Battery Boxes...What One Company Designed

Since I am starting the homepower/automated house journey, I have been collecting surplus commercial equipment that might prove useful. One of those items was a surplus Best battery box for a large UPS. Some comments on the construction and design follows.

The box is designed for sealed 6v batteries (two banks or four) with the second bank located above the first. The cabinet is metal with galvenized trays for the batteries to sit in. The box was wired for 12v at 200 amp with commercial welding cable. There are two in line fuses, one per bank. The cabinet is on wheels. The cabinet has two vents located on the back of the cabinet, one lower and one higher. The cabinet is NOT actively ventilated but relies on natural convection. On the front it has a single heavy duty switch to switch the direct current. The switch has a ceramic resistor on it (to quench arcs when switching?).

Several things caught my attention. The use of metal throughout the box...I would have expected fiberglass or plastic for corrosion resistance. Next was the absense of an active ventilation system. Third, the lack of an integrated charger for the battery box. I assume the batteries are charged through the UPS.

I plan on making some mods to this box for my home system.

One is to make plastic tray inserts to keep acid at bay.

Next is an active ventilation system.

Third is to consider doing some type of a sliding tray on the bottom level to allow one to access the batteries easier during maintainance.

Fourth is to incorporate a charging system.

Fifth is to place meters on the front to monitor voltage and amperage and add the option for remote sensing.

Sixth rewire it for a different voltage (it was 12v at 200a)...any suggestions?

I would be interested in any suggestions or comments as to what you have added to or wish you had designed into your system.

Thanks for any and all suggestions.

TMT

Reply to
Too_Many_Tools
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Thanks for the responses so far...

In answer to some of the questions, I could use the battery box just the way it is.

There is no corrosion to the box and all the parts, cables and such are there and all functional.

FWIW....I tend to be someone who tries to make something better than it was. The mods I have mentioned are ones that can be done with little effort.

I will be using it for emergency power backup with an eye towards alternative power generation as this project evolves.

As for voltages, since I don't have a alternative ppwer system I am open to what voltage the battery box will be wired for. From what I see, it seems that the voltages that alternative home power (AHP) is using is slowly creeping up. The battery box holds eight batterys...6v or 12v...so there is a range of voltages that can be used. As it was wired, it was for 12v at 200amps.

Again, any suggestions are welcomed.

TMT....already looking for that next hood ornament ;

Reply to
Too_Many_Tools

I ask what voltage because I can wire it in different arrangments...it was wired for 12v.

I am asking because as you point out there are different inverters out there.

I have a number of surplus UPS inverters that I may use...I am still in the design stage on this subject.

The APC Smart/Matrix UPSes are sine wave, are CHEAP and large enough to be worth using. The downside is that UPS inverters usually have higher idle current requirements that dedicated inverters available on the market now. I have yet to do the tradeoffs with a market survey. Any suggestions you can offer will be appreciated.

TMT

Reply to
Too_Many_Tools

Assuming that you are in US:

Check the National Electrical Code (NEC) which addresses both batteries and low voltage.

Make sure that the DC/charging system is isolated from the AC, draws not more than 20 (IIRC) amps source AC, is UL-listed and is not connected to earth ground.

Above 30 volts, or if the system is not isolated, the NEC is more restrictive.

(FWIW, I have some of your questions. I have a growing 28vdc system. A natural gas-powered 28VDC generator awaits installation. )

Marc Marc_F_Hult

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Reply to
Marc F Hult

My sons call this a " hood ornament project" Finding a neat hood ornament, they say, I would be inclined to build a car under it...

I can't answer for the original poster, but some projects, especially DIY home automation projects, can be driven by what one can do rather than what needs to be achieved. That's often OK.

(Ooops... I jist realized how cross-posted this thread is . Oh well)

A common constellation of reasons that do have specific, useful and attainable objectives (which also happen to be mine) is to provide a power system that provide:

1) protection of devices in the home/office/farm/cabin that contain semiconductors and so may be damaged by lightning and possibly other power-line disturbances

2) a useful amount of back-up power for lighting, electronic, and other electrical equipment devices that are needed in emergencies

3) some personal outlet for frustration over 'energy dependence' in all its contexts.

Gotta go! -- Lightning and thunder as I type this ;-)

.... Marc Marc_F_Hult

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Reply to
MFHult

In message , Too_Many_Tools writes

How should we know ? Did you have any particular load in mind ?

I suspect most of us select components and design systems in response to some particular need or requirement.

You seem to be coming at this the way a sculptor approaches a block of marble.

You sound like you've found an interesting item, that requires a total overhaul to be made stunningly excellent, to greatly exceed the spec required to meet some undefined purpose.

What are you actually wanting to achieve ?

Cheers, J/.

Reply to
John Beardmore

In message , snipped-for-privacy@nothydrologistnot.com writes

Yes - I've got no problem with that, but asking us what voltage to wire the bank to seems silly. Likely to be determined by available cable lengths and thicknesses, surplus or cheap inverters etc...

