Battery backup questions...

paulskirocks
paulskirocks Solar Expert Posts: 84 ✭✭✭✭
in Off Grid Solar & Battery Systems #1
I'm setting up a radio repeater/remote that will be powered by an Iota charger, with a battery for backup, for the very few times grid power is lost... The bulk charge is too high for AGM, so I assume a flooded deep cycle would be the way to go, unless I want to get another charger... Plus, AGM batteries are so dang expensive... If so, since I will be grid tied, would I need to routinely discharge the battery to maintain the battery life, since the charger will always be in line? Any suggestions?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: Battery backup questions...

    Someone here has opened the Iota and there is a ten turn pot they used to adjust the voltage to whatever value they wanted.

    You can go "cheap" on the batteries and plan on replacing them every two to three years. With proper maintenance, you might get 3-8 years out of a good quality flooded cell (assuming you are not looking for large forklift/traction batteries or Telecom batteries designed for float service).

    Personally, I am not sure smaller AGM batteries are going to last you longer than 3-5 years in any service. Typical UPS service seems to be 2 years or so (and if deeply cycled, probably need to replace once power is backup and stable again).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #3
    Re: Battery backup questions...

    Don't forget to look into 'wet NiCd's' from my experience they are a fair bit better for long periods between use. Here's one http://www.saftbatteries.com/ there are others http://www.cecns.co.uk/alcad/
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #4
    Re: Battery backup questions...

    Well, in my case, since the charger will always be plugged into the grid, the battery will never be cycled, unless there is a power outage, which is very rare... I have the Iota with the 3 stage charge option... It's my understanding that deep cycle batteries need to be cycled once in a while for long life? Just wondering what the best way would be to maintain the battery... I can check on the system once or twice a week, if needed...
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #5
    Re: Battery backup questions...
    paulskirocks wrote: »
    Well, in my case, since the charger will always be plugged into the grid, the battery will never be cycled, unless there is a power outage, which is very rare... I have the Iota with the 3 stage charge option... It's my understanding that deep cycle batteries need to be cycled once in a while for long life? Just wondering what the best way would be to maintain the battery... I can check on the system once or twice a week, if needed...
    Every 7 days your IOTA will run a full charge cycle automatically as long as it's plugged in. The only issue I have with it is that it runs a absorb cycle of 7 hours @ 13.6 V, not a big deal, but you should know.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #6
    Re: Battery backup questions...

    If you have any kind of emergency back-up power system you need to test it periodically to make sure it works. You don't want to find out it doesn't when the storm is raging and the grid is down. A generator ought to be started and warmed up at least every six months (checking oil level, controls, et cetera) is not every month. The same holds true for a battery-based system; kill the grid and let it power some loads once a month to make sure it all works and that the battery capacity is available. No matter how you use them, batteries die over time. So inevitably at some point you will find their capacity diminished to the point where they will no longer meet your needs. Better to use them 25% once a month and know in advance they won't see you through the winter than find out when everything shuts down after only two hours one icy day in January.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #7
    Re: Battery backup questions...

    sound like you need a timer that is incremented in days and hours so you can kill the grid for a set period then turn it back on, sort of like a Christmas light timer, but with a Day function. My Petwa water softener has one...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #8
    Re: Battery backup questions...

    OK, thanks for the replies, and good point about using the batteries periodically to make sure the system is functional when a power outage actually occurs...

    This is just a small setup at a family member's house so that I can better reach a few local repeaters from my off-grid cabin, which is only 20 minutes away, but in a canyon... One evening of me babbling on the radio will cycle my cabin battery to about 25%, so I figure I could setup a way to remotely turn on and off the charger for an evening once in a while...
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #9
    Re: Battery backup questions...
    Blackcherry04 wrote: »
    Every 7 days your IOTA will run a full charge cycle automatically as long as it's plugged in. The only issue I have with it is that it runs a absorb cycle of 7 hours @ 13.6 V, not a big deal, but you should know.

