Recommendation for New Batteries?

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Postby halfcrazy on Wed Nov 23, 2005 4:32 pm

crewzer i just ordered my other panels so i now have 1940 watts. i would like to get 16 of the L16's but may settle for 12 i have 16 u2200's now for 880ah i would like to be at least 11-1200 or better but i want a good balanced system. i use the average of 175ah a day in the winter with the boiler going so i would like to be able to span 3 days or so and i will look into the agms specially if i can get them to fit in my box
Magnum MS4448AE on Midnite Epanel, 800 ah of batteries, FM-60,2 Midnite Classic cc's one wind one solar, 1785 watts of panels and 10 ft Wind turbine off grid for 5 years
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Postby rplarry on Thu Nov 24, 2005 9:50 am

Brock
I use the Absolyte llp batteries, model 90a-13, and as I understand the mx60 manual the defaults are set to the gnb factory specs, so I just left my mx60 alone. The bulk is temp compensated to 14.4v for 2 hours and float at 13.6 Good luck with yours, I'm sure you'll be happy.
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Postby Brock on Fri Jan 13, 2006 9:51 am

Just got off the phone, my wife called, they delivered eight yes 8 8A8D Deka / East Penn batteries. When I first called we had talked about 8 4A4D's but decided to go with the 8D size, but he kept the total number as eight instead of four. Since he already had them there he gave me a deal on the cost, so now I have 8 of them, don't know if they will fit, I will work on it. I am still a bit amazed to think I will have 1900 amps at 12v. I am not sure how much I like the idea of eight in parallel though.
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Postby crewzer on Sat Jan 14, 2006 8:34 am

Brock,

Exciting news!

I sympathize with your concern about connecting 8 big batteries in parallel. There can be a lot of connections, with each being a potential failure point. My now-almost-new 12 V four-battery bank is interconnected with heavy cables (from NAWS), but it took a while to sort it out. After the initial set up {four batteries wired in parallel, (+) cable from charger to battery #1, and (-) cable to battery #4}, I measured the charging voltage at each battery as well as the voltage drop in each interconnect cable. I found one bad cable (excessive voltage drop) and replaced it with a spare. Periodic measurements indicate each battery regularly sees the same charging voltage.

In your case, I’d recommend considering a pair of copper buss bars to interconnect the batteries, and then connect the charging cables at opposite ends of the bank.

I have one other concern, and that’s the size of your new bank (~1,900 Ah) vs. the size of your array (still 480 W?). A mid-day charging current of ~28 A is but ~1.5% of the battery bank capacity, so that may be problematic while in BULK / MPPT mode. One solution, which I’m sure you’ve already considered, would be to have two sub-banks connected through a 1-BOTH-ALL battery selector switch like this one: http://www.bluesea.com/product.asp?Prod ... l1=7458&l2

No matter what, enjoy your new batteries, enjoy your retirement from most maintenance requirements :cool: , and I hope you'll keep us posted on your new bank’s performance.

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby Brock on Sat Jan 14, 2006 10:16 am

Yes the array is still only 480w, that tree has to come down soon to get me more space for panels. I thought about two banks, but since I am often gone for long periods while my wife and kids (9 months, 2 yrs 3 months and 3 years 9 months) are home alone I don't want to worry about the full bank being available if the power should go out. I also have the two DLS 55's as well and can charge from the grid or genset every so often to make sure they are good and topped off (once a week? Every three days?). Speaking of that I think the "smart" charger on the DLS is 14.6, then 14 and then 13.4 Does that sound OK for the AGM's. I think it is but would like confirmation of that.

About a buss bar, do you mean a bar right on the batteries or jump off the batteries to the bar and then connect the inverter (main) leads back on the batteries rather then the buss? It is a LOT of interconnect cables either way. I am also trying to figure out how to lay them out in the space. I am moving them to under the stairs in the basement right near the inverters, 4 feet wide by 10 feet deep. I was thinking terminal to terminal in 4 sets?

