LVC: What do you recommend for 2S, 4S, etc?

[JIM MARCUM]

I've read threads on Low Voltage Cutoff (LVC) threads where they say don't turn LVC off (Hi Doc). Is there a rule of thumb for what the LVC should be set at for various LIPO setups? i.e., 2S/4S/8S/10S?

As to turning the LVC off, is it always a bad idea? I'd rather risk frying a battery than loosing a race due to the LVC cutting in with 1 lap to go.

Whatta youse guys think? JIM

[Diesel6401]

It seems common w/ the seakings for that to happen. I always run w/ the lvc on and I also have a countdown timer on my radio so I do both. I usually never hit the lvc, I also don't race. I normally manually enter my cell count and use 3.2 per cell. Works for me. Those are the only esc's I've ever had the lvc prematurely kick in on me.

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[JIM MARCUM]

Thanks Dale. I'm more concerned about racing with 2S LIPOs, and having the LVC kick in on the last lap. My ESC is a T-180.

Any racers out there think running 2S2P 5000mah 45C would NOT last thru a 4 min. main? JIM

[Alexgar]

Maybe a stand alone esc such as a lipo shield or smart stop i have both and seem to work fine with some with my older schulze

[Rumdog]

Just run it and find out

[Make-a-Wake]

I have two Novak smart stops in the Items for sale section...............listed under "Lotsa stuff.........etc"

[NativePaul]

The cutoff voltage you need depends on the quality of your Lipos, I have chinese 30c LiPos that need a 3.2v/cell cutoff or the LVC will cut in early as with a decent load the voltage comes down and you wont get near full capacity at anything higher, better Chinese LiPos that I use 3.3v/cell for, and top quality LiPos that I have to run 3.4v/cell for which pretty much empties them and as they maintain good voltage under load for so long anything lower would overdischarge them and for sprint racing 3.5v/cell would be better to ensure there is still a little left at the end.

You don't Have to run a LVC if you have run it before and KNOW you can get more run time than you need for your race then turn the LVC off by all means as you wouldn't be hitting it in the race anyway.

Our races are 5mins (hydros) or 6mins (monos) with a 280g battery which is about 5000mAh for a 45C pack so my boats wouldn't have trouble lasting 4 mins, but its a pretty mild setup compared to most Americans boats, I guess you are talking about an offshore class here, I had assumed everyone was running 10,000mAh in offshore for the extra power it gives you, but if you are on 5000mAh you need to be pulling an average of 66A or under in order to have a 4.5 minute run time (enough for a 10 second mill, 4 min race, and finish the lap you are on if you just crossed the line at 4 mins) with 10.000mAh you could pull an average of 132A and still get the 4.5 min run time you need.

As to whether your battery/motor/prop/hull/setup/weight combo will last 4mins, I have no idea whatsoever, with the info given all I can say is that with a small prop it almost certainly will, and with a big prop it 100% certainly won't.

[JIM MARCUM]

Thanks Paul. My concern is that if the LVC cuts in during a race due to a load spike - regardless of what the "actual" unloaded voltage is - I will be floating in the lake with no power until the LVC resets.

I will be running 3-4 Offshore cats in the NAMBA FE Nationals next week. The only class I'm worried about is N-2 Offshore as it is limited to 2S2P, 5000 mAh each, 10,000mAh total, and would be subject to higher voltage spikes than races with more cells. I'll be test running my boats this week and will know for sure how long each one can safely run. THX, JIM

[EricSchlaifer]

The cutoff voltage you need depends on the quality of your Lipos, I have chinese 30c LiPos that need a 3.2v/cell cutoff or the LVC will cut in early as with a decent load the voltage comes down and you wont get near full capacity at anything higher, better Chinese LiPos that I use 3.3v/cell for, and top quality LiPos that I have to run 3.4v/cell for which pretty much empties them and as they maintain good voltage under load for so long anything lower would overdischarge them and for sprint racing 3.5v/cell would be better to ensure there is still a little left at the end.

You don't Have to run a LVC if you have run it before and KNOW you can get more run time than you need for your race then turn the LVC off by all means as you wouldn't be hitting it in the race anyway.

Our races are 5mins (hydros) or 6mins (monos) with a 280g battery which is about 5000mAh for a 45C pack so my boats wouldn't have trouble lasting 4 mins, but its a pretty mild setup compared to most Americans boats, I guess you are talking about an offshore class here, I had assumed everyone was running 10,000mAh in offshore for the extra power it gives you, but if you are on 5000mAh you need to be pulling an average of 66A or under in order to have a 4.5 minute run time (enough for a 10 second mill, 4 min race, and finish the lap you are on if you just crossed the line at 4 mins) with 10.000mAh you could pull an average of 132A and still get the 4.5 min run time you need.

As to whether your battery/motor/prop/hull/setup/weight combo will last 4mins, I have no idea whatsoever, with the info given all I can say is that with a small prop it almost certainly will, and with a big prop it 100% certainly won't.

What Paul said!!! :) It really comes down to the quality of you batteries. Voltage under load is the key here. It is possible to have a lower quality lipo dip below 3v per cell under load but be at say 3.4v per cell at rest. If you will be racing with the same packs consistently I would recommend setting the LVC at 3.0 per cell and testing your runtimes. This will help ensure you don't fry your pack while testing and you can get a few runs in and check what your at rest voltages are. When you charge back up you can also see if you've drained them past their rated capacity. If the packs seem dangerously low after a run raise the LVC until it starts to interfere with your runtimes.

[JIM MARCUM]

On my N-2 2S2P cat I'm running Hyperion EX G3, 45C, 5000mAh LIPOs. Hyperion makes one of best quality LIPOs out there & they state run at no less than 3.4v cutoff. That's where I'll start off.

All of the theory about how low you should set the max discharge voltage get is great. But, like Rumdog said, I need to test run the boats to find out how long they last. JIM

[EricSchlaifer]

On my N-2 2S2P cat I'm running Hyperion EX G3, 45C, 5000mAh LIPOs. Hyperion makes one of best quality LIPOs out there & they state run at no less than 3.4v cutoff. That's where I'll start off.

All of the theory about how low you should set the max discharge voltage get is great. But, like Rumdog said, I need to test run the boats to find out how long they last. JIM

:) I didn't mean to set the LVC at 3 and call it a day. It was only to test without the LVC tripping prematurely. LVC's vary from one ESC to another. Hyperion is aware of this and suggests a conservative number. When I am not racing I actually set my LVC's high at 3.6! I've found that my quality packs won't trip the LVC until 3.75-3.85 when set like this. Some of my cheaper packs will trip at 3.9 and even 4v