Battery Loosing Charge

Hi, I have a small system that has been installed for 2 years, as follows: 5 x 130w Kyocera panels, 45A Steca CC, 1.5Kw PSW inverter. 50Amp Charger and Fiamm Gamma OpzS 600Ah (C10) 900Ah (C100) batteries. The problem is the batteries are discharging with even a small load. So I have been testing as follows:

First - visual inspection, everything looks fine, no brown sludge or obvious plate buckling.
Second – check Specific Gravity (SG), this showed the batteries were at 50% capacity, so I ran an equalization charge using a Xantrex DR12 inverter/charger, after 3 goes it brought the SG up to 1.24 (Fiamm Spec), gassing nicely, so exactly what it should be, across all cells. It also got the batteries up to 12.71, voltage taken after 2 hours of rest. (I know it should be a longer rest, but it’s reasonably accurate after 2 hours - I think?)
Because I am using a load meter I can show (more or less) what is being taken out, and still find the batteries are losing charge.
Third - left the batteries overnight with no load – result batteries keep the charge.
Fourth – run an extension lead directly from the inverter to eliminate any wiring problems – result, still loosing power.
Fifth – use Zantrex as inverter for simple loads (as it is MSW) to check the PSW inverter – result, still loosing power.
Finally, a controlled load test using a 40w light bulb – results: at start, V = 12.71 after 8.5 hours the voltage is down to 12.36, left them for 2 hours and the voltage recovered to 12.47. Power used 360W measured by meter, battery loss 20% of the battery capacity, or 1.4Kw!

My question is, what am I missing :confused:, is it possible that batteries can have a good voltage, and SG have no signs of sulphation etc, but still have a very low capacity?

Comments

  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Battery Loosing Charge

    this sounds like the batteries have lost a great deal of capacity somewhere along the line provided there aren't any faults in any of the electronic devices or wiring connected to the batteries artificially drawing it away. even if you find another source to the problem i'd suspect the batteries to possibly fail soon. i do hope i'm wrong about this, but it sounds like it is so. if you can place an ammeter inline and verify that the loads are drawing properly as it would show a possible cause of this.
    you also did not say if the electrolyte levels are showing good and have only adding distilled water.
  • BB.BB. Super Moderators, Administrators Posts: 32,611 admin
    Re: Battery Loosing Charge

    Sounds like that you have been running at low charge levels 50%--and if the batteries have remained at those charge levels for weeks and months at a time--you will have sulfation problems--leading to decreased battery capacity.

    Have you recently changed how you check/charge your battery bank?

    You only have 650 watt of solar power and 1.5kW inverter... You may simply be taking more power than the solar panels can replace. Are you using a generator to ensure the batteries are full charged every few days--and how do you know when to run the generator (voltage, hydrometer, battery meter, etc.)?

    Lastly, at what voltages do the batteries obtain during charging, and how often do you equalize, and at what voltages do you normally equalize at? (on hot days, do the solar panels output enough voltage to

    How much water do you add every month or so... If you are adding little water, it may signify that you are not properly recharging the batteries.

    Have you looked at a battery monitor to see how well your batteries are being treated? I think that these types of meters are the best method of keeping track of your battery state of charge. Can give you an accurate state of charge at anytime (under load, under charge, or no load at all).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    Thanks for the input, electrolyte levels are fine, and have never needed to be topped up? The system has a generator as well, which is used for running large loads, like washing machine etc, and topping up the batteries. I did suspect sulphation, but as I managed to get the SG up by equalizing at 15v using the Xantrax DR. I ruled out sulphation on the premise that the sulphur was back in solution and not stuck to the plates?

    Over the two years no water has been added, so it could be a possibility that the batteries have not been fully charged, but there are no obvious signs of sulphation?

    I have experience of batteries that have been continually undercharged; I spent months trying to get the SG past 30%, had to replace the batteries in the end. In this case the SG came up to 100% on the third attempt?
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    Still scouring the web for answers and found some links suggesting that Pulse Charging can help restore a battery capacity, as used by Morning Star, could it be that over time the Steca is not so good? Also found this:

    “The main goal of charging a battery is the restoration of the battery’s name plate specific gravity. Even small variations in specific gravity translate into large changes in state of charge. A 1.260 specific gravity is simply not 100% but rather 85% to 90%.”