    I have the IQ4 3 stage controller option added... According to Iota:

    Charging Phase Voltage Charge per Cell:
    Bulk Charge 2.46
    Absorption Charge 2.36
    Float Charge 2.26

    So, for my 12 volt battery:

    Bulk 14.76
    Absorption 14.16
    Float 13.56
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #10
    Re: Battery backup questions...
    paulskirocks wrote: »
    I have the IQ4 3 stage controller option added... According to Iota:

    Charging Phase Voltage Charge per Cell:
    Bulk Charge 2.46
    Absorption Charge 2.36
    Float Charge 2.26

    So, for my 12 volt battery:

    Bulk 14.76
    Absorption 14.16
    Float 13.56
    Opp's your right my bad. It will run it every 7 days. As Bill said if you change the voltage, it really won't be those voltages, it will be a ratio of the three.
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #11
    Re: Battery backup questions...
    Blackcherry04 wrote: »
    Opp's your right my bad. It will run it every 7 days. As Bill said if you change the voltage, it really won't be those voltages, it will be a ratio of the three.

    So, is your concern the voltage, 7 day cycle if never exiting float stage, or 8 hour absorption time?
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #12
    Re: Battery backup questions...

    OK, I see:

    "If the DLS voltage remains in the Float stage for more
    than seven days, the IQ4 will automatically enter the Equalization stage
    for a predetermined time to help maintain the battery plates, and then
    resume float stage charging."

    Well, they are vague about what that equalization stage exactly is, but I find this:

    "The FLOAT STAGE will end when either the battery voltage drops below the “Low Trigger”
    point or at the end of seven days when the IQ4 initiates an equalization stage to remove sulfate layers from the battery
    plates. In either situation, the unit exits the FLOAT STAGE and enters the BULK STAGE."

    So, I assume every 7 days it sits idle in float, it hits the bulk charge, then goes back to float, bypassing absorption... It doesn't say how long it "equalize" before returning to float... Gotta love clear and concise manuals...
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #13
    Re: Battery backup questions...
    paulskirocks wrote: »
    So, is your concern the voltage, 7 day cycle if never exiting float stage, or 8 hour absorption time?
    It's the 7 hours of absorb time. It's a little long, but the voltage is reasonable. I have mine cut back to, 14.4 Bulk, 13.9 Absorb, 13.3 float. The difference between 14.16 and 13.9. As long as you control Voltage and Time it will work out the same. The IQ4's I have are the plug in type, yours could be different with a built in one.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #14
    Re: Battery backup questions...
    paulskirocks wrote: »
    OK, I see:

    "If the DLS voltage remains in the Float stage for more
    than seven days, the IQ4 will automatically enter the Equalization stage
    for a predetermined time to help maintain the battery plates, and then
    resume float stage charging."

    Well, they are vague about what that equalization stage exactly is, but I find this:

    "The FLOAT STAGE will end when either the battery voltage drops below the “Low Trigger”
    point or at the end of seven days when the IQ4 initiates an equalization stage to remove sulfate layers from the battery
    plates. In either situation, the unit exits the FLOAT STAGE and enters the BULK STAGE."

    So, I assume every 7 days it sits idle in float, it hits the bulk charge, then goes back to float, bypassing absorption... It doesn't say how long it "equalize" before returning to float... Gotta love clear and concise manuals...
    It does NOT bypass the "The Absorption " stage. I call it the middle voltage. I have a monitor and I watch it pretty close and I never seen it bypass the absorb. I have the plug in IQ4's they might be different on the built in ones.
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  • paulskirocks
    paulskirocks Solar Expert Posts: 84 ✭✭✭✭
    #15
    Re: Battery backup questions...
    Blackcherry04 wrote: »
    It does NOT bypass the "The Absorption " stage. I call it the middle voltage. I have a monitor and I watch it pretty close and I never seen it bypass the absorb.

    OK, so their idea if "equalization" is not a 15+ volt charge, but just going into its regular charge cycle of bulk, absorption, and float... I have yet to use this, so I'll keep an eye on it...
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #16
    Re: Battery backup questions...
    paulskirocks wrote: »
    OK, so their idea if "equalization" is not a 15+ volt charge, but just going into its regular charge cycle of bulk, absorption, and float... I have yet to use this, so I'll keep an eye on it...
    That is correct, what they call " Equalization " is NOT what we consider it to be. Others call that " Boost " or something else. It's 3 stage, but not exactly.
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #17
    Re: Battery backup questions...
    paulskirocks wrote: »
    since I will be grid tied, would I need to routinely discharge the battery to maintain the battery life, since the charger will always be in line?

    On the RE-wrenches listserve a Trojan rep answered this question (for Trojan batteries). The answer was no, you do not need to cycle them. However, floating them does cause electrolyte stratification and you should periodically run them through an absorb or equilization to destratify the electrolyte.

    It sounds to me like Iota has the right idea.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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