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Santiago
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One more AGM ? UPDATE and Controller issue?
Small system in off grid cabin in Bahia de los Angeles. Two 190 watt panels, thru Xantrex C60 controller to four 12v Deko 105AH AGM batteries. Xantrex
1500 watt modified sinewave inverter/charger to power center. The batteries will be new and a BTS will be used. The cabin is shut down for 4 to 6
months at a time; what would be the best way to leave the system when gone?
I have been told to bring them to full charge and turn everything off. What say you?
May 30:
Installed the 4 105, 12 volt AGMs on Monday morning with temp sensor. The Tri-Metric meter showed 100% charge.
The next day, at about 3:00 in the afternoon, The charge controller showed a solid green light (fully charged) but the Tri-metric showed only 50%
charged and the amps were a negative 6 amps. At 3:00pm, the only draw on the system was the router and modem. It dawned on me I forgot to change the
router settings which I did: Bulk at 14.5 and float at 13.5 per Deko specs.
I go to the panels and notice they are little dirty and clean them. It change to positive 7 amps, still not much for that time of day. AT 4:00pm I
hook the Honda 2000 up to the Trace inverter/charger and it start dumping 67 amps back into the batteries, bring them to 80% by 6:00. Out of
politeness to my neighbors, I turn the genny off as c-cktail hour was well underway.
At 4:00am this morning, they were at 70%.
From this info, do I have a bad charge controller, are the panels weak? If by early afternoon the percentage charge is not well on its way to 100%,
then I should run the genny to get there, correct? The panels, by the way, are on a flat roof and not tilted, but always worked with the four 6V golf
carts, also 440 AH.
[Edited on 5-30-2018 by Santiago]
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BajaBill74
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Leave that system with a really good guard dog.
[Edited on 4-2-2018 by BajaBill74]
What I'm doing at work is so secret, even I don't know what I'm doing!
One should believe in God, because even Google doesn't know everything.
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PaulW
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If your controller has the smart chip that provides a 3 stage charger/maintainer function then leave the batteries connected. If that controller does
not have that capability the buy a 3 stage unit and leave the batteries connected directly to the panel. The size (amps) of a standalone 3 stage
controller needs to be determined by calling the battery manufacturer. For my single 105AH battery the battery guy said to get a 10A max unit.
The above info was given to me by the Concord engineer.
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Mendodoc
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I use the same charge controller for 770 watts of panels, and (12) 6 volt Trojan T-105's with the 2400 watt Xantrex inverter and I have left the
system to it's own resources for months on end. Last saw the cabin 5 months ago but just had a friend check the system for me and the Tri-metric meter
is reading 28 volts (24 volt system obviously).
Just make sure that ALL your connections are clean, and tight, and you shouldn't have any issues...
[Edited on 4-2-2018 by Mendodoc]
"Nothing is really work, unless you would rather be doing something else"... Sir James Barrie
"It is better to travel hopefully than to arrive..." Robert Louis Stevenson
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DanO
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I switched to AGMs awhile back and because they lose very little charge over time I'm comfortable taking them offline when I'm gone. YMMV.
\"Without deviation from the norm, progress is not possible.\" -- Frank Zappa
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woody with a view
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What DanO said.
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larryC
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I agree with what PaulW said. AGM batteries like to be charged with 5 to 10% of the amphour capacity of the battery bank so in your case with 420
amphour bank somewhere between 20 and 40 amps at 12v. Your 2 190 watt panels probably put out about 22 to 24 amps so you are right in there amps wise.
Just set your controller to the charge voltage that the battery manufacturer recommends, connect the temp sensor and leave them hooked up while you
are gone. That is what I do and my batteries are 7.5 years old and still going strong.
Batteries that sit uncharged for extended periods of time will start to form sulfate on the plates which reduces their life span. You can see when
sulfation starts to happen because the battery starts to bulge on the ends.
[Edited on 4-2-2018 by larryC]
Off grid, 12-190 watt evergreen solar panels on solar trackers, 2-3648 stacked Outback inverters, 610ah LiFePo4 48v battery bank, FM 60 and MX60
Outback charge controllers, X-240 Outback transformer for 240v from inverters, 6500 watt Kubota diesel generator.
