How did you setup you cutoff?

[kalbien]

Hi

I was just running for some more time with RX8,
4s, 2000kv, 12/46 gearing, quite small track - maybe little slow, but both motor&esc were just completely cold.

However after coming home and charging my Lipos - Wide Energy 4300, 20c , one of them suddenly grew to like double size and my charger told me that "balancing voltage is too high" I guess it's dead.

Question is, if you guys set cutoff voltage for 3v per cell, or you set it little bit higher to be on a safe side? (I don't know if it was because of batteries, or because of undervoltage...)

any ideas?

[BrianG]

I set my cutoff such that when the pack is depleted and I let it sit for about 10-15 minutes, the voltage rebounds to 3.5-3.6v/cell unloaded. The LVC setting for the same pack can be different depending on what kind/weight/gearing/etc vehicle you run. Obviously, this takes a little trial and error. Start at a safe 3.2v/cell and go up or down from there.

[kalbien]

Originally Posted by BrianG

I set my cutoff such that when the pack is depleted and I let it sit for about 10-15 minutes, the voltage rebounds to 3.5-3.6v/cell unloaded. The LVC setting for the same pack can be different depending on what kind/weight/gearing/etc vehicle you run. Obviously, this takes a little trial and error. Start at a safe 3.2v/cell and go up or down from there.

Well this trail could be sort of expensive :) especially error . I will set it higher, 3.3v/cell probably and we will see how it will go. I just blindly (and apparently stupid me) put 4s cutoff there with "tekin knows what they are doing excuse" without much thinking about it :)

well hyperion VX 5s are coming... needed an upgrade

[Aceldama]

Yea, I think the 3.0v/cell for the default settings is a bit low. Like Brian, I generally lean somewhere between 3.2 and 3.4 per cell to be safe and depending on the quality of the pack.

[kalbien]

Originally Posted by Aceldama

Yea, I think the 3.0v/cell for the default settings is a bit low. Like Brian, I generally lean somewhere between 3.2 and 3.4 per cell to be safe and depending on the quality of the pack.

Well somewhat 3.3 per cell will be mine setting from now On.

[BrianG]

You may find that to be a tad too high and runtime may be reduced (probably only by about a minute though). Like I said before, set it to whatever, run your vehicle until the LVC kicks in, disconnect the batteries and let them sit for about 10-15 minutes disconnected. After that, see what the voltage is. If it's over 3.6v, you could bring the LVC down a tad. If the voltage is lower than 3.5v, bring the LVC even higher.

3.3v might be right for your vehicle/battery combo, but the idea is to find a LVC value so that the batteries are protected, yet don't have premature cutoff. Also, an LVC setting too high may introduce false cutoffs because the battery voltage does dip on high current starts.

[RBMike]

I use 3.5 V per cell & have never had a puffer. Conservitive I know but packs are expensive & I would rather loose 2 minutes of run time than kill a pack. 3.0v is way too low. Actually if I only run 1 type of pack (i.e. always 6 cell) in the car then I do a custom cutoff at 21.0V. Also if you have to replace that pack anyway now, get one with a higher C rating & charge rate.

[kalbien]

Originally Posted by BrianG

You may find that to be a tad too high and runtime may be reduced (probably only by about a minute though). Like I said before, set it to whatever, run your vehicle until the LVC kicks in, disconnect the batteries and let them sit for about 10-15 minutes disconnected. After that, see what the voltage is. If it's over 3.6v, you could bring the LVC down a tad. If the voltage is lower than 3.5v, bring the LVC even higher.

this one sounds really ok, I will do it like that , thanks a lot...


batteries I am getting are http://www.hyperion-eu.com/products/...-LG335-3300-5S with geared to 55-60km/h plenty of capacity for 7mins mains and charge/discharge rates are really nice.

Thanks for help , hopefully I won't fry those :)

[kalbien]

Just to be sure.. for 4s I am setting in hotwire Voltage Cutoff to value 13.2. Correct?
for 5s 16.5

thats 3.3 per pack and should be ok.

(rather ask stupid than fry another one)