Batteries' C rating?

[Hummina Shadeeba]

I'm new to this. I understand that the c rating is a
Multiple of how fast the battery can discharge amps but how does it
Relate to me and my set-up?
I got (3) 2s 20c 5000mah batteries I plan to use. What's going to happen?

Here's my parts:
our order details are:
2x #9261000012/28223 HobbyKing 90A Boat ESC 4A SBEC = 63.38
2x #SK3-5065-236/18126 Turnigy Aerodrive SK3 - 5065-236kv Brushless Outrunner Motor = 113.72
4x #Z50002S-20/8578 ZIPPY Flightmax 5000mAh 2S1P 20C = 61.48
1x #ACC6/7028 Turnigy Accucel-6 50W 6A Balancer/Charger w/ Accessories = 22.99
1x #9052000014-3/20968 Hobbyking 60w Power Supply = 9.99
1x #9114000006/31671 HobbyKing HK-GT2B 3CH 2.4GHz Transmitter and Receiver w/Rechargable Li-ion Battery = 23.63

 

[made_in_the_alps_legacy]

I'm new to this. I understand that the c rating is a
Multiple of how fast the battery can discharge amps but how does it
Relate to me and my set-up?
I got (3) 2s 20c 5000mah batteries I plan to use. What's going to happen?

- "C" is actually [/h] : (20C : 20 "time its capacity per hour")
meaning that a "20C 5Ah" battery like mentionned can discharge 20 x 5Ah, so 100A, which is generally not an issue.
- Other chemistry, can go down to 2C, which then become a limiter in your power train
ex: 12Ah 2C would discharge about 24A at its maximum
- you can work around the numbers if your battery will be able to supply the electrical power your ESC will ask from it
- you should also see a "C" rating for charging (not only discharging)

 

[666yeti666]

I have mentioned somewhere on this forum about " C ratings" and their meaning.

As mentioned by legacy_alps , C rating is an indication to what current a pack can be discharged. But don't take it too seriously since there is no more details under this specification that guarentees a certain voltage that it can keep under that C-rating, so it's a rather useless specification of a manufacturer.

Usually, the higher the C-rating the LOWER the internal resistance will be, and the HIGHER the battery voltage remains under load. But lots of reviews and tests revealed that brand A can perform significantly worse then brand B.

Unfortunately the voltage under load is not normalized by the battery industry.
(one could make a same kind of comparison to an audio amplifier of which the output power is stated as 1000Watts without mentioning the harmonic distortion, which is also useless without the latter...)

However, for our purpose of electric skateboards, the C-rating is of less importance since we use very low AVERAGE currents. 20C will be ok.

regards
Sebastien

 

[Rosco]

Only 5000mah though?

Most boards get about 1 mile per Ah. I'm taking it you're gonna hook up all batteries in series to make an 8S battery? Cause 2 or 4S won't have enough Voltage to push you very well...

If you are considering doing that, Have a look at the HobbyKing Quattro, makes charging batteries much faster. Also, these are very handy (I use the XT90 version cause I run 6x 6S batteries in my backpack), they save a lot of time soldering and make recharging a matter of unplugging and replugging.

http://www.hobbyking.com/hobbyking/store/__10264__xt60_harness_for_2_packs_in_series_1pc_.html

 

[torqueboards]

I've always found pre-made series connector wires way too short to be flexible. I'd probably suggest making your own as you can customize the length if you need too anyways and your able to bend the wires.

You don't necessarily need a HK Quattro charging in parallel works just the same unless your trying to charge 4x6 packs but then your charging amps goes down.

 

[Hummina Shadeeba]

Thanks for ur input. I plan to connect three of these batteries. 6s 15000mah is 15ah I hope.

I'll likely be having to lengthen lots of connections. Not that I have any idea how to do it but I'll be looking it up

The specific "skateboard etc" search function on this site doesn't seem to be working. I'm sure I'm asking things that've been asked before

 

[made_in_the_alps_legacy]

3X2s in series gives 6s, unfortunatly, in series, the capacities do not add up: u will have 5Ah...

 

[Hummina Shadeeba]

3X2s in series gives 6s, unfortunatly, in series, the capacities do not add up: u will have 5Ah...

