No wonder my battery is puffy, and I've been in the hobby for 3 years, thanks for the awsome video

@RcHelpDotCom

5 жыл бұрын

I'm glad I could help out 👍

I've watched ton of videos on youtube....but yours is the cleanest explanation so far...thank you !!!

finally got an answer to my puffy batteries - great vid

thank you for this ! been kinda worried when looking for batteries so this helped !!

Best explanation. Thanks for the rundown for dummies👍

Great video, to the point. Thanks bro!

Thanks so much for this.. got back into hobby few months ago still learning did not want to hurt my arrma outcast !

Great explanation!

💥 BOOM LOVED IT ! Simple and to the point thanks

@RcHelpDotCom

5 жыл бұрын

Glad I could help out Carlos. www.Rc-Help.com

Thanks that’s the answer to my issues, as my motor was cutting out, and I thought it was because I ran a 75c through a 30A esc

Thanks for the info, subscribed to your channel !!

@RcHelpDotCom

3 жыл бұрын

Thanks for the sub! www.Rc-Help.com

wow, this is the best info i have gotten on the C-Rating... i'm getting a higher C-rating...been trying to find the right combo .. i already have a 30C ESC and a 1534Kv 2-3s Li-Po electric motor for a foam training plane with a 48" wingspan (i know that's a lot smaller than a lot of Horizon Hobby trainers but it's hard to scratch-build a 51" or 58" wingspan guys, IMO). thanks for the great, great video. I will click your link for the combo suggestions.

@RcHelpDotCom

4 жыл бұрын

There is no such thing as a "30C ESC". I'm guessing you means 30 amps? Glad I could help out with some information.

Thanks, very informative. This helps out a lot! 👍

@RcHelpDotCom

Жыл бұрын

Glad it was helpful!

Well said. Completely understand now.2 thumbs up.

@RcHelpDotCom

4 жыл бұрын

Happy I could help out Buddy!

Thanks for the info, you've explained it pretty well. I've been considering getting back into rc trucks, but electric this time instead of nitro and I hop in seeing lipo this lipo that, when I was in the hobby last nimh was the thing to use and lipo was for the rich folk with nothing better to do lol. So I never learned about it. I know a bit about li-ion batteries but not lipo and this c rating I kept seeing with the brushless setups along with conflicting info saying I need this much but not that much blah blah. I think I know what I need to look for now for the motor set up I plan on running now that most of my confusion is gone.Thanks 😊

Thank you , it was very clarifying.

@RcHelpDotCom

6 жыл бұрын

My pleasure Calo. www.Rc-Help.com

Best explanation by far

Tony, Thanks this is Good info, I need to get back over to the forum..Its been a while.. James

@RcHelpDotCom

6 жыл бұрын

Hey James, it has been a while. Hope to see you over there soon. Thanks for posting on the video!

This came in handy while researching batteries for Airsoft. Thank you.

@RcHelpDotCom

2 жыл бұрын

My pleasure!

@Blizofoz45

Жыл бұрын

The lack of progress and knowhow is in the AEG hobby is amazing. People raving about Deans connectors and brushed motors...it's a hoot for anyone coming from the FPV hobby. You guys could do so much better...

thanks tony this helped allot keep it up

@RcHelpDotCom

6 жыл бұрын

My pleasure bro! Hope to see you tomorrow as long as the weather holds.

Great help👍

I've been using 75c lipos for my 3 and 4 inch quads. I accidentally bought two 850mah 45c batteries. I assume the 45c batteries are good for cruising but not for freestyle flying where I have a lot of full throttle blips?

Is higher c rating heavier or anything negative about going over board?

Thank you, i now understand!!!

I love your explanation, so spot on! Good job! Just one question, does higher C rating means it discharge the battery faster with a lower C rating?

@MohammedNovalija

8 ай бұрын

Obviously he never explained the "C" Rating so how is it a good job ?

Perfect info.

I have a castle creations Mamba Monster motor and esc in my RC8 with a Venum 4S 5300 70C battery that performed great. It recently died. I bought a Zeee 4S 6300 80C. Is this suitable or should I go higher on the C rating ?

Thank you so much love you man

Thank you ! Very helpful.

@RcHelpDotCom

Жыл бұрын

Glad it was helpful!

Wonderful , thank you!

