What’s your high charge rate experience?

[Adiabatic]

Contrary to popular belief, there's very little metallic lithium in a LiPo battery, and a fire from thermal runaway is mainly fuelled by the electrolyte, separator and case materials. Scientific studies show that these burn at only about 400°F, less than the temperature I sometimes bake at in my oven, so aluminum foil will definitely contain it.

Higher charge rate also means the batteries spend 10-20x less time on the charger, which means 10-20x less opportunity for a fire to start. Overall, very safe.

 

[SrC]

Dumb question here…. I’ve never used it on my chargers, but don’t most chargers have a “ fast charge” setting? What is that?

Fast charge Mode just means it omits the cell balancing at the end of the cycle. Usually found on old 2 line display SkyRC based chargers. Some chargers will even ask if you want to charge without the balance leads connected. I don't recommend it.
Never fast charge. Many newer smart chargers don't even offer Fast Charge mode these days.
But balancing can be overrided with some of them.
My ISDT and HM chargers will let you know Fast Charge is complete but continues to balance by Default , before it shuts off.

 

[stock20]

I've recently returned to the hobby after 10 years. One thing that's changed is that 10yrs ago most, if not all, lipo brands would print the charge rate on the battery's label. Not in fine print, but more as a marketing tool - even if it was 1C. Today they all print the discharge rate and I haven't found an example of one with charge rate displayed yet. What gives?

 

[stock20]

Contrary to popular belief, there's very little metallic lithium in a LiPo battery, and a fire from thermal runaway is mainly fuelled by the electrolyte, separator and case materials. Scientific studies show that these burn at only about 400°F, less than the temperature I sometimes bake at in my oven, so aluminum foil will definitely contain it.

Higher charge rate also means the batteries spend 10-20x less time on the charger, which means 10-20x less opportunity for a fire to start. Overall, very safe.

I would 2nd your last sentence. This is a real thing. The longer the charge, the more time a short can occur within battery or elsewhere. Have read many stories about fires during a 1C charge (and higher rates as well, of course).

I'm trying not to be naive - was that a serious comment above about charging at 20C? If so, I'd love to know what type/capacity of battery you're comfortable charging at this rate.

 

[SrC]

Contrary to popular belief, there's very little metallic lithium in a LiPo battery, and a fire from thermal runaway is mainly fuelled by the electrolyte, separator and case materials. Scientific studies show that these burn at only about 400°F, less than the temperature I sometimes bake at in my oven, so aluminum foil will definitely contain it.

Higher charge rate also means the batteries spend 10-20x less time on the charger, which means 10-20x less opportunity for a fire to start. Overall, very safe.

I say with that comes a 10-20x higher risk of fire.
Many Pro drivers at the track like their lipos literally "Hot" to the touch . And they do charge as high as 40 amps with the final charge cycle before a race. They say they get incredible Punch/ amp delivery. Usually done with Stock class. But they acknowledge that lipos don't last very long this way. Maybe a few months of racing every week before they become bench packs at best. Losing Mah Capacity, swelling, cell failure.
I don't think its practical for bashing purposes. Some would do this just to speed up charging time. Sacrificing the lipos longevity. 2c is not tragicI IMHO. But I find a 1c rate is most beneficial. Just a good habit. And I feel safer. Charging at higher amps also creates a liability for the charger as well. A charger can fail and cause a lipo to fire up. A fully charged lipo is at its most volitile state. So connected to a charger becomes a fire risk if the charger fails to time out when this happens. Thats why its always good to not let a charged lipo sit around needlessly. And long durations like this causes other issues.

 

[Diem Turner]

I say with that comes a 10-20x higher risk of fire.
Many Pro drivers at the track like their lipos literally "Hot" to the touch . And they do charge as high as 40 amps with the final charge cycle before a race. They say they get incredible Punch/ amp delivery. Usually done with Stock class. But they acknowledge that lipos don't last very long this way. Maybe a few months of racing every week before they become bench packs at best. Losing Mah Capacity, swelling, cell failure.
I don't think its practical for bashing purposes. Some would do this just to speed up charging time. Sacrificing the lipos longevity. 2c is not tragicI IMHO. But I find a 1c rate is most beneficial. Just a good habit. And I feel safer. Charging at higher amps also creates a liability for the charger as well. A charger can fail and cause a lipo to fire up. A fully charged lipo is at its most volitile state. So connected to a charger becomes a fire risk if the charger fails to time out when this happens. Thats why its always good to not let a charged lipo sit around needlessly. And long durations like this causes other issues.

Charging at high rates like pro drivers do is fine, if you consider that they probably all have battery sponsors. If you're paying for your own lipos, I'd think twice about it.

 

[SrC]

That's basically the gist of it.
Dam lipos are just so $$$$$$$$$$.
Lipo manufacturers know this. That is why Mah capacity is based and rated on an "Hour" which always equals 1C. (provided your charger can deliver a full 1c rate)
So in theory, a 1C rate always charges a lipo in 1 hour. (aprox)
Increasing the rate always reduces the time. Pick your poison.