As always thats for all the shared info!!!
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Postby rplarry on Mon Jan 16, 2006 9:29 am

I think what crewzer meant was to use copper bar stock to interconnect your batteries, then of course you will still need flexible cable to run to your inverter. One of the big advantages to the copper bar stock is that you no longer have the possibilty of a bad crimp or a poor connection. Once you get the batteries in place you can buy the copper in bulk from a metal supplier and cut and drill it to fit your battery lugs then just bolt them on.
Actually having 2 banks may insure that your family always has a full bank to use. If one gets low, instead of her starting the gen she can just turn the switch to the next or full bank and keep going till you get home. Just a thought.
Good luck,
Larry
PS the AGMs I used to use charged to 14.3-14.4 and floated at 13.5-13.6
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Postby Brock on Tue Jan 17, 2006 2:38 pm

I will have to take a picture of them in place, not wired yet, but a buss bar won't work because the terminals are all in a line, both pos and neg side. Jim will understand that ;)

I guess the idea of two banks to me anyway is I would rather have one bank. My reasoning is if I my wife uses say the oven and it pulls about 160 amps at 12v. If I have the whole bank that is only 20 amps per battery, if it is in two banks that is 40 amps per battery. So with the pukert (sp) effect it would be easier on the batteries for those short large pulls.

Maybe I am crazy though.

Jim are you using the iota charger?
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Postby crewzer on Wed Jan 18, 2006 6:24 am

Brock,

Larry did a good job of translating my recommendation for using copper buss bars. You’re right about the terminal alignment being a problem, but installing terminal adapters like the one I described earlier (Nov. 20) in an offset manner {(-) terminals pointing one way, (+) terminals the other} would allow you to install a set of parallel buss bars.

Just a thought… :wink: ... But, with what terminal style were your batteries delivered?

My personal AC-to-DC battery charger is a Xantrex TC-20+ w/ BTS. It’s a leftover from my old RV, and it doesn’t see much (any?) use these days, as its 20 A capacity is a bit on the low side for my ~800 Ah battery bank. In fact, it may soon end up on eBay.

I’m generally familiar with the Iota converter/chargers, and they enjoy an excellent reputation in the RV world. However, I have to admit that the IQ Smart Charger 12 V application specs have me somewhat corn-fuzed:

BULK: 2.46 V x 6 = 14.76 V
ABSORB: 2.36 V x 6 = 14.16 V
FLOAT: 2.26 v x 6 = 13.56 V

The BULK setting has me particularly puzzled. Instead of being fixed, this value typically rises along with battery voltage during the BULK (constant current) setting until it reaches the ABSORB setting, and then the charger switches to ABSORB (constant voltage, declining current). In fact, this is the behavior suggested by the voltage level “ribbon” in the IQ’s performance chart. Perhaps the no-load value for the bulk phase is 14.76 V. If, however, the charger does indeed get to 14.76 V while charging a large battery bank during the BULK stage, I’d think that would be a bit high for AGM batteries at 77F.

The ABSORB setting is a little low but probably OK. Trojan recommends something between 13.8 V and 14.1 V at 80 F, but MK / Deka / East Penn recommends 14.4 V at 68 F, which, allowing for the usual temp comp curve, equals 14.25 V at 77 F. FWIW, I have my MX-60’s ABSORB stage set for 14.3 V for my AGM bank.

13.56 V is OK for AGM FLOAT.

I’d recommend that you try a few experiments with your chargers and measure actual charging voltages at the battery terminals. Another option might be to contact Iota and ask for a confirmation and explanation of the published values.

I hope this helps, and I’m looking forward to some performance reports. My AGM bank has now been in service for ~ 2 months and appears to be operating right at spec. I just took out 380 Ah (~48% of rated capacity), and the bank measured 12.3 V (50% SOC) while almost resting but under a very light load (MX-60 and Link-10, both sleeping) – just right for a bank sitting at ~50 F. :cool: :grin:

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby Brock on Wed Jan 18, 2006 6:55 pm

I have the post terminals, as I think you do. I was having problems finding 16 matched post to wing nut terminal adapters so I just ordered them from the site you liked earlier (where I got my iota’s from as well). I feel compelled to get matching parts. I completely hadn’t thought of setting each terminal in the opposite direction, that should work, but the bars would be rather close, but they certainly couldn’t move once in place ;) Once I get them I will try it out.

As far as itoa charging, I have found it sits at 14.6 on my Fluke for a very short time, my guess is once the amperage starts to drop off or maybe 15-30 min max. Then falls off to the 14.1 volt setting for a while, 2 hours the time I was watching it, then finally falls in to float.

