diy solar

diy solar

Battery disconnect with a live load

H

hhtat

New Member
Joined
Apr 13, 2021
Messages
32
I'm considering using one of these battery disconnect switches between my battery bank and inverter but I'm a little confused about their current rating. If the switch is rate for 100A, can it safely switch on/off a live 100A load OR does it mean it can support a 100A load that's connected AFTER the switch is turned on (disconnected before the switch is turned off).

https://www.amazon.com/dp/B08HMWGT22 or https://www.amazon.com/dp/B082W24S4F
 
I think the rating of those switches are not real, 300A 60VDC for only $6.99, or 200A 24V for about the same price?
 
It isn’t a good idea to disconnect a large DC current with a switch. High current contactors have arc suppression for this reason.

I use fuse/disconnect units like the pictured one in my systems.
 

Attachments

  • 8ECD26EA-29BE-4E71-8A68-2E492DD12267.jpeg
    8ECD26EA-29BE-4E71-8A68-2E492DD12267.jpeg
    172.4 KB · Views: 38
It will handle 100amps load, and cheap switches like this, I will assume 100 amps for a short time. It will switch 100 amps. Maybe a 10 times before the contacts burn out.
 
Porch said:
It will handle 100amps load, and cheap switches like this, I will assume 100 amps for a short time. It will switch 100 amps. Maybe a 10 times before the contacts burn out.
Click to expand...

Or maybe the contacts arc weld together the first time you need to switch it off.

No point having a cheap switch there, might as well put a spanner nearby and undo the nut on a terminal.
 
100A rating means 100A will flow through the closed switch...

ALL low cost switches will clearly state NOT FOR LOADED DISCONNECT...
Switching with 100A flowing through will be a nice arc torch.
At 12v, 100A likely won't damage much... 24 or higher and the arc will be nasty.
 
The best quality battery disconnect switches instruct to "Turn all appliances off before turning the battery switch to OFF" also • "Do not switch to OFF while engine is running"
 
May I ask OP why not just turn the inverter off with the inverter ON/OFF switch? How much current does the inverter draw when inverter is turned off?
BTW, when inverter is disconnected from batteries so the capacitor banks are discharged, when you connect the inverter back to the batteries, you will have high inrush current unless you pre charge the capacitors first.
 
Thanks for all the insights. It sounds pretty clear these switches are not sufficient for my use case. My reasoning for switching the inverter on/off using these switches was to have a single power button for the system. It's a 12V system with 100A draw.
 
If you are switching often, try to minimize the load. If switching off in an emergency, don't hesitate.
Most components AFAIK prefer to be switched off with their own integrated power switch.
 
You must log in or register to reply here.

Similar threads

C
EcoFlow Dp reset
Replies
0
Views
100
CBSBERT
C
rhino
How to support 500A charge/discharge to battery?
Replies
10
Views
523
rhino
rhino
A
12v 10a 230Wh 18ah system with low temp protection under $200 without panels
Replies
15
Views
458
robbob2112
robbob2112
garetwo
Disconnect/Isolator misleading?
Replies
4
Views
322
garetwo
garetwo
JWLV
Output 240VAC split phase from 120VAC Inverter
Replies
3
Views
202
plympton
plympton
Back
Top