Backyard Aquaponics
A place to discuss aquaponics

Hi there, i got my hands on a Lge used gel battery that came out of a bank of batteries used as a back up for a commercial alarm system. It is apparently only 2 years old and working fine but as the building was struck with lightning they had them replaced.
I am planning to shift my system from grid onto solar if possible or at least run on battery at night and re-charge during the day as my house is on solar.
The guy who gave me the battery said that i need to ensure i either keep it charged or drain it almost completely before re-charging, or it will develop a memory and have a very short life. He said that i need a special charger that will determine when the battery is low enough that it needs to be charged.
Is this true???

Short answer- if it is a Pb-acid battery, No. If it is a NiCd battery, Yes.

It's probably a UPS Lead-acid gel battery, designed to be kept at a float voltage almost all the time, and subject to occasional deep disharge when doing backup duty in the event of mains failure. They are being used reasonably successfully as battery storage in off-grid and hybrid systems when subject to shallow discharges on a daily basis, not being run flat before recharge.

What are the battery details?

Hi Gunagulla, thanks for the reply, see pics attached. Also what setting should my charger be set on to charge this thing? it has a few settings but gel is not one of them.
Oh that is the inverter i was thinking of pairing it up with, its what i use for camping.
Cheers mate.

Oh and I have 3 pumps with a 4th to come, they are 40W, 70W, and 80W the 4th likely to be 40W or 70W.
So i expect there will be a bit of a drain on it at night but i could introduce a timer and only run half the night maybe?

Since you will be cycling it regularly, you need to charge it at 14.7 +/- 0.1V @25C, lower at higher temps and higher at cooler temps (temperature compensation is necessary if the battery is subject to a wide range of ambient temperature), and when charged, float should be 13.7 +/- 0.1V. Float transition, ie when it is fully charged, should be when the charging current drops down to about 2A @14.7V.
Does your charger have anything like those settings?

With all those pumps running, you'll be drawing close to 300W from the battery, ie 25A, so a timer will be necessary, otherwise you'll flatten the battery every night and it wont last long at all. I'd say you really should have more than 1 battery. At that current draw, your battery capacity will be quite a bit less than 150AH too (look up Peukert Effect as to why).

You'll need to charge the battery with about 50% more energy than you use in AC kWh, to cover inefficiencies with charging the battery and the inverter. You will need a lot more PV panels that you might expect, or else supplement from the house power in cloudy weather.

A quick google finds:

http://www.rpc.com.au/pdf/ritar_12V_150Ah.pdf

Looks like a nice find, wouldn't complain if I came across one or two those for the right price.

Cheers

Shane

From the {extremely} vague ideas department...

if your stocking density allows it, you might be able to get away with using airlifts overnight to just keep each system ticking over with just enough water through the growbeds until the sun comes out again.

or...

connect up all your systems and run them at night as constant flood with just one pump, and drop airstones directly into the growbeds where the water enters from the last growbed to supply O2 for a super low energy footprint. You could set a low flow so that your siphons didn't trigger, and run a small drain to connect all the growbeds for overnight flow. The small drains between the growbeds would also act as failsafes if a pump went down.

or...

employ a flow splitter and run one pump that directs water to each bed in turn at night. I happen to have invented a few They are free. (the designs are free, it costs around $15 in PVC and pingpong balls to build) The best one I designed can be seen here ... http://120thingsin20years.blogspot.com. ... ccess.html The other two work but are too complicated compared to this one. This one is very simple and very reliable. It lasts as long as a pingpong ball lasts. The video shows it dumping to the same container, but obviously you would create some plumbing to redirect the water to where you want so the flow switches between different growbeds each time it tilts.

Hi, thanks peeps for all the input, unfortunately i really need all pumps going when i am running, my system is actually 2 separate systems, then 1 system has a DWC and DW pond running off to the side and the other will soon have some strawberry towers running off to the side of it.
Yes the battery was a good score sweetened by the fact it was gifted to me, although i really would have liked to have scored one of the others, but they were spread out amongst friends.
I could buy another but i don't like adding new with old, any thoughts on this??

My charger has none of those settings so although it was $300 or so, i guess it not so good, it simply had Calsium, AGM, wet, etc. I will look into smart chargers and consider 1.

I have a 120W solar panel, is it possible hook it up and also hook a charger?? I can't see why not.

I am leaning towards this, feel free to comment.

Setting battery and smart charger up in pump shed (shaded area out of weather)
120W solar on pump shed roof.
all pumps running off inverter hooked to battery.
smart charger set to turn on around mid morning.
system on timer to run 3 X 2hr shifts during the night to reserve battery power. Or add another battery and run 24/7

As the house is on 3kw solar, any power used during the day is green power so i am happy to run charger during the day as we don't use all the power generated during the day, most our power is used during the night unfortunately.

It really depends on the condition of the old one... if it is in near new condition, then it will be fine. If it is on its last legs, then it will kill the new one.




As in a 240V powered charger? Yes.




You wont be reserving any energy - that will completely flatten the battery before the night is over, and within days it will be ready for the recyclers.

6 hours X 25A = 150AH, which is more than your battery's capacity at that load. If you aren't adding energy with the charger overnight, you should limit it to perhaps a total of 2 hours, which will be a ~40% discharge, if you want the battery to last very long at all.

I think it would be a better idea to have the charger set up so that it charges the battery whenever it gets down to say 70% state of charge.

Thanks Gunagulla, i appreciate your help, i think i could add a new one although at $450 each.
Plus a smart charger. Then what do i do when i go camping? I suppose i could pack up the inverter and panels and just run on mains while away but that means i am stuffed if the power goes off while away. Really i think need to commit 1-2k to the this going off the grid but not sure if i can just yet. (Although i estimate i would get 1-2k back over 2 years? Will have to think some more.

What is "the right price"?

http://www.solaronline.com.au/deep-cycle-batteries.html

They stock a similar UPS AGM battery.

Try haggling with them !

Thanks Gman, i decided to just run the air off the battery. i upgraded my house panels to 5KW so well and truly off-setting the AP during the day producing 8-12KW per day.
Pricing on those batteries is pretty good though.

Is that 8-12kWh per day from 5kW of panels in May?

No, 8-12 is an average, getting around 7-8KW on a nice day now, less on cloudy days. 12-13kw on a nice day in feb when we had the upgrade from 2.5 to 5kw.
Having said that we have about 6kw of panels on the roof with the 5kw inverter. But our panels are in 2 strings, 1 faces East and the other faces North but is low on the roof. Not ideal but was the way it had to be. I think the extra 1kw in panels helps for the not so perfect positioning. To make maters worse, we get a bit of shadow from close gum trees at certain times of the day.