Voltage cutoff with 2x 2S.

[Ascender]

The program says 3V per cell, so with 2 2S batts, would that be 12V?

[George16]

Play it safe and go with 3.2V per cell.

[lincpimp]

I would suggest a higher cutoff value, such as 3.1v or 3.2v per cell. Gives you a little extra insurance as the lvc reads the whole pack, and a weaker cell could drop below 3v per cell if you are pushing the pack hard, and the other cells could hold voltage well enough to keep the pack reading over 12v.

If your 2 2s packs are wired in series 12v would be correct given a 3v per cell desired cutoff.

[Ascender]

OK. Thank you for the quick response, you guys are awesome.

[Unsullied_Spy]

Running them in parallel (14.8v at nominal voltage) I set mine to 13v. Never under-discharged a lipo. Higher voltage cut-offs will cut your run time by a minute or two but your lipo cells will last a ton longer.

[SpEEdyBL]

Pdelcast posted this a while ago:

"Well, we will be adding an adjust to a future version of the software, so that the cutoff threshold can be changed.

As it is, the cutoff is closer to 3.1V than 3.0V right now, and Lipo chemistry doesn't actually start any damage until a cell hits about 2.4V -- so there isn't any problem with using 3.0V as a cutoff.

And yes, the auto-lipo mode assumes that the batteries are at full charge. HOWEVER, the Monster controller ALSO beeps back the number of cells to the user -- so the user can verify that the number of detected cells is correct. (you will hear the normal power-up beep, followed by beeps for the number of detected cells, and then followed by the arming tones.)"

[Patrick]

Originally Posted by Unsullied_Spy

Running them in parallel (14.8v at nominal voltage) I set mine to 13v.

That would be connected in series for 14.8v

[Unsullied_Spy]

Originally Posted by Patrick

That would be connected in series for 14.8v

Ahh crap, thanks for the correction.

IMO your truck will start to slow down before it hits the LVC, I set mine at 3.3 vpc

Originally Posted by azjc

IMO your truck will start to slow down before it hits the LVC, I set mine at 3.3 vpc

Exactly. I have mine sent at 3.2 per cell and you can tell its dead/slows way down right before it hits the LVC.

If Castle says 3.0v, thats good enough for me

[RUSTY XL-5]

Originally Posted by Foxracin

Exactly. I have mine sent at 3.2 per cell and you can tell its dead/slows way down right before it hits the LVC.

Same here, I think with a 3.3V cut off, it should stop just before the RC begins to slow down.

[mistercrash]

Is it true that lipos are supposed to be able to be safely brought down to 2.7 volts per cell? So this means that setting the LVC at 3 volts per cell would be very cautious? And the LVC set at anything more than 3 volts per cell would just take away at run time unnecessarily? I would love for someone with a lot of knowledge about lipos to answer these questions for me.

[BrianG]

2.7v is probably ok for medium to small loads like cellphones and laptops, but our stuff pulls a LOT of current and the 3v/cell+ is just extra insurance. One other thing; I noticed that cells stay in balance far better if the LVC is set to 3.1v/cell or more. Lower and one/some cells can be substantially lower.

Whether you choose 3, 3.1, or 2.7, I usually follow this rule of thumb: Set the LVC point such that when you remove a depleted pack from the load for ~10 minutes, the voltage should rebound to at least 3.5v/cell.

[mistercrash]

Thanks Brian, I know I can count on your opinion about these things. 3.2 volts it will be for me. 3.1 volts only if I need to squeeze as much run time as I can but mostly 3.2 v per cell.