Newbie with a question about equalizing my batteries

[Swampy]

Hi there. New to the forum and hope to learn/share with all of you. My question is about equalizing my battery bank. I have a cottage/cabin off grid with 4, 85 watt solar panels, a 2412 Trace DR Series Inverter/Charger, Solar Boost Charge controller and 12, 6 volt, 225 ah FLA batteries wired in series/parallel combination. I have been able to successfully equalize then in the past using a
generator but recently I cannot get the equalization voltage up and steady at 15 volts, therefore the equalization bulk/absorption/float charge process isn't happening. The batteries are 11 years old and made by Pow-er-Surge. I checked the SG of each cell and they are all in the "good" band. The generator is a Champion 9000/7200 watt gas powered unit.

Your thoughts/suggestions please.

[inetdog]

Welcome to Solar Panel Talk!

If your batteries are 11 years old you are very lucky and have been treating them very well.
Instead of looking at the "band" of the cell SG you need to use an accurate temperature compensated hydrometer and look at the actual SG number.
If the SG continues to rise as you equalize them, then you just need to equalize longer. If the SG stops rising at a value less than the initial SG specification from the battery manufacturer then the batteries have simple lost capacity over time as a result of sulfation or plate shedding and it is time to replace them.
If you were to do a controlled load test you would see that the battery capacity is now well below the initial capacity, and it will start to decrease even faster as you apply the same daily load cycle to "smaller" batteries.
Do your homework on what you want to replace you battery bank with and ask questions here as you go!

[Swampy]

Thanks inetdog for the reply and the advice. Yes, I think it is time to replace my batteries. I do try to look after them and was surprised myself that they have lasted this long. I have read were these batteries are usually have a 5-7 lifespan. Anyway, I'll start doing some homework as suggested and replace them. Thanks again.

[Wy_White_Wolf]

340 watts of panels and a 1350AH @12 battery bank. That is either way out of balance or you've been running the genny daily. At most, that array can only support a 340AH battery bank. I'd guess the reason they've lasted you this long is you're running on the 5 to 10% of the batteries instead of the usual 20 to 25% daily that is recommended.

With 6 strings I'd try breaking them apart and equalizing 2 batteries at a time. That should help to find the good ones and allow for a more controlled equalization of them. Take 6 out to start and when you get those six done replace the other 6 with them to finish the equalization.

Do a full load workup to determine what you really need for batteries. I'm guessing a single string of L-16s would supply your needs. They would also cut down on your maintenance with having only 6 cells to monitor and a single string.

WWW

[jflorey2]

With 6 strings I'd try breaking them apart and equalizing 2 batteries at a time.

Or just break the string connection at one end and equalize each battery individually. A 7.5 volt isolated power supply on each battery on the string will eventually bring all the batteries in the string into balance (but will not balance cells _within_ each battery.)

I have been able to successfully equalize then in the past using a generator but recently I cannot get the equalization voltage up and steady at 15 volts, therefore the equalization bulk/absorption/float charge process isn't happening.

This is odd. With old batteries you would more likely see a rapid voltage increase to EQ voltage without the consequent increase in SG. Why can't you get the voltage that high? Might want to look into your charger first.

[Swampy]

WWW.....as you can guess, I relied on the supplier to give me the system I needed when the system was installed. Time for me to better understand all this and do it right this time. One of the reasons I joined this forum is to do just that. I get great advice and help from the motorcycle forum I belong to so I figured why not try a solar energy form and this one is highly recommended on the net.

I appreciate your reply and suggestions and hope you don't mind if I ask some more dumb questions. Thanks.