according to the manual, a 50ah battery can reach 100a for about 3 secondsYou said they are 50AH batteries, and if they are "standard" that means they can output 50A, therefore the fuse should be 50A. Many suggest a factor of 1.25, which would make the next up fuse would be 75A which is also fine because most can handle a short surge spike.
All of my DC cabling is Royal Excelene 4/0 Wire even though I am 24V. That's partly because my length from Inverter to Batt terminals is 4.2m/14'.
All of my cabling IS equal Length. Batt to Busbar & Busbar through to inverter.
I am going into the Finishing Phase finally, thank goodness, which will see 6x280AH Packs in Parallel and I am switching down the Pack to Busbar cables to 2/0 because these are reasonably short and 2/0 will handle it with elbow room.
Note on the cabling. Royal Excelene is High Grade Ultra-fine wire Welding cable, very $ but some of the best out there. With DC systems, especially higher currents, Fine Wire Cabling is the proper solution... Coarse wire (like in AC Wires) are not acceptable for this application.
REF to Southwire Royal Excelene:
Flexible Cord & Welding SPEC 70305
cabletechsupport.southwire.com
stupid question
- Thread starter davy
- Start date
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
That is pretty normal, almost all can do a short surge but it's best never to do that.
on facebook someone had 3 100ah redodo batteries in parallel and he said you can place a fuse between the batteries but it is not necessary.of course happy with what he said. I saw what an MRBF fuse costs, they are not cheap,I should already have 3 MRBF fuses in my system...maybe a 4th. I was planning to connect a 4th battery.
The best fuse for the battery cables is a Class T fuse. The MRBF isn't bad. The AIC rating is higher for the Class T fuse.
If you think MRBF is expensive, wait until you price a quality Class T fuse.
If you think MRBF is expensive, wait until you price a quality Class T fuse.
yes i have a main fuse for the cable. but this is a fuse for between the batteries
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Facepox.. bleh.....
Everyone here knows (mostly) what the deal really is... some of us live the life, some of us also do this for a living (beyond the hobbyists).
1 Fuse per Battery.
1 Main Fuse/Breaker between bank & Inverter.
Simply Put:
It's your Money, Your Risk & Liability and the consequences of your choices are all yours.
We've given you proper information from a few people with years of field experience. You can choose to accept that & use it or not.
FacePox - saw one idjt tell a shmuch, that he can just wire his solar panels into the AC Main Box directly. Luckily a few smart folks leaped all over that, Thank Goodness. THIS IS A DIY & Solar Site and this is Our Bailiwhick.
Everyone here knows (mostly) what the deal really is... some of us live the life, some of us also do this for a living (beyond the hobbyists).
1 Fuse per Battery.
1 Main Fuse/Breaker between bank & Inverter.
Simply Put:
It's your Money, Your Risk & Liability and the consequences of your choices are all yours.
We've given you proper information from a few people with years of field experience. You can choose to accept that & use it or not.
FacePox - saw one idjt tell a shmuch, that he can just wire his solar panels into the AC Main Box directly. Luckily a few smart folks leaped all over that, Thank Goodness. THIS IS A DIY & Solar Site and this is Our Bailiwhick.
It's good to read any advice with skepticism. If it's a cheap solution, it may not be safe. Not to say that every expensive solution is safe, but quality usually isn't inexpensive.
The guiding principal when discussing over current protection (OCP) is that it's there to protect the wire/cable. You'll read that on this forum thousands of times.
The guiding principal when discussing over current protection (OCP) is that it's there to protect the wire/cable. You'll read that on this forum thousands of times.
Rednecktek
Solar Wizard
Something to be aware of when talking about cable lengths is that each side needs to be the same length, but both sides Don't. Let me give you an example:
Say the longest length from your positive bus bars to the farthest battery is 18in. That means all the positive cables need to be 18in. However, if the longest length from the Negative bus bars to the farthest battery is 30in, tgen only the Negative wires need to be 30in, you Don't need 30in Positive wires.
Make sense?
Say the longest length from your positive bus bars to the farthest battery is 18in. That means all the positive cables need to be 18in. However, if the longest length from the Negative bus bars to the farthest battery is 30in, tgen only the Negative wires need to be 30in, you Don't need 30in Positive wires.
Make sense?
