Connecting CC & Inverter to Battery Bank

[Sunking]

John do not get your shorts in a not worrying about what happens after the inverter. Battery inverters are such soft sources, especially in the capacity you are working with it is not possible to have any real arc flashes or even approach AIC rates. Th eonly area you want to pay close attention is any cables to or from the battery. At 150 AH battery is not going to create a plasma cloud. At most 300 to 500 amps dead bolt fault.

[johngalt]

John do not get your shorts in a not worrying about what happens after the inverter. Battery inverters are such soft sources, especially in the capacity you are working with it is not possible to have any real arc flashes or even approach AIC rates. Th eonly area you want to pay close attention is any cables to or from the battery. At 150 AH battery is not going to create a plasma cloud. At most 300 to 500 amps dead bolt fault.

Thanks, I needed that. I kinda thought I had an idea of what I was doing until I came here. I've learned a lot, but I've also become very paranoid of the wrath of electricity gone wild. Now I just imagine everything going poof the second I flip the switch. lol.

Someone once said: "There are thing you know you know, things you know you don't know, and things you don't know you don't know." I started with the things I knew and began teaching myself those things I knew I didn't know, but after reading you guys for awhile I quickly realized there may be many things I don't know I don't know that could hurt me.

I appreciate the patience and the pointers.

[Sunking]

Thanks, I needed that.

You are welcome, but do not let your guard down to low. Batteries are dangerous, very dangerous because you cannot turn them off so remember that. Your bank is not large enough to vaporize you, but large enough to blow a finger or hand off if mishandled and start a fire you cannot put out. The MRBF's you bought are more than adequate to do their intended job. But remember those battery terminal post are always hot and not protected. If you drop a wrench across the battery post, there is no switch, breaker, or fuse to turn the power off and and stop spewing molten steel and copper all over the place or prevent the battery from exploding covering you with boiling hot acid. I know a few electricians with missing fingers, or one with funny looking skin patterns from acid burns we call Patchy aka Lucky to his face

[johngalt]

I know a few electricians with missing fingers, or one with funny looking skin patterns from acid burns we call Patchy aka Lucky to his face

Good advice. I will do my best to never earn a "nickname" and respect the battery at all times.

I'll post an update when I progress further.

[FloridaSun]

You are welcome, but do not let your guard down to low. Batteries are dangerous, very dangerous because you cannot turn them off so remember that. Your bank is not large enough to vaporize you, but large enough to blow a finger or hand off if mishandled and start a fire you cannot put out. The MRBF's you bought are more than adequate to do their intended job. But remember those battery terminal post are always hot and not protected. If you drop a wrench across the battery post, there is no switch, breaker, or fuse to turn the power off and and stop spewing molten steel and copper all over the place or prevent the battery from exploding covering you with boiling hot acid. I know a few electricians with missing fingers, or one with funny looking skin patterns from acid burns we call Patchy aka Lucky to his face

I had an experience with an exploding battery once but only cause I forgot to remove it before welding near by. Not a fun experience but no great harm done that day. I was lucky, didn't get patchy.
Have a question for ya Dereck. John Wiles writes,
" In no case should charge controllers, switches, relays, or other devices capable of producing an electric spark be mounted in a battery enclosure or directly over a battery bank."
"The NEC requires certain spacing around battery enclosures and boxes and other equipment to allow for unrestricted servicing—generally about three feet [110.26]. Batteries should not be installed in living areas, nor should they be installed below any enclosures, panelboards, or load centers [110.26]."
Just how far below/away from charge controller, inverter should the batteries be for adequate safety in a small (2x 12V/100AH) system? I've seen many photos of systems with electronics right above battery banks before reading that. Seems a trade off between cable length and safe distance. I'm not expecting any excessive gassing or stray sparks but.... just how quickly does hydrogen gas disperse?

[Sunking]

In no case should charge controllers, switches, relays, or other devices capable of producing an electric spark be mounted in a battery enclosure or directly over a battery bank."

OK this is code talk and you have to read it very closely and know code talk to understand what is being said. So look at what I highlighted in Red . All he is saying is do not mount anything directly over a battery bank that could possible produce an electric spark. So if the battery bank is installed up against a wall. It is just fine to install a charge controller on the same wall above the batteries off to either side so it is not directly over the batteries. So iff you drew a vertical line up from the end of the batteries straight up, you do not want the vertical line of the CC crossing that line. It can touch, but not cross. Understand?

