What’s your high charge rate experience?

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I wasn’t suggesting charging at 10-20c
I was just saying I thought @Synchronicity was joking
My sarcasm meter when I read that post...
dc cinematic universe GIF
 
I can only tolerate very obvious jokes in these type threads.
When it comes to Lipo safety, I rather be straight forward and that tolerance of sarcasm is limited to 'wrap into gasoline soaked rags for cooling'.

There are 'speedcharge' people out there, and 10-20C is not unheard of in the crazy Quad racing world. At least based on some posts I have come across. Never seen it myself as it makes little to no sense.
 
I can only tolerate very obvious jokes in these type threads.
When it comes to Lipo safety, I rather be straight forward and that tolerance of sarcasm is limited to 'wrap into gasoline soaked rags for cooling'.

There are 'speedcharge' people out there, and 10-20C is not unheard of in the crazy Quad racing world. At least based on some posts I have come across. Never seen it myself as it makes little to no sense.
Fair point. Though I'd consider things like wrapping in aluminum fairly innocuous.

To be straight forth: the general consensus is charge at whatever the manufacturer recommends, or if not stated, 1C. Charge above that at your own risk, much the same you would driving faster than the speed limit. A few mph or kph over the limit will likely be fine. But when you far exceed the limit, you're rolling the dice. So be prepared to accept that risk and/or mitigate it somehow.

I think my general question for you high C chargers out there is: what the ultimate benefit for 2C+ charging (when not racing)?
 
Only benefit is less charge time, nothing else.

Example: I have 10 batteries to charge (normal day for me), cutting the time by ~1/3 is a big deal.
I bought a 2nd charger instead (2x dual ports), with parallel charging I'm done in 2h at regular 1C.

I can see some events where you are on site and you want to run again and have no patience, that is where it would come in handy but at a very high risk.
 
Only benefit is less charge time, nothing else.

Example: I have 10 batteries to charge (normal day for me), cutting the time by ~1/3 is a big deal.
I bought a 2nd charger instead (2x dual ports), with parallel charging I'm done in 2h at regular 1C.

I can see some events where you are on site and you want to run again and have no patience, that is where it would come in handy.
"Whether to fast charge or not" really ends up being a question about economics then. Fast charging will statistically shorten the life of your batteries, leading to buying more batteries.

So you as the end user get to decide whether you will spend more money buying new packs that potentially puff or fail in shorter time after successive fast charges, or to spend money up front and buy a second charger (or parallel charging board) to allow more charges at the normal C rating at any given time.

Does that seem like a reasonable assessment of the options?
 
Does that seem like a reasonable assessment of the options?

I think so, and I agree that it's an economics problem, though without good quantitative data on how much higher charge rates impact longevity and risk, we probably can't use the methods of economics to answer the question definitively.

Personally, I err on the side of conservatism and round to the nearest 0.5A multiple at or below 1C. 5200mAh gets 5.0A, etc.. jkflow is right to point out that once balancing time is factored in, the time savings of a higher charge rate is less alluring. Say within the manufacturer rating and you should be okay, but as this report points out (pg. 57-60), latent mechanical damage can still cause a battery with no visible damage and reasonable charging parameters to go up in thermal runaway. Latent mechanical damage is highly likely in our application, so I use something more robust than aluminum foil to contain a potential fire.

2022-08-01_batsafe_d6.jpg
 
I think so, and I agree that it's an economics problem, though without good quantitative data on how much higher charge rates impact longevity and risk, we probably can't use the methods of economics to answer the question definitively.

Personally, I err on the side of conservatism and round to the nearest 0.5A multiple at or below 1C. 5200mAh gets 5.0A, etc.. jkflow is right to point out that once balancing time is factored in, the time savings of a higher charge rate is less alluring. Say within the manufacturer rating and you should be okay,
Agreed, and the economics are going to be based on the batteries in question and how hard you abuse the lipos. Ultimately a case by case decision based on each person.

I will also add that as fast charging will more quickly increase IR. And as IR increases, charging time increases. Because the pack voltage will more significantly "swell" as external voltage is supplied from the charger, and once you remove the voltage from charging, pack voltage will "settle" back down. Essentially the same as voltage sag on high IR batteries during discharge, but in the opposite direction. This means that fast charging has short term benefits, long term drawbacks. I think that's something to consider too.
but as this report points out (pg. 57-60), latent mechanical damage can still cause a battery with no visible damage and reasonable charging parameters to go up in thermal runaway. Latent mechanical damage is highly likely in our application, so I use something more robust than aluminum foil to contain a potential fire.
Ugh i'm such a nerd. I actually wish I had time to read this whole report.
 
The reason I brought this up was because a lot of my understanding of lipos came from rcgroups. A lot of it is summarized here

https://www.rcgroups.com/forums/showthread.php?1330647-Proper-(-)-LiPoly-management

So this guy, everydayflyer, tested lipos and felt that charging at 5c was fine for quality batteries- thunder power at the time. There’s a link in there showing his data.

Based on no data. My guesstimate is I would think that 2-3 c would be fine for batteries of decent quality. ) 1c for Crap batteries.

This is from over 10 years ago. I would think lipo tech is better now.

