battery backup question.

[BeanAnimal]

You have to also understand what a UPS is really for...

We size UPS systems to hold a system up during a power outage LONG ENOUGH FOR THE GENSET TO KICK IN.

There are two ratings to consider. The CURRENT that the UPS can handle and the SIZE of the battery string.

SO when you see 500VA 750VA 1000VA etc, you are not just looking at battery size. The larger capacity units usually have larger batteries but that is only to keep up with the current draw.

It gets VERY expensive to add battery strings to ANY UPS system. It is almost always MUCH cheaper to only add enough cells to hold the system over for the genset (usually much less than 30 seconds).

I have a some VERY LARGE ups systems here, 1 with over 28 12.5Ah batteries. It will cost $400 every 3 years to replace those cells. The other UPS holds larger AGM batteries and costs around $800 when battery replacement comes around. I would be silly to put that thing on my aquarium. I can get a natural gas generator and automatic transfer switch for less than $2000.

 

[KyleO]

BeanAnimal is right...........on all counts. I manage server rooms for a living and I can tell you that most "UPS" units will not supply a fraction of the uptime or battery time that it claims to.

The true battery backups that live up to their rep are EXPENSIVE!!! If you are going to be using APC, Belkin or the like, under-estimate your downtime by a factor of 6 and then you are probably going to get some real world results.

What is wrong with haing two or three APC UPSs for two or three power heads???

 

[yeldarbj]

Can anyone give any specific details on run-time of a powerhead on a UPS? I understand that most basic UPS systems are designed to run a heavier load for a very short period. I want a UPS to run a single powerhead (~8 watts - Seio 620) for as long as possible.

With hurricane season approaching, I need something to help maintain some flow during a storm. I've got a generator for after a storm does its damage, but it's not feasible to run it while the storm is blowing through. We lost power for about 18 hours when Katrina hit almost 200 miles away. I didn't have a tank at the time though.

 

[kimboslice]

bean animal do u own a liebert? i am looking for a battery backup and want a good solid one but not too pricey
is liebert the way to go?

 

[BeanAnimal]

I own a pile of Lieberts

I like them so much, that I now sell them and have since dropped APC.

The GXT2 series units are rock solid and are true "online" ups systems. The DC bus powers the inverter ALL OF THE TIME. There is NO switchover time. When the mains power dies, the batteries are already connected to the DC bus. During mains power, the DC bus powers the inverter and keeps the batteries charged. This all means that the unit does NOT do voltage regulation, it does not need to, as the input voltage is meaningless. The true sinewave output is nice and clean and stays that way.

You can find them at several online vendors. provantage.com has decent pricing ($425 for the 700VA, $550 for the 1000VA, $725 for hte 1500VA) These units are NOTHING like the APC or other consumer garbage out there. These are the real deal.

However, you may want to just look into getting a GOOD inverter and a few deep cycle batteries if you are trying to get through short power outages. You can put the inverter and batteries OUTSIDE in a suitable "dog house" for safety. Much cheaper than commercial quality UPS. Depending on the relay setup you chose, you may or many not be able to prevent the halides from going out during the switchover.

 

[MeuserReef]

Here is a system that I am working on to satisfy my tank's battery backup needs. First, I must mention that I manage a foodservice warehouse in Houston that employs the use of powered lift trucks that run off of lead-acid batteries. I recently purchased some new batteries for the pallet jacks and had to dispose of the old batteries. Now these batteries used in the lifts are 24 Volt (12 cell) 750Ah(!!). I was able to convince the battery vendor that we used to dispose of our old batteries to "donate" 6 of the cells from one of the old batteries to me. He was even kid enough to build up posts on them so I could use car-battery terminals to connect the cells together. I now have these in my garage, charged up, ready to go.

My question is this.... on a 400W, 12V inverter (pure sine wave), do you see any issues using this "super battery" for my backup needs? I only want to run my powerheads, main pump, and a 65W Power Compact bulb (about 150W total). According to this website:

http://www.dcacpowerinverters.com/faq.htm#22

....my system will power the 150W load for 50 HOURS!!