@RcHelpDotCom

5 жыл бұрын

My pleasure. www.Rc-Help.com

Does putting them in series doubles the C rating? Or does the C rating stays the same. Say two 2s lipo with 50c makes a 4s 100c when connected in series?

I will need a battery pack that can take a continuous draw of 20.83 amps. I need to know if each battery in the pack has to meet that rate or if that rate is increased by wiring in series.

So my stock car came with 25c rating if I use a 30c rating it could in crease my performance, if it can handle more? Than 25 c?

I have one battery of mini RC Heli of 1S 3.7v And 300mAh and I bought new battery 3.7v And 500mAh thinking it will give me more fly Time but it just wont work. It stops immediately I think it has something to do with these C rating. Can I change C rating by manipulating circuit on battery?

Thanks. Does this mean lower c rating gives longer flight time! I am confused because I got 4S 120c packs which give me less flight time thinking of dumping the batteries, so why higher Cs are more expensive ? ! I just ordered 100c. Should I order 20c better! I am flying a T28 FMS Trojan 1400mm aircraft. Is this also applicable in rc cars ?! Looking for high speed and longer flight time. Thanks

I just bought a 2s lipo with 100c. I shouldn’t have to worry about it puffing up now right?

Hey I love ur videos! I have a 2300kv motor and a 40 amp ESC. The battery I wish to purchase is 1000mAH and has a C rating of 20. The voltage is 11.4V. I have calculated the continuous discharge is 20A. Will this work with the 40 amp ESC?

@RcHelpDotCom

4 жыл бұрын

From the number you have provided, I will have to take your word on the 20 amps for the motor. kv does not tell me anything about the motor other than how many rpm the motor will spin with a given voltage. But, at 20 amps, yes, the 40 amp speed control will be just fine.

Really helpful video.i have a question too.the esc i'm going to buy is 60a and it says maximum 3A.How to calculate the power to buy a lipo with correct power?

@RcHelpDotCom

5 жыл бұрын

The 60a rating is going to be your motor rating, the 3a is going to be your BEC rating or how much power your servos can pull. As for matching a battery to everything, check out this video kzread.info/dash/bejne/fqCHw5SfZ5m3mbg.html

Great video. You explained it well! But I still have a question(what else is new). How does one determine c rating? It it determined by how thick the connections are between the cells? Or is it how thick the lithium metal inside is?

@RcHelpDotCom

5 жыл бұрын

C rating is determined by the manufacturer with much more complicated electronics than I have access to. It has to do with the internal resistance of the cells and how well they do with high current loads. They usually set this figure conservatively and have what is known as a "burst rate" which can be done for no more than 10 seconds. You see this on packs where it says 35/65C and such. But as a consumer, we don't have a way to determine the C rating other than running it at a known amperage and seeing if the pack heats up. I don't have to tell you that this is quite dangerous. Too many amps equals bad things happening to a LiPo.

@Critter0817

5 жыл бұрын

@@RcHelpDotCom Alright thanks. That's helpful. I feel like it kinda had something to do with how thick the lithium metal inside is. Because it's basically lithium metal folded back and forth a lot of times. Say for example a 4000 mah 25c lipo and a 4000 man 50c lipo take up the same volume, but the lithium metal in the 50c battery is twice as thick than the 25c. Thicker metal = higher current. But as a result of it being thicker, it's more brittle and is much more difficult to fold. I only think I know what I'm talking about. I know it's not that simple but, that would make the most sense to me. What do you think?.

@RcHelpDotCom

5 жыл бұрын

In a way, it does have something to do with the thickness. But, the MAH makes more of a difference on the thickness of each cell. More MAH, more thick (bad grammar, I know lol). But I could see how a thicker cell with the same MAH (as you stated) could have a higher C rating. This would bring us back to the IR, and doing it that way may be the manufacturers way of getting around a slightly higher IR so that you can still pull a higher current. Just an aside, I love comments like this. Gets me to thinkin' lol. Thank you.

