Absorption voltage

Tumbleweeds
Tumbleweeds Registered Users Posts: 6 ✭
in Off Grid Solar & Battery Systems #1
I hope all my questions are as simple as this first one.
New 255 watt system on my 5th wheel, the Interstate batteries say to charge at 14.4v bulk, 15.5v absorption for 2-4 hrs, float 13.2.
OK, I can set all these parameters, but will that high of absorption voltage (granted that won't be all the time) harm any of the electronic control boards in the refer, furnace or WH?
My 4 stage charger hits 14.8v occasionally but only for a few minutes, then down to 14.4-14.6 for hours. So far no problems even with my 14 volt rated non-regulated leds.
Been wanting to try solar power since the 60's, finally have the time and resources.

Thanks early,
Tom
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #2
    Re: Absorption voltage

    Can you get any answers from the manufacturers of the items you're concerned about? Going from 12 volts to over 15 is around 30% increase. However, many "12 volt" items are designed assuming they will see at least 14.5, so another volt shouldn't be a killer. But only the manufacturer would know for sure.
    Your concern has also been a concern of mine, which is why I run most things off an inverter.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Absorption voltage

    Are you sure about those Voltages? I ask because there's no such thing as "Bulk Voltage". In the Bulk stage current is pushed 'til the Voltage level reaches Absorb set point, which is usually 14.2-14.4. Voltages of 15+ are usually Equalization Voltages.
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  • Tumbleweeds
    Tumbleweeds Registered Users Posts: 6 ✭
    #4
    Re: Absorption voltage

    Thanks Wayne,
    I tried looking up the operating voltages in the user manuals, most just say "12 volt operation", guess I'll try contacting the manufacturers. Meanwhile, every thing tops out at 14.8 volts 'til I learn more.
    Just found a thread on the 50% derating I should have figured in when designing my system! Rats, more panels.
    Tom
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #5
    Re: Absorption voltage

    when I researched the LEDs I use, various brands, most listed a max voltage around 14.5 v max +- .

    I would say that the only reason I have not had a problem is that I do not use any lights during the day.

    I have however had my TSW inverter go into shutdown for over-voltage...when, in the fall, the absorb voltage has reached >= 15 volts.

    cheers.
     
    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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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #6
    Re: Absorption voltage

    Normally, >15.0 volts is "equalization" for flooded cell storage batteries (not normally done on sealed/AGM).

    Equalization is normally only done ~2-12x a year. Normally, it is used to "equalize the state of charge" between cells (over charge the battery to get all cells to 100% state of charge).

    Equalization is hard on a battery bank and is usually only done when the specific gravity from high to low cell is >0.030 (Trojan recommendation) and only done in 1/2 hour increments. At the end of each 1/2 hour equalization period, measure the Specific Gravity of each cell and stop further equalization when none of the cells goes any higher in S.G.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #7
    Re: Absorption voltage

    look to see if it is sealed or not. it will list a sealed battery as sla. if it is sla then do not go over 14.4v. sealed batteries are sensitive to too high of charge voltage.
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #8
    Re: Absorption voltage

    sorry guys, didn't meant to mislead the OP

    the reference to ''in the fall'' was for a temp compensated voltage...'Fall' temps here are usually well below freezing and thus the CC temp adjustment takes the voltage to > 15 V. normally it is 14.3 for absorb, non adjusted. The battery is in an insulated but unheated space and does not warm up till after noon, if at all thus the large temp compensation.

    Point I was trying to make was that if like for most of us, the lighting is only used at night, or at least after max V point is achieved, the bulk/absorb/ float voltages should not be a great concern vis a vis the max voltage rating of the LED's, never the twain shall meet.

    BUT if lights are used in the day there might be an issue of over voltage and reduced LED life.

    cheers
     
    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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  • Tumbleweeds
    Tumbleweeds Registered Users Posts: 6 ✭
    #9
    Re: Absorption voltage

    I wondered how long it would be until someone told me my voltages were too high.
    This is a link to the Interstate Battery page on charging my batteries, mine are the 6v but adds up to the same as 1 12v. http://www.batteries-faq.com/activekb/questions.php?questionid=1 These ARE NOT Trojans, different batteries=different specs.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #10
    Re: Absorption voltage

    I use Interstate batteries right now. I do not follow these specs. In my opinion they're wrong. As I said, there's no separation of "Bulk Voltage" and "Absorb Voltage"; it's a switch-over point. The high Voltage levels indicated will use excess water, and the recommended Equalization ("always after a normal charge") is impossible and unworkable in an RE application.

    The batteries I got had a plate failure in there first year. That did not impress me. I will be switching to another brand ASAP, and certainly won't be recommending Interstates to anyone.