I could also use the Trace SW2512’s built in charger for normal charging while on grid and set that to the correct voltages. My biggest reason for purchasing the iota’s was for running on the genset or feeding from the grid while the grid is unstable, flipping on and off before finally staying off during a storm.

So if I use the solar to charge them I doubt I would get to absorb to often so would you think topping them off via the grid or a genset once a week would do it, or twice a week or?
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Postby crewzer on Thu Jan 19, 2006 6:06 am

Brock,

I understand your concern about the proximity of the two buss bars. The separation can be improved by drilling the bars' battery terminal holes off-center (closer to one long side that the other) and biasing the bars away from the battery terminals. Also, you may want to consider building a wooden insulator/protector that would look like a “T”-shaped extrusion (in two or three sections) and installing this contraption between and on top of the buss bars.

Another option might be to fashion a wooden separator (3/8" plywood?)with cut-outs on one side to allow it to fit between the buss bars, straddle each pair of terminals, and rest on the battery tops. It should be high enough to clear the tops of the buss bars and adapter hardware by an inch or two. Something like this should prevent a dropped metal object from being able to short the busses.

The IOTA’s sound fine for occasional use as you’ve described. I’d shoot for getting the batteries fully charged at least twice a week, and do a complete recharge as soon as possible after a deep discharge.

HTH,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby Brock on Thu Jan 19, 2006 9:55 am

Sounds good, The last bar I had I covered with electrical tape except near where the terminals were made. Any reason that isn't a good idea as well?

Alright, twice a week and any time I do a discharge more then 10% I wil use the inverter to charge them full.

Thanks again!
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Postby rplarry on Fri Jan 20, 2006 10:44 am

Brock
There's no reason not to tape the bars, shrink tube of the appropiate size would make a nice looking job also.
Larry
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Postby Brock on Sun Jan 22, 2006 2:23 pm

Can I just say, WOW. My new bank is over twice as large as my old one. I topped off the batteries Friday night via the inverters, they must have been charged since it went in to float after only 25 amp hours. Yesterday was cloudy and today I hit 14.4 at about noon, after only 20 amp hours. I needed about 35 to get my old bank to float. I am impressed. Now I have to re figure out my charge ratio, but I can assure you it's above 92%
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Postby crewzer on Mon Jan 23, 2006 5:46 am

Brock,

Tape and/or shrink tube will certainly help insulate and protect the buss bars. However, there's a lot of terminal post hardware that'll stick up through the bars, and the fence or "T" suggestions will help protect that as well.

Sounds like your new battery bank is off to a great start! FWIW, I've found my AGM bank's Ah recharging efficiency to be in the 98% to 99% range -- amazing :shock:

Enjoy!
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby Scott Payne on Mon Jan 23, 2006 12:08 pm

There is allot of great info in this thread, so I decided to make it a "sticky"


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Postby Brock on Mon Feb 13, 2006 1:45 pm

I have settled on 98% on the Bogart Trimetric, really it would be 98.5%, but 98 is close enough. I also hit float daily when I hadn't been with my old bank that was half the size.

The other thing is the lack of voltage sag, when my used to run the stove (220aamps at 12v) it would drop to 11.5 regularly. Now with the stove on it drops to 12.3, granted the bank is new and twice the size of my old bank, but still amazing.
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Postby crewzer on Sun Feb 19, 2006 2:34 pm

Here’s an update to my November 21, 2005 post describing my MX-60’s charger settings for my AGM battery bank:

Absorb: Increased from indicated 14.3 V to indicated 14.4 V (measurement at battery posts = 14.25 V ~ 14.35 V, depending on charge current; all ref. 77 degrees F). According to my Link 10, the batteries were not being fully recharged from the lower voltage setting before the MX-60 switched from ABSORB to FLOAT.

Float: 13.4 V (no change)

Absorb Time Limits: 30 min MIN and 3 hr MAX (increased from 2 hrs).

End Amps: Changed from 10 A to 0 A. Since my batteries are typically fully recharged but once or twice a week, I wanted to make sure that each ABSORB period runs for its full 3 hour cycle.

My MX-60 and the Link-10 are now fairly well synchronized.

