Batterys in the House

halfcrazy · July 2007

ok this has been a hotly discussed topic on another board so i thought i would open this can of worms here and get a good discussion going.
What is everyones stand on whether the battery should be in the house or not and why?
I personaly have mine in the house so they wont be subject to the freezing sub zero temps outside

crewzer · July 2007

Re: Batterys in the House

1/2,

Flooded-cell batteries vent both hydrogen and oxygen as a result of electrolysis while in the absorb- or EQ charge states. Occasional watering replaces the lost water. Hydrogen gas is explosive, so that's the cause for concern.

I gather that hydrogen gas concentration should be kept below 1%. 2% may cause a "flash" if ignited, and 4% will go "boom", or something like that.

You may find this link and its formulas to be of use: http://www.bhs1.com/batteryroom/ventilation.htm

HTH,
Jim / crewzer

Mangas · July 2007

Re: Batterys in the House

Our batteries, inverters and charge controllers are built into in a vented granite rock house with 8" walls located 100' from the ranch house and 120' from the solar array.

The interior temperature of the solar mechanical room ranges from the middle 50s' (winter) to the low 80s' (hot summers). We also installed an automated hooded air extraction system suspended over the battery banks to vent gassing to the outside as required. Probably overkill.

We decided on this approach for added fire protection and risk management for the main house. My opinion is if your are just setting things up and have the space this approach delivers some risk management, especially if you're running a large number of batteries.

System2 · July 2007

Re: Batterys in the House

I've been planning on building a "wood shed" to house the batteries, inverters, controller and provide a theft resistant mount for the PVs. About 100 feet fron the house. However, it hasn't stopped raining since early May, so I can't get the cement truck up across the wet and therefore very soft field to pour the slab. The truck would sink out of sight, so everything is on hold. I am very concerned however about winter battery temps. It's common to experience winter temps below 0F, and can at times hit -20F, but most of the winter, it hangs around +20F. I know well it will reduce battery efficiencies, but am wondering what others have experienced and how they at least partially overcame the problems.
They have been in an unheated outbuilding for at least 3 years, but not used in the winter (at the camp), just kept charged. I want to move the system home, eventually the camp will be sold.
Oh yes, I want to keep them out of the house for safety reasons. Six L-16, in a 12 volt system. 1000 watts PV, Morningstar TS-60. I know the TS-60 is being pushed hard at times, but not often. We have a lot of cloudy days, where the extra PV's come in handy.
Thanks for your input.
Wayne

Ralph Day · July 2007

Re: Batterys in the House

Hi

Wayne, what are the safety concerns? Power vent the battery box and all the gases get out of the house. For Eq charging i open the basement windows and run a 24" fan out the basement door.

Watch where you place inverters. Pg 17 of Xantrex manual "In a corrosive or condensing environment, the life expectancy of the inverter is indeterminated and the warranty is voided". I've seen inverters in a metal shed with water dirpping off the ceiling because of the fear of having batteries in the house and the long cable lengths to the inverters if they're not (don't know how long the inverters will last).

How close are you to the ocean, and boy, you've had it moist this spring and summer!

ralph

SolarJohn · July 2007

Re: Batterys in the House

Can anyone provide a link to a story about a serious incident (explosion, fire, etc.) directly related to batteries? I believe in safety, but I've never come across any such story. Could it be that all of us who have batteries as a part of our systems are doing it right?

John

mike95490 · July 2007

Re: Batterys in the House

SolarJohn wrote: »

Can anyone provide a link to a story about a serious incident (explosion, fire, etc.) directly related to batteries? I believe in safety, but I've never come across any such story. Could it be that all of us who have batteries as a part of our systems are doing it right?
John

Homepower had a very good article, with graphic photos, of a large battery bank, half vaporized, acid all over the ground. When they redid their site, they moved it to paid viewing only. I don't have the link any more. Something like When Batteries go bad, or how not to charge batteries. It was gross. It was outdoors, separate from the house, and happened to folks who should have known better.

crewzer · July 2007

Re: Batterys in the House

Can anyone provide a link to a story about a serious incident (explosion, fire, etc.) directly related to batteries?