    As for your situation, you are right to be concerned about such high Voltage levels interfering with equipment function or even damaging it. Many 12 Volt inverter will shut down with 15 Volts going to them and many other 12 Volt devices could indeed be damaged by such high Voltage. Much auto/RV equipment is designed to run at 13.8 Volts max. Certainly not 15.

    Again, just my opinion but it looks like the recommended Interstate Voltages are unworkable and unrealistic. Lower them to something normal and see what service you get or switch to another battery brand that can function properly within the Voltage ranges expected for a 12 Volt system.

    I'm scratching Interstate off the list. :grr
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #11
    Re: Absorption voltage

    I e-mailed Interstate to please explain why the Voltages they show in their chart are so high. I'll post the reply , if any. in the top chart they use 15.5 V for a 12 V and farther down they use 14.4 for one specific battery.

    This goes against every algorithm on every charger I know of. Absorption Voltage stays constant and current drops.

    My experience would be that you'd have a gassing mass of overheated battery's that would look like a pregnant whale in a couple months and the water usage would be unreal. They are in the business of selling battery's, but this would be a blatant destruction and dangerous to a point.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #12
    Re: Absorption voltage
    Blackcherry04 wrote: »
    I e-mailed Interstate to please explain why the Voltages they show in their chart are so high. I'll post the reply , if any. in the top chart they use 15.5 V for a 12 V and farther down they use 14.4 for one specific battery.

    This goes against every algorithm on every charger I know of. Absorption Voltage stays constant and current drops.

    My experience would be that you'd have a gassing mass of overheated battery's that would look like a pregnant whale in a couple months and the water usage would be unreal. They are in the business of selling battery's, but this would be a blatant destruction and dangerous to a point.

    I'm inclined to agree.
    Different batteries have different specs, but the internal workings of the same type batteries are basically the same so they shouldn't be that different. Those Voltage levels are unworkable in my opinion.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #13
    Re: Absorption voltage
    Cariboocoot wrote: »
    I'm inclined to agree.
    Different batteries have different specs, but the internal workings of the same type batteries are basically the same so they shouldn't be that different. Those Voltage levels are unworkable in my opinion.
    I have always tried to stay away from any charger or inverter that has a automatic EQ charge on them. The program has no idea of the condition of the battery's they are hooked to. You hook up a 125 amp charger to a dryed out bank of battery's you're looking at a melt down. Some of the old Trace Inverters have a automatic 21 day, 4 hour EQ cycle. I'v seen where they were setting on plywood and it looked like it could have caught on fire.
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  • SCharles
    SCharles Solar Expert Posts: 123 ✭✭
    #14
    Re: Absorption voltage
    Tumbleweeds wrote: »
    ...but will that high of absorption voltage (granted that won't be all the time) harm any of the electronic control boards in the refer, furnace or WH?


    Tom


    I recently became concerned about this same sort of thing, as I have some 12 v. appliances. The owner manuals gave maximum voltages; but, somewhat oddly, I thought, they all gave a max. allowable voltage of around 15.5 v. The only way I finally found out what the manufacturers knew was to call their tech departments. In all cases, I was able to speak with someone who had either done some testing or knew about the results. Some of them had really been tested to as high as 24 v. with no problem. [Well, at least no problem for the duration of whichever test.]

    But anyhow, call the tech dep'ts.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #15
    Re: Absorption voltage

    Here is the reply from Interstate Battery. You can see they pretty much are mixing EQ voltage with Absorption voltage. It's a goopy reply, telling you to do a EQ every 4 - 6 weeks.

    Reply :

    Thank you for your inquiry here at the home office of Interstate Battery System of America. The absorption stage does keep the voltage set with the current tapering for the specified time (usually 2-4 hours). Our recommendation is using a higher voltage for the absorption for finishing off the charge. Most chargers have an equalization stage that will raise the voltage to 15.5 after a complete charge to burn off any sulfation that may be building up on the plates. This should be done every 4-6 weeks in order to give the longevity of battery life that people want. Which chargers are you working with?

    Thanks,

    Engineering & Technical Service Specialist

    Interstate Battery System of America

    My Reply back :

    Hi , Thank you for the reply. I have many chargers and inverters. I have never saw a charger with a algorithm that for 12 V dc battery that had a rise in the absorption voltage go to 15.5.

    Bulk phase 14.2 to 14.4 rising voltage till reached, constant current.

    Absorption Phase 14.2 to 14.4 Current falling to trigger float 2-4 hrs.

    Float Phase 13.2 to 13.5 current as necessary to maintain voltage.