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
I did not mean to be harsh or rude. Too much information for desperate sources will only confuse. It takes a minimum of 6 months of intensive learning to understand all of this, on average it takes a person 1 year of average reading & study. It is a hell of a lot to absorb right from the get go. What makes it even worse, is if you have a background with AC Power Systems - you would think electricity is electricity which it is but AC & DC are Very Different Animals and the terminology, and several rules are different.I'm not saying that you don't know anything about it. I'm just saying that I saw this on Facebook. For me it's confusing because I still have a lot to learn.so thanks for all the tips
On Youtube, there are MANY MANY discussing solar, how to and more... Goodness Gracious I watched too many BUT quickly realized there are about a Dozen "On the ball & doing it right" and the rest are various degrees of ok to absolutely & horribly wrong. A couple are even downright frightening and SOME people actually try to do it too and get Poofed. We have seen some terribly scary stuff done, some got lucky, some didn't and a few of those had threads here too... Ever see a BMS Grenade ? Hard to do but it's been done.
Battery to battery is almost never fused unless you have a unusual distance between them. Anymore than battery cell to battery cell is fused. As others pointed out fuses are in place to protect the wire (and components). So if you are running separate cables to a bus bar you might wish to protect them with a fuse.
Yes there is a lot of confusing advice given on the net. When in doubt Common sense should be applied.
Yes there is a lot of confusing advice given on the net. When in doubt Common sense should be applied.
As I was out for my afternoon perambulation a thought about simplifying multiple batteries in parallel setup occurred to me. Solar panel arrays make use of a combiner box to connect safely several strings in parallel. A battery combiner box (perhaps with Anderson connectors for each battery input) could be designed.
It would certainly make removing a battery for maintenance easier as well as increasing a bank size depending on the amount of plugs available. Inside the box would be fused protection and a appropriate sized Breaker/disconnect. Pig tails from the Anderson plug than could run to the individual battery. The output of the unit could be also an Anderson plug, or maybe just a place to bring in heavy cable to a lug, that runs to the AIO or inverter.
Just a thought.
It would certainly make removing a battery for maintenance easier as well as increasing a bank size depending on the amount of plugs available. Inside the box would be fused protection and a appropriate sized Breaker/disconnect. Pig tails from the Anderson plug than could run to the individual battery. The output of the unit could be also an Anderson plug, or maybe just a place to bring in heavy cable to a lug, that runs to the AIO or inverter.
Just a thought.
Steve_S
Offgrid Cabineer, N.E. Ontario, Canada
Every item on the line introduces resistance & line losses. That is also a consideration.
So I want to take a different approach.i have 3 50ah lifepo4 powerqueen batteries.if i connect them in series than i have 36V ( 1920wh if im correct )
i can set my victron mppt to 36v so i only need a 36V inverter.It actually comes down to the same thing, but then I don't have to secure the batteries separately?
i can set my victron mppt to 36v so i only need a 36V inverter.It actually comes down to the same thing, but then I don't have to secure the batteries separately?
Daddy Tanuki
Solar Wizard
but then you have no redundancy, and 36 volt is the odd duck out for inverters.
12 volt inverters will exist and have lots of options as long as cars are 12 volt system.
24 volt due to boats, and large OTR rigs will be around a while.
36 will probably fade out over the next 10 years or so.
the current upvolt units overseas are 96 volts... which means that even 48 will start to have less options over the next 20 years. just a thought.
Nobodybusiness
Collecting the leftovers of the Great Sky Reactor.
True enough.
A lot to absorb even with a background in electronics/ Electrical.
If you have zero background even harder.
Nobodybusiness
Collecting the leftovers of the Great Sky Reactor.
Some use the Midnite combiner with the fuses at the battery, breaker at the combiner.
Works for me..
Oh I imagine I could build something I was just thinking of a ready made setup that a average person could basically plug and play.
Nobodybusiness
Collecting the leftovers of the Great Sky Reactor.
The Midnite is pretty much plug and play.
You have to buy the breakers and install them but other than that just connect your battery.
The class T fuse at the battery.
Now that isolates the battery.
I suppose you could put Anderson or something similar for a quick disconnect.
Looked up the Midnite lithium battery combiner enclosure. Boy they are pricey for a simple metal box with some bus bars. https://www.midnitesolar.com/productPhoto.php?product_ID=686&productCat_ID=9&sortOrder=1&act=p I also do not like the lack of isolation for pos and neg. I would want a insulating barrier dividing the two to help prevent any chance of short during wiring. I also would prefer a non metal enclosure.
However it is close to the concept if other components such as the fuse holders, disconnect breaker and also the Anderson connectors were incorporated. Perhaps some company will market one. Of course the Chinese will than make a cheap knock off version and flood the market.