A simple Google search turned up more than just a few hits:

http://www.detrick.army.mil/bulletin/safety/work/batteryexplosion.cfm
http://www.sacskyranch.com/lead12.htm
http://www.rayvaughan.com/battery_safety.htm

HTH,
Jim / crewzer

dulley · July 2007

Re: Batterys in the House

I was thinking of useing the sealed AGM { Absorbed Glass Mat } Gel Batterys when i put my system togather and putting them in a spare bebedroom I live where the winters temp can stay at { - 35 F } for a week or two

Ideal operatiing temperature is 68 deg
6 volt 225 amp Hour @ 100 hour rate.
Float voltage is 6.75 - 6.9 (2.27-2.3 Volts per cell).
Group GC2 size, 10.7" long x 7.3" wide x 10.9" high to top of terminal.
81lbs.
5/16" Copper female threaded insert terminals.
1042 maximum discharge current amps
Short circuit current is 6273 amps
Impendance is 1.10 milliohms
Ideal operating temperature is 68 degrees F - 77 degrees F

{ Should I do this } !!!! ????

mike95490 · July 2007

Re: Batterys in the House

well, in your favor, the AGM's are much safer for indoors, but to much charge current can blow them. Use the remote thermal option on your charge controller, and program the controller to AGM settings (not the default flooded cell)

And stock up on some baking soda!

dulley · July 2007

Re: Batterys in the House

mike90045 wrote: »

well, in your favor, the AGM's are much safer for indoors, but to much charge current can blow them. Use the remote thermal option on your charge controller, and program the controller to AGM settings (not the default flooded cell)

And stock up on some baking soda!

I dont understand the stock up on baking soda

BB. · July 2007

Re: Batterys in the House

After the batteries kept in the bedroom explodes and sprays the overnight guest sleeping in the spare bedroom (and everything in the bedroom) with concentrated sulfuric acid, use baking soda (mixed with some water for easier application) to neutralize the acid to reduce the risk of blinding and reconstructive surgery will be less expensive and less hazardous to dispose of everything sprayed with acid in the bedroom...

-Bill

niel · July 2007

Re: Batterys in the House

you won't need baking soda on agms unless you've severely overcharged them blowing out the vent seals and thusly ruining the batteries. you could use baking soda to clean off standard leadacid batteries, but extreme care must be taken so that none of it gets into the cells as this would neutralize the acid in the cells and ruin the batteries. i just use water and a disposable rag or paper towl to clean them off with.
hey bill, in a case like that hit the shower asap and the heck with baking soda.

dulley · July 2007

Re: Batterys in the House

niel wrote: »

you won't need baking soda on agms unless you've severely overcharged them blowing out the vent seals and thusly ruining the batteries. you could use baking soda to clean off standard leadacid batteries, but extreme care must be taken so that none of it gets into the cells as this would neutralize the acid in the cells and ruin the batteries. i just use water and a disposable rag or paper towl to clean them off with.
hey bill, in a case like that hit the shower asap and the heck with baking soda.

Thank you Neil for your reply I want to make sure I have all my ducks in a row before i start this project

halfcrazy · July 2007

Re: Batterys in the House

lots of good discussion here. in a lot of places it just doesnt seem practical to not have the batteries in the house. it seems to me if the batery box is properly built to contain the problem and vented properly that there wouldnt be a big issue here? as a electrician i have searched the code book and really cant find anything stating they cant be in the house?

i found 480.9 witch is battery locations and it states
A ventilation proper ventilation is required
B Live parts must be gaurded
C working space shall comply with standard working spaces similar to panels

Seems to me in real cold climates similar to ours that a proper battery box in say a mudroom or basement would sufice?

niel · July 2007

Re: Batterys in the House

dulley,
no problem as we want you to be not lost with hope instead of lost with no hope. i can appreciate his exaggerated reply with a twist of sarcasm meant in a humorous way to obviously be an indirect answer to your inquiry though. lol

BB. · July 2007

Re: Batterys in the House

There are several issues as to why any lead acid chemistry battery can fail and explode...

First, for UL, when dealing with any rechargeable battery/Lithium battery--they require a minimum of two components to ensure that if one fails, the second will be there for protection... For example, I had to place two resistors in series (simple "charge controller"), or if diodes were required (to prevent backfeeds from incorrectly charging a battery), again I had to place two in series to meet their minimum safety requirements.

For a Solar PV system to be even "minimally safe" for a inhabited room--I could see using two charge controllers--the normal one connected from the PV panels to the battery bus--and a second controller set up as a diversion controller--such that extra power is dumped so that the batteries cannot be overcharged. And, there should be some warning/test circuit to indicate when one or the other controllers has failed. (One of Jim's links was to a large UPS system where the hydrogen alarm was beeping (commented on by people working nearby) for three days after the building was left empty after a move).

The other issue is with the batteries themselves and much more difficult to build in safety redundancy.

More than a few batteries have been overcharged in their life and there is no way of looking at sealed/AGM batteries to know that they have been, or are currently being over charged (short of weighing the battery) to see that it may have been compromised.

The other issue is that battery cases can crack and leak acid... With the plates being exposed in one cell, while the others are fully submerged, the one leaking cell can easily outgas large amounts of hydrogen. Reading through the links given by Jim, at least one battery appeared to be completely dry when it exploded (probably boiled dry during charging).

