianG]

^ +1!

Anything over 2s or 6 cells need an external BEC...

[Robert]

So should I get one to run this pack?

[Robert]

well dang, Castle said it will be real close too and that I may need one. I'm going to run it and see if it thermals.

I used to run 14 cells on my maxx all day long and with a fan temps were good. Then i finally smoked it(back flip and throttling it sent amps threw the roof) is what im thinking. So i sent it in and they game me a brand new one. and now it wont run on 14 cells. It "arms" but it wont go. The new ones have somesort of overvolatage protection. It runs like a champ on 12 cells. I read somewere on here that there was a way around the protection, by turning of the lvc, but that didnt work for me. Im thinking about letting the 14 cell pack rest for an hour, and then trying again.
Or just maybe one day my stupid mmm will come :(

[Robert]

I ordered the castle ubec from Mike tonite. I'd rather have it and not need it then to need it and not have.