do low volt cut offs work with todays high powered batteries

[Jeepers]

At the last club race I ran my n2 sport hydro in competition and hit the lvc on my Hydra 240 set at 3.2v per cell, the set was 2s2p Hyperion G3 4200mah cells (8400mah) I put back in each pack nearly 4000mah each. The LVC kicked in and my packs were under 120.

[rcboatmanwithkids2880]

Hi Guy's ,

To LVC or not to LVC ?? , is there an Electrical Engineer that can outline the pros & cons of not running this setting . There seems to be a lot of misconception regarding this matter , mostly posted by self proclaimed F/E prophets . Is there a table that states what sytems should be set up at certain LVC points , or in what instance should it be used ?? .

Brad

[ozzie-crawl]

Hi Guy's ,

To LVC or not to LVC ?? , is there an Electrical Engineer that can outline the pros & cons of not running this setting . There seems to be a lot of misconception regarding this matter , mostly posted by self proclaimed F/E prophets . Is there a table that states what sytems should be set up at certain LVC points , or in what instance should it be used ?? .

Brad

why do you want advice,when all you will do is 10% of what your told to try.
then when your gear catches fire you will complain to other people that they advice you was given was wrong.
not the fact you did what you was told not to do with batteries you were told not to buy.or the fact your bullet conectors were that badly soldered they fell of when you touch them (see pics) or the fact that there was no heat shrink on them allowing them to short out.
and thats how you repay people who have given you rc gear for free.

[properchopper]

I'm not an electrical whiz, but after doing several EagleTree runs and looking at the voltage graphs, it's plain to see that the pack voltage varies up and down substantially during a run. Throttle settings [that is, where the trigger is set] and the in/out of the prop under most running conditions cause large peaks/dips in voltage. I believe the question is : do LVC settings look at instantaneous peaks/dips or average voltage over a specified time period before deciding when the cutoff kicks in ? Since EagleTree logic circuits can and do calculate MAH consumption, would it be better to have a cutoff point determined by a pre-set MAH usage number rather than voltage ? Just a thought. [ Great topic, Scott !]

[Rumdog]

seems to me that with higher c rated packs that the lvc may be more accurately working. If running a high amp setup, and packs that can barely produce ample current under load, the lvc will see thae voltage lag under hard acceleration, and kick in. Now use packs with plenty of capacity and higher discharge rate. Voltage will not sag nearly as bad giving a false low voltage reading. Therefore the lvc may actually cut in when the packs are actually sitting at that low voltage rather than voltage sag from amp spikes. Maybe i'm wrong, just my thoughts.

[ozzie-crawl]

if i run a 30c 5000mah turnigy in my rc truck with the lvc set to 3.4v and run till the lvc kicks in
i put back in 5200mah,both chargers are cheaper ones from hobby king so not sure how accurate they are. but the car wouldnt pull 60 amps under full load.
resting voltage after lvc cuts in is 3.65 volts per cell

[Rumdog]

it's hard to say how accurate these lvc's actually are. More setting options would be nice. Higher settings for the better packs may help as well.

[properchopper]

I thought I just throw this in : Last weekend at the NAMBA 2-Lap, Mark had his FE 30 ready to set a new P-Sport Hydro record. { My record, ouch !]. Every time the boat launched it went to half-throttle and blew his chances. Yesterday we re-programmed the Seaking 180 to eliminate the LVC and the boat was restored to full power. The battery was a fully charged 45C Thunderpower, btw. Hmmm..

[Flying Scotsman]

I thought I just throw this in : Last weekend at the NAMBA 2-Lap, Mark had his FE 30 ready to set a new P-Sport Hydro record. { My record, ouch !]. Every time the boat launched it went to half-throttle and blew his chances. Yesterday we re-programmed the Seaking 180 to eliminate the LVC and the boat was restored to full power. The battery was a fully charged 45C Thunderpower, btw. Hmmm..

Another moron boat addict in Tasmania that sleeps with his boats and his faithfull June on the floor had the same problem with that ESC lvc.