 

[#ARRMArcfanboy4life]

WE WANT TO AVOID ALL THIS. Don't charge your batteries higher than they are rated for. LiPo PSA over.

 

[Diem Turner]

 

[olds97_lss]

1C-2C at most for me.

I have 2 20A chargers that I use for parallel charging and I'll charge up 2 or 4 5000mah or 6200mah 6S packs on them at a time. If I have just 2 packs, I set the amps at 15/18 respectively. If I'm charging up 4 on each, then I set them to 20 and wait. I usually charge the night before now anyway, so 1C charge works fine. I lose a little off the top from letting the packs sit for 6-8 hours charged (finish charging at 1am-2am and get up at 7am to go run by 9am).

 

[dk10438]

I find it somewhat ironic that people are so concerned about charging over 1c but have no concerns about high rates of discharge such as speed running. That’s probably as hard or harder on the battery.

Not sure if aluminum foil would stop a fire but I thought he was facetious anyway. 10-20c would pretty powerful charger….

 

[Hector_Fisher]

I find it somewhat ironic that people are so concerned about charging over 1c but have no concerns about high rates of discharge such as speed running. That’s probably as hard or harder on the battery.

Not sure if aluminum foil would stop a fire but I thought he was facetious anyway. 10-20c would pretty powerful charger….

It's down to the chemistry of batteries. Nimh, Nicad, lipo, li-ion, lead-acid, all have to be charged slower than they can be discharged. Can you imagine being able to charge a car battery at 600 amps??? That would be freaking awesome!!!

 

[Diem Turner]

I find it somewhat ironic that people are so concerned about charging over 1c but have no concerns about high rates of discharge such as speed running. That’s probably as hard or harder on the battery.

Well, let's look at a battery's factory specs. They're typically rated for charge rates of 1-5C but have discharge rates of 30-100C. So there's definitely something about the battery that makes taking the energy out of them less stressful for the battery than putting the energy back in. I'm sure it has something to do with the chemistry and what's going inside the battery, but I just lack the technical knowledge to explain it. At any rate, this tells me that they're optimized for energy release and not energy absorption.

 

[olds97_lss]

Not sure if aluminum foil would stop a fire but I thought he was facetious anyway. 10-20c would pretty powerful charger….

Or a small pack. A 2000mah pack at 1C would be 2 Amps. Pretty easy to find a 20A charger to hammer that thing to death at 10C! LOL!

 

[dk10438]

Or a small pack. A 2000mah pack at 1C would be 2 Amps. Pretty easy to find a 20A charger to hammer that thing to death at 10C! LOL!

it's wattage of the charger that's going to be the limiting step....LOL

 

[olds97_lss]

it's wattage of the charger that's going to be the limiting step....LOL

150W/20A would do 10C for a 2000mah 2S pack, right?

 

[jkflow]

Late to the game, always follow the suggested charge rate direction by manufacturer. Example: Some older Zeee were only rated at 0.8C.
I usually follow the 1C rule, but more often than not I just set the charger to max amps (6.2 ~150W on 6S) and charge everything that way. That is of no impact at 1.2C and saves fiddling with settings.
Some are rated at 5C, don't have supplies with sufficient ooompphh to do it, but would without hesitation on those packs. Yes, there is always a safety margin.

All Lipos will see an impact on life if you go higher. Charging generate heat that will cause degradation or catastrophic failure. The actually anode/kathode will degrade, and you will be able to transfer less power (IR increases as well).
You will always chemically alter the cell which releases more gas and that might cause slight puffing, not a big deal, but for some it's the end of the world.

Aluminum foil wrap is more effective acting as a tinfoil hat, definitely won't do anything for a lipo fire, but feel free to show us otherwise.

10-20C charge rate, simply dangerous and will destroy the Lipo in a short period of time. My guess 20 cycles max and it's done. Extreme high risk of something going wrong. Outdoors only, if you do it. Seen claims of many doing flight packs or Quads that will do this, seen many of them blow up as well. Never seen a claim that they do this by default, or they accept that lipos only last a short duration.

In all cases the balancing eats a lot of time
1C ~30 min charge from storing + 10min balance)
2C ~15Min + 10min
3C ~8min + 10 min
etc
Insert your real life timing, but going from 3C to 30C to gain a 5-min reward seems a little silly to say the least. Cheaper to buy additional packs and have less risk.

 

[SrC]

I find it somewhat ironic that people are so concerned about charging over 1c but have no concerns about high rates of discharge such as speed running. That’s probably as hard or harder on the battery.

Not sure if aluminum foil would stop a fire but I thought he was facetious anyway. 10-20c would pretty powerful charger….

Sorry but at 20C rate, no lipo will survive. Do it and risk all.
You might as well just use a high amp settable DC power supply to charge direct at that point.

 

[Diem Turner]

FWIW, I took that as a joke. Same with the tin foil. Same with the 400° temperature.

 

[SrC]

Yeah its more like 3 times 400F to be exact.