    Back to my original question, if the SG is correct - 1.24 as on the battery(I’ve checked it with 2 separate hydrometers) is all the sulphur in solution and therefore not on the plates, ergo, no sulphation?
  • BB.BB. Super Moderators, Administrators Posts: 32,611 admin
    Re: Battery Loosing Charge

    I am not an expert in batteries--but not needing to add water (assuming you don't have those hydrolyzing caps with the catalyst) could be a warning sign of under charging.

    And from what I understand, the sulfates start to harden as soon as 24 hour after discharge. And, once the sulfates have hardened--they will not reconvert back. Here is one description:
    If the battery is left discharged too long, the lead sulphate will form large, hard crystals on the plates and will not be able to be forced back into the acid. These crystals are large enough to physically clog the pores in the plate surface. The whitish appearance of plates is this permanent PbSO4 which seals the plate surface off from the electrolyte, rendering it useless.

    It appears(from reading around) that if your battery SG and/or resting voltage indicates 75% charged (after charging and equalization), then it is probably sulfated.

    Probably about the limits of my battery chemistry knowledge...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 32,611 admin
    Re: Battery Loosing Charge

    You will have to go by the battery documentation on what SG vs state of charge is... Typically, full charge should be 1.265 to 1.270 (at 80F).

    Your charge level is above 1.225 / 75% that I have seen in several places that talked about "bad" sulfated batteries...

    Regarding "pulse chargers" and chemicals added to batteries to repair sulfate problems--I have about quite a few--but never have really seen anyone that has had success in using them... Maybe somebody else here has had good luck with one or the other (and given the price of batteries--it would be worth it to find one that worked).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    That's the confusing thing, the battery documentation from FIAMM states: “The electrolyte specific gravity is 1.24 (+/- 0.01) at 20 deg C.”
    The sulphur can either be crystallised on the plates or in solution, if I can measure it as 1.24 with a hydrometer, it must be in solution, or am in the Matri
  • BB.BB. Super Moderators, Administrators Posts: 32,611 admin
    Re: Battery Loosing Charge

    If the 1.24 number is correct, and the acid was properly mixed when the battery was first filled and nothing other than distilled water was added--then you are correct from what I can see.

    Last think, that I can think of, to check... When the battery is discharged, are all of the electrolyte and voltages equal? No "dead cell"? (can you measure individual cell voltages on this battery style?)

    You appear to have several sizes of batteries series/parallel (?) connected together... Generally it is not a good idea to mix sizes of batteries--but assuming that they are the same age and chemistry--I guess you could parallel them and they might charge/discharge OK.

    What is your overall capacity (kW*Hours or Amp*Hours at what bank voltage). Is it a total of 1,500 amp*hours at 12 VDC?

    If so, it would seem that solar panel sizing is certainly at the low end of the ability to do much charging with that size of battery bank if you have much of any load at all without using the generator very often (every few days???)...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    Thanks for staying with this Bill, The batteries are deep cycle solar, 6 x 2v cells, capacity is stated as 600Ah at C10 (I normally go for the C100 value for solar, in this case it’s 900Ah at C100) if we take the low end, the capacity should be at least 7.2Kw – 4.2Kw generator runs every few days with 50Amp charger to top up…

    Tried another load test last night using a 100w bulb for 8 hours,

    Start: V=12.72 under load 12.50 (could be a little too much of a drop?)
    Fin: V=12.47 (after 2 hours rest)
    KWh meter shows 800Watts

    So, about 20% of capacity used, which puts the battery capacity at 4 Kw, about 50% of the C10 value

    I’m going to try another equalization charge at 25Amps / 15v over the weekend.