If you try to contain the battery/bank in a container--the container itself needs positive ventilation (again, ideally with a failure resistant design), and be able, at a minimum, to contain the force of any one battery failing explosively (without the battery container adding to the flying debris).

All in all, the risk of any single failure causing an explosion is very small--but the resultant damage and injury possibilities are large. It just is not safe to keep large storage batteries (and banks) in an occupied residence.

Notice that many of Jim's explosions did not ever find evidence of any electrical problems--and, in fact, many of the "systems" worked just fine again after the battery was replaced and the mess cleaned up.

Yes, sorry, I was being a bit sarcastic with the reply about the baking soda, immediate showering is a very good method to quickly remove/neutralize the acid--trying the hard way to make a point about safety... Nothing ill was intended.

-Bill

PS: Just to be clear, proper ventilation and ensuring that any failures/explosions do the least amount of damage... For example, building a battery box with a "weak wall" that would protect people walking by in a mud room (say, strong front and top), but allow the overpressure to blow out against a wall/safe direction. Building a very strong box on all sides, then you cannot control where it will fail.

The failures are not often--but if you can plan for a "safe" failure, you are better off... Acid burns are among the worst that can happen to people-BB

dulley · July 2007

Re: Batterys in the House

niel wrote: »

dulley,
no problem as we want you to be not lost with hope instead of lost with no hope. i can appreciate his exaggerated reply with a twist of sarcasm meant in a humorous way to obviously be an indirect answer to your inquiry though. lol

You think I need to put some oil on them

crewzer · July 2007

Re: Batterys in the House

½,

See NEC 480.9(A) re requirements for battery ventilation.

Here’s a possible solution to your battery box issue:

1) House the batteries in boxes like the large Contico Pro Tuff Bin from Lowes or HD.
2) Build a PVC “exhaust” manifold to vent the boxes; box inlet vents are also needed.
3) Insert a ventilation fan like this in the “exhaust pipe” that leads to the outside: http://www.solarseller.com/battery_box_power_vent_by_zephyr_industries.htm
4) The 12 V fan can be powered from the MX60’s AUX connections with the AUX function set to “Vent Fan” and the appropriate voltage (~ absorb target voltage)

HTH,
Jim / crewzer

dulley · July 2007

Re: Batterys in the House

I like that wire it to a programable timer switch to run for 5 min.s every 8 hours

crewzer · July 2007

Re: Batterys in the House

I like that wire it to a programable timer switch to run for 5 min.s every 8 hours

Batteries gas while they're in absorb mode, which can last for a couple of hours, and in EQ mode, which can last for an hour or more. Accordingly, "5 minutes every 8 hours" probably isn't anywhere near good enough, and the fan may not even operate during the absorb and/or EQ stages.

A voltage controlled switch, like the MX60's "Vent Fan" AUX function, can be set to operate a vent fan when the charge voltage exceeds a certain setting, i.e., 14 V in a "12 V" system.

HTH,
Jim / crewzer

BB. · July 2007

Re: Batterys in the House

I have worked around HCL acid quite a bit in years pass (radiator repair shop), and never took the stuff very seriously--so I got a bit cavalier about the whole acid thing...

Over the last few days been reading a thread on another board about exploding lithium batteries in flashlights (primaries and rechargeable--and another thread here) about the violence and the chemical releases from the venting/burning of their failures.

That, plus reading the Lead Acid battery failures got me to thinking again about how careless we all tend to be around these incredibly powerful energy storage devices...

No body would think twice about the wisdom of not storing and using 5 gallon cans of gasoline in the house--but we usually don't usually think twice about batteries.

-Bill

Mangas · July 2007

Re: Batterys in the House

Jim's comment,

"A voltage controlled switch, like the MX60's "Vent Fan" AUX function, can be set to operate a vent fan when the charge voltage exceeds a certain setting, i.e., 14 V in a "12 V" system."

That's exactly how we electronically controlled our air extraction fans. They're interfaced to the MX60s', plumbed into the hoods and then ductwork vents the air to the outside.

Scott

halfcrazy · July 2007

Re: Batterys in the House

Crewzer i have all that i was just curius as to what everyone else does or feels my box is on a concrete floor all 3/4 oak wood and screwed and glued and will be lined with a rubber roof membrane and is vented with the zephyr battery box fan with pvc straight up and thru the roof with a 180 turn on top screened for bugs and the fan is controlled by the mx60.

System2 · July 2007

Re: Batterys in the House

dulley wrote: »

You think I need to put some oil on them

Oil won't help them, because the teeth don't mesh, so by now there's nothing left of them anyway. Sorry.