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Cancamo
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As long as you've got someone checking the water level, and the controller goes through the cycle, (charge, bulk, float), leave them connected.
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Bob and Susan
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batteries bulge because of gas not venting correctly...
my advice...charge them then disconnect them
reconnect them when you get back
its a fire danger to leave them connected when you are gone long periods of time...the cables can actually vibrate loose and spark
you don't want that
or some field mouse will eat a hot wire and ground it
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willardguy
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I vote for bringing em up to FLOAT ( battery mfg specs) and disconnecting 
[Edited on 4-2-2018 by willardguy]
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Santiago
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the Xantrex C60 is a 3 stage charge controller - I think that is what is meant by "Smart chip"?
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willardguy
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your controller has no idea what your battery bank consists of, obviously the default set points have to be conservative....this is why most batteries
end up under charged. listen to the battery manufacturer!
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rts551
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The xantrex c40 and c60 controllers have to be set for your batteries. Jumpers and dials inside. Read the instructions on how to set for AGM
batteries per the battery manufacturer settings. They are a three stage controller...but the first 2 stages are manually adjustable.
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larryC
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Quote: Originally posted by Bob and Susan  |
batteries bulge because of gas not venting correctly...
my advice...charge them then disconnect them
reconnect them when you get back
its a fire danger to leave them connected when you are gone long periods of time...the cables can actually vibrate loose and spark
you don't want that
or some field mouse will eat a hot wire and ground it
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batteries bulge because of gas not venting correctly...
That statement is completely wrong. Google it if you still have doubts.
Off grid, 12-190 watt evergreen solar panels on solar trackers, 2-3648 stacked Outback inverters, 610ah LiFePo4 48v battery bank, FM 60 and MX60
Outback charge controllers, X-240 Outback transformer for 240v from inverters, 6500 watt Kubota diesel generator.
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Santiago
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Deka provides a tech bulletin that sets the charge parameters for these batteries at the bulk, absorption, float and equalization stages. The C60 has
two adjustable dials: the Bulk can be set from 13.0 to 15.0 volts and the Float from 12.5 to 14.5.
The Float parameters given by Deka is between 13.44 and 13.56volts - am I to assume that this is what I set it to while at the cabin and on leaving?
By the way, I have the charger set so that equalization charge is manual, not automatic.
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woody with a view
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Set it and forget it. I was under the impression agm batteries dont require equalization. Am i wrong again?
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larryC
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Usually you set the float about 1v below bulk.
Woody, agm batteries can be equalized but it is usually a fairly mild equalize compared to a FLA battery. Again follow the manufacturers
recommendations. AGM batteries are sensitive to over charging and if you screw up and let some of the electrolyte boil out there is no way to replace
it and the battery life is shortened.
Off grid, 12-190 watt evergreen solar panels on solar trackers, 2-3648 stacked Outback inverters, 610ah LiFePo4 48v battery bank, FM 60 and MX60
Outback charge controllers, X-240 Outback transformer for 240v from inverters, 6500 watt Kubota diesel generator.
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Bob and Susan
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you mean if you overcharge...the fluid inside expands and the battery explodes? seems pretty dangerous
disconnect the batteries if you are not home
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larryC
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Bob, I have no idea where you come up with this stuff. AGM batteries are also sometimes called VRLA (Valve Regulated Lead Acid) batteries which means
they have valves/vents built into each cell and if the battery is overcharged or the internal pressure of the cell is too great the valve will open
and vent the pressure to the atmosphere. FLA (Flooded Lead Acid) do this all the time while being charged those are the bubbles you see in the cell
during the charging process but the fluid in an FLA battery can be replaced periodically during maintenance the advantage to using an AGM battery is
that no fluid needs to be replaced because if the proper charge voltages are maintained then no fluid is lost . That is what makes AGM batteries a
good choice for a solar system that is not maintained but once or twice a year.
Hope I explained it clearly.
Off grid, 12-190 watt evergreen solar panels on solar trackers, 2-3648 stacked Outback inverters, 610ah LiFePo4 48v battery bank, FM 60 and MX60
Outback charge controllers, X-240 Outback transformer for 240v from inverters, 6500 watt Kubota diesel generator.
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Santiago
Ultra Nomad
Posts: 3499
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Update on first post, above
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