    Tim
  • Ralph DayRalph Day Solar Expert Posts: 975 ✭✭✭✭
    Re: Battery Loosing Charge

    THere are good bulletins from Surrette Battery regarding just these kind of concerns. 605 and 614 are good ones to study. They're too big to attach, go to the Surrette/Rolls site and contact them to send the pdf fliles regarding equalization charging and 614 for maintenance charging.

    Ralph
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Battery Loosing Charge

    One thing I didn't see in this discourse is what has your average loading been? It seems with a quick calc that you are getting a potential of ~160ah/day out of your panels. If your loading has been anywhere near close to that, and you haven't been keeping up with the genny, then perhaps you have a chronic undercharge condition. (As mentioned before). Do you have metering and data about the loads. I found that until I have a good metering system in place I had no idea of what I was using, except for intuition. It turns out I was using way LESS than I thought, which was a pleasent surprise.

    Clearly there are battery experts here who can give you a more difinitve answer. I also would look at a dead cell possibilty. I had a cell fail in my L-16 type battery that was sucking down the whole bank. Sg readings should confirm this.

    Good luck.

    Icarus
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    I’m posting this as hopefully someone out there will benefit from it in the future, and not have to spend 2 weeks scratching their heads…

    Icarus – we have tested the loads using a Kwh meter, it was recorded as about 1Kw / day, very lean! Dead cell does seem most likely, but the SG and V on all cells are equal. However, apparently, you can have a condition where a cell is defective, but still shows the correct voltage and SG, it shows up by the fact that when under charge it becomes warmer than all the others. When under load it fails and brings the bank down. I have not read this anywhere but been told by another solar installer. I will test this out today and let the forum know…

    For those who might be interested:

    We tested with a 200w load this time, this is regarded as ‘a significant load’ for this size battery bank – I found this table in a very good article (I welcome any comments from battery experts)

    A 50-Watt light bulb is a significant load for a 100 to 200 amp/hour battery bank.
    A 75-Watt light bulb is a significant load for a 200 to 400 amp/hour battery bank.
    A 100-Watt light bulb is a significant load for a 400 to 600 amp/hour battery bank.
    For a battery bank larger than 600 amp/hours, use two 75-Watt light bulbs.

    Start 8 pm V=12.82 load = 200w
    1 am v = 12.12
    1 30 am light off v = 12.42

    Therefore: 5.5hrs @ 200w 1.1Kw
    SOC around 75% Capacity 4.4Kw – this supports the previous nights tests that the batteries are at 50%!

    Sulphation or ‘sulfation’? I have also noted that when a battery is in good condition and fully charged the positive plates are chocolate brown, negative plates are silver. As the cells discharge, a layer of lead sulphate is formed on all plates and all the plates turn grey. On recharging the plates return to their original colours. On a severely sulphated battery the sulphur crystallizes on the plates, which means the plates to not return to their original colours. Physics bit over, in this case the positive plates are chocolate brown after charging.

    So today it is low current (25A) and high voltage 15v, check SG and V every hour and look for a defective cell that will possibly show up as being warmer than all the others…

    Tim
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Battery Loosing Charge
    We tested with a 200w load this time, this is regarded as ‘a significant load’ for this size battery bank – I found this table in a very good article (I welcome any comments from battery experts)

    A 50-Watt light bulb is a significant load for a 100 to 200 amp/hour battery bank.
    A 75-Watt light bulb is a significant load for a 200 to 400 amp/hour battery bank.
    A 100-Watt light bulb is a significant load for a 400 to 600 amp/hour battery bank.
    For a battery bank larger than 600 amp/hours, use two 75-Watt light bulbs.
    A 100 Ah battery is supposed to deliver 5 A for 20 hours. This “20 hour rate” (or C/20) is an industry standard for measuring meaningful maximum battery capacity.

    Assuming a 12 V battery, a 5 A discharge current translates into a 60 W load, which is larger than the suggested 50 W “significant load”. Accordingly, I wouldn’t consider a 50 W load on a 100 Ah (12 V) battery to be a significant load, and, in my view, 50 W is nowhere near a significant load on a 200 Ah (12 V) battery.