So I guess I’m surprised everyone is freaked out about greater than 1c charging.

I seem to remember charge rates above 3c are kind of diminishing returns. Greater than 5c charging might save you a few minutes. But isn’t really worth the strain on the equipment for benefit. I seem to remember 1hour for 1c. Maybe 30min for 2C. 20-25min for 3c. I think at 5c you could get down to about 15 min.
I think because the constant voltage stage of the charge is the slow part. Most of the battery is charged in the constant amp stage of the charge algorithm.

Since I don’t have any studies or vast experience to draw from, I guess I was hoping someone would know.
 
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At the end of the day, it boils down to your risk tolerance. There are many things you can do.

As long as you stay within the manufacturer rating you should be fine, but for me the time savings of >1C isn't worth any additional risk. The batteries most of us are probably buying are likely not of the highest quality and consistency.
 
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?
But they do, though
This is a 3S 8000mah gens-ace-r-spam.

IMG_20221119_125154736.jpg

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.
Fast charge does balance. Charging a brand new 4S 8000 mah for the first time right now.
 

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Slow and steady wins the race.

If you have multiple batteries and at least one dual charger, even a single port charger, then you can charge one or two batteries up hours before you run your RC, or the night before. You then always have one battery on charge while you use the other, and you wont run out of batteries during your RC run time. Its just a matter of timing things and planning ahead. If you cant charge while running your RC, maybe because you don't want to leave it unattended (which you shouldn’t) then charge up the predicted amount of batteries you think you’ll use during your fun time the night before. I also noticed I can cram a few more mAh into the battery when I charge at lower rates. I always charge my batteries in lipo bags in the middle of my garage floor with nothing even close that can burn so if god forbid, something does go, it is not going to burn down my house.

I usually charge my 5000 mAh batteries at 2 amps balance charge and they have been charged a lot over the last year plus and they are still going strong. I always store mode them at the end of that day to keep them in a stable state.

The argument that longer charge times at lower amperage vs shorter charge times at higher amperage's is safer doesn’t hold water. No battery technology likes to be charged at or near its maximum limit. Charging any battery at lower rates is safer than doing it at a higher rate. The harder you push almost anything, the more likely you will experience a failure, or reduced life. Same applies with the discharge rates too.
 
I charged my two 4s 11Ah lipos in parallel yesterday at (almost) 2C. So that's 44amp charge rate, but my Powerlab8 v2 is limited to 40amps. My two 12v DC Dell server power supplies wired in series were pulling 1000watts combined from the wall.

It's neat to charge at higher speeds, but I won't be doing this regularly. Whole thing felt like a ticking bomb.😬
 
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.
Diminishing returns is a fickle mistress.
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?
All of mine say the charge rate on the battery except for the ones that came with some RTR cheapos.
But they do, though
This is a 3S 8000mah gens-ace-r-spam.

View attachment 257099

Fast charge does balance. Charging a brand new 4S 8000 mah for the first time right now.

Idk why but I thought I remember reading that the fast charge didn't balance and that is what made it "fast" so Ive never bothered to try it.
 
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The reason I brought this up was because a lot of my understanding of lipos came from rcgroups. A lot of it is summarized here

https://www.rcgroups.com/forums/showthread.php?1330647-Proper-(-)-LiPoly-management

So this guy, everydayflyer, tested lipos and felt that charging at 5c was fine for quality batteries- thunder power at the time. There’s a link in there showing his data.

Based on no data. My guesstimate is I would think that 2-3 c would be fine for batteries of decent quality. ) 1c for Crap batteries.

This is from over 10 years ago. I would think lipo tech is better now.

So I guess I’m surprised everyone is freaked out about greater than 1c charging.

I seem to remember charge rates above 3c are kind of diminishing returns. Greater than 5c charging might save you a few minutes. But isn’t really worth the strain on the equipment for benefit. I seem to remember 1hour for 1c. Maybe 30min for 2C. 20-25min for 3c. I think at 5c you could get down to about 15 min.
I think because the constant voltage stage of the charge is the slow part. Most of the battery is charged in the constant amp stage of the charge algorithm.

Since I don’t have any studies or vast experience to draw from, I guess I was hoping someone would know.

Some high end packs like SMC are rated at 1-5C, and while I personally wouldn't do it, you may find it acceptable to use the upper end of this range, though their website notes that high charge rates will put less energy into the battery and reduce the cycle life. 2-3C should be reasonably safe, but I question if it's even worthwhile to go above 2C in any circumstances. Assuming 10m balancing time, 1C from storage to full is ~40m, 2C ~25m, 3C ~20m, 5C ~16m. The latter two save minimal time but increase risk and decrease longevity.

Lower end packs are typically rated at 1-2C, and I definitely wouldn't exceed the upper end of this range. 1C is the standard, conservative recommendation for a reason, and 1.5-2C is for if you're in a hurry and can tolerate more risk and degradation.
 
Have been charging all of my packs at 3c for years. Never a problem. All are like new and doing great. It won’t hurt a thing.
Thank you for reporting your experience! Do you have all different kinds of lipos?
 
I'm a 1C guy, Don't have too many high quality batteries.l, so I keep it simple. Also have a Bat box. Will probably get another before nexts years bash season.
 
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