@Critter0817

5 жыл бұрын

@@RcHelpDotCom No problem! But what I actually meant by thickness was not the thickness of the cell itself, but the thickness of the lithium metal inside each cell. Like, the inside of a lipo is basically a long but thin sheet of lithium metal I think. And that sheet is folded over many times and I believe theres an insulin that separates each fold. So lets say, for example, you have two batteries. Both batteries and the same physical size. Wont say the mah of them, but let's say you have a 25c battery. Inside, the lithium metal is folded 50 times. Now the other one is a 50c battery but inside of this battery, the lithium metal is only folded over 25 times. You see where I'm going with this? The litium metal in the 50c battery is twice as thick so it was folded half as many times while still being the same amount of lithium metal as the 25c. As you know, the thicker a wire is, the more current you can safely flow through it without it heating up. Maybe the same goes for lithium metal. 🤷🏻‍♂️

Thank u so much for sharing 👍👍👍👍🙂

@RcHelpDotCom

2 жыл бұрын

My pleasure 😊 www.Rc-Help.com

Sir one cell samsung original i take nd c rate is 2A then our fast charger is 9V 2A so how its use nd plzz explain how it work adapator nd battery

so my rc car has a warning saying that it can only run batteries less than or equal to 25c, why is that warning there, can i run a higher C rating battery even though the car warns me against it?

Question, I have an EDF 5075 kv650 with a hobbywing 160A ESC. It’s rated for 50volts. I used 4x 11.1 3500mah 60C Lipo Batteries in series. And they heat up fast, 1 of them even puffed up. I won’t be able to fly the jet in that state. Will this problem be solved if I go for a bigger C-rating?

@RcHelpDotCom

4 жыл бұрын

Those batteries should be good to 210 amps if they are true 60c packs. The motor, if the one I found is the one that you have (kv means nothing when talking about current, I need wattage or amperage numbers, kv is only rpm per volt), only pulls 140 amps so you are well under the max capacity of the batteries. My guess is that you have not enough air flow over the packs (maybe) or the IR of the packs (internal resistance) is high causing a lot of heat. This is a real issue in cheaper packs. www.Rc-Help.com

Thanks

Tony I got a question for you I want to run a dual two 3s 5000mah lipos instead of a single 5000 pack for scale 600 size helicopter the weight is about the same, with two lipos I can put the on each side and slide them for CG adjustment?

@RcHelpDotCom

5 жыл бұрын

As long as they are secure and your CoG is adjusted correctly, I don't see why not. www.Rc-Help.com

Done subcribe bro.. bro, i have question.. quad fpv can use the 20C rate??

When using a dual connector for such as the arrma kraton, needing to batteries instead of one to the esc, can the discharge rate or c rate be different between both batteries/packs?

@RcHelpDotCom

4 жыл бұрын

They can, but be very careful. When running parallel, it's the voltage (S rating) that really matters.

What's the meaning of to charge at 1c to 3c please explain in simple terms thanks.

What if i need tham in serial and thay have not the same c rating like one is 50 c and second is 80 c it is for small quad but here shouldn't be diference with plane or car

So I still don't know what it means, just that I should use at least 35C or larger, but watching this video I still don't know what C is. Is there a unit of C? How do we apply it?

I have a question, I am looking to buy new lipos for my brushed 1/16 e revo. Is there any difference or drawbacks to going with 35C from my previous 25C? Exact same battery. Also, i am buying new ones because the old ones are bloated, but i think thats just because i improperly stored them for a long time.

@RcHelpDotCom

5 жыл бұрын

There are never any drawbacks to going with a higher C, only advantages. In no way will you hurt anything (other than your wallet) by going with the highest C rating you can afford. And when you store the packs, store them at 3.7 to 3.8 volts per cell. Basically the nominal voltage of the pack. So for a 3s, that would be 11.1. Hope this helps. www.Rc-Help.com

Saw a video on taking the c rating and times it by the mah gets you the amps mine was 15c x 1.5mah = 22.5amps my battery is 1500mah \ 15c .... Not enough play time trying to figure out if it my esc/motor will be ok if i buy a 4000mah \ 30c battery?

@RcHelpDotCom

5 жыл бұрын

You can get as large of a mah and C as you can afford and as the model can carry. Voltage is what matters here. The motor pulls the power, the ESC regulates the power, the battery is just a storage container. C is how fast you can pull that power from the battery. www.Rc-Help.com

Best explanation 🍺

@RcHelpDotCom

Жыл бұрын

Thanks 🙂

Are you sure? Because I got a battery GNB HV 120/240 C and seems like it damaged my ESC (speedybee F405 55A). One of the 4 ESCs of the 4 in 1 ESC sometimes work and sometimes don't after I used this battery. I saw a video from JB saying the opposite. Thanks in advance for your return.

