lvc on quark monster pro

[no mods]

how does the detection process work when hooking up lipo bats on the quark monster pro? i have it set to its highest 3.volt setting but ovb i am running more than one cell.(5s to be exact) can anyone shed some light? and what else can i do to make absolute sure bats are not being overused past the point of no return?

keep in mind i need something compatible with more than 4 cells.

[BrianG]

Most of the ESCs that have a "per-cell" cutoff setting "read" the voltage hooked up to it and calculate the number of cells that way. Of course, they probably assume a charged battery so if you hook a depleted 5s pack (~15v), it might think it's a 4s pack with at least 3.75v/cell. Of course, this would drain the battery down to 12v, which would be way too low for 5s. So, make sure you don't turn off/on the ESC towards the end of the charge or it might read it wrong.

IMO, lipos usually dump very noticeably so I think you'd see the loss of speed before you got to that point.

The Quark is supposed to be able to detect the number of cells in the pack. The cutoff voltage represents the voltage of each cell that is reached before the LVC will kick in.

This is all fine and dandy, except that the Quark "measures" the voltage of the pack when you first plug it in and then makes a determination of the number of cells based on the voltage that it read. The downside to this is that if you plug in a pack that isn't fully charged, the esc could misread the number of cells in the pack. For example, it could misread a 5S pack as a 4S pack, and then the lvc wouldn't kick in until the pack reached 12v, at which point your 5S pack would be dead, dead, dead.

I don't rely on the voltage cutoff. I have a rough idea of how long my batteries will last on a charge and I just look at my watch when I plug the battery in. Personally, I don't think that the built in lvc on the Quark is of much use anyway. Most of the newer 20C packs really shouldn't be discharged below 3.2v anyway. If you run a 20C lipo pack down until the lvc cuts off, you may have already done some damage. That's my opinion anyway.

OK, Brian beat me to it.

[zeropointbug]

Yeah, right. Now I don't know which setup for LVC I should use, because a couple of times with my first Quark it cut out. I had to restart it.

When I connect my batts, they are 18V (A123's), then as soon as I discharge them only a bit, they quickly settle down around nominal charge. But, I am just wondering with the relatively higher voltage drop compared to LiPo's, should I use NiMH mode instead? Does NiMH normal mode deliver as much power as LiPo normal, if anyone knows?

zpb, I wouldn't worry about it if I were you. From what I've seen, the A123s dump long before they reach the critical (if you want to call it that) 1v per cell. I wouldn't worry about an LVC at all with A123 cells.

[zeropointbug]

Oh believe me, I know the A123's don't need it, I turn it off as soon as it happens... you don't have much time though, I still can't get over how fast they dump. It's just that the Quark turned off a couple times when I was really (really) working it hard, so maybe the volts touched the cutoff point (the Quark thought wrong or something?) for a millisecond. Or it maybe it had a thermal, but I doubt it, I did the internal mod, and it was only 10'C outside.

I guess I'll just use NiMH mode then. Oh, and just so you know, it's 2.0v cut-off point for A123's... 1.0v, yikes.

The manual that came with the A123Racing packs said not to discharge them below 1v, IIRC.

[zeropointbug]

really, that's different from the developer's kit that I bought which is 2.0v cut-off standard. But we all know that they can handle being discharged below that point, and even over charging, no problem.

I could be wrong. In any case, the voltage was still way over 1v when the pack that I was uising dumped hard. I don't think that overdischarging is a problem with the A123s. The only thing that you really have to watch out for is accidentally leaving it plugged in and the electronics over discharging the cells.

[zeropointbug]

Originally Posted by AAngel

I could be wrong. In any case, the voltage was still way over 1v when the pack that I was uising dumped hard. I don't think that overdischarging is a problem with the A123s. The only thing that you really have to watch out for is accidentally leaving it plugged in and the electronics over discharging the cells.

Yeah, that would not be good for them at all. I wonder how many mA current there is when you leave it plugged in like that.

My cells are still going strong surprisingly, I have over discharged them, shorted them out repeatedly, and still they are over rated capacity still. :027:

[no mods]

is there any after market lipo cutoff that simply interface with battery and when voltage drops it shuts off current?

reason i ask is i want a double redundancy system cause the quark has already let me wreck a battery. if i were to run a system that is either 5 cell capable or two separate systems 1 for my 2 cell pack and the other for my 3 then i would be good to go. just dont know if that is doable because of the way most interface with the receiver.

[no mods]

nevermind... the broken pack was due to a faulty cell not running it past lvc. however i contacted novak ( i run one of their 4s lvc in my boat) about building a 5s cut while this is not in the works they have suggested i may be able to mod one to work.