Building eScooter battery - 1C/2C discharge-rate sufficient?

[MadVlrus]

Hello there. I am new to these forums and battery making. I hoped some of you kind folks would like to drop me some advice on making my first lipo battery. I already know sufficient (including which BMS to use, etc) but just need a few clarifications.

I am making a 40ah battery for my 60v 3000w scooter. I haven't measured the current of my motor yet, but it's safe to assume that it peaks at 50amp and constantly draws probably around 30amps-40amps max. I am using li-po batteries and my layout will be 16S and around 8P-18P. (depending on battery mA)

Q1) If I have for example 14x300mA batteries in parallel (16 in S to make up 60 volt): then the 40amp current gets divided between the 14 of them. Which means that 2.8 amps is drawn from each battery. Is that correct?

Q2) So if each battery is discharged at 2.8amps per second: Then it means that 3000mA batteries with low discharge-rate, like 1C or 2C, should be sufficient for my purposes. Is that right? No need to go 15C?

Thank you very much for clarifying.

 

[amberwolf]

There may be some help for you in these threads at the top of this Battery Technology forum, if you haven't gone thru them already:
General FAQ
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=26621

Specific to RC LiPo
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=52240


This one doesn't have any specific to your type of pack but does have links to a number of things you may consider later on:
http://www.endless-sphere.com/forums/viewtopic.php?f=14&t=69683

 

[dogman dan]

I would say stuff rated at 2c, discharged at 1c or less would work. But a better battery will sag less under the most severe spikes.

40 ah at 1c is 40 amps, So ideally you'd have amp spikes 1c or less, that is to say, 40 amps controller vs 50 amps. But a 50 amps pull still well within the specified discharge rate.

But if you went with a 3c cell, then you'd have lots of room for amp spikes.

1c cells not really adequate for 40 ah size,

2c cells, ok but not ideal

3c or higher, best for your needs. Your highest possible amps would be well under half the c rate. I like to cut all claimed c rates in half. That way you get less sag under load, a battery that tends to stay balanced better, and a better performing setup.

 

[wesnewell]

I can't make heads or tails from your post, but if you want a 40ah 60V battery capable of a 50A draw from the controller (the motor itself doesn't draw anything from the battery, only the controller does, so motor size doesn't matter) you need at least 2C cells to make it. If you're talking about using rc lipo, they will all be a minimum of 10C, so don't even worry about it. if you're talking 18650 cells, then your best bet would be 2C or higher rated cells. 16s will be 57.6-59.2V nominal depending on which chemistry you choose.

 

[MadVlrus]

Thank you so much fellas for your replies! I will definitely have a look at those posts, they seem to have a lot of valuable and clear information. I believe 3C is indeed the most practical and safe for my needs. All replies are much appreciated.

 

[999zip999]

Higher c~rate is for the buffer zone needed for hills or longer hills your weight and riding style. Hard start ect. Plus higher c~rate higher quality higher price. A pack that keeps balance. How much money you have to spend ? As going to cheap and you will be buying a second battery. I want see the size of the battery box ?