do low volt cut offs work with todays high powered batteries

[drwayne]

I use to puff a lot and get lvc on accel until I added a capacitor bank and a soft start circuit.

zero probs since then.

I set my lvc at 3.5 and batts after rest show 3.65+ and require <80% recharge

batts that take 5200/5000 [for eg] consume more charge due inefficiency of plugs and then heating of pack under charge.
A warm pack charges better than a cold one.

for the bloke with the pink boat.
poorly soldered leads = poor availability of current/voltage = early lvc activation.
fix your plugs and leads before trying anything re setups.
Eagle tree logs are brilliant when your setup doesnt detract from the tabulated data.
Inexperience/Ignorance is the killer of your batteries from what you've said above


DocW

[Flying Scotsman]

This is a great thread.....Doc, what soft start circuit?...spark elimination resistors?

Douggie

[properchopper]

This is a great thread.....Doc, what soft start circuit?...spark elimination resistors?

Douggie

Douggie, Many ESC's have a "soft start circuit" which applies initial output to the motor gradually instead of in a quick burst to prevent gear stripping [common in helis] as the motor attemps to overcome the resting inertia of the blades. OTOH my ex-wife had a device with a "soft start circuit" to keep her from banging her head on the headboard when starting out with it

[Flying Scotsman]

Speechless......I was wondering if the doc had some other outboard device.

Douggie

[Alexgar]

chopper your to much

[785boats]

That's a great description of how a 'soft start' setting can save a lot of headaches Chopper.

But yes the 'ACCELERATE' mode in the programming is the one.
I always set mine to 'LOW' in my ESCs. It's just so much easier on the poor thing.

On the depletion of a pack , though, I was led to believe that under load as the pack ran out of capacity before the voltage dropped the Temps begin to climb rapidly due to the internal resistance dropping due to the chemical changes. Then the temps reach what is called a 'runaway' state where temperature rises at an exponential rate & the packs puff. This all happens in a very short space of time depending on the load, but can be measured in seconds.

Time for some research.
Paul.

EDIT: Just found this for some light reading. I know it talks about Lithium ion but Lipos are basically the same chemistries with the same properties & problems.

http://www.mpoweruk.com/lithium_failures.htm

[Flying Scotsman]

I feel great the animals have been let out of the zoo....Tony, you are priceless and know your crap....well almost

Douggie

[drwayne]

Speechless......I was wondering if the doc had some other outboard device.

Douggie

I do love the similes some people use to aid in detail......

.. my external soft start mentioned for an esc involves a resistor leakdown which soft charges buffer caps on the esc..saving the battery from a dead short scenario on first connect.
39ohm1W for 4S
52ohm1W for 6s

A Y lead on esc positive RED .. one is main power lead.. other is bypass with resistor in series..a charge lead

Not the black (-ve) because controllers use this as absolute zero ...a floating Gnd on connect introduces issues as each fet controller is buffered from the circuit .. makes staging fet output inconsistent.

connect black leads together.
connect esc red bypass lead with resistor to battery red .... soft charges caps before connecting main red leads.
[Ive a 3mm flylead attached the 6mm mains on battery red.]
The initial charge current for caps can be massive .. and this draw from a fresh pack unaligned internally can cause unrepairable damage to the cell structure.

and further for those adjusted to non US giggles .

Be like chopper's ex plugging in the 'appliance' on 100% when target is cold..get nasty real quick.. fun's over.

page 1 of the beginners handbook on esc/sex..start slow, go hard..disconnect, cool down. .
Some esc have an antispark switch..starts at the flick of a finger. Same concept applies.
You're a smart fella ( self declared) , you understand those words Douglas ?


soft start for heli gets motor to rpm with minimal load applied .....this spoolup would not fire fets at 100%...until target head speed achieved

Different scenario here where marine has full load on startup due prop engaged in water.

[Flying Scotsman]

I do not believe it a marsupial who has a brain...thanks Doc.

Douggie

[drwayne]

I do not believe it a marsupial who has a brain...thanks Doc.

Douggie

I collect them from visiting tourists.

[properchopper]

I do love the similes some people use to aid in detail......

.. my external soft start mentioned for an esc involves a resistor leakdown which soft charges buffer caps on the esc..saving the battery from a dead short scenario on first connect.
39ohm1W for 4S
52ohm1W for 6s

A Y lead on esc positive RED .. one is main power lead.. other is bypass with resistor in series..a charge lead

Not the black (-ve) because controllers use this as absolute zero ...a floating Gnd on connect introduces issues as each fet controller is buffered from the circuit .. makes staging fet output inconsistent.

connect black leads together.
connect esc red bypass lead with resistor to battery red .... soft charges caps before connecting main red leads.
[Ive a 3mm flylead attached the 6mm mains on battery red.]
The initial charge current for caps can be massive .. and this draw from a fresh pack unaligned internally can cause unrepairable damage to the cell structure.

and further for those adjusted to non US giggles .

Be like chopper's ex plugging in the 'appliance' on 100% when target is cold..get nasty real quick.. fun's over.

page 1 of the beginners handbook on esc/sex..start slow, go hard..disconnect, cool down. .
Some esc have an antispark switch..starts at the flick of a finger. Same concept applies.
You're a smart fella ( self declared) , you understand those words Douglas ?


soft start for heli gets motor to rpm with minimal load applied .....this spoolup would not fire fets at 100%...until target head speed achieved

Different scenario here where marine has full load on startup due prop engaged in water.

"My Amp Goes to Eleven" !

[Name that quote ]

[Rumdog]

^^^Spinal Tap^^^

[properchopper]

^^^Spinal Tap^^^

Yeah Buddy ! What a great movie !!

[drwayne]

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 ?

as simply as can be said in 1000 characters or less...
newer cells have better/larger anode/cathode inside pack... along with a more dense compound ( nanotech )
more transfer contact area, less hyperdischarged chemistry due more chemical actively involved in direct contact to energy sump
The more compound directly involved in energy discharge to the drain, the less are hyperdischarged which is what initiated heat build up propogating the collapse of cojoining cell structures.

in addition ( because I hit the save in error.. )

Repeated hyperdischarge of compound is not a recoverable scenario.
Dead compound becomes a hurdle for energy discharge within the pack... causing rapid heating promoting further brakdown.
Once it's started.. it's downhill from there.

If you run new technology cells below a figure of 3.4V you will cause damage to the cell structure.

W

[properchopper]

as simply as can be said in 1000 characters or less...
newer cells have better/larger anode/cathode inside pack... along with a more dense compound ( nanotech )
more transfer contact area, less hyperdischarged chemistry due more chemical actively involved in direct contact to energy sump
The more compound directly involved in energy discharge to the drain, the less are hyperdischarged which initiated heat build up propogating the collapse of cojoining cell structures.

If you run new technology cells below a figure of 3.4V you will cause damage to the cell structure.

Well, I just ordered a pair of the new Turnigy nano 45C-90C 5000 mah packs from HK which just came in stock today. My plan is to Eagletree the voltage drop on the 1P setup in my spec FE 30 with a Hyperion G3 [35C-70C],
Turnigy [35C-40C], and the new nanos. I'll be sure, Dr Wayne, to set the LVC to 13.6 according to what you recommend.

My Amp Still Goes to Eleven