Uggghh!
I planned to connect three 2s 5000mah because they were thin and I thought I then had 15ah. Should've known it was too good to be true. I'm not returning them because it's too far...if anyone is interested in them....or maybe it'll be a shorter trip board

I'll be looking for the thinnest 6s I can find if anyone thinks they know. Or maybe I'll be learning about how not to
blow one's self up making battery packs. I have an obsession with getting it all super thin and mounting everything IN the board and doing layers of carbon on the bottom to support

 

[made_in_the_alps_legacy]

5Ah x 22.2V = 111Wh
Assuming 10 to 15 Wh/km gives 7.4 to 11 kms,
Not too bad for a "Short trip" Don't u think ?

 

[psychotiller]

3x2s 5000mah in series = 6s @ 5000mah This is alright but you wont get the milage you're likely after.

3x2s 5000mah in parallel = 2s @ 15000mah This really wont work because you wont have the voltage you need.


3x2s 5000mah in series = 6s @ 5000mah + 3x2s 5000mah in series = 6s @ 5000mah = 6s @ 10000mah

Or 2 6s 5000mah Zippy Compacts will get you the same thing for $105 (but they are thicker)

 

[Hummina Shadeeba]

Thanks. I get it. Duu.

I really want an 8-10 mile range though. Otherwise I'll get to town n be pushing home

What u think about making a pack or isn't there something thinner out there already made? I
guess not or people would be using it. I want to get it about 20mm thick. No one wants to ride a brick.

 

[torqueboards]

Thanks. I get it. Duu.

I really want an 8-10 mile range though. Otherwise I'll get to town n be pushing home

What u think about making a pack or isn't there something thinner out there already made? I
guess not or people would be using it. I must get it about 20mm thick? No one wants to ride a brick.

I use (2) Zippy Flightmax 3S 5000mah 20c in series for 6S as one pack. I carry (2) sets of these packs along with me. Each pack gets me 6-8 miles on average. 6 miles x 3 = 18 miles to 24 miles. I charge these (3) packs 6 batteries in total with a HobbyKing 350W and iCharger 208B Charger at 20 Amps ($160 for the charger set) in parallel in about 30-45 minutes. I get 18-24 mile range from those 3 packs. IMO, that's the best way to go about doing it. Even a BMS setup isn't really worth the hassle since the range isn't that much further and you can't charge at 20 amps like I can on an RC charger. You are most likely charging at 2A or 5A.

The battery packs are still small at 25mm in height. The issue is that most if not all longboards do not have a flat bottom. They are all concave which adds to the height. These packs are by far the most economical as they are only $20 bucks or so per battery.

If you have a fairly long longboard. I would also look into these 6S 5000mah 30C Long Lipo packs - http://www.hobbyking.com/hobbyking/store/__8579__zippy_flightmax_5000mah_3s1p_20c.html. They aren't as cheap but they get you more range. You can wire in parallel for 6S 10,000mah which should be good for about 10-14 miles if not a bit more per pack of 2.

 

[JackHMcD]

⏆⏆⏆⏆

 

[Hummina Shadeeba]

Thanks. I get it. Duu.

I really want an 8-10 mile range though. Otherwise I'll get to town n be pushing home

What u think about making a pack or isn't there something thinner out there already made? I
guess not or people would be using it. I must get it about 20mm thick? No one wants to ride a brick.

I use (2) Zippy Flightmax 3S 5000mah 20c in series for 6S as one pack. I carry (2) sets of these packs along with me. Each pack gets me 6-8 miles on average. 6 miles x 3 = 18 miles to 24 miles. I charge these (3) packs 6 batteries in total with a HobbyKing 350W and iCharger 208B Charger at 20 Amps ($160 for the charger set) in parallel in about 30-45 minutes. I get 18-24 mile range from those 3 packs. IMO, that's the best way to go about doing it. Even a BMS setup isn't really worth the hassle since the range isn't that much further and you can't charge at 20 amps like I can on an RC charger. You are most likely charging at 2A or 5A.

