Lipo dropped below 3.2v :(

[Mulisha]

Turnigy nano tech 5s 5000mah. Ran in zonda few times, no idea what happenedthis time but one cell dropped below 3.2 (checked with cellmeter7) got home put on charger says R: 4ser S:5ser. But on the cellmeter and on the charger when I charger it I can see each cell and after a little balance charge they all around 3.5-3.6. HelP please what does this mean? Charging it when it says 4ser 5ser a bad thing?

[Mulisha]

Also after the weekends fun you should store the batteries around 3.8 I have read? To charge them up do you put on storage mode or just balance mode and keep an eye on the charger and stop when they get to 3.8?

[Peter A]

The cell voltage can be down after running, mostly I set LVC at 3.2v, they will come back up and at 3.5-6v are good to storage charge to. Use the storage function, that's what its designed for. Storage voltage is 3.8v.

[Mulisha]

What about both my chargers reading the lipos as 4 cell when they are 5 cell? Used these batts in the boat 5-6 times never had them drop that low lvc is set.

[Mulisha]

All good balanced charged at 0.1 for 10 mins and now reads R 5ser S 5ser putting on storage charge for next weekend

[785boats]

Mulisha.
What I'm reading is that you are over discharging the packs.
After a run in the boat the resting voltage should be no less than 3.7V. That leaves the packs with 20% remaining capacity.
Yet you state that after some charging they have come up to only 3.5-3.6V.
Because the voltage is so low, especially with one cell at only 3.2V your charger only registers the voltage of a 4s pack,even though you have it set for 5s. Your charger is telling you that the pack is over discharged.
What value is the LVC set at? What ever it is, it is too low. Raise it up a couple of points. At least 3.4V - 3.5V
You should time your runs to leave more in the packs, not until it hits the LVC.
If the resting voltage after a run is only 3.2V, then under load, the voltage would have been a lot lower. That's bad for the packs. They won't last long if you keep doing that. It sounds like that one cell has already developed a higher resistance than the others & may become a problem.

Cheers.
Paul.

[Mulisha]

First time it has ever happened I know the cells got to low. I think it was because we were testing the new rudder, so taking it out giving it a small run then checking water was flowing and temps. Just forgot to check the batteries, to many short runs. Will have to double check the LVC setting the new cell meter just turned up so that will make it easier to check as well. Def not going to happen again I don't want ruined batts

[MarkF]

3.7 is now the new recommended cut off for today's Lipos.

Mark

[Peter A]

3.7 is now the new recommended cut off for today's Lipos.

How does this leave us for lvc on existing esc's, eg the program card for turnigy/seaking has 3.4v as the lowest lvc. Also will the higher lvc give sufficient runtime for races, or does improved cell design hold higher voltages?

[BHChieftain]

Hi,
Using the voltage as an indicator of remaining pack capacity is not very accurate-- you should calculate how many mah you actually put back in the packs and adjust your runtimes accordingly-- use a timer vs. using the ESC LVC.

Chief

[MarkF]

To add to what Steven just said I have never had a speed controller lvc work correctly. Usually when they kick in its already to late. That's why 3.7 or 3.6 is recommended. But it's best to time your runs and never hit lvc.

Mark

[kitekook]

I had the same problems with my ESC Aquastar120A/Nano Tech's


I thought it was the cheap batteries....then I came up with this solution.


I was helping a friend program his ESC...he was using 5S ,and at the time, I was still using 4S

The Aquastar can be programmed to accept several size batteries....

It dawned on me that the ESC is not measuring individual cells...only total voltage!


So, running 5S ....I tell my esc that I am running 6S and set the LVC to 3.0v


6 x 3.0 =18v will trigger the LVC

18 / 5 = 3.6v

Now, the LVC kicks and I come in to 3.6 -3.7v/cell ~14-18%


I have been running this way for at least 500 cycles,

This has made my batteries much happier! Cooler, better balanced, and not a hint of puffiness!



Do the math to find the combo that gives you the desired V...

3.0v/set at 6S... works great for 5S

2.9v/set at 5S... works great for 4S

[Mulisha]

Kite thats pretty good way to work it out, even with timing runs working the LVC out like that is extra protection

[martin]

I take it that if your running 6s you cant set the esc in this way as most esc that I have jump up to 8s with no 7s. Just checked & most of my esc are 6s max so looks like setting higher cell count is not possible.Thanks.

[urbs00007]

3.7 is now the new recommended cut off for today's Lipos.

Mark i have a cell checker. so when i bring the boat in and check cell voltage, dont run anymore when i hit 3.7 volts?

[urbs00007]

i have a cell checker. so when i bring the boat in and check cell voltage, dont run anymore when i hit 3.7 volts? can you figure a voltage drop for a sport set-up and come up with a lvc that will work at that number and eliminate timing runs? pita timing when you are tuning a boat constantly changing strut etc.

[MarkF]

You are at 80% at 3.72 resting voltage. This is the # you don't want to go under. So your cut off can be set to 3.5 or 3.6 The higher the amp draw your boats pulling the lower you can set your LVC because it will spring back up more. For sport set up I would use 3.6 and then check your voltage after your run to see if the LVC worked correctly or not. I have found the LVC on most esc do not work that well so you need to adjust your LVC untill it does.
Thats why most people say time your runs. When I go out I do 7 laps and bring it in because that is how long a race is. I never try to squeeze every mah out of my pack when I run my boats. I think the sweet spot for a 5000 mah pack is no more than 3500 mah when I recharge. Your packs will last so much longer if you can do this. This by the way is for all lipos, not just the ones I sell.

Mark

[jcald2000]

I agree 100% with Mark!

[Brushless55]

Turnigy nano tech 5s 5000mah. Ran in zonda few times, no idea what happenedthis time but one cell dropped below 3.2 (checked with cellmeter7) got home put on charger says R: 4ser S:5ser. But on the cellmeter and on the charger when I charger it I can see each cell and after a little balance charge they all around 3.5-3.6. HelP please what does this mean? Charging it when it says 4ser 5ser a bad thing?

If your pulling more than 80% out of your packs with these high amp toys you run a risk of hurting your packs
I've actually ran some packs to 3% before on acident and they bounced back but I do not recommend that