Author Topic: 1 Year Plus on Batteries  (Read 2395 times)

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Bigbear

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1 Year Plus on Batteries
« on: September 18, 2007, 05:56:02 PM »
Well, it's been over a year being off grid with the system and all is running fine.  I do have a question about my batteries though.  I have 8 12volt sump pump batteries all tied to - and + buss bars.  They are charged with solar panels, and on Sundays, (wash day) with the large generator and Truecharge 40+ and on occasion when we have no sun.  I have never had to add water to any of these batteries and I don't know whether to be alarmed or jump for joy.  We never let the volts drop very long below 12.3, and after an evenings use and the next morning, before going to work, they are usually at 12.4 or 12.5 with everything turned off.  I have checked specific gravity, and they are all up where they should be, and the water level is up in the safe level.  Should I be concerned, or have I found a good balance for storage verses usage.
« Last Edit: September 18, 2007, 05:56:02 PM by (unknown) »

Volvo farmer

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Re: 1 Year Plus on Batteries
« Reply #1 on: September 18, 2007, 12:30:54 PM »
What solar charge controller are you using? The Truecharge 40+ says it will do three-stage charging on a 120V source, but obviously only on Sundays in your case. The thing that causes batteries to use water is charging them at higher voltages. I try and get my bank up to 28.8V (14.4V in your case) every day for two hours. I can hear the batteries boiling a bit at this voltage. Once a month I equalize them at about 31.5V (15.7V for you), because that's what the manufacturer recommends.


Everyone's got different theories about lead acid batteries but I've drifted into the camp that would rather cook them a little and add water once in a while. It seems that many many RE batteries have been murdered by chronic undercharging and sulfation. I've heard very few stories of batteries being ruined by boiling them a bit each day at a reasonable voltage, for a reasonable amount of time.  


Your voltage numbers sound pretty good, and the hydrometer doesn't lie, still you should at least be equalizing this bank every few months, especially since you seem to be running eight parallel strings. Seems voltages can get more out of whack between strings, the more of them you stack up. Did you ever unhook everything and voltage test each battery at rest? I bet you find some are a few tenths below the others if you've never equalized them.

« Last Edit: September 18, 2007, 12:30:54 PM by Volvo farmer »
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Bigbear

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Re: 1 Year Plus on Batteries
« Reply #2 on: September 18, 2007, 01:45:17 PM »
Thanks Volvo, I have the solar panels hooked to a ProStar that is supposed to equalize on occation.  Since I'm gone most of the full sun hours, I can't say for sure.  I do have a TriMetric hooked in the system and it does show the voltage has been up to 15 something volts on occasion.  I must admit, I have not unhooked all batteries, but I did unhook 4 of them, and they all tested good, so I did not check the other 4.  A couple times during their life, I set the battery charger to equilize when the generator was running, and did notice some vapor on the top of the caps and case, but nothing severe.  The sulfation thing has me wondering if things are as good as they appear, or something just waiting to happen.  BEAR
« Last Edit: September 18, 2007, 01:45:17 PM by Bigbear »

Ungrounded Lightning Rod

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Re: 1 Year Plus on Batteries
« Reply #3 on: September 18, 2007, 02:08:20 PM »
Sounds like they're getting equalized adequately.


If:

 - within each battery, the specific gravity in all the cells is equal to about as well as you can measure it with a good hydrometer,

 - it's about the same from battery to battery, and

 - it's about right for the amount of discharge you've done in the hours since the last full-charge time,

I'd say pat yourself on the back for building a good setup and sleep well.

« Last Edit: September 18, 2007, 02:08:20 PM by Ungrounded Lightning Rod »

nothing to lose

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Re: 1 Year Plus on Batteries
« Reply #4 on: September 18, 2007, 04:27:58 PM »
"We never let the volts drop very long below 12.3"


Sounds like your not really using the batteries that much. Normally I think you lose the most water durring charging, if your batteries are really low and your charging allot you lose more water. If your batteries are close to full and you barely charge then you don't lose much water.

Also heat and rate of charge effect water loss.

