SOLVED BATTERY QUESTION


MASSIVE restock of EV Batteries at www.batteryhookup.com 5% coupon "POWERWALLS"

atlas7

New member
Joined
Mar 9, 2021
Messages
16
My battery pack is a 12S13P. The following is my schematic of how the cells will be connected together - soldering copper bus leads and fuse wire. As I am dealing with large amount of current, is it recommended that I use this copper wire as my bus leads?

Yes, I will definitely be using a BMS and a cooling system for added safety

please help if you can thanks! :)
 
Last edited:

Wolf

Active member
Joined
Sep 25, 2018
Messages
1,693
Ok you need to clarify a couple of things.

First 13s is 46.8V nominal 14s is 48V nominal why 13s?
15p of the Sony "MURATA VTC6 18650 3000MAH 15A BATTERY" is 225 Amps max (15 X 15 = 225) so why 450 amp cables?
Are you going to run 15 amp fuses from each cell?
At max load of 225 Amps this battery pack would last ≈20 min before complete DOD.
46.8V X 225 Amps = 10530 Watts what are you cooking here? Maple syrup? They have wood for that you know.
This all becomes more head scratching if you did perchance draw 450 Amps thats 21060 Watts.
What are you building a Tesla jump start kit?
1615379419780.png

 
Last edited:

ajw22

Member
Joined
Nov 16, 2018
Messages
664
That cable rating of "450A" is a little misleading. It certainly will conduct 450Amps, but probably only for a few minutes, after which it'll start smoking. More suitable for 200A~300A if for sustained use.

What are you trying to power with this battery?
 

atlas7

New member
Joined
Mar 9, 2021
Messages
16
Ok you need to clarify a couple of things.

First 13s is 46.8V nominal 14s is 48V nominal why 13s?
15p of the Sony "MURATA VTC6 18650 3000MAH 15A BATTERY" is 225 Amps max (15 X 15 = 225) so why 450 amp cables?
Are you going to run 15 amp fuses from each cell?
At max load of 225 Amps this battery pack would last ≈20 min before complete DOD.
46.8V X 225 Amps = 10530 Watts what are you cooking here? Maple syrup? They have wood for that you know.
This all becomes more head scratching if you did perchance draw 450 Amps thats 21060 Watts.
What are you building a Tesla jump start kit?
View attachment 24178

This cell discharges a max of 30A provided the temperature stays below 80C, which is the reason as to why I will implement a liquid cooling system. I've used this particular 18650 cell before and the specs are authentic so this part is indeed satisfying. Nominal was found to be 3.7v from testing hence the 48V. The motor will draw approximately 315A so it wouldn't overwork such cable. I was thinking using 21A fuse wire per cell; concentrated on the current the load will draw rather than the maximum current the battery can provide. The need of 15 in parallel per string is to up the capacity for a longer run time. We are aiming to power a formula student electric vehicle following a set of guidelines for the competition to take place this summer so everything is according to the guidelines :)
 
Last edited:

atlas7

New member
Joined
Mar 9, 2021
Messages
16
That cable rating of "450A" is a little misleading. It certainly will conduct 450Amps, but probably only for a few minutes, after which it'll start smoking. More suitable for 200A~300A if for sustained use.

What are you trying to power with this battery?
Exactly, the motor will draw just over 300A so it won't overwork the cable. We wanted a higher capacity rate but the number of parallel cells determines current as well as capacity rating hence the 450A versus 312A. Overall we're building a formula student electric vehicle following strict guidelines provided to us else we can't take part in the competition this summer :)
 
Last edited:

Wolf

Active member
Joined
Sep 25, 2018
Messages
1,693
We are aiming to power a formula student electric vehicle
I guess I wasn't to far of with the Tesla jump start kit. 😛
So the "Military Style Battery Terminal 2/0 awg Gauge Wire Kit" should be just fine.
As they take the 2/0 cables and run them in parallel so in essence 2p 2/0 cable is good for 450A+ especially if it is a short run.
I would personally add a 3rd run to decrease the V Drop to a minimum. I understand it adds weight but I think the benefit will outway the cost as this I am assuming is for some sort of drag race where you need maximum performance for a minimal amount of time.
I mean pulling ≈300A from this battery will DOD it in no time. Even when the LV cutoff is 2.0V
The good thing is the max V of the VTC6 is 4.25V. Not that there is a lot of usable energy at that V level but the initial dump of current to get the motor to torque up will use it nevertheless.
Sounds like a fun project best of luck.

Wolf

1615387749517.png1615387846834.png
 

gpn

Member
Joined
Jan 21, 2018
Messages
250
Why did you delete your original post? That really makes this thread useless for other people to learn.
 

atlas7

New member
Joined
Mar 9, 2021
Messages
16
Why did you delete your original post? That really makes this thread useless for other people to learn.
It was just to confirm the use of a 450A copper cable for a 315A load that's the jist of it. I'll keep that in mind next time
 
Top