    Another problem with the table is that the battery voltage is not specified. Without the battery voltage, it’s difficult to correlate true battery capacity (V x Ah) to load and time (W x hrs). A 50 W load on a 12 V x 100 Ah battery is one thing, and a 50 W load on a 48 V x 100 Ah battery bank is another.

    A 200 W (net?) load on your (12 V?) 600 Ah (C/10) battery bank is a 16.67 A = C/36 load. That’s not a significant load, in my view.

    Trojan’s T-105 battery’s 20 hour spec is 225 Ah, and their 5 hour spec (C/5) is 185 Ah. The latter spec suggests a 37 A discharge current. With two of these batteries wired in series to form a 12 V x 225 Ah bank, the load would be 444 W, or ~16% of the bank’s 2,700 Wh capacity. To me, that’s a significant load.

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    Thanks Jim, I was hoping you’d drop by…

    The C/20 rule has been duly noted for future tests. Out of interest, what do you interpret the industry standard for the capacity of a OPzS deep cycle solar batteries, Exide quote a C120 value (make their batteries look bigger?) FIAMM use a C10 – which I would equate to a cart battery, discharge and recharge in a day. I design based on 50% capacity and 3 days standby time (6 x the projected energy need), so size a system battery using the C100 capacity - but have never found a definitive answer, everyone just quotes the Ah value, which is meaningless without the C value.
  • BB.BB. Super Moderators, Administrators Posts: 32,611 admin
    Re: Battery Loosing Charge

    Any of those C/xx values are perfectly valid numbers--just depends on the usage.

    I sort of tend towards the C/20 values because--If we a assume a battery charges over a 3 day period (any longer, sulphation becomes a problem as it hardens, and worsens--apparently--at less than 80% state of charge), if you assume that you have 4-6 hours per day of effective sun (and/or your generator runtime per day), that works out to ~12-18 hours to charge... And if you assume the battery is used (heavily) over an 8 hour period per night, that again works out to a 24 hour rate over three days--not a 3x24=72 hour rate...

    Technically, since a standard flooded cell battery is sized to 50% discharge level, those C/XX values should be 2x as large, and therefore somewhat more effective capacity--but I use the C/20 rate as one of the "hidden" safety factors to slightly error towards recommending a larger battery bank (allows for aging like sulphation, batteries operating cooler than ~77F, the occasional heavy loads like well pumps, etc.).

    I would agree with Jim that discharging a battery using a heavy load would probably be more current than the C/10 or C/20 rates--but closer to a C/4-C/1 rate (assuming it does not damage the battery--and that I would this would be for a short time--10-20 minutes maximum or less required to measure an elevated temperature). At a C/20 or lower rate, it would be much more difficult to identify a "hot" cell as thermal transfer would probably equalized the temperature over the entire battery.

    If you have two or more batteries (or cells where you can measure individual voltages) in series, using a (calibrated or known good) meter to monitor individual cell/unit battery voltages would help you identify a single unit for replacement in a bank (examples, 2x12v batteries or 3x6v batteries in a 24 VDC bank).

    And this is another reason I like a series bank--it is easy to identify a weak/failing replaceable unit. It is much more difficult in, for example, a bank of two or more 12 VDC batteries in parallel in a 12 volt bank. They all have the same temperature, and a "weak battery" will simple supply less current--making looking for the "hot battery" possibly point to the only one actually supplying useful current.

    For parallel banks, you would need to use other methods to detect weak units. Using a DC current clamp meter to measure individual currents, disconnecting the banks and testing each battery separately, monitoring specific gravity of all cells during test (gel and AGM types you can't).

    I "trick" I have used to measure DC currents in parallel paths and I don't have a DC current clamp is I look for equal sized wire runs between the parallel circuits and place a DVM across one in each parallel path just like it was a shunt--works pretty well to find those connections that are carrying more or less than their fair value of current.

    In the end, finding a "bad cell" in a battery can help with warranty claims (see, the rest of the battery is good--just one cell had early life failure). If you return an entire bank of batteries, all failing capacity testing, then it looks (to me) more like the entire bank was abused (poor charging, excessive discharging, sitting discharged for long time periods, etc.).

