Choosing Ground

N

n1866878

100 mW

Joined

Jul 9, 2018

Messages

47

• Aug 13, 2018

• #1

Hey,

We're building an electric go-kart with a 48V main battery and 18V secondary battery. We have an old go-kart chassis with a metal core structure. I'm just wondering - is there a need to connect the negative terminals of the batteries to the chassis metal frame?

 

teklektik

100 MW

Joined

Mar 26, 2011

Messages

4,019

Location

CT, USA

• Aug 13, 2018

• #2

Don't do it.
Hot chassis NG...

 

Hwy89

10 kW

Joined

Mar 3, 2013

Messages

554

Location

Northern Arizona

• Aug 13, 2018

• #3

Run all ground wires back to the negative terminal of the battery. What does the secondary battery do?

 

N

n1866878

100 mW

Joined

Jul 9, 2018

Messages

47

• Aug 14, 2018

• #4

Hwy89 said:

Run all ground wires back to the negative terminal of the battery. What does the secondary battery do?

Click to expand...

Secondary battery is for powering the controller at 18V and also for switching the coils on the main contactor on/off.
Right so - I'll keep the two batteries in their own loops then without touching the chassis frame.

What's the reason behind not connecting negative terminals to the chassis frame? I mean GND is GND right, why is it dangerous?

 

J

Jon NCal

1 kW

Joined

Jun 15, 2015

Messages

369

Location

Mendocino, California

• Aug 14, 2018

• #5

One, there is no reason for it. Two, increases the possibility of an accidental short circuit.

 

V

Voltron

1 MW

Joined

May 2, 2013

Messages

2,803

Location

Santa Barbara CA

• Aug 14, 2018

• #6

Especially with the higher voltages of normal bike batteries compared to car 12v.

 

N

n1866878

100 mW

Joined

Jul 9, 2018

Messages

47

• Aug 14, 2018

• #7

Perfect. Thank you all.