Location: Northeastern AZ 5500 ft elevation. Full sun exposure 6 am to 7 pm midsummer.
48 volt system 16 Interstate L16 new in 7/2014 with water miser caps in Battery box with Auto exhaust
MX-60 Charge Conroller
Xantrex 5500(?) Inverter Charger
16 Kyocera 140 watt with Wattsun Tracker
900W Wind Generator
12 kw Kohler Propane Auto Backup Gen installed Dec 2015. It has come on automatically twice in this time due to low battery voltage. Batteries are in perfect condition 99% of the time.
The controller, wind gen, inverter are all original equipment 2007. The home is occupied 1/3 of the year. The power usage occupied is 5 kw per day, away is 2.3 kw per day. Generator has been used twice by auto on feature meaning thatthe batteries are 99.9 OK all the time.
FYI I am a retired electronics engineer. I take care of my system like it was my first born, always super maintained. I check SG, battery individual voltages at night, etc.
Problem #1: February 2011 original Trojan L-16s failed catastrophically due to boil out, Service company said the Trojans failer all over and they were junk after making some construction change in 2006. Thet were replaced with Rolls 400(?) @ $6,000
Problem #2: Rolls began to have some batteries with low SG after about one year. I tried making a claim which went largely nowhere even though I keep records of SG, temps, usage etc. The rest had some catastrophic failures (not all about half) in July 2014. Different sevice company found that 25% of my panels were disconnected internally due to water leakage in a junction box and corroded open leaving 75% power. I thought that probably explained A) why my power output was only getting to 1500 watts and why the batteries may have failed in the end. There was no auto backup gen in that time period, however, power never went down then either.
Replaced Rolls with Interstate L-16 in July 2014, Different Service company replaced the batteries, found the panel problem and fixed that. The Outback Watt power jumped to 2490 watts in November 2016 with current at 46.2 amps (53.9 vdc in bulk charge mode). I managed a manual Equalize that month with no issue. In June July 2017 it still cannot get past 1750 watts in hot weather.
We believe now that during equalization in the hot months our sixteen 140 watt rated solar panels cannot get to full power due to temperature de-rating. Checking the Outback output watt meter it gets to about 1750 watts at best in high temps (July Aug 100 degrees ambient). The Equalize setpoint is 60.4Vdc @ max current, so the "Outback" charge controller simply keeps on trying and goes as high as it can (59.1 Vdc) and hangs there. This output is just above the absorb setpoint (which it has no problem with). There is no Equalize time limit function if it never gets to the Equalize voltage setpoint. The Outback repeats an Equalize function day after day until the Equalize cycle of three hours is satisfied (which it never can get to then). It keeps boiling the batteries. I determined this by noting that the power output on the Outback can only get to 1,720 watts (59 volts @ 30 amps) while trying to equalize. In cold months it can get to 2400 watts, so there is no problem getting 60.2 Vdc at 40 amps in cold weather. It simply does not produce enough power to raise the voltage high enough at the current needed for equalization when it is hot. I have investigated extensively and no one, including two installer companies ever heard of this issue. I had replaced the caps on my new batteries with Water Miser caps due to excessive water loss (spitting up on the tops), although I had no idea why this happened so much especially in the hot months. I had serviced the batteries on July 29th 2017 and all the cells were full of distilled water at that time. I was away from July 29th and did not return until Sept 6th (a broken rib ouch) only to catch the system stuck in Equalize mode which it was programmed to start on August 25th. I determined that it had been in Equalize for 11 days straight (the last float day was 11 days before that, and it is ALWAYS in float every day unless it is cloudy). I was fortunate to catch it when I did, as some of the plates were just slightly exposed (1/16 inch maybe and sill wet), the thermocouple between the batteries read 124 degrees F (ambient temperature was 98 degrees). There was NO WATER on the exterior of the batteries. The Water Miser caps probably saved me $6,000. If factory caps were on the batteries there would have probably boiled out after only a couple of days much as my previous set of Rolls batteries had, having their "factory caps". My "new" batteries seem to have recovered and seem to be OK today with SG variance about 25 points on two battery cells, 5-10 on the rest and all the night time voltages are 6.37 +/- 55 mv (not in float mode).
1) Is my theory correct? Is solar panel voltage limitation causing the equalize hang up?
2) Setting see below: do these look right to you?
3) I never tried to use the generator to Equalize. I am sure that it could if the settings were correct...?
3) I turned off my Outback Auto Equalize (a little late if my theory is correct) and will manually equalize in the winter only.
4) Two of my batteries on the end row have little black specks floating up in the SG bulb. What to make of that?
Thank you Experts for any help!
Clem (Sakamochi) also email me [email protected] if you would like to
|Voltage Set Points|
|per||Bulk||Absorb 2 hrs||Float||Equalize 3 hrs|
|MX60 actual original 2007 set point||--------------||57.6||54.4||60.2|
|MX60 Manual reccommendation||--------------||59.2||53.6||57.6|
|Roll Service Answer (old battery set #2)||59.2||52.8||61.92|
|Specific Gravity||Full Charge||1.265|
|New Interstate Batteries 7/9/2014||58.4||53.2||60.4|