    In the end, unless you do capacity testing when the bank is first installed and write the values and test conditions down, you really don't know if your batteries are aging poorly or if you got a bad set in the first place.

    Lastly, you have been focusing on battery capacity issues... Another thing to check for are poor electrical connections (loose or corroded terminals, corrosion in cables, failed cable crimps, etc.). Using your tools to check for excessive voltage drops or poor current sharing, and if you have "heavy" loads, you can even check for hot spots in your wiring.

    Bad connections can mimic flaky battery problems too... And they can be anywhere in the circuit (at the battery banks, bus bars, circuit breakers, inverter/charger connections, etc.).

    -Bill

    PS: I should add, to be clear, that the C/XX capacity is based on actual current draw over time, not average current draw over time (C/10 over 10 hours is, effectively, the same load as a C/10 load at 10% duty cycle over 100 hours). Because the discharge curves at different load ratings are not linear (a C/10 at 10% duty cycle rating will be lower than a C/100 discharge).

    In my every humble opinion, a C/120 load for a Lead Acid battery would be a useful rating where you had a worst case steady state load of (say a cell phone tower installation) with relatively constant load over a three day period of no-sun and a discharge maximum of 50% (3x24/50% capacity=144 hour discharge rate). After three days, you would want to fire up the generator and quickly recharge the battery bank to prevent the sulfates from hardening.

    But in the case of most off-grid solar installations, most loads are going to be in the evenings and mornings (assume 4 hours each), so the effective current the battery supplies is 8 hours per 24 hour day for thee days--using the C/20 (really C/24) rate capacity for planning.

    In the end, there are so many derating factors (temperature, losses due to battery chemistry, losses due to equalization, manufacturing variations, aging, etc.) that you can go nuts trying to figure out the optimum capacity...

    To simplify, we tend towards rules of thumb that get us "close enough" (50% maximum discharge, 3 days of no sun, insulated or controlled temperature environments, rounding capacity requirements "up", etc.).

    On of my simplification rules from engineering is the rule of 2 and 10... If one thing is 10x (or more) larger than something else, then the "smaller thing" can be ignored. If something has 2x or less difference, then they are close enough to being equal in effect.

    This, at first, does not seem like a realistic set of rules for life. For example, a 6 foot person vs a 12 foot person seems ridiculous to call "almost the same"... However, measuring height is a "linear measurement" of the differences. However, if we did this comparison using volume (or weight in this analogy), a person 2x as "large" would weigh ~8x as much (think 2*2*2 or the volume of a cube). In real life, we assume that the adult population's average weight is around 100-200 lbs--a real world example of a 2:1 range applied to humans... Most of the "calculations" in engineering are frequently based on area and volumes, not linear--hence the engineering rule of thumb of 2:1 and 10:1...

    So, in my thinking C/10 and C/20 rates are pretty close to the same--so I don't get too excited about the difference between them. However, a C/10 vs C/120 rate is quite a difference and would demand close examination as to how it would affect my plans.

    Another helpful rule of 10 is the 10C (Celsius) rule for temperature effects... The physics of "activation energy" for most common materials, once you do the math (details long forgotten from my schooling), works out to a change in temperature by 10C will result in a factor of two difference in effective life. For example, if you can cool your electronics by 10C, they will last twice as long. If you run something 40C hotter, its life will be 1/(2*2*2*2)=1/16 the life.

    On the other hand, if you run your batteries 10C cooler, their self discharge rates will effectively halve (and their lifetime would double)... However, because of the chemistry, their capacity also drops (in this case, by roughly 10%).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,436 ✭✭✭✭
    Re: Battery Loosing Charge

    I concede that I'm no expert, in fact I defer to Jim and Bill on all of this but in simple terms here is how I see it. (Correct me,,please is my assumptions are wrong).

    You have 390 watts of panel. Assuming 4 hours of sun per day you would average 1560 watts of power or at 12vdc ~ 43.33 amp/hours into you panels, for 4 hours =130amp/hours 12vdc per day.