The battery packs are still small at 25mm in height. The issue is that most if not all longboards do not have a flat bottom. They are all concave which adds to the height. These packs are by far the most economical as they are only $20 bucks or so per battery.

If you have a fairly long longboard. I would also look into these 6S 5000mah 30C Long Lipo packs - http://www.hobbyking.com/hobbyking/store/__8579__zippy_flightmax_5000mah_3s1p_20c.html. They aren't as cheap but they get you more range. You can wire in parallel for 6S 10,000mah which should be good for about 10-14 miles if not a bit more per pack of 2.

Isn't it
Risky without a bms?

 

[Hummina Shadeeba]

Thanks. I get it. Duu.

I really want an 8-10 mile range though. Otherwise I'll get to town n be pushing home

What u think about making a pack or isn't there something thinner out there already made? I
guess not or people would be using it. I must get it about 20mm thick? No one wants to ride a brick.

I use (2) Zippy Flightmax 3S 5000mah 20c in series for 6S as one pack. I carry (2) sets of these packs along with me. Each pack gets me 6-8 miles on average. 6 miles x 3 = 18 miles to 24 miles. I charge these (3) packs 6 batteries in total with a HobbyKing 350W and iCharger 208B Charger at 20 Amps ($160 for the charger set) in parallel in about 30-45 minutes. I get 18-24 mile range from those 3 packs. IMO, that's the best way to go about doing it. Even a BMS setup isn't really worth the hassle since the range isn't that much further and you can't charge at 20 amps like I can on an RC charger. You are most likely charging at 2A or 5A.

The battery packs are still small at 25mm in height. The issue is that most if not all longboards do not have a flat bottom.

They are all concave which adds to the height. These packs are by far the most economical as they are only $20 bucks or so per battery.

If you have a fairly long longboard. I would also look into these 6S 5000mah 30C Long Lipo packs - http://www.hobbyking.com/hobbyking/store/__8579__zippy_flightmax_5000mah_3s1p_20c.html. They aren't as cheap but they get you more range. You can wire in parallel for 6S 10,000mah which should be good for about 10-14 miles if not a bit more per pack of 2.

That last link is for 3s. Building 6s 10ah w these? That's not possible right?
Or maybe w 8
Batteries

 

[Rosco]

http://www.hobbyking.com/hobbyking/store/__8579__zippy_flightmax_5000mah_3s1p_20c.html

Two of these linked in Series double the load voltage of 11.1v to 22.2v however the capacity will remain the same at 5Ah (it's easier to talk in Ah than mah at high capacity)

But you can link in Series and Parallel simultaneously.

Observe

http://www.batterystuff.com/images/knowledge-base/Series-Parallel.jpg

Make sense?

 

[torqueboards]

You would connect ZIPPY Flightmax 5000mAh 3S1P 20C in series for 6S 5ah. 2 packs = $22.07/ea = $44.14
You can use Turnigy 5000mAh 6S 25C Long Lipo Pack in parallel for 6S 10ah. 2 packs = $65.29/ea = $130.58

IMO - You can buy 3 sets of 5ah 3s which is why I choose those packs. Why I'm telling you when you will buy all stock Backorder now

 

[Hummina Shadeeba]

Im looking to get 18650 batteries and they have low c. Whats the lowest amp draw a board could safely get away with? Probably do 5ah pack n 6 or 8s. I guess the voltage doesnt matter though

 

[rsilvers]

My 20Ah 13S pack is reported as 17.3Ah by my V3CA. It would seem like I could charge it at 8 amps and be at 1/2 a C.

My charger is listed as 2A, and my Kill-A-Watt reports it drawing 122 volts at 1.33 amps, so at 48 volts it should be well into the 2A range on the output.

How many amps should I charge with before battery cycle life becomes significantly worse? 4A? 8A?

 

[agraham]

3X2s in series gives 6s, unfortunatly, in series, the capacities do not add up: u will have 5Ah...

Adding more cells in series does cause your capacity increase of course. Since the voltage is higher you will draw less amps so you don't need as many amp hours to go the same distance.
It would be better to think of capacity in terms of watt hours not amp hours. Adding cells in either series or parallel will cause your watt hours to go up.