Can i pair a 35c and a 50c lipo? both have 5000mah

Can I use a 2s lipo 80c for Traxxas slash 4x4 without damaging anything. Been using 2s lipo 65c for my truck.

@RcHelpDotCom

2 жыл бұрын

Yes, the C rating can never be too large. Using too low of a C rating will cause the battery to heat up. The only downside to using too high of a C rating is they are more expensive. www.Rc-Help.com

Can we calculate the c rating of a lithium Ion battery?

Ok thanks. At least I get the basic idea and not confusion.

Hi I’m in the beginning process of building an electric surfboard but I don’t want an ESC unless I really need it , can I run my battery straight to an ON OFF switch ? Cheers 🍺

@RcHelpDotCom

4 жыл бұрын

If you have a brushed motor, then yes. If you are using a brushless motor, then no.

Hi there I have a 2s 980mah 30 c.lipo What amp charge rates the best to charge thanks

@RcHelpDotCom

2 жыл бұрын

Depends on the battery. 980mah would equate to the following: 1c charge rate - 0.98 amps 2c charge rate - 1.96 amps Unless your battery states specifically it can handle a higher charge rate I definitely would not go over a 2c charge rate. But to make things easier, you can just use 1amp and 2 amps respectively. No need to worry about hundredths of an amp. www.Rc-Help.com

Okay so my 5000mh with 20c gives me 100amp discharge and that is exactly how much I need, what about if my battery is half full, will It be safe for a battery to pull 100amps ?

@RcHelpDotCom

4 жыл бұрын

I usually like to go with a little higher C so that I'm not maxing out my batteries discharge capability. Just keep an eye on the battery temp. If it is getting warm, you might look into a larger C rating.

Thanks for taking time and sharing all these helpfull tips, this is the best educational video. Tons of videos up in here, most of them are conplete BS and collecting view counts with headlines. But I still have one more question, how can person choose proper C rating battery for a given DC motor ? Thanks

@RcHelpDotCom

4 жыл бұрын

You will need to know what kind of power the motor is pulling. Check out my other video, Matching Motor Battery & ESC --> kzread.info/dash/bejne/fqCHw5SfZ5m3mbg.html

The stock batt in my heli is 300mAh 30C and it always comes down hot, about 120F. I tried a 350mAh 50C. Same thing. You want to take a guess what the problem might be?

@RcHelpDotCom

5 жыл бұрын

That is about 48ºc which is on the warm side, but for a very small battery like this is about normal. However, the 50c should have come down a little cooler unless it was a pretty cheap battery, in which case they like to fudge the numbers a bit. If this is a collective pitch helicopter, I would try lowering the head speed slightly to reduce the strain on the helicopter. If it is a fixed pitch, there is not much you can do unfortunately to save power. Come over to the forum and post this up and lets get some heads thinking on this. www.Rc-Help.com

I got a question sir if i may, will a 2200 mah 20c battery give me the same punch in a multiroter as 1800 mah 25c?

@RcHelpDotCom

5 жыл бұрын

You may absolutely ask questions, in fact I encourage it! In your application, the 2200mah 20c pack will give you 44 amps, the 1800mah 25c will give you 45 amps. So the smaller battery is theoretically able to give one amp more than the later capacity pack. However, your motors will only draw what they need. If you have motors that are only drawing 40 amps, then both batteries are going to be exactly the same as far as "punch" goes because the motors are determining that factor. However, if the motors are wanting 45 amps, then the 1800mah pack will give more "punch", but only because you have exceeded the maximum amp draw of the 2200. With that said though, the 2200 is going to be heavier than the 1800 so even if your motors are only needing 40 amps, it may 'FEEL' like the 1800 has more punch. To understand what I mean by the motor only drawing what it needs, take a look at the video linked below. kzread.info/dash/bejne/fqCHw5SfZ5m3mbg.html

