Suggestions for failing agm battery?

System

Hi all, relative newbie but learning.

Have a battery system that runs part of our home in the upper Midwest which was installed 12/05. Battery system consists of 4 Datasafe HR 500 UPS batteries manufactured 7/03. 135 amp hr (and heavy-110 lb each!) wired in parallel These were purchased from a supposedly lightly used telephone switching system and have been reliable. Recommended float charge for batteries is 13.5-13.6volts which I have been trying to maintain using a Solar Boost 50 charge controller. (I initially charged system using bulk/float settings but changed to bulk/acceptance/float settings in 9/06 and adjusted the float settings to what I believe is 13.6 volts.) Batteries DO have a temperature sensor for charging. Batteries run only a portion of our home and I switch a breaker back to the grid when I do not want to run the batteries.

System is: 2-125 Kyocera(rated voltage 17.4 volts) and 2-85 watt shell panels (rated voltage 17.2 volts) on the roof wired to the SB 50 (24 volt in, 12 volt out) in our basement where the battery box is. We monitor via a trimetric 2020 monitor upstairs in the rooms we run off grid. I try to maintain the batteries at 80% or greater, so they infrequently get to < 80%.

I disconnected the 4 batteries 2 days ago and had them sit for 12 hrs.
Charges were: 12.25 volts, 12.91 volts, 12.90 volts, 12. 89 volts. So it appears the first battery is failing.

A) Should I just get rid of the low one? Can it be renovated? They are extremely heavy. Right now I just reconnected all the batteries back together. Batteries are expensive (these were a good deal) and I cannot get this type of battery anymore. All batteries looked fine when checked, no leaks, cracks or bulging was noted.

Am I undercharging my system using these setting and do you think my battery bank is chronically undercharged, leading to earlier failure? I must admit I "baby" the batteries as I do not know how much they were used prior to my purchase, altho I believe they were from a reliable source.

C) Our utility is reliable where we live (WI)...and I also have 2 85 watt kyocera panels (rated voltage 17.4 volts) not yet installed on our roof. If our battery system appears to be failing, would we be wise to install a grid tie Sunny Boy 700 using all the panels? They are slightly different voltages but very close, 17.4 and 17.2 volts. ( I asked the Sunny Boy website if I could mix different voltage panels but did not receive a reply). We did the battery system on the cheap; I am not an electrician and a certified solar electrician did the work, the most cost of the project! (They did a great job, by the way, money well spent).

Thanks all, I learn much from this forum and the knowledgeable people here. Regards, MJBY1

Solar Guppy

Re: Suggestions for failing agm battery?

I'd hookup the low battery by itself and let it do a full charging cycle, based on your panels, it would take about 2-3 days with no loads.

You can also boost the bulk charge by about 1/2 volt for this onetime charge cycle. At the end and after a rest period see how the battery is doing.

If the battery comes back, I'd change the order in the parrallel bank, could be something as simple as the wiring starving the low battery

mike95490

Re: Suggestions for failing agm battery?

You say you changed settings 9/06 ? What was the voltage setpoint before ? Higher or lower?

A brief overcharge, and you vent water, that cannot be restored.


" How " were they wired in parallel is crucial, while one would think that it does not matter, it really does, and can kill 1 battery before the others. Somewhere here on these boards, are several sketches of how to and not wire in parallel. diagonal is the key word

Mike

Here's a great writeup on how to properly wire your battery bank (diagonally)
http://www.smartgauge.co.uk/batt_con.html

nigtomdaw

Re: Suggestions for failing agm battery?

Mike what a great link Ive just spent about 20 minutes reading his article on Watts VA and Powerfactor and I now have a much greater understanding on something I was aware of but didnt understand. Worth the read 8)

PS Also liked his perfect wiring for muliple stringed batter banks.

System2

Re: Suggestions for failing agm battery?

Thanks all, the smartguage link for wiring a battery bank was particularly helpful. I need to put my batteries on a buss bar, I think.