Batteries not using water, etc

palausystem

I've had these batteries for a little less than a year and until recently it's been pretty sunny, not using much of the 800 ah. I've watered them ONCE.  Also seems the EQ set point voltage is reached more quickly and takes less amps to keep it there than with my last set of Rolls batteries. Also they don't seem to heat up much under EQ. Haven't done SG's lately.  My knowledge is still spotty; someone suggested I do a load test on each battery, I used a 1300 watt heater and tested each battery and did not notice a drop.  Is that enough watts to have a significant reading?
Thanks
 

westbranch

Please tell us what your charging specs are.  The faster charge may be an indication of a less than 'full' charge and the fact that the batteries are new..and a different brand...  the usage of less water may be a result of their age, brand and a low charge setting.  Did you do a commissioning charge when you installed the new ones?

Dave Angelini

They will not heat up much on Palau unless you are measuring the temperature. You need to do SG measurments. At least measure SG on a pilot cell ineach of your 2 strings. Measure them all now because you have been neglecting this. 
The low water use can also be a result of your not cycling the battery along with westbranch comments. Use them or lose them.
Get a 1500 watt heater and run them down 50% several times a year. If you are using the US battery specs for your settings you should be fine. They are good batteries but only as good as you are with them!

palausystem

(Ignore that Solar Expert label by my username)
Charging specs -
We have an interesting system: the Sunny Island (SI) goes into charge mode (they call it "boost") when the soc gets down to 70% or every three days.  Currently that is set for 2 hrs absorb at 2.52 vpc.  The battery spec says charge at 2.45v (+/- 0.05) for 2-3 hrs.
When I do an EQ I like to set it at 2.62v (that's the highest setting on the SI) for 8 hrs. 
I did not do a commissioning charge - I suppose it's too late for that, and I don't know what that is.

I'm at a bit of a loss as the previous batteries were being managed by someone else, then I took over and  basically winged it in getting another 4 or so years out of them.  Those old Rolls got hot and took all available amps to to keep them at 2.62vpc. With these new batts I watch the amps taper off....makes me wonder if somethings wrong. 

 

Estragon

My USB L16s also used hardly any water at first. After a couple of years they use around 1 gal/ yr. Normally not cycled too deep (80%) but I do deliberately run them down to ~50% if only light cycled for a month or two.

I do full SG as a long weekend thing so I remember. That way it's usually about every couple of months. I charge to full, check SG, check water, then EQ if needed. Not sure how much more a load test will tell you than regular SG checks.

palausystem

Estragon,
good to know about the water...
could you tell me what your charging specs are for your system and how you got there? 

palausystem

Dave Angelini-
"They will not heat up much on Palau unless you are measuring the temperature."
Not sure what you mean by that. 

westbranch

If you had a way of monitoring the Amps delivered in ABSORB phase, you would see the line fall quite regularly in a curved line, starting at the max Amps when it entered ABSORB and it will fall quickly at first and then start to level off as it fills the batteries.  Once the line levels off and you see a minimum amount of Amps being accepted, ie the line is almost flat, that is the time to go into float...  The setting most used when you are getting good sun (summer)  is ~ 1% of the Ahr rating of the batteries, which looks to be 401Ahr at the 20 hr rating. http://usbattery.com/wp-content/uploads/2014/07/usb_REL16xc_data_lowres_2.pdf

I assume you have 2 strings to get 800Ahr, so you need an END AMPS setting of 8A(1%).
the above specs say

Constant voltage (2.45+/-0.05 vpc) to 3% of C/20 Ah in amps then hold for 2-3 hours and terminate charge

Charge termination can be by maximum time (2-4 hr) or dV/dt (4 mv/cell per hour)
and
Absorption charge time is determined by the battery but will usually be ~3 hours at 2.45 volts per cell.

these instructions say that you would do a 2 stage  ABSORB first  down to  24A, and HOLD 24 A for another 2 - 3 hrs...  In would try an Absorb set to 16A and watch to see just how long it takes to get to 24A and add that time to the 3 hrs  as above ... so in reality it looks like you could be in ABSORB for 5 to 6? hrs ...  You may have to contact Sunny for their advice as well as US battery as the SI seems to have a different protocol than most solar Charge controllers...

Dave Angelini

800 Ah is usually at correct SG @ 2% or 16 amps BTW. Your charger should stop there and go to float.
 Palau is in the tropics and batteries do not get noticably warmer unless you have the numbers from your temp sensor. You are not going to feel it with your hands unless something is wrong. Not sure why you did before??
How much energy are you using in amp hours daily?
My Uncle was near you on Pelieu during the war. He was very lucky!

Estragon

@palausystem - pretty much the USB recommended settings with ending amps a bit lower in charge controllers. Iota couldn't exactly match those but chargers are only used to bulk with generator if no solar so close enough for my needs. I have the IQ add-on for them.

Estragon

Also, is there a reason for doing an EQ for 8hrs? Do you have cells way off or that take that long to stop rising?