Energy Matters Forums

[dunach1]

Hi all, I have picked up 16 x 6 volt 75 amphr batteries from a UPS and was wondering if they would be suitable to use for expanding my existing battery bank. They are all in excellent condiion and holding charge well. I would appreciate any advice.

Thanks
Dunach1

[Gordon-Loomberah]

As is so often said on here... more information required! You'd better tell us all about it now, to save people having to guess your system details, or keep on asking for each tidbit of info.

[Smurf1976]

What type of batteries are they? Flooded? Gel? AGM?

Post a photo of whatever is written on them if you aren't sure and we'll see if we can work it out...

[lantern]

One thing I will say is that before you go connecting more than two batteries in parallel then have a read of this.
I think you will be very surprised.

http://www.smartgauge.co.uk/batt_con.html

It's not as simple as most think.

[dunach1]

Sorry for the late reply. The system I have is very basic as it is only powering a weekender. I will get all the details this weekend while I am thereand post them. It consists of a single BP 80 watt 12 volt panel, a wind generator and a bank of 6 flooded 2 volt batteries. I cant remember the inverter brand or details off hand. The ups batteries I have are yuasa uxh75-6 and are a sealed no maintenance lead acid unit.

[Gordon-Loomberah]

Without knowing all the battery details, unless it is a particularly windy place I suspect that single PV panel is barely enough for the existing batteries, and certainly wont be enough if you add a whole lot more. More panels required!
Also, since you are only running a 12V battery, you are going to have 8 strings of 6V batteries in parallel with the existing 2 volt string. Overall, that is a very bad idea. The chance of battery problems goes up dramatically with greater number of parallel strings, and 9 is way, way too many. If one cell goes, it drags the rest of the batteries in other strings down, and it would be a nightmare trying to figure out the health of so many batteries.

EDIT: Additionally, the flooded Lead-acid batteries will have different charging requirements and voltages to the UPS batteries, so connecting them all together will likely result in the premature demise of one lot or the other.

[dunach1]

Thanks for your answers. The existing set up has been more than adequate for our needs over the last 6 years. I just thought if they were suitable I would increase the storage capacity. I guess I can sell them off.

Thanks again for the advice.

[Gordon-Loomberah]

The single panel and WTG with the existing battery bank may be enough for occasional use, but is it enough to keep the batteries from becoming stratified and sulphated, especially in winter? It's good to get some ~C/10 (ie 10A for a 100AH (20hr rate) battery) charging into the flooded cells to stir up the electrolyte on a reasonably regular basis.

[gyro]

Hi
Can I suggest an alternative to just adding the UPS Batteries to the system?
If you were to set up the UPS batteries in a separate bank with a diode and heavy duty switch you could keep them as a back-up just by adding either a wind turbine or solar array to that set. With a volt meter on each set you can then swap from one set to the other if you run into cloudy period of weather. I also find an easy method for interconnecting batteries is to use 1/2 inch copper pipe flattened out and drilled to connect batteries together it is easy and cheaper the cables with lugs.

[dunach1]

Thanks. That could be the way to go with this. The batteries came with all connecting cables too. I also thought I could set them up as a small stand alone system to run lighting in the sheds.