Voltage cutoff with 2x 2S.
 

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

Play it safe and go with 3.2V per cell.

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.

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

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.

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.)"

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

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

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

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.

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.

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.

Brian, I have to ask. WTF is up with the no fan avatar? :whistle:

Oh no you didn't! :surprised: Your in for it now. :rofl:

Yeah it'll work, but I like to turn mine up just to stay safe. The new auto-lipo with customizable V/cell is awesome (I set mine to 3.4, when you have Maxamps lipos you can't be too careful :rules:).

Do you have a CC Link for your Flux yet? If not, I have a spare one you can have.

Nope, I don't have $25 on me for one. I'd like one, it looks nice and easy, at least compared to using the transmitter.

Would that explain why on my first long bash session with my Savage flux, it all of a sudden got VERY slow and then actually stopped and wouldn't go anymore unless I let it sit for a second and if I blipped the throttle, it would go for a few feet then stop again?

I was running SMC 6000mAh 28C 2S.

:lol: I've got a spare one from my replacement Mamba Monster that I'm not using (only need 1 and you can program all kinds of CC stuff). We live close enough we could meet up to bash sometime and I can give it to you then or I can put it in an envelope and mail it.

That sounds exactly like the voltage cut off to me. It slows you down at first to let you know you're running out of juice, then it will cut out to keep the cells from going under the LVC threshold. The reason it will move a few feet after waiting is the voltage in the cells recover a little when there's no load.

Wow, so its the same thing you can order from Castle for the Flux? So all I need to download the software? It comes with all the cables? How much you want for it? I live in Missoula, FYI. I tried to send you a PM, but its not showing I sent it. :neutral:

Ah ok, so I didn't hurt my Lipo's then, they were just really drained mAH wise but the voltage was still safe? :neutral:

I posted my first bash session with my Flux today here: http://www.rc-monster.com/forum/showthread.php?t=20716 Was fun as hell, I was just worried cause I didnt' know how a "voltage cutoff" for a Lipo worked or how my truck would react to it.

No no, I'll be gentle (this time :smile:). My personal opinion is that no BL system should need a fan if it is set up right. If it heats up, then you are pushing the system beyond it's specifications. Besides, a fan cures the symptom, not the problem. Not only that, but a fan can (and will) fail, so if you are relying on a fan to maintain good temps, then the system will thermal when it fails.

However, if you are using a fan to supplement a system that runs cool without one, then that's fine. But I still think the benefits are not worth it. The only systems I have that run fans are the ones with a MMM, and that's because the warranty will be void if I remove it. Heck, I even run a couple of Quark 125's perfectly fine (temps ~30-40* above ambient) with no fan, and those are known for running hot.

I'll let you convince the CEO of Castle Creations. :mdr:If Castle thinks I need one, then by God, I will use it. Besides, I like fans. I used to have a custom built PC gaming rig with 12 fans in it.

lol, I think CC is just trying to guard against people pushing their product too far. I ran my MMMv1 fanless until it blew, and not from high temps; it was just sitting there and then poof!

Computers are a different story. Generally, you computers are not running in dusty/dirty conditions bouncing all over the place. And if yours does, you have more problems than just fans. :wink:

But hey, if you like fans, then more power to ya! I just think they have a time and place, and R/C is not one of those...

12 fans :gasp: I've got 1 on my storage drives, 2 on the cooler for my raptor, 1 in my PSU, 1 in the rear of my case (don't really need it with the way my CPU cooler is setup), 1 for my CPU, and 1 for my GPU. That's half as many fans including HDD cooling. Your computer must sound like a Jet :lol:

I agree with Brian's position on fans. You shouldn't NEED them, but they are a nice addition to make your system run even cooler.

Yep, the "Blur" ESC is a Mamba Monster with different stickers on it. If we meet up soon to bash I'll give it to you then, if not I can always drop it in the mail. I'll just send it to you as it's a spare that I don't need, even though you are a Grizz :tongue: I'm getting PMs, don't worry.

I try not to run mine very long once the voltage cut-off kicks in. I don't think you damaged your lipos but I primarily run Maxamps packs, and I treat them like they're made of glass so they don't fail on me.

I saw your vid and all the pics (the pics were excellent!), some friends and I will be out there sometime for a bash. There's a place in Rocker, MT that has some great bashing and also some rock crawling that we may be going to tomorrow.

"Mini Death Valley" also has a dirt/rock piles the guys take their rock crawlers on. We also set up a dirt/obstacle course that the guys use to race their Baja's.

Basically, we have it all in one big ass place. :yipi: To see how big, check out my vid here

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