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diy solar

Breaker for Battery bank

latinhawk

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Nov 10, 2022
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Looking for ideas. Trying to figure out what breaker to use for my eg4 lifepo4 48v battery bank besides the one each battery has built in.Any ideas?
 
Are you looking for a breaker to put on each battery or a breaker for the combined battery bank?

What trip current do you need?

A few of my thoughts:

  • Stick with a name brand. You can find a lot of cheap breakers that are more of a hazard device than a safety device.
  • The breaker must be bi-directional. Unidirectional breakers have a nasty characteristic of catching fire if they are manually opened when the current is running in the wrong direction. (Not to mention that they don't trip for over-current in the wrong direction)
  • The breaker must have a very high interrupt rating. (This is different than the trip rating)
  • Above ~150 Amps, good DC breakers start to get very expensive.

When I first got into solar, I wanted breakers everywhere. I viewed fuses as inconvenient and old-school. However, I have changed my mind on that.
  1. If a 100A+ breaker or fuse blows, either the design is very poor or something catastrophic happened. Either way, the system should not be turned back on till the issue is understood and resolved.
  2. Fuses are more reliable than breakers
  3. Fuses are cheaper than breakers unless you keep blowing them....but see point 1
  4. In most cases, high-current fuses are easier to mount than high-current breakers.
 
Midnight Solar has 125A, 175A and 250A non polarized DC breakers with and without remote trip option. The breaker is actually a Carling Technologies type F.

Schneider also makes a good DC breaker that they use for the Power Distribution Panels sold as accessories for their inverters.
 
As filterguy was alluding to, the interrupt rating is why many of us use fuses, more specifically, class t fuses for the battery bank. They work, and the cost is reasonable DonRowe class t fuse
 
This is what I'm looking for, an easy way to switch between two battery banks. One is sla the other lifepo4. My idea is to run in sla where I have 18kwh usable and if needed switch to the lifepo4 bank where I have 10kwh.
 
Any appropriately rated change-over switch would do the job.
There are plenty of purpose made switches sold for the purpose. Typically, battery isolator switches offer Off, A, B, A+B input options.
They are commonly used on trucks and boats if you are looking for a local stockist.

battery switch.jpg
 
I have spent the last 2 hours searching but all I find doesn't have the amperage or the voltage I need. If anyone has an idea where to find a selector switch for 48+ volts and at least 600a please let me know.
 
I have a question. Even though my battery bank is 600a storage capacity, could I get by a lesser rated switch being that my inverter is only 6kw?
 
Looking for ideas. Trying to figure out what breaker to use for my eg4 lifepo4 48v battery bank besides the one each battery has built in.Any ideas?

I put one on each + for each inverter after the bus bar. Both of them into a box. Worked out OK.
 
I have a question. Even though my battery bank is 600a storage capacity, could I get by a lesser rated switch being that my inverter is only 6kw?
6000 ac watts / .85 conversion factor / 48 volts low cutoff = 147.058823529 inverter amps
147.058823529 inverter amps / .8 fuse headroom = 183.823529412 fuse amps
 
Are you sure that isn't 183.823529413 amps? :ROFLMAO:
Maybe but probably not. :)

jt9D4.jpg
 
Midnight Solar has 125A, 175A and 250A non polarized DC breakers with and without remote trip option. The breaker is actually a Carling Technologies type F.

Schneider also makes a good DC breaker that they use for the Power Distribution Panels sold as accessories for their inverters.
I believe these 2 pole remote trip with aux terminals will suit this need but one still has to come up with a way to install them since they are panel mount style. No need for the remote trip but the price is right. I just bought one for my new Victron 450/100 charge controller to go into my Outback DC load center. It arrived brand new and as described.

Is there such a thing a panel mount adapter to <something handy> kit? It's that or buy an DC load center which seem pretty pricey for no more than they are.


edit to fix typos (that just needs to be in my signature line... :ROFLMAO: )
 
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I have spent the last 2 hours searching but all I find doesn't have the amperage or the voltage I need. If anyone has an idea where to find a selector switch for 48+ volts and at least 600a please let me know.
Bluesea makes some of the best quality equipment out there but most of their stuff is rated for 32v and below when it comes to battery switches.
 
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I have a question. Even though my battery bank is 600a storage capacity, could I get by a lesser rated switch being that my inverter is only 6kw?
It depends on the max draw your inverter is capable of.
But don't forget to put a Class T fuse close to your battery bank for protection.
 
I believe these 2 pole remote trip will suit this need but one still has to come up with a way to install them since they are panel mount style. No need for the remote trip but the price is right. I just bought one for my new Victron 450/100 charge controller to go into my Outback DC load center. It arrived brand new and as decribed.

Is there such a thing a panel mount adapter to <something handy> kit? It's that or buy an DC load center which seem pretty pricey for no more than they are.


edit to fix typos (that just needs to be in my signature line... :ROFLMAO: )
Hi Oz..,

Good that you do not need Remote Trip, as, the extra terminals on the rear are an Aux Switch, which, I believve, indicates weather this breaker is Open. or Closed, IIRC.

A good find, though. BTW, think in the Wind-Sun store, the Schneider 125 A Panel Mt breaker (without RT) is very inexpensive.:

This may be SE closing them out. Am a real MN fan, but, this breaker seems like a deal FWIW, etc, Luke
 
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