NICEEE

based on the weight of your rc being runned on a single battery pack.. higher c rating means higher torque potential, higher brake power potential and higher acceleration potential. higher c rating wont affect maximum speed. Also too much acceleration is funny first, but it destroy your transmission and differentials...it is better to lower acceleration input by 50% on 2wd cars and 20% on 4wd cars. This way you stay in control and your car doesn't always do whellies. Also your differential will last longer. If you decide to lower your gear ratio to have higher maxium speed. it is very important that acceleration input be reduce otherwise you cause big stress on the motor. This is where higher c rated battries offset can be used to gain back the lost acceleration. instead of putting all the stress to your motor, your battery is going to get stressed so your motor doesn'T over do it. when doing those setups remember to apply auto brakes around 20% and brake power at maximum 50% This way your motor will remain warm and you will not deplete your battery too quickly. There is a reason why huge tires are made for higher gear ratios... not for low ratios.. the transmission and the differentials. when 4 small wheels turn very fast it is easy to make them stop or turn the other way around. Bigger wheels tend to disbalance if you turn to fast and braking them to fast will send all that energy/mass stright to your drive shaft and differentials.. anything can be done on rc cars.. and every rc cars can be lightning fast... but then there is physics..

@RcHelpDotCom

5 жыл бұрын

Higher C Rating only means it can withstand a higher constant draw from the battery by other electronics. It has nothing to do with torque potential. If going to a larger C rating battery gives you more power out of your motor (I use "your" loosely here), then your current battery has a C rating that is too low. The battery is only a storage device. It gives out power to what needs it when they need it. If other items are requesting more power than the pack can handle, then things will start to slow down and the pack will start to get warm. And a warm-hot LiPo is never good as we all know. Thanks for the comment monsterrun.

can i ask you something how much " c " is there in a 1200mAh 7.4v LiPo battery?

@RcHelpDotCom

3 жыл бұрын

It doesn't work like that. "C" is a calculation from the manufacturer that is based on the internal resistance of the pack and what the pack can handle to discharge at one time. As a safe bet, you can calculate almost any battery at a 20c discharge rate unless the IR is extremely high. www.Rc-Help.com

What battery do you recommend?

@RcHelpDotCom

4 жыл бұрын

They are all about the same pretty much. But Tattu is what I use, Pulse and Glacier are some of the best.

If your C rating is to low can it hurt your battery? Thanks!

@RcHelpDotCom

4 жыл бұрын

Yes, it can make the pack overheat, puff and possibly catch on fire.

Is it okay if may esc is 125a and my lipo rating is 110c ? Thankyou

@RcHelpDotCom

5 жыл бұрын

I have no idea because you didn't tell me how much power your motor pulls. www.Rc-Help.com

@ivansanjosestaana7010

5 жыл бұрын

@@RcHelpDotCom i don't exactly know but i think is 22v with 3100 kv motor

@ivansanjosestaana7010

5 жыл бұрын

thinking if the 110c lipo might damage the esc?

@RcHelpDotCom

5 жыл бұрын

Well, the 22v would be your battery, and there is no way of knowing how many amps a motor pulls from the kv rating, which only RPM per Volt. You can put a 9000C battery on anything, and it will not hurt it. The battery does not push the power, the motor pulls the power. So without knowing how many amps the motor is pulling, I have no way of knowing if anything is going to be damaged. www.Rc-Help.com

What happens if you mix c ratings if building a bigger battery ?

@RcHelpDotCom

3 жыл бұрын

To keep it safe, you will need to know what the lowest C rating is in the pack, and never go above it, no matter what the higher cells are calculated at. I do not suggest building your own battery, but just know what you are working with. www.Rc-Help.com

@stephenclayton999

3 жыл бұрын

@@RcHelpDotCom thanks, i have an ebike and was wondering if i could mix c ratings in parallel

Thanks hey tony where you been no videos in a little while?

@RcHelpDotCom

6 жыл бұрын

Hey bro, yea things went a little south for us here. First my well pump dies again, that's a grand out of pocket, then the washer and dryer start to go out then the fridge starts to go out and that forces me back into a truck driving again. First week in the truck and our granddaughter passes away and we are having to do all of that junk with DHS now since my grandmother has custody of the other granddaughter. It's been a nightmare here lately. I'm trying to get back on track though. Sorry for the delay. Hope to see you on the forum soon. I don't do much here on youtube at the moment (trying though lol) but I try to get on the forum every day.

@drummerdad80

6 жыл бұрын

RcHelpDotCom wow that's a lot to deal with, sorry for your loss

@RcHelpDotCom

6 жыл бұрын

Yea, times are not good, but they will get better. Just sucks that it takes me away from what I love doing.