Cheers, J/.

Reply to
John Beardmore

I think that is the path I may take...in the past I have found that since the electronics continue to get "better" it is usually not worth trying to design in old stuff....and sometimes "old" means just a few years old.

My cost for the UPS equipment I am able to find is nil but one needs to factor in long time power usage (idle current), ability to replace it when it fails and suitability for the home enviroment. It is a fool who designs a system around a surplus component that when it fails, you have to toss the whole system. This battery box in question is a component that can be useful as my system evolves as it will.

This is one reason for the question of "what voltage" since it is apparent that the trend is to different voltages than in the past.

TMT

Reply to
Too_Many_Tools

Thanks...that is the type of information that I am looking for.

What do you use the 12vdc side of the system for? Lighting?

TMT

Reply to
Too_Many_Tools

We run our house on a 12vdc/120vac system. A 2500 watt inverter is sufficient for our daily loads, the generator picks up the big occasional loads, as well as some batteyr charging.

Reply to
Steve Spence

Computer and network equipment, emergency lighting and water. We use a SHURflo pump connected to rain water system. Also have a 12vdc fridge we use on occasion.

Reply to
Steve Spence

In message , Too_Many_Tools writes

But only you know what they cost YOU.

Personally I have done a lot of mobile stuff on 24 volts because that's what trucks use. I don't like 12 because the current requires huge wires, though I've done a bit of that. If it was for home / stationary use I'd expect to see some efficiency advantages by going to higher voltages, but if you charge from PV for example, will you be able to get say a 96V OPT regulator off the shelf ? And what if one battery or PV in a string fails ? Probability goes up as strings get longer. Lots to consider.

Good...

None really. The inverters we have used have been cheap, modern, fairly efficient, fragile, small, switching technology, square wave out and nasty, or have been hugely heavy, inefficient thyristor fired 50Hz 1960s technology with massive transformers and sin wave output. All down to what has come out way.

We also have a huge, and I suspect fairly inefficient 7kW UPS inverter lurking around but there isn't much point in telling you about that. One day it will come in handy though.

But given the price of modern inverters, is it worth your just going out and buying what you need when you know what you need ?

Cheers, J/.

Reply to
John Beardmore

Well, with 8 6 volt batteries, the obvious alternatives are 12, 16 (not common at all), 24,32 or 48 volts.36 volts doesn't work out too well, and 72 and 96 are out of the question. The most common voltages for low cost inverters and UPS systems are 12 and 24 - with 48 being used on several large units. Problem with 48 volt systems is they are generally larger capacity - and should really have a larger battery pack than you have.

I'd suspect 24 volts is the most likely scenario in your position. (or wire it as 2 12 volt packs that you can easily switch s/p for 12 or

24)
Reply to
nospam.clare.nce

I should mention that I was really surprised that the box relied on only a passive system (a couple of small vents in the back) to vent hydrogen.

Is this common with commercial equipment?

The box is stamped with UL and NEC approvals.

TMT

Reply to
Too_Many_Tools

FWIW, here's what I do (use fixed-spacing font to view ASCII diagram):

Internet | Home Automation Control System | Genset controller | +-----------------+ | | | |

28vdc NG Genset -->| Switch over------+ | | AC line --+--60amp charger/converter -+-- 14vdc batteries ---o 28vdc | | | | | +-------+--------+ | | +--80amp charger/converter -+-- 14vdc batteries ---o 14vdc | | | +-------+--------+-------------o vdc 'grnd'

In words:

A bank of deep-cycle lead batteries is series connected to provide 14vdc (nominal 12vdc) and 28vdc (nominal 24vdc).

Most loads including home automation computers, UPS, and low-voltage light dimmers are connected to the 28vdc output.

Home control and other devices that can run off 12vdc (security panel, home automation controllers, video modulators multiplexors, cameras, audio equipment) are connected to the 14vdc rail.

Devices that need other voltages are supplied via DC-DC converters (eg 5vdv for microcontrollers, router, switches and so on) or DC-AC inverters (eg

24VAC for HVAC)

The 'lower' (0-14vdc) bank of batteries is recharged and powered by a UL-listed 80 amp Inteli-power (one "l") charger/supply

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The 'upper bank' (14-28vdc) is recharged and powered by an 60 amp Inteli-power charger/supply.

Together they provide nominal 60 amps at 28vdc and 20 amps 14vdc =~2000 watts.

A Baldor natural gas 28vdc genset has been purchased (not yet installed) to kick in during power outages that has additional capacity for additional 28vdc and 120VAC UPS needs. Controller is a Bouchette A120

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The choice of 28vdc was driven in large part because this the highest nominal voltage that meets the requirements of the under-30-volt sections of the National Electrical code (NEC). A 14vdc system would require conductors (wires) with twice the cross-sectional area to have the same distribution IR losses.