System2 · July 2007

Re: Batterys in the House

Ralph Day wrote: »

Hi

Wayne, what are the safety concerns?

How close are you to the ocean, and boy, you've had it moist this spring and summer! ralph

Safety concerns: Anything that can go wrong, will go wrong, and I'd like whatever it is that's going to happen, to do so outside the house.

Re the ocean, as the crow flies, less than a mile from Chedabucto Bay. In fact, when the surfs up, I can hear the rocks being tumbled and knocked into each other by the waves, along with the sound of the crashing surf. And yes, up until 3 days ago, we've had some rain almost every day since early May. Summer MAY have FINALLY kicked in 3 days ago, but time will tell. LOL

Funny little story about car batteries stored in the house. (NOT mine LOL)
When I was with the local Fire Dept, we got called out one evening to a house fire. Saved the house, but some damage to bedroom. Seems the owner had stored an extra car battery under the bed and, we think, sort of forgot about it. Anyway, he ended up having a party, and when everyone had left except for one "lady" who decided to spend the night, the kissing started. Things apparently moved to the bedroom, and eventually to the bed. As things progressed, it seems there was some, shall we say, "bouncing" on the bed. Eventually, the bed springs were able to make contact across the battery terminals. The springs welded to the battery posts, became hot enough to set the mattress on fire, which was immediately followed by the explosion of the battery. Buddy was the laugh of the village for months.
Wayne

niel · July 2007

Re: Batterys in the House

boy, talk about a hot night. lol

System2 · August 2007

Re: Batterys in the House

Well, it's LOTS of rain here in the Wisconsin Midwest and I am looking ahead in case our basement floods (thankfully, still dry!) We live a block from the lake and in past years when the water table is high we have had some seepage/flooding into our basement, even tho we have taken precautions to prevent it. Last time it happened was 12 yrs ago, but the way it keeps raining, I'm concerned it could happen again. No sump pump here.

We have a small battery (4 used DATASAFE HR500 VRLA back up batteries, each originally 135 amp hour) system that runs a coupla rooms in our house with the panels on the roof. The system was installed by a reputable electrician and the batteries are in a vented battery box in the basement. The set up allows us to go back on grid if the batteries need to be recharged.

They are heavy buggers, approx 110# each so there's about 440# in the battery box. Besides disconnecting the system, any suggestions what the safest way to deal with this if the basement floods and H2O is on the floor and gets into the battery box? (Yes rubber boots!) We did not think this type of weather could happen again, foolish optimists that we are. I am thinking we ought to get a pump, just in case. Maybe I am worrying needlessly, but it is best to be prepared...just in case. How does one move charged batteries safely if the surrounding area is water? Thanks in advance, I continue to learn a lot at this site. MJBY1

BB. · August 2007

Re: Batterys in the House

Assuming you safely disconnect the battery leads and there are no shorts to 120/240 VAC--moving 12 volt batteries would be just the normal precautions... Don't get water inside the battery (will permanently damage), don't drop it and crack the case, etc.

But, you are probably correct in that you plan for the worst and hope for the best. Were I used to live on the coast, they used to get flooding from storm surges and (I guess) city pump failures. Every time they fixed it and said it could not happen again, it happened again.

It would probably be better for you to move it now (or at least put them up on well braced shelves)--and not have to worry about it in the middle of an emergency.

If the batteries flood, floating debris could short the leads and acid could leak into the water and further damage items in the basement. But probably the batteries will not be the worst of your problem.

If a sump pump will "fix" the problem--it is probably worth doing it--perhaps even digging down a few feet and pumping out ground water--may keep the basement drier and save expensive repairs if it ever happens again (probably when you are on vacation). You can get a 12 VDC sump pump and use the batteries for backup power.

-Bill

niel · August 2007

Re: Batterys in the House

if it were me i'd get them raised too, but higher than the water had ever gone if that's possible. i say this because the worst case scenario would be the batteries running the pump and because of no power to the batteries(usually stormy and rainy weather) the batteries run down and flooding occurs anyway. or the flooding happens fast making a pump useless.

lamplight · August 2007

Re: Batterys in the House

i thought i read something in the electrical code a couple years ago (discussed it here too i am pretty sure) that said it was considered safe to have a moderate sized bank in a moderate sized room, unvented. i seem to recall the example was 12 batteries but i forget.. i know it was more than i have.. nonetheless this thread has gotten me in gear: i just ordered the tuffbox and at least will put in some intake and outtake venting, if not powered.

does it seem reasonable to have a hole near the bottom for intake and a hole at the top to allow the hydrogen to naturally rise and escape. i know im missing something or they wouldnt sell the fans. but it seems this should work fine without power?!?

Batterys in the House

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