I have the cells connected with 12 guage wire, with a 20A DC fuse on the negative lead coming off of the battery. I dont ever plan on having enough load (or a big enough inverter) to need to pull more than 20A off the battery at one time.

Sorry for the thread hijack MaGNuS042!!... just seemed like an appropriate thread to share this thing!

Heres a couple of pics of the setup. (spray paint can for scale)

 

[BeanAnimal]

You have a lot of things you need to consider.

1) Safety. There is a LOT of current available there. Enough to kill you.

Always disconnect the negative terminal first and hook it up last. (This hold true for working on your car also).

1 Fuse is NOT going to do it...

Here is the problem. SERIES cells will discharge evenly according to their own charge. PARALLEL cells will not. As cells discharge at a different rate (or have different capacities) they will draw current from adjacent parallel cells (trying to recharge). This can create HUGE current draws. If one cell has a shorted plate it will start a cascaseding current through all of the parallel cells. DISASTER! You can have a very serious meltdown.

SO.... Each parallel set of cells needs a DC rated fuse.

At 12V you should be OK with a blade fuse. At 24 volts or above things change. DC current does not self extinguish once it arcs. DC fuses are much different than AC fuses.

You mentioned that these are 24V cells but you have a 12V inverter? Can you clarify... as that is not going to work.

Do not expect 50 hours out of USED cells. They were replaced for a reason

What are you using for a charging circuit?

Those are wet cells and can therfore outgas a decent amount of hydrogen. You may want to store them outside in a purpose built doghouse for safety (both from explosion and fire due to short circuits).

I think you already undertand this... but
Cells in series add volts but not AmpHours.
Cells in parallel add AmpHours but not volts.

Other than that, you should be fine.

Please just remember that these are serious batteries, not toys. They CAN certainly maim or kill you.

We use very large arrays in underground coal mines to run mobile equipment. http://www.ausmet.com.au/operationnews/index.htm check out the "battery scoop" on that page (click on the thumbnail for a hi-res image). The whole back end of that machine is batteries. It will run that piece of equipment for an 8 hour shift!

Anyway... I hope that helps. Please be carefull!

 

[KyleO]

I hate to be the nay-sayer but this looks like a serious accident in the making to me............please tell me you don't have any kids!!!

Are you planning on shielding or containing this monster in any way?

What equipment are you planning on running on batteries in the case of an outage?

 

[MeuserReef]

Bean -

These cells are wired in series. If you look closely, you will see that the positive terminal is connected to the negative terminal of the adjacent cell. The fuse is on the negative "lead" that comes off the cell to the far left. The positive lead comes off the cell to the far right.

As far as voltage, each cell is only capable of producing ~2V (which is why I run them in series). With 6 cells in series, I get to my 12V. My earlier comment was that these cells came from a 24V battery used on a pallet jack. I will clarify that the 24V batteries have 12 of these cells in them (12*2 = 24V), not 6. I will be using a 12V inverter on this battery. Im looking at a 400W, pure sine wave model. Im not looking to power the entire tank system, but rather just the pumps and the dusk/dawn light.

Good point about the "new vs. used" cells. I might add that I did have these cells acid-adjusted by the battery vendor and each cell was tested to make sure that they would charge up to a correct voltage (~2.15V fully charged)

As for the Hydrogen concern.... I am using a 2A (12V) charger to charge the cells. This low amperage charge causes a VERY slow charging rate as well as a slow gassing rate. The chargers that I use at my job are 775A chargers that charge these batteries in 8 hours, producing much more Hydrogen than my setup. There are 30 batteries (with 12 cells each) that charge in our facility. Im not too concerned with the levels of H in my garage suddenly climbing to an unsafe level, but I do think that I will move them to a weatherproof location outside of my house just in case. Good idea.

I'll post my "Auto On/Off" relay schematic that will automate this puppy once I get my drawing into MS Paint so that I can post it.

Thanks for the comments and for the reply Bean.

Oh and KyleO..... no kids yet... (didnt know being a parent was a requirement for this thread?!?) LOL