I just fried my ESC 2s 5200 100c had two batterys in series making a 4s

can higher c rating than recommended damage my rc vehicle?

@RcHelpDotCom

4 жыл бұрын

No, C rating is only the current limit that can be drawn from the battery.

Is c affect the duration of playtime?

@RcHelpDotCom

5 жыл бұрын

No, it only shows what the discharge capability is of the pack. the MAH is your flight time. www.Rc-Help.com

I have a 2s 220c

Any time you say go bigger in a youtube video you get an automatic like

@RcHelpDotCom

5 жыл бұрын

So what you are saying is I should "Tim Allen" more things? lol. NICE!

What about airsoft guns would it be the same

Does the same go for Airsoft ?

@RcHelpDotCom

Жыл бұрын

Yes, A battery is a battery.

Sooooo higher C rating means less flight time??

@RcHelpDotCom

2 жыл бұрын

No, higher C rating means the battery can withstand a higher current draw. www.Rc-Help.com

The Sonicwake V2 36, recamends 50c ratings ,my batteries are 80 C ,horizon Hobbies ,say I can go bigger,new to the hobby.🇨🇦80 c is better than 50c correct thanks

@RcHelpDotCom

2 жыл бұрын

Not better unless your motor needs more than the 50c. Remember, the motor pulls power, the ESC only regulates power and the battery only stores power. www.Rc-Help.com

And voltage

It doesn't help that some batteries fudge their C ratings. My power hobby 50C/100C gets way hotter than my 25C/50C Traxxas

@DaveElectric

7 ай бұрын

Over what period of time? C ratings are based on sub 10 second applications. The actual continuous c rating is 20c or less.

@Ryan96se

7 ай бұрын

@@DaveElectric This was a while back and ended up being a defective battery. Power Hobby reached out to me and replaced it free of charge. The new one only gets warm like the others

All of these BS videos on the internet. Glad this one helped me.

My battery is a 3000 mah 30C, so 30×3000/1000= 90amps max discharge rate, my motor pulls 20A peak+ few amps for receiver and servos, I should be chilling in here ahaha

@RcHelpDotCom

4 жыл бұрын

Yea, that pack shouldn't even get warm lol.

You know your batteries

I suggest Everyone to buy zop power batterys, they Are soo Dubable and dirt cheap! I got like 10 of them, 4 2s, 2 3s and 4 4s (between 60 and 120c

@augustestrellado1156

3 жыл бұрын

I hope someone will also see this comment, you are right that ZOP is cheap i had checked it out, however the durability,,,,, hmmm, let us check it out too,,, anyway.... thank you sir for your very good recommendation and support.

@fran.6496

3 жыл бұрын

@@augustestrellado1156 they Are good!! SOO Durable, i got those 4s for OVER 3 Years and they Are still on 95% health! Perfect

Ohhhhh that why my cheap ass battery is so easily Puffy.

Don't know or understand why anyone would want a 30C battery? I don't own any batteries less than 50C rated.

@RcHelpDotCom

Жыл бұрын

Those packs are quite old and that was the norm back in the day. I do agree though, the higher C you can afford/get, the better! Example, I have a new project I'm working on, Agusta A109 600 size electric, and I'm going to be running a Pulse 5000mah 6s 50c. Thanks for the comment V.E. www.Rc-Help.com

So higher c rating means battery will drain faster?

Does he even explain what the C stands for??

@mamun2a

4 жыл бұрын

1c = 2.2A discharge capacity

@RcHelpDotCom

4 жыл бұрын

C is MAH divided by 1000. As Mamun2a stated, a 2200mah battery at a 1c rate would be 2.2 amps. at 2c, it would be 4.4 amps.

If the "C" rating was explained , how come I am none the wiser ? Because it wasn't.

Go out and get the highest C rated battery that you can find... Don't get more than 35...😏

LOL! First comment!

@RcHelpDotCom

6 жыл бұрын

You are always the first comment lol.

@JaredElliott1

6 жыл бұрын

I'm usually last at everything else...second place is the first loser. LMAO! This is a great explanation though.

@RcHelpDotCom

6 жыл бұрын

Thank you kind sir!

You didn’t at all explain the c number. You simply said the higher the better. Stop making videos that waste people’s time