HTH,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby Frank on Wed Mar 22, 2006 1:37 pm

Brock wrote:I have settled on 98% on the Bogart Trimetric, really it would be 98.5%, but 98 is close enough. I also hit float daily when I hadn't been with my old bank that was half the size.


I use 99% with my Concorde's and it still doesn't get back to zero before charge current drops to "full" levels i.e. it's actually a bit higher!
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Postby crewzer on Mon Mar 27, 2006 10:42 am

The AGM batteries' charging efficiency continues to amaze me. :grin: My Link-10 automatically calculates the Ah recharge efficiency, and, using the charging protocol described above, it's settled in at 99%. :grin: :grin: This is consistent with claims made by both Concorde and Trojan.

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby Brock on Tue Mar 28, 2006 4:28 pm

Yup after a few cycles to 80% full I am now above 99% and it is still not quite there. I would rather have it bit a touch much at 99% then be a bit low at 100%. These batteries are amazing, especially going from 90% on my old dying bank.
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Postby crewzer on Wed Nov 15, 2006 7:17 am

Here’s an update for my AGM battery bank's MX60 charger setting based on reconfiguring my system from 12 V to 24 V:

Absorb: 28.8 V ref 77F / 25C

Float: 26.8V ref 77F / 25C

Absorb Time Limits: 30 min MIN and 3 hr MAX

The PV array remains at 36 V nominal.

HTH,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Battery spares to make pack last longer

Postby H2SO4_guy on Fri Dec 22, 2006 7:18 pm

In November 2006 the telco here replaced a good number of batteries. I was wondering what would be the better way to go. For $21.20 each The Lucent 4VR125E is a 150 AH @ the 20 hour rate AGM, made by Deka. Every one that I have tested have been fully charged except the ones with cracked cases. One option with the 4VR125E is go with 3 strings @ 48 volts to get 450 AH at the 20 hour rate. These are 4 volt units Valve regulated AGM non spillable, and weigh 53 pounds. They have a design life of 12 years and have been floated to be ready in case of emergency backup by the phone company. Each 4 volt unit can be disassembled by taking the top off and exposing each 2 volt cell with the copper buss bars that connect them together. They would still be sealed units.. Very cool. So if one cell fails, just take it out and insert another one because there will be a whole string of spares. Each string of 150 AH @ 48 volts would be $254.40 or 150 AH @ 24 volts for $127.20. I was thinking of buying 4 strings and attaching all of them to a buss bar turning one string off for a month and using 3 strings to get 450 AH @ 48 volts. The other string could be switched on after a month and the next string could rest for a month making sure to charge the rested string before putting it back onto the buss bar. When any cell fails, it will just be a matter of replacing each cell or 4 volt unit as there will be spares available. Then they can be charged as 24 volt, or 12 volt strings and still rotate a smaller number of cells, but this would require more than a switch, and they would have to be physically placed in the string and rotated that way. So 450 AH @ 24 volts with an entire extra string of replacements would cost $508.80, or if I go 48 volts $1017.60. Not too bad for high quality maintainence free valve regulated AGM batteries. The terminals are in front and screw on type. Here is a link to them found by Jim (Thanks)

Is my reasoning sound? When most strings fail it is usually because of only a single cell or only a few, so if there are a whole string of spares it could keep the pack alive for the longest period possible. Is this a wacky idea? I was thinking about those off brand $145 L-16’s for $1160, but they wouldn’t have any spares and they would require much more maintenance than AGM batteries.

Thanks in advance,

Skip in Kansas City, Missouri
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Trouble with AGM Batteries

Postby Dwight on Fri Jan 26, 2007 10:12 pm

I gave a lengthy response to this but I must not have sent it right, so I'm doing it over.

I have a VFX 3648, MX-60, Mate, 15 Kyocera 125s, all hooked into 24 East Penn 200 aH 8A4D AGM batteries (6 banks of 48v). I have the the Remote Temperature Sensor (RTS) and the Trimetric 2020. While many, including me are concerned about ruining the AGMs with overcharging, you can ruin them just as quickly with undercharging. Let me explain.