"The NEC requires certain spacing around battery enclosures and boxes and other equipment to allow for unrestricted servicing—generally about three feet [110.26]. Batteries should not be installed in living areas, nor should they be installed below any enclosures, panelboards, or load centers [110.26]."
Just how far below/away from charge controller, inverter should the batteries be for adequate safety in a small (2x 12V/100AH) system? I've seen many photos of systems with electronics right above battery banks before reading that. Seems a trade off between cable length and safe distance. I'm not expecting any excessive gassing or stray sparks but.... just how quickly does hydrogen gas disperse?

OK let's try a mental picture. If it can fall straight down on the batteries, relocate it. If something metallic or other wise conductive falls on the batteries you have BOOM. Think out of the box for a second like your clumsy kid working with a wrench above the batteries and drops the wrench.

OK how fast does hydrogen disperse? Too complicated to answer as it depends on ventilation and where that ventilation is. For example if you say have a roof with a high point like an arch or dome, and at the high if you have either a vent pipe or exhaust vent the hydrogen is out of there in seconds. Hydrogen is lighter than air like helium is except even lighter. Every seen a helium balloon rise up. Hydrogen will rise even a bit faster. So if the enclosed room does not have ventilation up on the ceiling, the hydrogen will be trapped and accumulate.

Now don't get freaked out. Hydrogen does not get explosive until it reaches 4% minimum saturation. That may not sound like much but is a significant amount of gas.

[FloridaSun]

OK this is code talk and you have to read it very closely and know code talk to understand what is being said. So look at what I highlighted in Red . All he is saying is do not mount anything directly over a battery bank that could possible produce an electric spark. So if the battery bank is installed up against a wall. It is just fine to install a charge controller on the same wall above the batteries off to either side so it is not directly over the batteries. So iff you drew a vertical line up from the end of the batteries straight up, you do not want the vertical line of the CC crossing that line. It can touch, but not cross. Understand?

OK let's try a mental picture. If it can fall straight down on the batteries, relocate it. If something metallic or other wise conductive falls on the batteries you have BOOM. Think out of the box for a second like your clumsy kid working with a wrench above the batteries and drops the wrench.

OK how fast does hydrogen disperse? Too complicated to answer as it depends on ventilation and where that ventilation is. For example if you say have a roof with a high point like an arch or dome, and at the high if you have either a vent pipe or exhaust vent the hydrogen is out of there in seconds. Hydrogen is lighter than air like helium is except even lighter. Every seen a helium balloon rise up. Hydrogen will rise even a bit faster. So if the enclosed room does not have ventilation up on the ceiling, the hydrogen will be trapped and accumulate.

Now don't get freaked out. Hydrogen does not get explosive until it reaches 4% minimum saturation. That may not sound like much but is a significant amount of gas.

ok, 4%, lighter than helium. That helps me to understand the situation.
A straight line off the side of battery... now that is what I questioned in my mind, knowing sparks can go horizontal as well as vertical.
My mind tends to be more nit picky than my actions and my 'in the sticks' location allows me to do much without permits but I do like to follow the NEC code and be as safe as possible even with my small system. I suppose redundant safety would be a short divider wall between electronics and battery box.... not that I would go that far yet.
Thanks

[russ]

Static electricity is more than adequate to ignite hydrogen.

[johngalt]

I am using high-end AGM batteries. According to Hazmat they are said to be safe for shipping and indoor use. The amount of hydrogen gas is supposed to be miniscule unless severely overcharged which should not be possible with my limited system. As long as the area remains ventilated it should disperse very quickly.

Nonetheless, the arrangement of equipment to battery placement is prudent and I will make sure there is adequate clearance for safety.

The battery terminals are recessed below the top of the battery which also serves as a grip for carrying the battery. I think I will get a piece of rubber mat and cut it into small squares and use some duck tape to make some rubber flaps over the terminals. I can easily tape one side of the rubber to the top of the battery case and let it flop down to cover the terminal and cable. I will do this for all battery connections to help protect against any accidental contact between posts.

Safety First!