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Battery Life and Charging

Posted: Mon Aug 10, 2015 6:01 pm
by jwypick
Hi, I live in Puerto Rico and we are living off the grid, solar power and well. We just recently went completey off the grid because of so many problems with the electric company. We have updated the system three times because of bad workmanship. First guys used speaker wire to put everything together. Second guy had everything homemade, didn't change speaker wire. An improvement but still weak. The last and final guy outfitted us with all Out Back equipment and rewired everything correctly.
Our problem is the battery power at night seems to only last a few hours even with a minimum load.
I'm not sure what info you may need but here's what I have:
21 170 (?) watt solar panels.
8 UB4D batteries wired in parallel of 4 each. (24 volt?)
Flexmax 80
MME250st inverter (?)

At night we like to run the fridge (optional), a couple of lights, maybe a couple of ceiling fans and a computer with modem.

Setting as I see them are:

Current limit: 80a
Absorb limit: 28.8v
Float 27.2v

absorb hours .0
float 27.2
float .o hrs
refloat 25 voc
equalize 28.8voc
equalizer .0 hrs

If you need anymore info please let me know. I'm very curious about the settings because the guy that did do the installation basically specializes in hooking up to the grid.
Thanks,
jw

Re: Battery Life and Charging

Posted: Tue Aug 11, 2015 12:07 am
by SandyP
Here is a link to your battery spec sheet : http://upgi.com/Themes/leanandgreen/ima ... /40701.pdf

Based on this info, for cyclic use, I believe your charging absorb limit voltage setting should be 28V (at 25 deg C)
The float setting should be 26.8V.

From the PDF file it looks like this info is printed on the side of the batteries?

Re: Battery Life and Charging

Posted: Tue Aug 11, 2015 2:13 am
by blackswan555
The default settings in the FM 80 are too low (which I presume have not been changed) The default absorb time of 1 hr is too short, Try 3hrs,
Did the installer fit a battery temperature sensor ? should be about half way down warmest cell, VERY IMPORTANT !


Tim

Re: Battery Life and Charging

Posted: Tue Aug 11, 2015 4:29 pm
by jwypick
Thank you for your reply. I have one question, do I have enough battery power to run a refrigerator, a couple of overhead fans, light bulbs and computer?

Sandy, I didn't change the voltage and float settings because our temperature here runs about 30-33c, for the highs, cooler for the mornings/evenings, more like 23c. How would I figure the adjustments taking into account our temperatures in PR?

Blackswan, yes there is a RTS and it seems placed correctly. When I check the temps though it gives me a number and specifies that it is not in deg c or f. It seems like it is set-up to shut down should temps reach too high.

I was really interested in the Absorb and the float times. I changed the absorb time to 2 hours, very cautious. Are there any dangers if I raise it to 3 hours? I think the problem may be that the batteries are not being fully charged. Could that be the case? What about the setting for the float time, this is still set at 0.

I wonder if I should run the equalize function to "reboot" the batteries? Any suggestions?

Once again thank you both for the input, look forward to resolving this issue.

JW

Re: Battery Life and Charging

Posted: Tue Aug 11, 2015 5:38 pm
by SandyP
jwypick wrote:Thank you for your reply. I have one question, do I have enough battery power to run a refrigerator, a couple of overhead fans, light bulbs and computer?
JW
Please can you give us an indication of the power usage (per hour or day) of each of the pieces of equipment you want to use?
Also, on your original post, you placed a question mark against the Wattage of solar panels - can you confirm if 170W is correct?

Re: Battery Life and Charging

Posted: Wed Aug 12, 2015 4:25 pm
by jwypick
Hi Sandy, thanks so much for helping me figure this out.

I have 21 180 watt panels: model number Sun HS1-180-RL.

We have
1)an older refrigerator, about 5 years, but seems to work well. That runs 7.7amps/924watts (2.4kwh day)
2) imac, runs about 8 hours a day 2 amps/205watts (1 kwh day)
3) T5 flourescent lights, run about 6 hours a day 1.5amps/178watts (1 kwh day)
4) 4 ceiling fans, 8 hours per day 4 amps/480watts ( 3 kwh day)
Totals: 15.2amps/1787watts (7.4kwh day) ?

Not sure if the estimates are right, but was curious.

JW