This provides isolated, UL-listed, NEC-compliant single-conversion power for the most/all of critically needed devices including lighting. There is no interruption whatever if line power goes down because the system is connected directly to batteries at all times. A power outage simply changes the charging source from line AC to genset.

The system can be expanded to higher voltages or currents with additional batteries and chargers. and additional charging sources (eg photovoltaic) merged.

DC Grounding and maintaining isolation of subsystems that need to have separate "grounds" is _very_ important and a whole 'nuther topic.

HTH ... Marc Marc_F_Hult

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Reply to
Marc F Hult

FWIW, here's what I do (use fixed-spacing font to view ASCII diagram):

Internet | Home Automation Control System | Genset controller | +-----------------+ | | | |

28vdc NG Genset -->| Switch over------+ | | AC line --+--60amp charger/converter -+-- 14vdc batteries ---o 28vdc | | | | | +-------+--------+ | | +--80amp charger/converter -+-- 14vdc batteries ---o 14vdc | | | +-------+--------+-------------o vdc 'grnd'

In words:

A bank of deep-cycle lead batteries is series connected to provide 14vdc (nominal 12vdc) and 28vdc (nominal 24vdc).

Most loads including home automation computers, UPS, and low-voltage light dimmers are connected to the 28vdc output.

Home control and other devices that can run off 12vdc (security panel, home automation controllers, video modulators multiplexors, cameras, audio equipment) are connected to the 14vdc rail.

Devices that need other voltages are supplied via DC-DC converters (eg 5vdv for microcontrollers, router, switches and so on) or DC-AC inverters (eg

24VAC for HVAC)

The 'lower' (0-14vdc) bank of batteries is recharged and powered by a UL-listed 80 amp Inteli-power (one "l") charger/supply

formatting link
The 'upper bank' (14-28vdc) is recharged and powered by an 60 amp Inteli-power charger/supply.

Together they provide nominal 60 amps at 28vdc and 20 amps 14vdc =~2000 watts.

A Baldor natural gas 28vdc genset has been purchased (not yet installed) to kick in during power outages that has additional capacity for additional 28vdc and 120VAC UPS needs. Controller is a Bouchette A120

formatting link
The choice of 28vdc was driven in large part because this the highest nominal voltage that meets the requirements of the under-30-volt sections of the National Electrical code (NEC). A 14vdc system would require conductors (wires) with twice the cross-sectional area to have the same distribution IR losses.

This provides isolated, UL-listed, NEC-compliant single-conversion power for the most/all of critically needed devices including lighting. There is no interruption whatever if line power goes down because the system is connected directly to batteries at all times. A power outage simply changes the charging source from line AC to genset.

The system can be expanded to higher voltages or currents with additional batteries and chargers. and additional charging sources (eg photovoltaic) merged.

DC Grounding and maintaining isolation of subsystems that need to have separate "grounds" is _very_ important and a whole 'nuther topic.

HTH ... Marc Marc_F_Hult

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Reply to
Marc F Hult

In message , Too_Many_Tools writes

I don't know. Any future 'surplus' inverter is likely to be smaller, cheaper and more powerful than its predecessor, and it's easy enough to rewire to another battery voltage.

But not to a single obvious choice of voltage I fear.

Cheers, J/.

Reply to
John Beardmore

Depends on how smart the charger is, condition of battery, how quickly you want to recharge the battery after it has been drained, how deeply you drain cycle it, how anxious you are to prevent stratification of the electrolyte and sulfation -- among other things ;-)

If it is a standby systems that is seldom actually used (as opposed to a diurnally cycled system with eg photovoltaics) the use of a smart charger like in the url below should keep H2 concentration in even lightly convected air to below the level of concern for explosion unless the space itself is too small.

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There are hydrogen sensors one could use for monitoring. My now-dated experience with them was that they were more trouble than they were worth. Presumably they have improved.

My qualitative experience on what is "too much hydrogen" is limited to having one largish battery blow up in my face 20 years ago. It hurt (including pride) but miraculously I suffered no permanent damage.

Marc Marc_F_Hult

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Reply to
Marc F Hult
[big snip] | Together they provide nominal 60 amps at 28vdc and 20 amps 14vdc =~2000 watts. | | A Baldor natural gas 28vdc genset has been purchased (not yet installed) to | kick in during power outages that has additional capacity for additional 28vdc | and 120VAC UPS needs. Controller is a Bouchette A120 | |
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| | The choice of 28vdc was driven in large part because this the highest nominal | voltage that meets the requirements of the under-30-volt sections of the | National Electrical code (NEC).

What NEC circuit class does your 28V wiring fall under?

Dan Lanciani ddl@danlan.*com

Reply to
Dan Lanciani

In message , snipped-for-privacy@sny.der.on.ca writes

You mean 18 ?

32 ?

Don't know that they are, though these and higher voltages tend to be used with wild inputs from wind turbines etc.

Not a bad strategy.

J/.

Reply to
John Beardmore

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