I wouldn’t rule out a potential situation where you need to do that, and at that point the ability to do so will be priceless.
Battery cutoff switch on negative or positive cable?
- Thread starter Thodoris
- Start date
I wouldn’t rule out a potential situation where you need to do that, and at that point the ability to do so will be priceless.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Someone a while back posted photo's of a cheapo knockoff switch on a 48V system that not only arced but totally melted. Only takes ONE oopsie and your life can be changed drastically & FAST. As I said before, stick to high quality safely components, breakers, fuses & switches, the otherside is not worth a few pennies saved.
TomC4306
Solar Obsessive
For me a Blue Sea e9003, 275 amp continuous rating at 48 volts is adequate. I have one on each 160 amp hour battery. Each battery has a 150 amp class t fuse for ocp. These switches will only ever get turned on or off when there is virtually no current flowing. Purely as an isolator.
Typically during my semiannual balancing festival. When everyone is in absorption or float.
Do you remember which switch was used? I am concerned whether mine is one of those or not.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Unfortunately I do not, it was posted in here about 6-8 months ago or so. There have been a couple of posts over the years showing the results of cheap knock offs.
The GOTCHA that catches people with their pants down is the common assumption that when someone says 48 Volt, that this is the voltage limit they need to support but in reality is HAS to be 60 Volts. Even with Lead Acid when running Equalization you are above 48V, and LFP for example can see 58V without effort, let alone other chemisries....
timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
- Messages
- 18,854
We never plan to do that. But in an emergency, it would be bad if the only option caught on fire.
timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
- Messages
- 18,854
Hopefully
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
FIRST & MOST IMPORTANT RULE !
NEVER EVER TEMPT Murphy's Laws !
NEVER EVER TEMPT Murphy's Laws !
My system also includes a larger class-T fuse between the battery busbar and disconnect switch. I'm not completely sure if that adds any value since I already have individual 125A fuses for each battery. I have read conflicting opinions on that, but wanted to err on the side of caution.Blue Sea has similar switches some of which can support 80V (72 Volt system). WARNING, there are cheap knockoffs out there, be aware of that and don't furtle with switches, breakers or fuses, that is NOT where to pinch pennies.
Battery Switches - Blue Sea Systems
Engineering high quality marine electrical components for safety, reliability and performancewww.bluesea.com
Below is one my generic diagrams to help you out.
View attachment 173533
It's not the only option. Each battery has an ON/OFF switch.
timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
- Messages
- 18,854
As long as you are the only person who will have access to it. And you never actually use it as it's intended. You might get lucky and never have a bad day. All that I can do is make recommendations.
It's your risk, so it's your choice.
Like others, I'd shy away from a cheap switch. When do you expect to use it and why?
Why only one pole? What about using a proper fused battery disconnector like this - designed for the job (up to 400V) and won't break the bank... (about 50 euro) - available with different size fuses from 40A up to 160A?
www.segen.co.uk
Why only one pole? What about using a proper fused battery disconnector like this - designed for the job (up to 400V) and won't break the bank... (about 50 euro) - available with different size fuses from 40A up to 160A?
Jean Muller Fuse-switch-disconnector KETO size 00 body (battery isolator)
Add robust and secure battery disconnection with the Keto range from Jean Müller. They are well known for their attention to detail in ensuring maximum user safety. Keto size 00 […]
www.segen.co.uk
Partimewages
Solar Addict
So I went to Blue Sea but every switch available that I found is 32 or 48 volt rated. I didn't find anything for 72-80 volt rated. Maybe I looking in the wrong place. I've got a ton of NEC behind me but the DC and solar is not in that. Please point me in the right direction.