    Your chart ( attached ) calls for 15.5 on a 12 V absorption stage voltage, that means you would be doing a EQ charge every time the battery was charged. I don't think the battery would last very long.

    Edit : Their final reply. Let your conscience be your guide.

    We understand your concern and after testing multiple batteries we have found that the absorption stage has really helped the battery perform better and even run longer between cycles. The cycle life testing has also proven to be better than that of our competitors in the field by using the higher absorption setting.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #16
    Re: Absorption voltage

    Their reply speaks volumes about their company. To quote "Pete" from "O Brother, Where Art Thou?":

    "That don't make no sense!" :p

    I think I'll stick with Voltage levels that I know work, because what they suggest I know won't work.
    Pure gibberish and a non-answer.
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #17
    Re: Absorption voltage
    Cariboocoot wrote: »
    Their reply speaks volumes about their company. To quote "Pete" from "O Brother, Where Art Thou?":

    "That don't make no sense!" :p
    I did a edit with what I consider a final reply.

    ""We understand your concern and after testing multiple batteries we have found that the absorption stage has really helped the battery perform better and even run longer between cycles. The cycle life testing has also proven to be better than that of our competitors in the field by using the higher absorption setting. ""

    Most are lucky to be reaching 14.4 or so in the Bulk Phase, much less reaching 15.5 to trigger the absorption stage.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #18
    Re: Absorption voltage
    Blackcherry04 wrote: »
    I did a edit with what I consider a final reply.

    ""We understand your concern and after testing multiple batteries we have found that the absorption stage has really helped the battery perform better and even run longer between cycles. The cycle life testing has also proven to be better than that of our competitors in the field by using the higher absorption setting. ""

    Which only serves to emphasize their lack of understanding the original question. You didn't ask about whether or not an Absorb cycle was necessary; you were (rightly) inquiring after the Voltage levels. They didn't address this at all!

    If an old schmoe like me living in the middle of nowhere can comprehend this, why can't a very large company hire people with sufficient communications skills to read and understand the questions people have - and give an intelligent response? Makes me wonder if the answers are being "outsourced" and lose something in the translation (as is so often the case).

    Thanks for giving this a try, Blackcherry04. I don't know if it will clear things up for the OP or make it fuzzier. Seems to me Interstate Batteries doesn't know what it's talking about and we'd all be better off following the "rule of thumb" charging levels.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #19
    Re: Absorption voltage

    to reach an absorb voltage of 15.5v it must stay in bulk until that voltage is reached. they say they do better and longer? i would give the batteries more generic charges of maybe 14.4v to 14.6v or so for absorb trigger voltage and float as speced.

    for a battery company to list a bulk charge voltage and then a higher absorb voltage does show incompetence in my opinion. i should emphasize there isn't any such thing as a bulk charge voltage and when i see it termed that way i assume it to mean the absorb trigger voltage and there can't be 2 absorb trigger voltages.:roll:
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #20
    Re: Absorption voltage

    Check this not too old of discussion...

    http://forum.solar-electric.com/showthread.php?t=10231


    Trojan recommends from 14.7 V to 16.74 V (12V battery) for Wet/Flooded batteries. I know that I had seen 15.5 Volts for L-16s in the past.
    2.45V to 2.79V per 2V cell and at 25 degrees C of course

    You just have to check you water level more often for the higher voltages.

    14.4V for VRLAs.

    http://www.trojanbattery.com/pdf/UsersGuide_English.pdf

    boB
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  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    #21
    Re: Absorption voltage

    Table 2. Charger Voltage Settings for Flooded Batteries

    System Voltage
    Charger Voltage Setting.... 12V
    Daily Charge.... 14.8
    Float .... 13.2
    Equalize .... 15.5


    http://www.trojanbattery.com/BatteryMaintenance/Charging.aspx
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #22
    Re: Absorption voltage

    I am somewhat disappointed that so many including at least 2 moderators appear to think all batteries are made the same, and suggest Trojan specs for others.

    Trojans are the only deep cycle battery I know of that does NOT recomend a regular equalizing charge. I have mostly checked the specific gravity(SG) of my batteries on a regular basis, and started writing it down for a while. I find the regular equalizing, done but my charge controler does a good job of maintaining my batteries.

    Here is a link to their seperator and paste development.

    I don't know if it's hooy, but I know of no other battery manufactorers who don't recomend a regular equalizing charge, I know, Rolls, Crown, U.S, all do.

    Having watch independently my SG and just allowing my Charge Controller to do a regular equalizing charge has kept my batteries in pretty good shape, they are on their 6th year, and I do abuse them running an AC off of 4 Golf Cart batteries the past 4 summers. In fact, I've ignored checking the SG for the most part in the past year, as my batteries have past my expectations of 4 years use, in these abusive conditions.

