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diy solar

Battery Disconnect Switch Recommendations

Rui Ponte said:
Is this a good option?

125A DC Circuit Breaker MCB Solar Fuse 250v Single Pole 1P Ebike TOB1Z-125 C125 : Amazon.co.uk: DIY & Tools

Free delivery and returns on all eligible orders. Shop 125A DC Circuit Breaker MCB Solar Fuse 250v Single Pole 1P Ebike TOB1Z-125 C125.
www.amazon.co.uk

It's "only" 125A. I would prefer something closer to 200A.
Click to expand...
I use similar to those and have never had a problem with that style. You can use 2 in parallel if you have too many amps for a 125. I do not know if they come in 200Amp versions
 
Craig said:
I use similar to those and have never had a problem with that style. You can use 2 in parallel if you have too many amps for a 125. I do not know if they come in 200Amp versions
Click to expand...

Ok, great.
Have no idea on how to connect one of those to the "cable" coming from my battery :)

20200509_195643.jpg
 
Hmm... checking the Amazon Q&A, they state this:

Question:
hi, are these breakers bi-directional?
Answer:
No. Breaking capability only in a single direction - source in the top and load out the bottom.
By TorqueTech SELLER on 16 May 2019

Isn't this a deal breaker?
Or is it a non-necessity to protect the battery from the rest of the DC bus? (2 MPPT's and 1 Inverter/Charger)?
 
From my experience they will break in either direction however the majority of the current should flow in the direction of the breaker. I actually use double pole breakers that you use on both the positive and negative leads. I have never had a problem and have managed to trip and reset them multiple times. They tripped when I did something I wasn't supposed to. Or had too much current
 
I figure I'll add this in. Over teh years I have used assorted fuses and most had their own quirks (not necessarily bad ones just quirks). To that end I have my system setup with proper Carling (TM) DC Breakers actually supplied from Midnite Solar but for my fuses I(which are still in place) are now all MRBF type fuses and never a lick of trouble,

Last batch of MRBF Fuses I bought came from Justin Laurentec of Bay Marine a member here.

Blue Sea MRBF Terminal Fuse Block

<div class="product-description"> <p>These fuses fit Blue Sea models 2151 and 5191 battery terminal fuse blocks, and also the Bay Marine Supply MRBF blocks.</span></p> <ul> <li>Interrupt rating satisfies ABYC requirements for DC Main circuit protection
baymarinesupply.com baymarinesupply.com

properly sizing them is essential just like the wiring gauge used on the equipment. * Remember that you are looking at the MAXIMUM amperage you "could" potential pull. IE: 3000 Pure Sine LF Inverter with 9000W Surge capacity on 24VDC = 375A @ 48VDC = 187.5A
 
Steve_S said:
I figure I'll add this in. Over teh years I have used assorted fuses and most had their own quirks (not necessarily bad ones just quirks). To that end I have my system setup with proper Carling (TM) DC Breakers actually supplied from Midnite Solar but for my fuses I(which are still in place) are now all MRBF type fuses and never a lick of trouble,

Last batch of MRBF Fuses I bought came from Justin Laurentec of Bay Marine a member here.

Blue Sea MRBF Terminal Fuse Block

<div class="product-description"> <p>These fuses fit Blue Sea models 2151 and 5191 battery terminal fuse blocks, and also the Bay Marine Supply MRBF blocks.</span></p> <ul> <li>Interrupt rating satisfies ABYC requirements for DC Main circuit protection
baymarinesupply.com baymarinesupply.com

properly sizing them is essential just like the wiring gauge used on the equipment. * Remember that you are looking at the MAXIMUM amperage you "could" potential pull. IE: 3000 Pure Sine LF Inverter with 9000W Surge capacity on 24VDC = 375A @ 48VDC = 187.5A
Click to expand...