Another question are the ones experiencing this probem with the Seaking/Turnigy 180 marine esc...does it have 2 mounting tabs?

Douggie

[Xzessperated]

Another moron boat addict in Tasmania that sleeps with his boats and his faithfull June on the floor had the same problem with that ESC lvc.

Another question are the ones experiencing this probem with the Seaking/Turnigy 180 marine esc...does it have 2 mounting tabs?

Douggie

I have told you before, that is Mr Moron Douggie and yes mine has 2 mounting tabs.

[785boats]

From what I've read & from personal experience I can say that the newer High discharge rate packs hold the voltage up higher & longer under load. This allows the tank (mah) to be fully depleted before the LVC cuts in if it is still set to say 3.0- 3.3 volts. By fully depleted, I mean even the 20% that we like to leave in the packs is gone & sometimes even more than that. This usually leads to hot & swollen packs.
The LVC needs to be set higher. Some are using up to 3.6 & 3.7 volts. Depends on the load.
The lighter the load the higher you need to set the LVC, because the voltage sag is even less & this allows more capacity to be drawn out of the pack before the LVC cuts out.

Asyou all know, you should never run to the LVC anyway. Get to know your packs. Time your runs, or know how many laps you can do to still put back 80% of the packs capacity when it is recharged. And know what resting voltage that is per cell at the lakeside after a run.

There are many testing devices on the market that can be plugged onto the balance plug & they show cell voltage & remaining capacity in the cells. Very usefull.

Cheers.
Paul.

[ozzie-crawl]

From what I've read & from personal experience I can say that the newer High discharge rate packs hold the voltage up higher & longer under load. This allows the tank (mah) to be fully depleted before the LVC cuts in if it is still set to say 3.0- 3.3 volts. By fully depleted, I mean even the 20% that we like to leave in the packs is gone & sometimes even more than that. This usually leads to hot & swollen packs.
The LVC needs to be set higher. Some are using up to 3.6 & 3.7 volts. Depends on the load.
The lighter the load the higher you need to set the LVC, because the voltage sag is even less & this allows more capacity to be drawn out of the pack before the LVC cuts out.

Asyou all know, you should never run to the LVC anyway. Get to know your packs. Time your runs, or know how many laps you can do to still put back 80% of the packs capacity when it is recharged. And know what resting voltage that is per cell at the lakeside after a run.

There are many testing devices on the market that can be plugged onto the balance plug & they show cell voltage & remaining capacity in the cells. Very usefull.

Cheers.
Paul.

yes this was my main reason for starting this thread,a lot of esc,s have a very lvc
of 3 or 3.2 volts which was fine with some of the older lower C rated packs
but even $20 packs these days from HK hold there voltage under load rather well
resulting in over discharge of the packs.
i have not tried the castle esc,s but maybe the more expensive esc,s have more higher volt options

[properchopper]

One thing I've never been clear on is just what actually causes degradation of the cells. Is it a voltage threshold, or a capacity drain lower limit. In my experience, the cells I've puffed came in at unnacceptable temps. Is this a product of lowered voltage or excessive current drain ? Given that puffing is caused by the chemicals inside the cells outgassing from reaching their boiling point, what is the actual cause ? Should we be more concerned with a temp cutoff rather than the two above-mentioned suspects. Anyone ?

[ozzie-crawl]

One thing I've never been clear on is just what actually causes degradation of the cells. Is it a voltage threshold, or a capacity drain lower limit. In my experience, the cells I've puffed came in at unnacceptable temps. Is this a product of lowered voltage or excessive current drain ? Given that puffing is caused by the chemicals inside the cells outgassing from reaching their boiling point, what is the actual cause ? Should we be more concerned with a temp cutoff rather than the two above-mentioned suspects. Anyone ?

but is it the fact they have dropped to much capacity or voltage causeing the cells to break down and get hot.
i have only puffed 2 packs,both at the same time,sucked to much capacity out but cells were at acceptable temps

[SweetZ28]

I have a seaking esc it has setting for different LVC i set mine to the highest voltage setting i believe its 3.4V cell mine works ok at that voltage.