    FWIW - I do think the Interstates response is pretty poor and dosn't appear that anyone spent any time looking at the question or comparing it to it's specs.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #23
    Re: Absorption voltage

    Photowit;

    This thread isn't about whether or not you should equalize batteries. It's about Interstate's confusing Voltage information, and their even more confusing response to inquiries about same. I think even boB got confused about what the issue is. Vis: an Absorb Voltage level that is in the realm of what would normally be used for Equalization. Not whether or not either stage is necessary, just the levels.

    Every 12 Volt inverter I've had/known would scream and shut down with Voltage going over 15. Although that's certainly not every inverter in the world, it's enough to tell me that Interstate's recommending an Absorb Voltage of 15.5 is unworkable for RE.

    It would be interesting to know if other companies recommend regular Equalization out of a "just in case" scenario or if there really is significant performance difference in the battery technologies. But that's not the issue here.
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #24
    Re: Absorption voltage

    see that marc, just because you're a moderator you get a target painted on your back no matter what you're trying to say.:roll::confused:
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #25
    Re: Absorption voltage
    niel wrote: »
    see that marc, just because you're a moderator you get a target painted on your back no matter what you're trying to say.:roll::confused:

    I'm sorry, perhaps I am over sensative as I arrived here after I got to the total frustration point at another forum, where a reported expert in the field, a regular "SunGod" would rant on and on and tell untruths arout solar. I corrected him repeatedly and finally complained to the Admin, after he stated solar was only 80% reliable(went back and check, he said "90% availability"). His experience was in partly with repeater towers) I feel a moderator must besure they aren't passing along untruthful statements as facts;

    That said to my knowledge most inverters for off grid will take up to 16 volts, here are links;

    PROsine 1000 Watt and 1800 Watt Sine Wave Inverters

    OutBack inverter

    Magnum Inverters

    Likely for the monthly maintanance equalizing, some of us like to do.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #26
    Re: Absorption voltage

    Let me say that I look up to Moderators who do a great deal to make this and other sites pallatable to people visiting, It's only that you are also looked up to as an expert in the field as well that it might be prudent to check statements, less you give people false impressions.

    It's easy for someone to ignore a statement by some assorted person posting. The reason I try to post links, particularly if I'm disagreeing with someone, but a moderator is more likely to be believed.

    Much thanks to Marc, Niel, Tony and Bill!

    God Bless You! (hope I didn't miss others)
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #27
    Re: Absorption voltage

    Only 80% reliable? :confused: How did he figure that? I've found it to be 100% reliable if the system is set-up right to start with.

    To that end there is an old saying: "All things in moderation". Never count on systems operating on the fringes. That means high Voltage as well as low Voltage. Counting on 5% charge rate can be foolish. Counting on 100% nameplate output of panels definitely is. You can't even trust batteries to really have the Amp hours they claim to, especially as this will diminish over time. You need margins to operate within.

    I am getting a bit weary of repeating my explanation of starting with generalized guidelines to get people in the right neighbourhood before fine-tuning a system for the specifics.

    No one has to agree with me or follow my advice. It's not my money you're spending. :p
    Other people's input and experiences are always welcome here.
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  • boB
    boB Solar Expert Posts: 1,032 ✭✭✭✭
    #28
    Re: Absorption voltage
    Photowhit wrote: »
    That said to my knowledge most inverters for off grid will take up to 16 volts, here are links;

    PROsine 1000 Watt and 1800 Watt Sine Wave Inverters

    OutBack inverter

    Magnum Inverters

    Likely for the monthly maintanance equalizing, some of us like to do.

    Those 12V inverters didn't used to be "most" inverters, but I guess that as far as high end 12V inverters go, they are now..

    The cheap-O 12V MSW inverters will usually beep or turn off above 15 or so V.

    The Trace DR used to do that.... Hopefully, even the El-Cheap-O inverter companies will change their ways and allow an extra volt or volt and 1/2 at least.

    boB
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #29
    Re: Absorption voltage

    What bugs me about those Interstate numbers is that there is only a .1v difference between absorb and EQ, so it looks to me like they are basically getting EQ'd at every absorb.

    So what's the point of doing a separate EQ that is only .1v higher?
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #30
    Re: Absorption voltage
    dwh wrote: »
    What bugs me about those Interstate numbers is that there is only a .1v difference between absorb and EQ, so it looks to me like they are basically getting EQ'd at every absorb.

    So what's the point of doing a separate EQ that is only .1v higher?

    Exactly.
    It's a shame Interstate's response was so "unhelpful". :roll:
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