Thanks Steve.
Regarding the Carling DC Breakers, are you using the F-Series? https://www.carlingtech.com/hm-cb-f-series

I believe this model would do the trick, even though at ~$100 it's not exactly cheap!
On the other hand, its terminal is a threaded stud, which is great for my setup.

Thanks
 
Steve_S said:
I figure I'll add this in. Over teh years I have used assorted fuses and most had their own quirks (not necessarily bad ones just quirks). To that end I have my system setup with proper Carling (TM) DC Breakers actually supplied from Midnite Solar but for my fuses I(which are still in place) are now all MRBF type fuses and never a lick of trouble,

Last batch of MRBF Fuses I bought came from Justin Laurentec of Bay Marine a member here.

Blue Sea MRBF Terminal Fuse Block

<div class="product-description"> <p>These fuses fit Blue Sea models 2151 and 5191 battery terminal fuse blocks, and also the Bay Marine Supply MRBF blocks.</span></p> <ul> <li>Interrupt rating satisfies ABYC requirements for DC Main circuit protection
baymarinesupply.com baymarinesupply.com

properly sizing them is essential just like the wiring gauge used on the equipment. * Remember that you are looking at the MAXIMUM amperage you "could" potential pull. IE: 3000 Pure Sine LF Inverter with 9000W Surge capacity on 24VDC = 375A @ 48VDC = 187.5A
Click to expand...

Question (and sorry for the multiple questions, but it's a steep learning curve): If I use a DC breaker like this Carling FA1-B0-14-815-12A-BG (150A), it wouldn't be necessary to use a fuse in series with it, right?
 
I think that in some cases that the location of a disconnect is not considered. If something is going wrong do you want to put your hands near the source of smoke and fire. Another consideration is that the person who is on site may not have knowledge of the system. A disconnecting switch which is marked and which is on the outside of a cabinet makes it more likely that it could be operated in a emergency.
 
evad said:
I think that in some cases that the location of a disconnect is not considered. If something is going wrong do you want to put your hands near the source of smoke and fire. Another consideration is that the person who is on site may not have knowledge of the system. A disconnecting switch which is marked and which is on the outside of a cabinet makes it more likely that it could be operated in a emergency.
Click to expand...

Yep a big red button for when things get out of hand.
 
Rui Ponte said:
Question (and sorry for the multiple questions, but it's a steep learning curve): If I use a DC breaker like this Carling FA1-B0-14-815-12A-BG (150A), it wouldn't be necessary to use a fuse in series with it, right?
Click to expand...
I am using a 250A Main Breaker. Because it is installed in the E-Panel, I can't get the exact part numbers off of it. Th link to it is: http://www.midnitesolar.com/product...=Breakers&productCat_ID=16&sortOrder=15&act=p

I have a 175A one as well which will be used for another installation, it is an : FR1-B0-14-917-12A-BG
This has the 3/8" Lugs. It is 7-1/8" (18cm) High X 3-1/8" (8cm) deep and 1-3/8 (37mm) wide. The 250A has the same dimensions.

I still have a fuse on my FLA battery Bank and one for every LFP pack.
 
One thing that I've been searching for a while is a high power contactor that can handle DC currents. The reason is that I would like to be able to open it remotely. But good DC contactors go over 300 Euro
To Will: another wild reason to disconnect is this one - I have a lead acid OPzS in parallel (yes, crazy I know) with LifePO4. The charge profile is by default "Lithium" and lead acid is only acting as "standby power". But when discharge cyles deplete lithium and go eat a little of the lead acid, I have to change a little the profile the next morning to make sure LA fully charges again. And is better to take the LifePO4 out of the parallel than to let the BMS open on HVD (absorption or equalize of the OPzS).
Weird, no?:) Another solution for my problem is also to get more Lithium and remove the LA bank...

Anyway, whilst I can't find an affordable contactor, I also do like to use circuit breakers, or MCBs.
In Europe there are some brands that specify being able to break DC. The one that I like most is "Schneider" and I use the iC60H or N series for up to 63A and I just got a C120H breaker for 125A.
 
