How many volts/cell do you guys generally program your esc's for at 100-150 amps on gp3300's and gp2200's? I presume gp3700's will be the same as the 3300's?

thanks
Greg

I never use cutoff in high power applications. I can tell when it's time to quit - my LMR sailplanes have enough capacity for the task they are designed to fly. For just blasting around F5B style, I quit when I sense a drop in power - it's VERY noticible.
The last thing I want, however, is a cutoff at an inconvenient time.
..a

Andy, this is not helping me program my new controller. I too have used auto in the past but with the new castle software you must select a voltage...

I have an electronic model F5D controller modified for 7 cells with a cutoff at 3,5 volts......

Originally Posted by Sebastien

I have an electronic model F5D controller modified for 7 cells with a cutoff at 3,5 volts......

That's interesting. Can you tell some specs about it? weight, amps...PRICE?
I think 5V cut off is low enough for F5D 7 cells and protects little bit the batteries.

Originally Posted by argarre

Andy, this is not helping me program my new controller. I too have used auto in the past but with the new castle software you must select a voltage...

Greg, this question came up in the batteries forum a few days ago.

What Andy says IS helping you to program the new controller. Set the voltage as low as you can.

Mike

thanks Mike! I just hope I don't damage my cells by going past that point (whatever it may be)

Greg

The only way you can damage them is if you don't recognize when you're low on power and land. Even so, a well balanced pack (i.e. a slow charge the night before you fly to ensure all cells are fully charged) will prevent any damage.

Repeated flying to some magical "LVC" level and simple peak charging WILL cause cells to go out of balance, resulting in damage to one or more cells. Regular slow charging (once every 10 cycles or more) and NOT running to cutoff will cause your cells to live a long and happy life.. at least, as long and happy as 120A+ current draw can provide!
..a

Like Andy says...you won't damage nickel cells by running them down. They are incredibly robust. A year or so ago this question would never have come up. But now we have a lot of people who are starting and, quite rightly, being concerned with all the safety info associated with lithium cells. The assumption is that there must be a similar low voltage minimum for nickel. There isn't. In flight, the power will drop noticeably and at this point you will HAVE to land. If you fly to this point with Lithium cells you could well have damaged your pack.

Mike

Thx for adding that, Mike.
I think this stuff, but to be frank, we've all posted it time and time again over the years, so you get tired of repeating yourself..

It should be in an updated FAQ, don't you think?
..a

IMHO, don't trust the LVC settings in the ESC, difficult to know whether they kick in at the right time really. I have ruinned at least 2 lipo pack already.And I got help from a kontronik agent tell me no one in HK flying he knows of counting on LVC the so-call lithium cells adaptable ESC for high power purpose. Should have couples of bad thing happened.
A hk guy fly here taught me predict max motor run time by calculating the charging in back current amount. Never failed since then.
Example:
1) record charging back current=A, eg.: 2050mA,
2) check the timer (thr.>50%) of throttle up time=B, eg.2min18 sec=138sec.
3) thus the motor used:C = 2050mA/138sec.=14.85mA/s
4) Use 80% of nominal cap of pack as max.usable batt. cap. eg 2.6A pack =2600*0.8=2080mA
5) USE D/C=140 sec.MAX=T.
6) Then use T to set the timer in Tx.
If tx has 3 timers, then beep at 80% ,70%...

Look like trouble but it takes 2~3 records, then you have reliable timer values.
Another advantage is able to check whether something goes wrong in the power chain.

Johnson

Good grief! Just fly until you detect a drop in power!
..a

Originally Posted by WFJS

I have ruinned at least 2 lipo pack already.
Johnson

Johnson. This thread is about LVC for NiMH not Lipo cells. I agree that flying to LVC with lipo is not a very clever way to do it, but with NiMH and NiCd there is no problem flying until 0V if using a separate receiver battery or 4.8V is using BEC.
Read all the information here again. LVC will save a 2 or 3 cell lipo pack if set correctly. LVC will save a NiMH BEC powered model if set correctly. As far as I know, there is no way to use LVC to protect 4 or more lipo. No one makes an ESC with a 12V LVC, do they?

Mike

Originally Posted by Mike Seale

Like Andy says...you won't damage nickel cells by running them down. They are incredibly robust....The assumption is that there must be a similar low voltage minimum for nickel. There isn't....Mike

Can you elaborate on this Mike? I assumed that even with a well matched nimh pack, when you dragged the (pack) voltage down too low, the slightly weaker cells would suffer as a result. Schulze & other charger manufacturs seem to make a big deal about cutoff voltages when discharging in terms of the cells becoming sluggish & similar discussion regarding charge state when storing nimh cells. So why wouldnt the same rules apply when running them down through normal flight use? Otherwise why even have a voltage cutoff at all on non-bec ESC's for nimh & extract every last maH?

Intersting discussion, I put the LVC cutoff at 7.2 volts for 10 cells, and 5v or so for 7 cells. That said, I never experience LVC, I generally fly until a loss of power. I set it low intentionally so that the LVC doesn't kick in sooner than it should.

If you are using the cc80, and running over 120 amps, you are going to experience thermal shut down before low voltage cutoff...