In my initial system, I had 8 Kyocera 125s in two banks of 48v and 8 - 200 aH AGMs. Then I added two more 125s so that I could have 60v rather than 48v banks of panels. (After I read the MX-60's instructions and recommendations.) So then I added another 8 batteries. My original batteries are only 1 and a half years old. I added another bank of 5 Kyocera 125s and then added another 8 batteries to bring the total up to 24. 6 - 48v banks, total 1200 aH of 48v. The last 8 are only a year old.

Currently, the system does not get up to the top voltage and rapidly depletes to about 48.0 to 48.5v after a 120 aH discharge, about a quarter of what I calculate it should be.

The literature from Outback and other sources suggest that if you keep your voltage above 48v (12.0 per battery), 50%, your batteries will last many years. When I got my batteries, I got no documentation with them but have recently downloaded the technical bulletins from East Penn. Here is where the sources conflict. Most literature says that 50% charged is 12.0/48.0v. According to East Penn 12.0/48.0v is only 25%! They list 50% at 12.3/49.2v. Outback and others lists 100% charged at 12.6 plus/50.4 plus volts. East Penn says this is only 75% charged, 100% is 12.8plus/51.2plus volts.

My Trimetric adjusted to the max reads some 0.6 volts less than what my digital voltmeter reads. My Outback reads 0.4v less than what my voltmeter reads. While the voltmeter (multimeter) is professional grade, its literature admits plus or minus 1% error. 1% of 50v is 0.5v so to be on the safe side and avoid overcharging I went with the Outback reading.

Here are the ways in which I believe I undercharged. I never let the batteries get below 12/48 v at rest, but this is 25% (75% discharged not 50%.) At 50% 12.3/49.2v AGMs are only good for 500 cycles, about a year and a half to two years if you cycle down to 50% nearly daily. Gel cells are roughly double throughout the range and give about 1000 cycles. At 100% discharge AGMs are only good for 200 cycles, Gel 450. At 80% discharge AGM is only good for 250, Gel 600. At 25% discharge (75% charged), AGM is good for 1200 cycles or about 4 years. For Gel, this is 2,100 or about 7 years. At 10%, discharge AGM gives you 3200 cycles (about 10 years), Gel 5,700! Someone said earlier in this string that you should only discharge 10-20%, they are right.

The batteries had a label which says do not charge over 14.6 v (58.4 with 48V banks). To be on the safe side, I set my absorb to 57.2v. However, when I am home and the voltage exceeds 57 volts, I add other loads to bring it down. I also set up a diversion circuit from the FX to a relay which energizes a dedicated circuit at 57.6v to run an AC in summer or heater in winter. I thought I was being smart, maximizing usage of the energy produced, but what I must have been doing is depriving my batteries of absorb and float charging.

Where I have my batteries, I have 12 on the cold floor, and the other on a heavy duty shelf I built some 41 inches higher. My RTS was attached to a battery on the floor. However, today I did a temperature reading with a thermometer with a stick on sensor. The floor batteries were some 15 degrees cooler than the upper ones! (55 v 70 degrees) So when absorbing the upper batteries were making bubbling sounds. (Not too long, I switched to trickle with my FX's charger.)

Another mistake I made was that the RTS should be attacked to the FX not the MX. I had attached it to the MX-60. I asked someone this question and they said it didn't make a difference (I have the Hub). It does. Attached to the MX, you only get temperature compensation for the MX only. To get it for both, it must be attached to the FX. (The instructions in the literature are a little vague on this.)

I have tried varying lengths of absorbing and trickling to try to restore the batteries, all for naught. If you discharge AGMs greater than 10% or Gels greater than 15 or 20%, the cost of batteries will not pay for the electricity harvested.

Comments anyone?
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Postby crewzer on Sat Jan 27, 2007 7:04 am

Dwight,

Bad news! :sad: I’ll post comments later.

Regards,
Jim / crewzer
090805 System Configuration: 966 W STC (849 W CEC PTC) 48V PV array, FM80, 24V x 400 Ah AGM battery bank, FX2524T w/ BTS, Hub-4 & Mate; Link-10 w/ BTS, & E-Panel.
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Postby sparky on Sat Jan 27, 2007 8:06 am

Yea that is bad ! Keep an open mind for the root cause as it often will help you see the problem. I would like to read more of your thoughts and data. Can you summerize?
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