Last edited:
Go to EVDrives for 400A high quality contactor that does not cost over $100. Folks building Electric Vehicles are switching huge amps all the time. I just built an electric tractor with 48V battery system and a 200-400a motor. Used a Amazon 400a disconnect, ANL 400a fuse and a 400a contactor.....Works the charm!
 
So, this weekend I swapped the 200A waterproof breaker-thingy with the a (massive!) Carling 150A DC Breaker.
It's huge, heavy and with those M10 terminals I immediately realized that the thing is on a totally different level!
I've stressed tested it a bit and it didn't break a sweat (ie, no heat build up).

1591594705484.png

1591594713238.png


PS: I can attach a string to the breaker's lever, and run it down and front, so that I can trip the breaker without opening the cabinet ?
 
LOL, I did warn you that they are Big and even gave you the dimensions I think. I hate to say it BUT I do chuckle when someone pops up with a tiny 200A sealed breaker and think it is comparable to a real Heavy Duty DC Breaker.... I only use Carling Breakers, even for the smaller 30A, 90A type stuff, more $ but also peace of mind too which has it's own special value. Even with that, battery packs are fused with MRBF fuses... no such thing as being too safe IMO.
 
Rui, is any chance of posting a photo of the front of this switch? Fixing details. I have a quote for a similar one, but my assembly is on the wall. I currently have DIN breakers installed. Don't know if this is compatible, somehow...
 
Mtour said:
I have two them, they only handle 60amps without heating up. At 130amps continuous charging from my lv5048 they are getting ready to melt. I will have to replace with another switch, thinking the bluesea..
Click to expand...
Picture looks like a BEP Marine clone. Genuine BEP Marine products are high quality like BlueSea Systems products.

RV's and Boats typically have installation details that utilize master disconnect and or combining switches or switches that combine both functions into one device. These switches are used for many purposes in mobile installations - maintenance, safety, isolation, redundancy just to name a few.

I always oversize this device, if used, due to the abuse it can see.
 
elimac_pt said:
Rui, is any chance of posting a photo of the front of this switch? Fixing details. I have a quote for a similar one, but my assembly is on the wall. I currently have DIN breakers installed. Don't know if this is compatible, somehow...
Click to expand...

I've made a custom support, out of a 20cm x 10cm board:

1591627140831.png

1591627150849.png



They have different mounts for their breakers. Including back loading and front loading.
 
Will Prowse said:
61185AA6-A7FF-4316-823C-49F0280F9538.jpegC7773AF3-3C1B-4635-818E-29401F5DBED4.jpegI prefer using a heavy-duty UL listed circuit breaker as a manual disconnect switch if I need it.

I hate those large high current switches. Just another part that can fail. I had an expensive one melt in the past, and now I avoid using them entirely.

I have never seen the need for a large manual disconnect switch except for maintenance of system parts, or for grid-tie operation solar input kill switch (required in NEC) for emergency workers.

What is the purpose of these switches for you guys? Just curious.

I prefer most safety/switching functions to be autonomous. And maintenance is very rare in a well-designed system. So I cannot think of a single reason to have these large switches.
Click to expand...
Hi,
I am setting up my first RV Solar project and would like to have some guidance and or thought on my current layout.
I have 17 12v 100AH LiFePo4 batteries 4 banks of 4 wired in series 48v then to the Victron Lynx Distributor with 4-125 amp fuses going into a Victron battery disconnect then to a main 200amp fuse. Then to my Deye 8k inverter.
My worry is do I need to have disconnects from my batteries to the Lynx distributor because after I hook up the batteries the Lynx distributor will always be live unless I unhook a battery terminal. I wouldn’t be to concerned about a 12v setup. But I see the arc that is coming off of the posts when you hook up your 48v batteries and not sure if I I I shouldn’t even be concerned.
Please let me know your thoughts thanks
 
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