    You have average loading of ~1kwh per day or ~83 amp/hours 12vdc.

    If you take an average of the c10 rate and the c100 rate you have a bank capacity of somewhere in between of perhaps 750amp/hours. You suggest that your loading of ~1kwh/day is "lean", somewhere ~11% of bank capacity. I agree.

    What seems to me, ( assuming that I'm somewhere close in my assumptions and calcs,,,theres no assurance of that)! is that you are using ~75% of charge capacity on a good day, but more than 100% on a not so good day, and therefore over time you are have been chronicly undercharging the bank.

    If indeed this were the case, that would lead to the sulphation conditions that the others have described before.

    Good luck,

    Icarus
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Battery Loosing Charge

    Tim,

    Great question! Personally, I think that the C/x value for a battery bank should be chosen based on anticipated/actual discharge rather than treating C/20 as a golden rule. However, since the impact of Peukert’s Law is logarithmic, don’t expect a huge jump is high-quality battery capacity from C/20 to C/100.

    I’ve not been able to locate Fiamm’s specs for the OPzS batteries. But, Exide makes the Classic OPzS, and their spec sheet and instruction manual might be useful.

    See: http://www.industrialenergy.exide.com/exidepdfs/Classic_Opzs_t_en.pdf
    And: http://www.industrialenergy.exide.com/exidepdfs/GNB_Flooded_Installation_operating.pdf

    HTH,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    On this same vein, guys, I have a small system in a cabin here in the Veracruz mountains of Mexico. Using EVERSTART #27DC-6 12 volt marine batteries 230AH total, I stupidly let the water level get real low and had to add about a liter of water to each battery. I added it little by little over 3 days, and I used RAIN WATER since the cabin has a rain collection water system. Did I do right? Batteries seem ok so far after 5 days. I will be going there tomorrow and will check the spec. gravity.
  • BB.BB. Super Moderators, Administrators Posts: 32,611 admin
    Re: Battery Loosing Charge

    If the tops of the plates were dry--then just cross your fingers and hope that all is OK.

    Regarding rain water--I kind of doubt that is "clean" enough for battery usage. Distilled or Deionized water is pretty much the only liquid that should be used.

    There are various home made and other types of stills that you can use at your cabin (solar or flame powered) if distilled water is not handy.

    At this point, there is nothing more (that I am aware of) short of emptying your batteries and refilling them with new electrolyte (and even that is an iffy situation since you may not know what the current level of charge it)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • crewzercrewzer Registered Users, Solar Expert Posts: 1,832 ✭✭✭✭
    Re: Battery Loosing Charge

    Frankania,

    Your (Wal-Mart) Everstart #27DC-6 batteries are deep-cycle (“trolling motor”) flooded-cell batteries are manufactured by either Johnson or Exide. These Group 27 size 12 V batteries are each rated at RC 160 and 115 Ah. I’m not sure why, but they tend to out-gas pretty easily, so you do need to keep an eye on the electrolyte levels.

    I suspect that rain water is better than no water, as long as it was collected in a clean vessel. However, as Bill indicated, distilled- or deionized water is preferred. Adding a liter to each battery (~33.8 oz.;~5.6 oz./cell) wasn’t a good thing. It certainly means that the tops of the internal plates were exposed air and may have oxidized a bit.

    At this point, I’d worry more about trying to salvage the batteries by fully recharging and then equalizing them. A couple of hours at absorb voltage (14.4 V, ref 25 C / 77 F), followed by 2-3 hours at EQ voltage (~15.1 V) should help. The battery cells will bubble vigorously during the EQ cycle. This is normal, but you’ll need to carefully clean the tops of the batteries with a mild baking soda solution when you’re done.

    Best of luck to you,
    Jim / crewzer
  • System2System2 Posts: 6,290 admin
    Re: Battery Loosing Charge

    Thanks Fellows, The good thing, I guess, is that they only cost about $55 each and I have had them 3 years so far. We use the cabin infrequently and so the batteries are almost always fully charged and last the weekend without too much dimming.
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