 If your batteries are not in a hot area, and with solar you may charge slow all day but low amps, so not much water should be lost. Compare that to my L16P trojans I used to carry in the back of my truck, Hot sun all day and bulk charge at near 50-70 amps as needed when driving, lots of water loss per month not years. LOL

 But they served the purpose great, I still use some of them, not all died yet, been years, was brought home form a scrap yard for about $5 each when I got them. LOL


Sulphation is mostly when batteries are drained low and sit low for awhile, a nearly full charged bank should not sulphate much. Does not sound like you drain low or let them sit low very often, that is good.

« Last Edit: September 18, 2007, 04:27:58 PM by nothing to lose »

veewee77

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Re: 1 Year Plus on Batteries
« Reply #5 on: September 19, 2007, 11:05:59 AM »
Here is a possibility. . . If you have a LOT of amp-hour capacity in your battery bank, but you only actually use a little of it, the batteries may provide all you need for the time you need it.  But the capacity may be creeping down on you unknown to you. Say you have 500AH battery and you use 50. 50 is all you needed.  Now, let's say your battery capacity has decreased to 300AH. You still only need 50. So you wouldn't know if you had more capacity until you started trying to use it. The way to find this out is to put a known load on over a known time and see how the battery performs.


An example of this phenomenon is like this;


You drive your car daily and it starts pretty easy and don't take much cranking. Your battery starts it right up. Under normal battery conditions, that battery should be able to crank that car for a few minutes anyway before getting too low to start the car. You never need this much cranking. . . One day, you run out of gas and have a mechanical fuel pump on your car. You add gas and start cranking. Usually it starts right up and it whizzes as it should but this time it is going to take a lot more cranking to get it going and it runs down in about 10 to 15 seconds. . .UH-OH. . .that battery was good yesterday! What happened. . .It's capacity had degraded over time. Had it's capacity stayed up there, it should have kept right on cranking for enough time to get the fuel pumped up to the engine. It was still charging and showing good voltage and all until an extended load was put on it and it was discovered that the capacity had decreased. . .


Kinda long, but maybe it is understandable. . .


Doug

« Last Edit: September 19, 2007, 11:05:59 AM by veewee77 »

wooferhound

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Re: 1 Year Plus on Batteries
« Reply #6 on: September 19, 2007, 02:38:21 PM »
« Last Edit: September 19, 2007, 02:38:21 PM by wooferhound »

nothing to lose

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Re: 1 Year Plus on Batteries
« Reply #7 on: September 22, 2007, 03:43:18 AM »
Good point, but if battery is kept full charged at most times, normal use, then you should not loose capacity much.


It's mostly when the battery is drained low and let set for weeks or months or longer that most capacity is lost. Like I go out and try to crank a car or truck in the yard not started for weeks or months, takes lots of cranking on those old carburated things with manual pumps, I get them running (or not) and battery is ran down, then let them sit for weeks or more with a low battery. Sulphation works in and capacity is lost, next try after charging maybe half the cranking time?


Kept full charge I seldom had such problems with lost capacity on said cars and trucks.

 Keeping 30 batteries full charged for months of non-use is not so great either, so I let them sit till I want them and they sulphate from self discharge, computers, clocks and other power eating things! I used to take better care of such things, last year or two I just said heck with them, start them once in 3-4 months, forget about the batteries altogether, let the tires dry rot on flats, etc..


Also another reason why I think pulse charging works even if some say it don't. With over 30 cars in the yard I know the ones that should not start and the ones that should!

 After pulse charging some old batteries for a bit I crank and crank cars far longer than I should be able too with some old and abused batteries.

 Then I have some newer old batteries with less abuse, never been pulsed and they crank 2 minutes and shot!

 I just got a free replacement for a 2 year battery, It would not hold a charge, run it dead fast after a minute or so etc... was like 18-20 months old when it gave me problems at first, so I just took it back for a new one. I maybe could have done some tricks to it as I did others, but why bother. I got another NEW 2 year free replacement battery, if I had revived the old one for another year I would still have lost out, I got another 2 years with this new one for sure, longer it if it lasts longer. if it dies in 20 months, well then I get another free 2year :)

 Really as it goes right now, if a battery dies every 20 months, I can live forever and never buy a new one :)

 20 months and get a free 24 month battery that lasts 20 months, then get a free 24 month again, a great cycle I think!!! I almost hope none of these replacements ever last more than 18-20 months as long as they replace them free with a new 24 :)

« Last Edit: September 22, 2007, 03:43:18 AM by nothing to lose »